null  User manual
DOCUMENT RESUME
CE 003 681
ED 106 514
TITLE
INSTITUTION
IC [Interior Communications] Electrician 3 and 2:
Rate Training Manual. Revised.
Naval Education and Training Command, Pensacola,
Fla.
REPORT NO
PUB DATE
NOTE
AVAILABLE FROM
NAVEDTRA 10558-B
73
EDRS PRICE
DESCRIPTORS
MF-S 1.08 HC-$29.83 PLUS POSTAGE
Communications; Course Content; *Electrical Systems;
*Electricians; *Electronic Equipment; *Job Training;
Manuals; Military Personnel; Military Training;
Safety Education; *Telecommunication
Navy
IDENTIFIERS
582p.
Superintendent of Documents, U. S. Government
Printing Office, Washington, D. C. 20402 (Stock
Number 0502-LP-052-7910)
ABSTRACT
The rate training manual provides information related
to the tasks assigned to the Interior Communications (IC)
Electricians Third and Second Class who operate and maintain the
interior communications systems and associated equipment. Chapter one
discusses career challenges for the IC Electrician in terms of
responsibilities, advancement qualifications; naval training
publications; and basic rules for studying. Chapters two through
nineteen, illustrated throughout with photographs and diagrams, cover
safety; switches, protective devices, and cables; power distribution
systems; test equipment; sound-powered telephones; alarm and warning
systems; announcing and intercommunicating systems; dial telephone
systems; sound recording and reproducing systems; gyrocompasses;
ships control order and indicating systems; ships metering and
indicating system; plotting systems; maintenance; new installations
and equipment; and closely regulated power supplies. A section on
security, a glossary of computer terms, and a key to electronics
symbols are appended. (Author/BP)
U S DEPARTMENT OF HEALTH.
EDUCATION &WELFARE
NATIONAL INSTITUTE OF
EDUCATION
THIS DOCUMENT HAS BEEN REPRO
D UCED EXACTLY AS RECEIVED FROM
THE PERSON OR ORGANIZATION ORIGIN
ATINO IT POINTS OP VIEW OR OPINIONS
S TATED DO NOT NECESSARILY REPRE
SENT OFFICIAL NATIONAL INSTITUTE OF
EDUCATION POSITION OR POLICY
1,11016'
a
IC ELECTRICIAN 3 &
PREFACE
The primary purpose of training is to produce a combat Navy
which can maintain control of the sea and guarantee victory. Victory
at sea depends upon the state of readiness of shipboard personnel
to perform tasks assigned to them in accordance with the needs of
the ship. This Rate Training Manual provides information related to
the tasks assigned to the IC Electricians Third and Second Class who
operate and maintain the interior communications systems and associated equipment. It is only when shipboard personnel can and do perform
their tasks efficiently that each ship will be operating at a high state
of readiness and adding her contribution which is essential to guarantee
victory at sea. As an IC3 or IC2, you will be expected to know the information in this manual and to perform your assigned tasks. The degree
of success of the Navy will depend in part on your ability and the Timmer
in which you perform your duties.
This manual was prepared by the Naval Education and Training
Program Development Center, Pensacola, Florida, fir the Chief of
Naval Education and Training. Information provided by numerous manufacturers and technical societies is gratefully acknowledged. Technical
assistance was provided by the Naval Ship Engineering Center, Washing-
ton; Service School Command, San Diego; Service School Command,
Great Lakes; and Fleet Training Center, Norfolk.
Published by
NAVAL EDUCATION AND TRAINING SUPPORT COMMAND
First Edition 1966
Revised 1970
Revised 1973
Stock Ordering No.
0502-LP-052-7910
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.:. 1974
3
THE UNITED STATES NAVY
GUARDIAN OF OUR COUNTRY
The United States Navy is responsible for maintaining control of the sea
and is a ready force on watch at home and overseas, capable of strong
action to preserve the peace or of instant offensive action to win in war.
It is upon the maintenance of this control that our country'sglorious
future depends; the United States Navy exists to make it so.
WE SERVE WITH HONOR
Tradition, valor, and victory are the Navy's heritage from the past. To
these may be added dedication, discipline, and vigilance as the watchwords
of the present and the future.
At home or on distant stations we serve with pride, confident in the respect
of our country, our shipmates, and our families.
Our responsibilities sober us; our adversities strengthen us.
Service to God and Country is our special privilege. We serve with honor.
THE FUTURE OF THE NAVY
The Navy will always employ new weapons, new techniques, and
greater power to protect and defend the United States on the sea, under
the sea, and in the air.
Now and in the future, control of the sea gives the United States her
greatest advantage for the maintenance of peace and for victory in war.
Mobility, surprise, dispersal, and offensive power are the keynotes of
the new Navy. The roots of the Navy lie in a strong belief in the
future. in continued dedication to our tasks, and in reflection on our
heritage from the past.
Never have our opportunities and our responsibilities been greater.
ii
CONTENTS
Page
CHAPTER
1. Career Challenges for the IC Electrician
1
2. Safety
3. Switches, Protective Devices, and Cables
8
4. Power Distribution Systems
5. Test Equipment
6. Sound-Powered Telephones
7. Alarm and Warning Systems
8. Announcing and Intercommunicating Systems
31
86
114
147
171
193
9. Dial Telephone Systems, Part I
235
10. Dial Telephone Systems, Part II
274
11. Sound Recording and Reproducing Systems
289
12. Gyrocompasses, Part I
305
13. Gyrocompasses, Part II
343
14. Ships Control Order and Indicating Systems
15. Ships Metering and Indicating System
16. Plotting Systems
17. Maintenance
18. New Installations Equipment
372
19. Closely Regulated Power Supplies
520
383
419
458
497
APPENDIX
550
I. Security
II. Glossary of Computer Terms
555
557
III. Electronics Symbols
560.
INDEX
iii
S
CREDITS
The illustrations indicated below are included in this edition of
IC Electrician 3 & 2 through the courtesy of the designated companies.
Permission to use these illustrations is gratefully acknowledged.
SOURCE
FIGURES
Gems Co., Inc.
3-19
Jones Motrola Corp & Bert A. Shields
5-14
James G. Biddle Co.
5-1.5
General Radio Co.
5-16
U. S. Instrument Co.
6-7, 6-8, and 6-11
iv
6
CHAPTER 1
CAREER CHALLENGES FOR THE IC ELECTRICIAN
This Rate Training Manual is intended to
THE IC ELECTRICIAN RATING
help you develop your technical skills, since it is
Before World War II the interior communi-
the knowledge and skill of men like yourself
that make our modern Navy possible. By learning cations of a ship consisted of sound-powered
thf; information in this manual and gaining prac- phones, automatic telephones, general announ-
tical experience on the job, you will prepare cing systems, and synchronous telegraph sysyourself for a successful and rewarding Navy tenis. These were cared for by Electrician's
career. The Navy has developed a training Mates, who could receive special trainingthrough
system to help you learn the duties of the a gyrocompass class B school and an interior
next higher grade in your rating. When you can communications class B school.
Duriug World War II the trainees in the IC
demonstrate, by your performance on the job,
by your mastery of the required skills, and by class B school studied algebra, trigonmetry,
written examination, that you are well qualified gyrocompasses, movie projectors, automatic
to perform these duties, you will be advanced. telephones, and synchro systems. They were
Even as you are working toward advancement also required to build a 50-watt amplifier.
The rapid advances in interior communithe extra effort and study that you devote to
learning your rate will reward you in terms cations and navigation equipment during World
of greater job satisfaction, and by your becom- War II led to the establishment of the IC rating
ming able to do more important and interesting in 1948. To train men in the new rating anIC
class A school was established at Great Lakes,
work.
Ill., and another at San Diego, Cal. In 1957
Work in interior communications (IC) con- the IC class B school moved from Washington,
cerns the inventions of several engineers and D.C. to its present location, the Great Lakes,
scientists of the 19th and 20th centures; the Naval Training Station. The number of*IC class
telephone of Bell, Sperry's gyrocompass, and C schools has increased to eight as more soinduction devices pioneered by William Sturgeon. phisticated communications systems and naviAs with any electrical work, the theories of gational tracking systems have been developed.
The IC Electrician rating is a general rating,
Georg Ohm and Alesandra Volta are applied
daily. It is common for the IC Electrician to and is not divided into service ratings. (An
use routinely concepts which a hundred years example of a rating divided into service ratings
ago were as advanced as the theories of Einstein is the ET; its service ratings are the ETN and
the ETR. The ETN specializes in communiare today.
cations equipment, the ETR specializes In raYour training for the IC Electrician rating dar.)
will include electronics and electrical theory,
and fundamentals of operation of motors, genRESPONSIBILITIES OF
erators, alarms, sensors, telemetering systems,
TODAY'S IC ELECTRICIAN
and other electrical equipment. You must become
proficient in using handtools and electrical meas-
Modern warships are capable of defending
uring instruments. In troubleshooting IC syP-
tems, for example, you must be able to read and themselves against supersonic aircraft and miswork from blueprints and electrical schematics siles. The ships have complex interior communand analyze the performance of a circuit and its ications systems to carry information oetween
their various control and cOmmand centers.
4..omporients.
1
7
IC ELECTRICIAN 3 & 2-
These systems are vital to a warship's combat
IC 4712 Automatic Telephone Repairman
Applicable Course: Automatic Telephones,
Class C (A-623-0014)
readiness and safety.
As defined in the Manual of Qualifications
for Advancement or so-called Qua ls Manual,
the scope o the IC rating is:
IC 4722 Gyrocompass (Mechanical) Technician
Applicable Course: Gyrocompass Technician
"Interior Communications Electricians operate and perform organizational and intermediate maintenance on interior communications
(Mechanical), Class C (A-670-0014)
IC 4724 Gyrocompass (Electrical) Technician
Applicable Course: Gyrocompass Technician
(Electrical), Class C (A-670-0021)
systems including voice interior communications,
alarm, warning, ship's control,entertainment,
gyrocompass, and plotting; stand watch on related equipment, and ensure the enfozcement of
safety precautions,"
The qualifications of the IC Electrician are
oriented to shipboard duties; he is found on
almost all naval vessels. Ashore, he may work
IC 4746 Closed-Circuit TV Technician
Applicable Course: Closed Circuit TV
Maintenance, Class C (A-198-0020)
For more information on obtaining NECs,
in his rating in a repair facility or as an instructor, but is just as likely to be working
outside his rating in a duty, such as shore
you should contact your leading petty officer or
personnel office.
patrol or recruiting.
QUALIFICATIONS FOR ADVANCEMENT
The requirements for advancement outlined by
the Quals Manual are designed to ensure that an
As an IC Electrician you will perform bath
military and professional duties. The military
IC ETEETRZIE7n assigned to any ship in the fleet
will have the general qualifications to perform
his assigned duties. Since some ships, particularly the more modern ones, have special interior communications equipment, the IC Flectricians assigned to them must have special
training. A Navy Enlisted Classification (NEC)
coding system helps identify the men who have
this special training.
requirements and professional qualifications for
all ratings in the Navy are listed in the Quals
Manual which is periodically revised to reflect
organizational and procedural changes in the Navy
that affect the ratings, and to incorporate addi-
tional skills and techniques required by the
development and installation of new equipment.
The military duties for the IC Electrician
are the same as those for other petty officers.
This Rate Training Manual primarily concerns the
professional duties of IC Electricians and does not
attempt any detailed consideration of the military
NAVY ENLISTED CLASSIFICATION CODES
duties. The military requirements are discussed
in Military Requirements for Petty Officer 3 & 2.
Figure 1-1 shows the requirements for advancement of active duty personnel; figure 1-2 does
the same for inactive duty personnel.
Though your rate shows what you are qualified
to do, it does not by itself show any of your special
qualifications or skills, either within your rate or
outside of it. NECs are used to show significant
qualifications not shown by the rate designation.
The NEC coding system identifies special qualifications through a four digit number, such as
IC 4712 or IC 4724. Not everyone in the Navy
has a special code number, but some individuals
have more than one, depending on their qualifications. The qualification considered to be the
The professional or technical duties performed
by the IC Electrician include avariety of tasks that
require many specialized skills and techniques
necessary to perform properly the occupational
duties of his rate. The professional qualifications
for the IC rating have been used as a guide in
preparing this Rate Training Manual and will be
most important is identified by the first cocle used by the Naval Examining Center in connumber; the one considered to be of secondary structing the servicewide competitive examinaimportance by the second code number. These. tions. In preparing to take these examinations
code numbers can be obtained by completing you should consult the latest revision of the Quals
special training or class C schools.
Manual for changes distributed after the publiSome of the NECs that may be assigned to cation of this Rate Training Manual. The next
qualified IC Electricians and applicable courses change to the Quals Manual for the IC rating is
they must complete are:
scheduled for distribution in June 1977.
2
-8
Chapter 1- CAREER CHALLENGES FOR THE IC ELECTRICIAN
REQUIREMENTS*
9 E3
El to E2 E2 to E3 to E4
4 mos.
serviceor
SERVICE
iit E4
to E5
t E5
to E6
12 mos. 24 mos.
as E-4. as E-5.
3 years 6 years
t E6
to E7
tE7
to E8
36 mos.
as E-6.
8 mos. 6 mos.
8 years 36 mos.
comple- as E-2. as E-3.
time
in
time
in
time in ai E-7.
tion of
service.
service. 8 of 11
service,
Recruit
years
Training
........................,
time in
Class A ::::::::::.:". ::::::::::::.
Recruit
service
for p113.:.:::::::::.:::::::::::::::::::::::::.::;::::::::::.
Training.
be
:.
Class B must
:
(C .O.
li
listed
::::::::::::::f :::::::::::::: for AGC,
:: PT3,
may ad-........:..: MUC,
AME 3, :::
vance up
i
SCHOOL
to 10%
of graduating
:.
class.)
PRACTICAL
FACTORS
PERFORMANCE
Locally
prepared
checkoffs.
I.':':::::::'::'::'':
::.
24 mos.
as E-8.
10 of 13
years
time in
service
must be
enlisted.
enlisted
MNC.t f
Record of Practical Factors, NavEdTra 1414/1, must be
completed for E-3 and all PO advancements.
--
::::.::.:..:
TEST......................
, ...,,,
As used by CO
when approving
advancement,
Locally
See
EXAMINATIONS** prepared below .
ENLISTED
PERFORMANCE
EVALUATION
:':;
NH 3, :::::*1
PN 3, :'::::::::::' ,:::::::::::::::::::::::
FTB 3,
MT 3, :'::::::::::: ,,.. .."'
t E8
to E9
.....
.77.,..
Specified ratings must complete
applicable performance tests b 3fore taking examinations.
%.
::;:
Counts toward performance factor credit in advancemen m ple.
Navy-wide examinations
required for all PO
Navy-wide selection board.
tests.
advancements.
Required for E-3 and all PO advancements
RATE TBA1ING
unless waived because of school compleMANUAL (INC LUD- -::::::::::::::.- tion, but need not be repeated if identical
ING MILITARY
::::::::":%:::. course has already been completed. See
REQUIREMENTS)
NavEdTra 10052 (current edition).
..............
..............
::.
:'...:
::
.............,,,,,,,
AUTHORIZATION
Commanding
Officer
Nonresident career
courses and
recommended
reading. See
NavEdTra 10052
(current edition).
NAVEDTRAPRODEVCEN
All advancements require commanding officer's recommendation.
1 year obligated service required for E-5, and E-6; 2 years for E-7, E-8, and E-9.
Military leadership exam required for E-4 and E-5.
be use.
For E-2 to E-3, NAVEDTRAPRODEVCEN exams or locally prepared tests may
it Waived for qualified EOD personnel.
Figure 1-1.Active duty advancement requirements.
3
IC ELECTRICIAN 3 & 2
1
REQUIREMENTS
(I I°
(2 I°
E2
E3
1310
14 I°
E4
TOTAL TIME
IN GRADE
4 mos.
(510
E5
8 mos. 6 mos.
E6
16 I°
El
El
El
36 mos 36 mos. 24 mos.
with
with
with
12 mos. 24 mos. total
total
total
8 yrs 11 yrs 13 yrs
service service service
TOTAL TRAINING
DUTY IN
GRADE t
14 days 14 days 14 days 14 days 28 days 41 days 41 days 28 days
.....:
'..:::.::...:,...:..i:....
::::
PERFORMANCE
TESTS
. .:
6::::6i.;.i,;:::;i1 ................
DRILL
PARTICIPATION
Specified ratings must complete applicab e
performance tests before taking examinat on
Satisfactory participation as a member of a drill unit
in accordance with OUP(RSINST 5400.42 series.
PRACTICAL FACTORS
oNcIADING MILITARY
REQUIREMENTS)
Record of Practical Factors, NavEdTra 1414/1, must
be completed for all advancements.
RATE TRAINING
MANUAL (INCLUDING
Completion of applicable course or courses must be entered
MILITARY REQUIRE
In service record.
MENTS)
Standard Exam
required for all PO
EXAMINATION
Standard Elm
advancements.
Standard Exam,
Also pass
Selection hard.
Military Leadership Exam
Ts E.4 and El.
Commanding
AUTHORIZATION
NAVEDTRAPRODEVCEN
011icer
...
Recommendation by commanding officer required for all advancements.
f Active duty periods may be substituted for training duty.
Figure 1-2. Inactive duty advancement requirements.
41.0
Chapter 1- CAREER CHALLENGES FOR THE IC ELECTRICIAN
and issued annually by the Naval Education and
Training Support Command. Each revised edition
SOURCES OF INFORMATION
is identified by a letter following the NAVEDTRA
number. When using the bibliography, be sure
you have the most recent edition.
The working list contains required and recom-
No single publication can give you all the
information you need to perform the duties of
your rating. You ehould learn where to look for
accurate, authoritative, up-to-date information
on all subjects related to the military requirements for advancement and the professional
qualifications of your rating. Information related
mended Rate Training Manuals and other references. A Rate Training Manual marked with
to requisitioning materials, required maintenance
forms, leadership and supervision should be
obtained from Military Requirements for Petty
Officer S & 2.
Some of the publications described here are
subject to change or revision from time to
time some at regular intervals, others as the
need arises. When using any publication that is
subject to change or revision, le sure that you
have the latest edition. When using any publication that is kept current by means of changes,
be sure you have a c py in which all official
changes have been made. Studying canceled or
obsolete information will not help you to do your
work or to advance; it is likely to be a waste of
time, and may even be seriously misleading.
You must bear in mind, however, that you
cannot depend on the printed word alone; you
must supplement the information you obtain
from books with actual practice, and with the
knowledge acquire from observing experienced
men at work.
an asterisk (*) in NAVEDTRA 10062 is MANDATORY at the indicated rate level. Remember,
however, that you are responsible for all references at lower levels, as well as those listed
for the rate to which you are seeking advance-
ment. A mandatory Rate Training Manual may
be completed bv (1) passing the appropriate
nonresident career course (formerly called correspondence course), based on the manual, (2)
prepared tests based on the manpassing
datory training manual, or (3) in some cases,
successfully completing an appropriate Navy
school.
All references, whether mandatory or recommended, listed in NAVEDTRA 10052 may be
used as source material for the written advance-
ment examination, at the appropriate levels.
In addition, references cited in a mandatory or
recommended Rate Training Manual may be
used as source material for examination questions.
Rate Training Manuals
These manuals help enlisted personnel fulfill
NAVAL TRAINING (NAVEDTRA) PUBLICATIONS
their job requirements as expressed by the
practical and knowledge factors that they must
acquire for advancement. Some manuals are
general, and intended for more than one rating;
others, such as this one, are specific to the
particular rating.
Rate Training Manuals are revised from time
to time to bring them up-to-date. The revision
of a Rate Training Manual is identified by a
letter following the NAVEDTRA number. You
can tell whether a Rate Training Manual is the
Effective 15 January 1972, the Naval Training
Support Command and its field activities came
directly under the command of the Chief of
Naval Training instead of the Chief of Naval
Personnel. Training materials published by the
Naval Training Support Command after the above
date are designated NAVEDTRA in lieu of NAV-
PERS; in most cases, the numbers remain as
originally assigned. The designators of publications printed before the above date will be
latest edition by cheqking the NAVEDTRA number
and the letter following the number in the most
recent edition of the List of TrainiN Manuals
and Correspondence Courses, NAVEDTRA 10061
(revised).
changed as each publication is revised.
The naval training publications described
here include some that are absolutely essential
for meeting your job requirements and some that
are extremely helpful, although not essential.
DOD INFORMATION SECURITY PROGRAM
REGULATION
Bibliography for Advancement Study
NAVEDTRA 10052
This regulation or DODISPR (for short) is the
basic directive for administering the Information
Security Program. throughout the Department of
This pamphlet provides a working list of
material for enlisted personnel who are studying
for their advancement examinations. It is revised
5
11
IC ELECTRICIAN 3 & 2
Defense. It ensures the protection of official DOD
Safety Review, published monthly by the Naval
information relating to national security. DOD-
Material Command, contains information on the
safe storage, handling, or other use of products
ISPR is supplemented by OPNAV INSTRUCTION
5610.1D to provide necessary instructions and
policy guidance for the Department of the Navy.
The format of the Navy supplement corresponds
to that of DODISPR, except that the supplement
contains additional information which concerns
the Department of the Navy Information Security
Program. DODISPR and OPNAVINST 5510.1D
supersede the canceled Navy Security Manual
for Classified Information. Appendix I of this
Rate Training Manual contains basic principles
of security relative to the access, tlissem'nation, storage, transmission, compromise, and
destruction of classified material.
TECHNICAL MANUALS
Although much of your work 'rill be routine,
you will always face new problems, and have to
look up information to solve them. The log room
of your ship will contain a comprehensive technical library. The books in this library are
primarily designed for the engineer officer to
use, but you will have occasion to use them.
Manufacturers' technical manuals for most of
the equipment in the ship will be found in the
log room library. They are valuable sources of
information on operation, maintenance, and
repair.
The l'encylopedia" of Davy engineering- -
Naval Ship Systems Command Technical Manual
or so-called NAVSHIPS Tech Manuals is also
kept in the log room. Unless assigned to work
there, you will not have an opportunity to study
the J4AYSHIPS Tech Manual, so all the information in it relating to your advancement requirements is included in this Rate Training Manual.
There are occasions, however, when you will
and materials. Fathom, published quarterly by
the Naval Safety Center, provides accurate, and
current information on nautical accident prevention.
The Electronics Information Bulletin (EIB)
is published biweekly by the Naval Ship Engineer-
ing Center. EIB articles contain advance
mation on field changes, installation techniques,
maintenance notes, beneficial suggestions, and
technical manual distribution. Articles of lasting
interest are transcribed into the Electronics
Installation and Maintenance Book (EIMB). The
EIMB is a single-source reference document of
maintenance and repair policies, installation
practices, and overall electronics equipment and
material-handling procedures for implementing
the major policies set forth in chapter 9670
of NAVSHIPS Tech Manual.
HOW TO STUDY
The general methods of study are tke same
for everyone, but the real art entails discovery
of the methods that are best for you. It is
always best to study about a particular equipment
while working on it. With a piece of equipment
available, study the technical manual and relate
the physical location and size of the component
with it. On the job, learn by doing.
When studying theory or fundamentals of
operation, always set up some plan of study.
Study is a habit. It is best done under conditions
and surroundings that do not distract. Learn
in an orderly fashion so that the acquired bite
of knowledge will serve as stet .4ng stones in the
process of learning. Read and study the material
at hand with as much concentrenn as possible.
Remember that electricity cannot be learned in
a hurry. A consistent application of effort, how-
have to use the NAVSHIPS Tech Manual and
manufacturers' technical manuals, such as, when
you are assigned responsibilities for equipment
with which you are not familiar or have to perform complex maintenance or repair operations
ever, brings a man to his goal sooner than he
thinks.
which you have not done before.
BASIC RULES OF STUDY
PERIODICALS
The following rules of study will benefit
those who find it difficult to learn and retain
The Naval Ship Systems Command Techanical
News is a monthly publication with useful articles
what they have read.
on all aspects of shipboard engineering. It supplements and clarifies information contained in
the NAVSHIPS Tech Manual and also presents
Choose a comfortable, quiet, and welllighted location. Read with pencil and paper
information on new developments.
handy for recording notes.
6
12
Chapter 1 CAREER CHALLENGES FOR THE IC ELECTRICIAN
Decide upon a portion of a chapter and
the number of pages to be studied.
Read quickly in order to get the main
point of the subject.
Reread carefully, then put the study
material aside.
List the main points, then check them
with manual open.
Reread the material more slowly. Try
to remember the details and connection of each
part.
Write a detailed summary, using the
manual only if necessary.
STUDYING THIS RATE TRAINING MANUAL
Before proceeding further in this Rate Train-
ing Manual, you should know its scope and purpose.
Go over the table of contents and note the
arrangement of topics. Subject matter can be
organized and presented in many different ways.
You will find it helpful to get an overall view of
It must be satisfactorily completed before
you can advance to IC3 or IC2, whether you are
in the Regular Navy or in the Naval Reserve.
It is designed to provide information on the
occupational qualifications for advancement to
ICS and IC2.
The occupational qualifications that were
used as a guide in the preparation of this manual
were those promulgated in change 3 of the Manual
of Qualifications for Advancement, NAVPERS
18068-C (June 1973). Changes in the IC Electrician's qualifications occurring after this edi-
tion of the Quals Manual became effective may
not be reflected in the topics of this training
manual.
It includes subject matter that is related
to both the KNOWLEDGE FACTORS and the
PRACTICAL FACTORS of the qualifications for
advancement to IC3 and IC2. No Rate Training
Manual, however, can take the place of on-thejob experience for developing skill in the practical factors. When possible, this manual should
be used in conjunction with the Record of Practical Factors, NAVPERS 1414/1.
this manual's organization before starting to
study. Here are some points of interest concerning
this manual:
13
It is NOT designed to provide information
on the military requirements for petty officers.
7
CHAPTER 2
SAFETY
The Secretary of the Navy, in establishing a
Department of the Navy Safety Program, stressed,
"Safety is an inherent responsibility of
command..." He further outlined that "Assignment of safety responsibility at all echelons of
command is a basic requirement." This means
responsibility right down through second and
third class petty officers. Most accidents which
occur in noncombat operations can be prevented if all personnel cooperate ineliminatingunsafe
conditions and acts.
To assist shipboard personnel in carrying
out their responsibilities concerning safety, the
Chief of Naval Operations has issued the Shipboard Accident Prevention Manual, OPNAVINST
5101.2. In addition, safety information is issued
periodically in various publications, pamphlets,
and directives by commands, bureaus, and offices
of the Navy Department. Also, the Naval Safety
Center, Norfolk, Virginia, a portion of whose
mission is to monitor safety in the fleet, obtains
accident data from completed Accident/Near
Accident Reports (3040 forms) and Accidental
Injury/Death Reports (5100 forms) and from
Safetygrams, which are submitted informally by
ships. Publications issued by the Center of particular interest to forces afloat include FATHOM
various manuals. Safety precautions related to
specific equipment are included at appropriate
points throughout this training manual.
SAFETY REQUIREMENTS
All individuals have the responsibility to
understand and observe safety standards and
regulations which are established for the prevention of injury to themselves and other persons and damage to property and equipment.
As a supervisor, you have the responsibility
of setting a good example; you cannot ignore
safety regulations and expect others to follow
them.
EFFECTS OF ELECTRICITY
Because of the inherent danger of electrical
shock safety must rank as a prime concern to
all IC linen.
The factors that determine whether you receive a slight or fatal shock are (1) the amount
and duration of current flow, (2) the parts of the
body involved, and (3) the frequency of the current
if it is A-C. Generally, the greater the current
flow and the length of time one is subjected to it
and Ships Safety Bulletin.
will determine the extent of the damage done. The
Navy has also found that life or death may be
determined by the nearness of the current path,
It is also your job as a petty officer to know
and be able to perform the proper action when an
accident does occur.
This chapter will cover some of the areas in
which you as an IC man should exercise aboveaverage naution. It will further give you some
facts so that you can teach safety accurately and
through you, to vital nerve centers or organs.
Frequency is also a determining factor, with 60
hertz current flow being slightly more dangerous
than direct current.
The ability to resist an electrical shock
effectively. Finally, it will give the approved
varies from sailor to sailor and from day to day.
However, NavShips has summarized the relationship of current magnitude to degree of shock
methods of action so that you will be able to rehearse your actions and thus be ready in the
event of a casualty.
as follows:
1. At about one milliamp (.001 ampere) shock
Instructions and procedures pertaining to
safety aspects are contained in general and
is perceptible.
2. At about ten milliamp (.01 ampere) shock
is sufficient to prevent voluntary control of the
muscles.
specific manuals such as Naval Ships Technical
Manual. The safety precautions discussed in this
chapter are not intended to replace those in
8
1.4
Chapter 2SAFETY
(2) If pertinent, inform the remote station
Effects
No sensation.
Mild sensation to pain-
Current Value
--Less-than 4 -ma
1 to 20 ma
ful
shock, may lose
control of adjacent
muscles between 10 to
20 ma.
20 to 50 ma
Painful shock, severe
50 to 200 ma
Same as above, only
muscular contractions,
breathing difficult.
more severe, up to 100
ma. A heart condition
known as ventricular
fibrillation may occur
anywhere between 100
and 200 ma usually
causing death almost
immediately.
Severe burns and muscular contractions so
Over 200 ma
severe that the chest
muscles
clamp
the
heart and stop it for
the d .Ation of the
shock.
111.131
Table 2-1. Sixty-Hertz Current Values Affecting
Human Beings.
3. At about one hundred milliamp (.1 ampere)
shock is usually fatal if it lasts for one second
or more.
regarding the circuit on which work will be performed.
(3) Use one hand when turning switches on
or -off. Keep the doors to switch-and-fuse -boxes
closed, except when working inside or replacing
fuses.
(4) After first making certain that the circuit is dead, use a fuse puller to remove cartridge fuses.
(5) All supply switches or cutout switches
from which power could possibly be fed should
be secured in the off or open (safety) position and
tagged. The tag should read "THIS CIRCUIT WAS
ORDERED OPEN FOR REPAIRS AND SHALL
NOT BE CLOSED EXCEPT BY DIRECT ORDER
OF (name and rank of person making, or directly
in charge of repairs)," or "DANGER-SHOCK
HAZARDDo not change position of switch
EXCEPT by direction of (name and rank of per?
son making or directly in charge of repairs)."
(6) Keep clothing, hands, and feet dry if at
all possible, When it is necessary to work in wet
or damp locations, use a dry platform or wooden
stool to sit or stand on, and place a rubber mat
or other nonconductive material on top of the
wood. Use insulated tools and insulated flashlights of the molded type when required to work
on exposed parts. In all instances, repairs on
energized circuits shall not be made with the
primary power applied except in case of emergency, and then only after specific approval
has been given by your supervisor, the chief IC
electrician or electrical material fficer. When
has been obtained to work on
approval
equipment with the power applied, keep one hand
free at all times (BEHIND YOU OR IN YOUR
POCKET).
Table 2-1 may be an aid to you when you are
instructing your strikers, as it points out the
current
values and their expected effects.
SAFE PRACTICES
(7) Never short out, tamper with, or block
open an interlock switch,
(8) Keep clear of exposed equipment; when
it is necessary to work on it, work with one hand
as much as possible.
When working on electrical or electronic circuits there are certain general precautions which
must be observed. These precautions should be
scrupulously followed by both yourself and the
striker who is working with you.
___
(1) Remember that electrical and electronic
circuits often have more than one source of
power. Take time to study the schematics or
wiring diagrams of the entire system to ensure
that all power sources are deactivated.
15 9
(9) Avoid reaching into enclosures except
when absolutely necessary; when reaching into an
enclosure, use rubber blankets to prevent accidental contact with the enclosure.
(10) Make certain that equipment is properly
grounded.
(11) Turn off the power before connecting
alligator clips to any circuit.
(12) Never use your finger to test a "hot"
line. Use approved meters or other indicating
devices.
IC ELECTRICIAN 3 & 2
HIGH VOLTAGE PRECAUTIONS
frames which are not intended to be aboveground
potential are effectively grounded, and the possibility of electrical shock to personnel coming in
Do NOT work with high voltage by yourself;
have another person (safety observer), qualified
contact with metal parts of the equipment is
in first Aid_for lectrical shock, present at all
times. The man stationed nearby should also
know the circuits and location of the switches
minimized.
The secondary function of grounds is to improve the operation and continuity of service of
controlling the equipment, and should be given
instructions to pull the switch immediately if
certain electronic equipments. Faulty ground
anything unforeseen happens.
returns are detrimental to this function, and can
result in intermodulation and noise voltage buildup, with associated service interruptions, false
signals, equipment damage, or distortion as well
as'personnel hazard.
Remove all metal objects from your person.
Always be aware of the nearness of high voltage
lines or circuits. Use rubber gloves where applicable and stand on approved rubber matting.
Not all
so-called rubber mats are good in-
sulators.
Always discharge the high voltage from com-
of the application, must meet certain require-
similar to the one described later.
Do NOT hold the test probe when measuring
circuits over 300 volts.
ments as contained in the General Specifications
for Ships of the U. S. Navy, and the Naval Ships
Technical Manual (NavShips 0901-960-0000 and
0901-967-0000, chapters 9600 and 9670). The
A satisfactory ground connection, regardless
ponents or terminals by using a safety probe
characteristics of grounds are tested by the
REPLACEMENT OF ELECTRON TUBES
manufacturer of the equipment or by the naval
development laboratories. Therefore, maintenance of ground conductors and connectors
consists primarily of corrective and preventive
Do NOT use bare hands to remove hot tubes
from their sockets; use asbestos gloves or a tube
puller.
Before replacing high voltage tubes, ensure
mdintenance.
In all instances where equipment grounding
is provided, certain general precautions andpreventive maintenance measures must be taken to
ensure that' all bonding surfaces (connection
points or metallic junctions) are securely fastened
and free of paint, grease, or other
that the plate (anode) cap or the lead terminal
(on CRTs) has been properly discharged.
When replacing (or working close to) radio-
active tubes, ensure that special precautions
(discussed later) are observed.
foreign matter that could interfere with the
positive metal-to-metal contact at the ground
GROUNDING OF POWER TOOLS
AND EQUIPMENT
connection point. A few of the precautions are:
The possibility of electrical shock can be
(1) Periodically clean all strap-and-clamp
type connectors to ensure that all direct metalto-metal contacts are free from foreign matter.
(2) Check all mounting hardware for me-
reduced by ensuring that all motor and generator
frames, metal bases, and other structural parts
of electrical and electronic equipment are at
ground potential.
Normally, on steel-hull vessels, such grounds
chanical failure or loose connections.
(3) Replace any faulty, rusted, or otherwise
are inherently provided because the metal cases
or frames of the equipment are in contact with
one another and with the metal structure of the
vessel. In some instances where such inherent
grounding is not provided by the mounting ar-
unfit grounding strap, clamp, connection, or
component between the equipment and the ground
to the ship hull.
(4) When replacing a part of the ground con-
nection, make certain that the metallic contact
surfaces are clean, and that electrical continuity
is reestablished.
(5) After the foregoing steps have been completed, recheck to be sure that the connection is
rangements, such as equipment supported on
shock mounts, suitable ground connnections must
be provided.
The conductors employed for this purpose
generally are composed of flexible material
(copper or aluminum) that provides sufficient
securely fastened with the correct mounting
hardware, and paint the ground strap and hardwater in accordance with current accepted procedures.
current-carrying capacity to ensure an effective
ground. In this manner, equipment cases and
10
16
Chapter 2 SAFETY
Because of the electrical shock hazards that
could be encountered aboard ship, plugs and
convenience outlets for use with portable test
equipment and power tools normally are of the
grounded type and are so designed that the plug
must be rotated to the correct position before
it can be inserted into the receptable. To ensure
that the safety factors incorporated in these
devices are in serviceable condition and are safe
for use, the following precautions and inspections
must be performed,
(1) Inspect the phenolic pin-guide insert of
the receptacle to see that it is firmly in place and
that the guide pin is not bent or damaged.
(2) Check the wiring terminals and connections of the plug. Loose connections and frayed
wires on the plug surface must be corrected, and
any foreign matter removed, before the plug is
inserted into the receptacle.
(3) Do not attempt to insert a grounded type
plug into a grounded receptacle without first
aligning it properly. Always rotate the plug to
such a position that its goove is aligned with
the polarity pin inside the receptacle.
(4) Remember, NEVER USE A POWER
measure around electrical and electronic equipments where electrical potentials up to but not
exceeding 3000 volts may be encountered.
In addition, the matting will improve the general
overall appearance of the interior communications spaces.
Careful design and fabrication of the floor
matting material does reduce the possbility of
accidents. However, to ensure that the safety
factors that were incorporated in the manufacture of the material are effective, and the
matting is completely safe for use, operation
and maintenance personnel must make certain
that all foreign substances that could possibly
contaminate or impair the dielectric properties
of the matting material are promptly removed
from its surface areas. For this reason, a
scheduled. periodic visual inspection procedure
and cleaning practice should be established.
During the visual inspection procedure, person-
nel should make certain the dielectric properties of the .zailting have not been impaired or
destroyed by oil impregnation, piercing by metal
chips, cracking, or other defects, If it is apparent that the matting is defective for any
TOOL OR A PIECE OF PORTABLE TEST
reason, a replaceable section of matting material
should be employed to cover the area affected.
EQUIPMENT UNLESS YOU ARE ABSOLUTELY
SURE THAT IT IS PROPERLY GROUNDED.
SAFETY SHORTING PROBE
RUBBER FLOOR MATTING
It is of the utmost importance that technical
and maintenance personnel engaged in repairs of
deenergized circuits which employ large
To eliminate likely causes of accidents and
to afford maximum protection to personnel from
the hazards associated with electrical shock,
only the approved rubber floor matting for elec-
trical and electronic spaces shall be used. In
many instances after accidents have occurred.
investigations showed that the operating loca-
tions and areas around electrical and electronic
equipments have been provided with only general
purpose black rubber floor matting. This type of
matting should not be used because its electrical
characteristics do not provide adequate insulating properties to protect personnel from the
possibility of electric shock. In addition, the
material used in the manufacture of this matting
is not fire retardant.
For the protection of personnel when work is
being performed on electricl or electronic equipments, steps should be taken to ensure that
only the approved rubber floor matting (currently
being specified by Military Specification MIL-M15562)
capacitors use a safety shorting probe to dis-
charge the circuits before performing any work
on them.
Figure 2-1 illustrates and provides the necessary details for the fabrication of an approved safety shorting probe. It is possible that
the dimensions given may not be suitable for all
the various types of equipment located within a
specific area; therefore, the length can best be
determined by the requirement. However,
materials used should be in conformance with or
equivalent to those in the recommended list of
materials required.
Construction details and the list of materials
are self-explanatory; however, the following
hints are included to help clarify any construction
problems.
WARNING
Never reduce the length of the handle
to the point where there will be less than
is used. The matting is a gray fire-
1 foot of clearance between the grip and the
shorting rod.
retardant material with a diamond-shaped surface. Use of this matting will serve as a safety
11
17
I
IC ELECTRICIAN 3 & 2
BAKELITE HANDLE
PROTECTIVE SHIELD
4 IN. DIA. X 1/4 4HK.
18
3 FT ROD
24.
30 IN. LENGTH BARE, FLEXIBLE, BRAIDED,
TUBULAR, COPPER WIRE 1/2" ID, 30 AWGN
MECHANICAL & SOLDER CONNECTION
5°
TEST CUP
Figure 24. Safety shorting probe.
Place the copper rod in a vise and bend the
probe end in accordance with dimensions given
in figure 2-1. Drill and tap the prescribed holes
in the larger diameter end of the bakelite handle.
Drill and tap the protective shield and attach it
to the bakelite handle. Thread the unbent end of
the copper rod and screw the rod into the bakelite
handle. Attach one end of the ground wire to the
copper rod, and attach the mesh-teeth clip at the
other end of the ground wire. Copies of NavShips
drawing, RE 10D 280 titled Safety Shorting Probe
Fabrication Detail can be obtained from NavShips.
When using The safety shorting probe, always
be sure first to connect the test clip to a good
ground (if necessary, scrape the paint off of the
grounding metal to make a good contact). Then
hold the safety shorting probe by the handle and
touch the probe end of the shorting rod to the
point to be shorted out. The probe end is fashioned so that it can be hooked over the part
or terminal to provide a constant connection by
the weight of the handle alone. Always take care
not to touch any of the metal parts of the safety
1.1(77C)
STEEL WOOL
It is a recognized fact that the use of steel
wool for cleaning in IC equipment spaces is harm-
ful to the operation of the equipment. A specific
directive of Naval Ships Technical Manual, Chapter 9670, states; "Steel wool or emery in any
form shall not be used on or near electronic
equipment." In chapter 9660 of the same manual,
comments on the maintenance of electronic contacts are as follows; "Emery paper or cloth or
steel wool must never be used to clean contacts."
The same paragraph then makes the following
statements, indicating that steel wool particles
are a menace: "Ventilation currents distribute
them where they do the most harm." and "Magnetic materials, often being present, will collect
ferrous particles."
Another publication which treats the harmful
effects of using steel wool in electronic equipment spaces is the Naval Ship Systems Command
Handbook of Cleaning Practices, NavShips
250342 -1. Under the paragraph entitled Soil Re-
shorting probe while touching the probe to the
exposed "hot" terminal. It pays to be safe; use
moval from Aluminum, the handbook states:
"The use of steel wool on electronic equipment
the safety shorting probe with care.
is not permitted, since residual particles of steel
12
18
Chapter 2SAFETY
may cause a short circuit." Additionally, further some of the general safety precautions that you
in the same handbook, the paragraph entitled should observe when your work requires the use
Electrical Contacts, directs "clean with silver of portable power tools.
polish, fine sandpaper, Jr burnishing tools. Do
(a) Ensure that all metal-cased portable
not use emery or steel wool. Use vacuum to remove dust." Thus, the Nav Ships directives are power tools are grounded.
(b) Do not use spliced cables.
clear and to the point: When cleaning electrical
(c) Inspect the cord and plug for proper
and electronic parts, DO NOT USE STEEL
connection. Do not use any tool that has a frayed
cord or broken or damaged plug.
WOOL.
(d) Always connect the cord of a portable
power tool into the extension cord before the
SOLDERING IRONS
When using a soldering iron, always bear in extension cord is inserted into a live receptacle.
(e) Always unplug the extension cord from
mind the following:
the receptacle before the cord Of the portable
(a) In order to avoid burns, ALWAYS AS- power tool is unplugged from the extension cord.
(f) See that all cables are positioned so that
SUME that a soldering iron is hot.
(b) Never rest a heated iron anywhere but they will not constitute a tripping hazard.
(g) Wear eye protection when orking where
on a metal surface or rack provided for this
purpose. Faulty action on your part coald result particles may strike the eyes.
(h) After completing the task requiring the
in fire, extensive equipment damage, and serious
use
of a portable power tool, disconnect the power
injuries.
(c) Never use an excessive amount of solder, cord as described in step (e) and stow the tool in
since drippings may cause serious skin or eye its assigned location.
burns.
(d) Do not swing an iron to remove excess HANDTOOLS
solder. Bits of hot solder that are removed in
For your safety, certain precautions should
this manner can cause serious skin or eye burns,
or bits of hot solder may ignite combustible be taken when working with handtools. Normally,
there should be no problems when working with
material in the work area.
(e) When cleaning. an iron, use a cleaning these tools, but there are certain conditions uncloth but DO NOT hold the cleaning cloth in your der which they may constitute a danger to you.
hand. Always place the cloth on a suitable surface Listed below are some of the dangers and safety
and wipe the iron across it to prevent burning precautions to be considered when using handtools.
your hand.
(k Hold small soldering jobs with pliers or
(a) One source of danger
a suitable clamping device to avoid burns. Never
hold the work in your hand.
(g) Do not use an iron that has a frayed cord
or damaged plug.
(h) Do not solder components unless the
equipment is disconnected from the power supply
that often
is
neglected or ignored is the use of handtools which
are no longer considered serviceable. Tools
having plastic or wooden handles that are
cracked, chipped, splintered, or broken may result in injuries to personnel from cuts, bruises,
circuit. Serious burns or death can result from particles striking the eye, and the like. Such tools
should be condemned, replaced, or, if at all poscontact with a high voltage.
(i) After completing the task requiring the sible, repaired, before they cause accidents.
(b) Another source of danger that often is
use of a soldering iron, disconnect the power cord
from the receptacle and, when the iron has cooled neglected or ignored is the unsafe work practice
of covering the metal handle of a toolwith a layer
off, stow it in its assigned storage area.
of friction tape or with a cambric sleeving to
form an improvised insulated tool. This practice
does not afford an adequate insulating barrier to
The hazards associated with the use of port- protect personnel from dangerous voltages;
POWER TOOLS
able power tools are electrical shock, bruises, therefore, steps should be taken to ensure that
cuts, particles in the eye, falls, and explosions. this unsafe practice is discontinued immediately.
(c) When it is necessary (in an emergency
Safe practice in the use of these tools will reduce
or eliminate such accidents. Listed below are only) to improvise an insulating barrier between
13
19
IC ELECTRICIAN 3 & 2
the tool and the individual's hand, the approved
method is first to apply several layers of approved rubber insulating tape on the metal surface areas to be covered, and then to apply a
layer or two of friction tape over the insulation
material. In this manner, an adequate insulating
barrier is provided, and the possibility of accidental contact with a lethal voltage is minimized.
AEROSOL DISPENSERS
Deviation from prescribed procedures on the
part of IC men in the selection, application,
storage, or disposal of aerosol dispensers con-
taining industrial sprays has resulted in serious
injury to personnel because of toxic effects, fire,
and explosion. Specific instructions concerning
the precautions and procedures that must be observed to prevent physical injury cannot be
given because there are so many types of industrial sprays available. However, all personnel concerned with the handling of aerosol
dispensers containing volatile substances should
clearly understand the hazards involved and the
need to use all protective measures required
to prevent personal injury. Strict compliance
with the instructions printed on the aerosol
dispenser will prevent many of the accidents
which result from misapplication, mishandling,
or improper storage of industrial sprays used
in the Naval service for electrical and electronic equipment.
Basic rules which must be observed by
operating and maintenance personnel in order
to ensure safety in the use of aerosol dispensers are:
(a) Carefully read and comply with the in-
structions printed on the can.
(b) Do not use any dispenser that is capable
of producing dangerous gases or other toxic
effects in an enclosed area unless the area is
adequately ventilated.
(c) If a protective coating must be sprayed
in a space which lacks adequate ventilation, an
air respirator, self-contained breathing apparatus, or preferably, fresh air supplied
from outside the enclosure by use of portable
blowers or exhaust fans should be provided:
Such equipment will prevent inhalation of toxic
vapors.
(d) Do not spray protective coatings on warm
or energized equipment, because to do so-creates
a fire or toxic gas hazard.
.
(e) Prevent all contact to the skin with the
liquid contained in the dispenser. Contact with
some of the liquids being used may result in
burns, while milder exposures may cause
rashes.
(f) Do not puncture the dispenser. It is pressurized; therefore, injury can result from this
practice.
(g) Do not discard used dispensers in wastebaskets that are to be emptied into an incinerator, or an explosion of the dispenser case
may result.
(h) Keep dispensers away from direct sunlight, heaters, and other sources of heat.
(i) Do not store dispensers in an environment
where the temperature is above the temperature
limits printed on the dispenser case. Exposure
to high temperature may cause bursting of the
container.
BUILT-IN SAFETY DEVICES
Many modern equipments are provided with
built-in safety devices (interlock switches and
such) to prevent technical and maintenance personnel from coming into contact with electrical
potentials in excess of 50 volts RMS, However,
some of these protective devices are removed
or destroyed by personnel who tamper with,
block open, or otherwise "override" the L ifety
devices. The' foregoing practices are actions
which MUST NOT BE PERFORMED. They are
practices that could lead to personal injury or
death.
After an accident has occurred, investigation
almost a/wt,ys shows that it could have been
prevented by following established safety precautions and procedures. Among these ale the
following:
(a) Do not troubleshoot a circuit with the
primary power applied. This includes the aforementioned unsafe practice of "overriding" the
equipment's built-in safety devices.
(b) Carefully study the schematic and wiring
diagrams of the entire circuit, noting which
circuits must be deenergized in addition to the
main power supply.
(c) Obtain permission from your supervisor
if it becomes necessary to work on energized
equipment.
-(d) If approval is given to work on equipment
with the power applied, never work alone;
always have an assistant who can provide or get
help in an emergency.
14
20
Chapter 2SAFETY
(e) When making measurements or tests,
always keep one hand behind your back or in
your pocket.
(1) Do not reach into the equipment enclosure
unless absolutely necessary; when this must be
done, make sure that approved insulating material and procedures are used(stand on a rubber
matting, wear rubber gloves).
Because of the hazards which confront IC
Electricians in the performance of their duties,
each man concerned should make it his responsibility to read and thoroughly understand the
safety practices and procedures contained in applicable plublications before attempting to make
repairs or adjustments on the equipment. He
should never endanger his life or the lives of his
associates by disregarding or taking too lightly
the built-in devices that are provided for his
safety.
Hints pertaining to proper handling of radio-
active tubes, precautions to ensure personnel
safety, and a list of tubes containing radioactive
material are provided herein. The following
precautions should be taken to ensure proper
handling of radioactive electron tubes and to
ensure safety of personnel.
Radioactive tubes should not be removed
from cartons until immediately prior to actual
installation.
When a tube containing a radioactive material is removed from an equipment, it should
be placed in an appropriate carton to prevent
possible breakage.
A radioactive tube should never be carried
in your pocket, or elsewhere about you in such
a manner that breakage can occur.
If breakage does occur during handling or
removing of a radioactive electron tube, notify
the cognizant authority and obtain the services
of qualified radiological personnel immediately.
RADIOACTIVE ELECTRON TUBES
Isolate the immediate area of exposure to
prevent other personnel from possible con-
Electron tubes containing radioactive material are now commonly used. These tubes are
tamination and exposure.
Do not permit contaminated material to come
in contact with any part of your body.
as TR, A TR, PRE-TR, spark -gap,
voltage-regulator, gas-switching, and coldcathode gas-rectifier tubes. Some of these tubes
contain radioactive material and have intensity
levels which are dangerous; they are so marked
in accordance with Military Specifications. The
majority of these tubes contain radioactive cobalt
known
Take care to avoid breathing any vapor or
dust which may be released by tube breakage.
Wear rubber or plastic gloves at all times
during cleanup and decontamination procedures.
Use forceps for the removal of large fragments of a broken radioactive tube. The re-
mai ling small particles can be removed with a
vacuum cleaner, using an approved disposal
collection bag. If a vacuum cleaner is not available, use a wet cloth to wipe the affected area.
(Co-60), radium (Ra-226), or carbon (C-114);
several contain nickel (Ni-63); and a relative
few contain cesium-barium (Cs Ba-137).
So long as the electron tube containing any of
In this case, be sure to make one stroke at a
time. DO NOT use a back-and-forth motion.
the previously listed radioactive material re-
mains intact and is not broken, no great hazard
exists. However, if the tube is broken and the
radioactive material is exposed, or escapes
After each stroke, fold the cloth in half, always
holding one clean side and using the other for
the new stroke. Dispose of the cloth in the manner states later.
No food or drink should be brought into the
contaminated area or near any radioactive material.
Immediately after leaving a contaminated
area, personnel who have handled radioactive
material in any way should remove any clothing found to be contaminated. They should also
from the confines of the electron tube, the
radioactive material becomes a potential hazard.
The concentration of radioactivity in a normal
collection of electron tubes at a maintenance
shop does not approach a dangerous level, and
the hazards of injury from exposure are slight.
However, at major supply points, the storage of
large quantities of radioactive electron tubes
in a relatively small area may create a hazard.
For this reason, personnel working with equipments employing electron tubes containing radioactive material, or
thoroughly wash their hands and arms with
soap and water, and rinse- with clean water.
Immediately notify a medical officer if a
personnel wound is sustained from a sharp
in areas where a large
quantity of radioactive tubes is stored, should
read and become thoroughly familiar with the
safety practices promulgated in shipboard in-
radioactive object. If a medical officer cannot
reach the scene immediately, mild bleeding
should be stimulated by pressure about the
structions.
15
21
IC ELECTRICIAN 3 & 2
wound and the use of suction bulbs. DO NOT
3. Place a fire extinguisher close by, ready
USE THE MOUTH.
for use.
If the wound is of the puncture type, or the
opening is small, make an incision to promote
free bleeding, and to facilitate cleaning and
4. Use water compounds in lieu of other
solvents where feasible.
flushing of the wound.
When cleaning a contaminated area, seal all
debris, cleaning cloths, and collection bags in a
5. Wear rubber gloves to prevent direct
contact.
container such as a plastic bag, heavy wax
paper, or glass jar, and place in a steel can
6. Use goggles when a solvent is being sprayed
on surfaces.
until disposed of in accordance with existing
instruction.
Decontaminate all tools and implements used
to remove a radioactive substance, using soap
and water. Monitor the tools and implements for
7. Hold the nozzle close to the object being
sprayed.
Inhibited methyl chloroform (1, 1, 1, Trich-
loroethane) should be used only where water compounds are not feasible. Methyl chloroform has
a threshold of 500 parts-per-million (PPM) in
air. The threshold is the point nbove which the
concentration in air becomes dangerous. Methyl
chloroform is toxic and should be used with care
radiation with an AN/PDR-270; they should
emit less than 0.1 MR/HR at the surface.
CLEANING SOLVENTS
IC men who smoke while using a volatile
cleaning solvent are inviting disaster. Unfortunately, many such disasters have occurred. For
this reason, the Navy does not permit the use of
gasoline, benzine, ether, or like substances
for cleaning solvent purposes. Only nonvolatile
as concentrations of the vapor are anesthetic
and can be fatal. Care requires plenty of ventilation and observance of fire precautions. Avoid
direct inhalation of the vapor. Inhibited methyl
chloroform is not safe for use with a gas mask,
since the vapor displaces oxygen in the air.
solvents should be used to clean electrical or
electronic apparatus.
In addition to the potential hazard of acci-
CATHODE-RAY TUBES (CRTs)
dental fires, many cleaning solvents are capable
of damaging the human respiratory system in
cases of prolonged inhalation. The following list
of "DO NOTs" will serve as effective reminders
to men who must use cleaning solvents.
Cathode-ray tubes should always be handled
with extreme caution. The glass envelope encloses a high vacuum and, because of its large
surface area, is subject to considerable force
caused by atmospheric pressure. (The total
force on the surface of a 10-inch CRT is 3750
pounds, or nearly two tons; over 1000 pounc's
is exerted on its face alone.) Proper handling
1. DO NOT work alone or in a poorly ventilated compartment.
2. DO NOT use carbon tetrachloride. This
3. DO NOT breathe directly the vapor of any
is a highly toxic compound.
and disposal instructions for CRTs are as follows:
cleaning solvent for a long time.
4. DO NOT spray cleaning solvents on electrical windings or insulation.
1. Avoid scratching or striking the surface.
2. Do not use excessive force when removing
or replacing the CRT in its deflection yoke or its
hazard.
3. Do not try to remove an electromagnetic
type CRT from its yoke until you make sure
socket.
5. DO NOT apply solvents to warm or hot
equipment, since this increases the toxicity
The following reminders are positive safety
steps to be taken when cleaning operations are
that the high voltage has been discharged frcm
1. Use a blower or canvas wind chute to
blow air into a compartment in which a cleaning
solvent is being used.
2. Open all usable portholes, and place wind
scoops in them.
a thick piece of felt, rubber, or smooth cloth.
6. Always handle the CRT gently. Rough
handling or a sharp blow on the service bench
can displace the electrodes within the tube,
its anode connector (hole).
4. Never hold the CRT by its neck.
5. Always set a CRT with its face down on
underway.
causing faulty operation.
16
22
Chapter 2SAFETY
by eliminating or controlling either fuel, oxygen,
or heat. If the oxygen can be diluted or prevented
from coming into contact with the aubstance, or
if the heat can be reduced by cooling the fuel to
a temperature below that at which it ignites, the
fire will be extinguished. In an electrical fire, it
is not very likely that the fuel (a combustible substance) can be removed from the oxygen and heat;
NECK OF CRT
LOCATING
PIN
therefore, to extinguish the fire, either the heat
Or oxygen, or both, must be controlled or re-
GLASS
VACUUM
SEAL
moved.
20.320(40)
Figure 2-2. Cathode-ray tube base structure.
Electrical or electronic equipment fires result from overheating, short circuits (parts
failure), friction (static electricity), or radiofrequency arcs. Also, an equipment may be
ignited by exposure to nearby Class A or B fires.
Before a CRT is discarded, it should be
made harmless by breaking the vacuum glass
seal. To accomplish this, proceed as follows:
1. Place the tube that is to be discarded in
an empty carton, with its face down.
Since Class C fires involve electrical circuits,
electrical shock is an added dangerous and hazardous condition. Thus, whenever possible, any
electrical equipments exposed to a Class A or
Class B fire, or actually ignited by such a fire,
should be deenergized immediately. If the equip-
2. Carefully break off the locating pin from
its base (fig. 2-2).
ment cannot be deenergized completely, protective measures must be enforced to guard
WARNING
ing agents other than gases will contami..ate
delicate instruments, contacts and similar electrical devices. Therefore, carbon dioxide
(CO2) is the preferred extinguishing agent for
electrical fires because it does not conduct
electricity and is a protective measure against
shock; also, there is much less likelihood of
The chemical phosphor coating of the
CRT face is extremely toxic. When disposing
of a broken tube, be careful not to come
into contact with this compound.
An alternate method of rendering a CRT
harmless is to place it in a carton. Then, using
a long, thin rod, pierce through the carton and
the side of the CRT.
ELECTRICAL FIRES
The three general classes of fires are A,
B, and C. Class A fires involve wood, paper, cotton and wool fabrics rubbish, and the like. Class
B fires involve oil, grease, gasoline and air-
craft fuels, paints, and oil-soaked materials.
Class C fires involve insulation and other combustible materials in electrical and electronic
equipment.
Fire is not only a hazard to personnel safety,
but may result in damage to or loss of equipment. Fuel (a combustible substance), oxygen
(air), and sufficient heat to vaporize the fuel
must be present simultaneously to ignite a fire.
When a substance burns, however, it is the vapor
of the substance combined with oxygen that burns
and not the actual substance in its solid or liquid
form. Fire can be controlled and/or extinguished
against electrical shock. In addition, extinguish-
equipment damage.
A dry chemical type of extinguishing agent,
composed chiefly of sodium bicarbonate, is suitable for electrical fires because it also is a nonconductor and, therefore, protects against elec-
trical shock. However, damage to electrical or
electronic parts may result from the use of
this agent. The dry chemical extinguisher is
similar in appearance to the CO2 extinguisher.
A SOLID STREAM OF WATER MUST NEVER
BE USED TO EXTINGUISH ELECTRICAL FIRES
IN ENERGIZED EQUIPMENT because water
usually contains minerals which make it
conductive; the conductivity of sea water is many
times greater than that of fresh wafer. If
circumstances warrant the use of fresh or sea
water, fog produced by a special hose nozzle
(iog head or tip) may be used in electrical or
electronic equipments spaces. However, even
though the fog is a fine diffusion or mist of water
particles with very little conductivity, there is
still some danger of electric shock, unless the
equipment is completely deenergized. Also, fog
condensation on electrical equipment frequently
17
23
IC ELECTRICIAN 3 & 2
damages the components, and this damage must
be corrected after the fire. The nozzle should
never be removed from the end of the hose since
the water pressure at the fireplug may be upwards to 100 PSI. If this is done, a dangerous
whip-lash action of the hose may result and cause
injury to yourself or nearby personnel.
materials surrounding an electrical fire; however, carbon dioxide must be used as the extinguishing
on the actual electrical fire.
Control of Mr (Oxygen)
Air, which is composed of approximately 21
percent oxygen and 79 percent nitrogen and other
Foam is not recommended for electrical
gases, is difficult to control in most cases because it is impossible to remove air from the
atmosphere surroundin, he fire. However, the
air can be diluted adch noncombustible gases
fires because of equipment damage and the possible shock hazard to personnel; however, if
required, foam should be used only on DEENERGIZED circuits. When a blanket of foam
is applied to a burning substance, the foam
which will reduce the oxygen content. The atmospheric c'cygen content reduction will, in turn, extinguish the fire. The oxygen must be diluted to
smothers the fire; that is, it cuts off the air supply to the burning substance. Thus, the supply of
oxygen necessary to support combustion is
isolated from the substance, and the fire will be
a certain saturation point before the fire is extinguished. Thus, sufficient carbon dioxide must
be added to the atmosphere to lower the percentage of the oxygen ontent to the saturation point
which will not support the combustion of the
extinguished.
substance involved.
METHODS OF FIREFIGHTING
Carbon dioxide, a noncorrosive gas, is one
and one-half times heavier than air and thus remains close to the surface of the deck or floor.
It cannot be seen or smelled; its presence gives
no evidence that can be recognized by the senses.
When used, this gas flows down and over the fire
to smother it. However, the very qualities which
make carbon dioxide a valuable extinguishing
agent also make it dangerous to life; when carbon
dioxide dilutes and replaces the oxygen in the air
to the extent that combustion cannot be sustained,
respiration cannot be sustained either. Personnel should be aware that prolonged exposure to
an atmosphere heavily laden with carbon dioxide
will cause suffocation unless special breathing
apparatu: is used. Personnel suffering from
prolonged exposure to carbon dioxide must be
administered artificial respiration and oxygen,
and must be kept warm and quiet. Personnel
using the carbon dioxide fire extinguisher must
also be aware of the fact that the "snow" discharge from the extinguisher blisters the skin
The three methods of firefighting, that is, the
removal of fuel, the removal of heat, or the control of air (oxygen), are described in the following paragraphs.
Removal of Fuel
When fighting a fire, remove any combustible
materials (fuel) f::om the area to prevent their
coming in contact with the fire. In an electrical
fire, this is done primarily to prevent the fire
from spreading. Since it is not very practical to
remove combustible substances from the source
of fire within electrical or electronic equipment,
either the removal of heat or the control of air
(or both) is the most practical approach in combatting an electrical fire.
Removal of Heat
Heat is transmitted by radiation, conduction,
and convection. In radiation, heat radiates in all
directions from the fire, thus raising the
temperature of nearby substances or materials.
In conduction, heat is transmitted through a substance by contact with fire, which, in turn, gives
off heat along the length and mass of the substance, such as along metal work benches or
through compartment or cabinet walls. In
convection, heated air and gases rise from a fire
to contact and transfer heat to other substances
or materials nearby. Water fog and water can be
used only to remove heat from the substances or
agent
and causes painful "burns" if it is allowed to
contact and remain on the skin. The cooling
effect of this gas upon the fire is slight, notwith-
standing its low temperature resulting from
rapid expansion as it leaves the fire extinguisher
cylinder.
When carbon dioxide is properly directed and
applied to a Class C fire, there is no danger of
an electrical shock (since carbon dioxide is a
nonconductor of electricity). However, if the discharge horn of a portable carbon dioxide extinguisher collects ice and the horn is allowed to
accidentally touch an energized circuit, the horn
18
24
Chapter 2 SA FE TY
may transmit a shock to the person handling the
extinguisher.
Most portable CO2 extinguishers have a locking pin that must be removed in order to operate
the release valve. It is imperative that the user
check to be sure that this pin is removed before
deciding that he has an inoperative extinguisher.
Once the pin is removed, the squeeze-grip type
release valve extinguisher is operated by a
sim?le "squeeze grip" of the handle; the older
CO2 extinguisher having a disk type release valve
is operated by turning a smallwheel. Once opened
(the release valve sealing disk ruptured) the disk
type valve cannot be closed to hold the unexpended
gas indefinitely; the entire charge will eventually
leak out requiring that the cylinder be refilled
and a new sealing disk be inserted in the release
valve. On the other hand, the squeeze grip type
valve mazes a gastight seal when pressure on the
"squeeze-grip" is released; it can be opened and
closed repeatedly without loss of gas from
leakage.
The following general procedure is used for
fighting an electrical fire:
1. Promptly deenergize the circuit or equipment affected. Shift the operation to standby circuit or equipment, if possible.
2. Sound an alarm in accordance with station
regulations or the ship's fire bill. When ashore,
notify the fire department; if afloat, notify the
Officer of the Deck. Give the fire location and
state what is burning. If possible, report the
extent of the fire, that is, what its effects are
coot the substances (fuels) involved and prevent
a rekindling of the fire.
5. Avoid prolonged exposure to high concen-
trations of carbon dioxide in confined spaces
since there is danger of suffocation unless
special breathing apparatus is available.
6. Administer artificial respirati;In and oxygen to any personnel overcome by carbon dioxide fumes and keep the patient warm.
Fire aboard a Navy vessel at sea under norconditions sometimes is more fatal and
damaging to both personnel and the ship itself,
than that resulting from battle. It is extremely
important for all personnel to know and understand the danger of fires. Part of this knowledge
mal
is to know the type and location of all firefighting
equipment and apparatus in the immediate working and berthing spaces, and throughout the ship.
It is too late to get this knowledge after a fire is
started; the time is now.
FIRE EXTINGUISHERS
In addition to the aforementioned fire precautions, fire extinguishers of proper type must
be conveniently located near all places that are
exposed to constant fire danger, especially places
near high-voltage equipment. Table 2-2 lists the
types of fire extinguishers that are normally
available for use.
upon the surrounding area.
3. Secure ventilation by closing compart-
ment air vents or windows.
4. Attack the fire with portable CO3 extinguishers (or a CO2 hose reel system, if available)
as follows:
a. Remove the locking pin from the re-
lease valve.
b. Grasp the horn handle by the insula-
tion (thermal) grip; the grip is insulated against
possible hand frostbite.
c. Squeeze the release lever (or turn the
wheel) to open the valve and thus release the car-
bon dioxide; at the same time, direct the discharge flow of the carbon dioxide toward the
base of the fire.
d. Aim and move the horn of the extin-
guisher slowly from side to side.
e. Do not stop the discharge from the extinguisher too soon. When the fire has been ex-
tinguished, coat the critical surface areas involved with carbon dioxide "snow" in order to
ELECTRIC SHOCK
In the case of severe electric shock, the victim is usually very white or blue. His pulse is
extremely weak or entirely absent, and unconciousness is complete. Burns are usually present. The victim's body may become rigid or
stiff in a few minutes. This condition can be
caused by muscular reaction, and is not necessarily to be considered as rigor mortis. Therefore, artificial respiration is necessary, regardless of body stiffness, as recovery has
been reported in such cases. The ordinary general test for death, or the appearance of rigor
mortis should not be accepted as valid.
RESCUE OF VICTIMS
The rescue of electric shock victims is dependent upon prompt first aid.
19
gs
IC ELECTRICIAN 3 & 2
EXTINGUISHER
RESUSCITATION AND ARTIFICIAL
RESPIRATION
USE
CO2 Gas
Resuscitation for electric shock. NOTE: The
following instructions on resuscitation were furnished by the Bureau of Medicine and Surgery.
Effective on any type fire,
particularly electrical
fires.
Soda-Acid
Artificial resuscitation, after electric shock,
artificial respiration to reestablish
breathing, and external heart massage to reestablish heart beat and blood circulatic.. (fig.
2-3).
To aid a victim of electric shock after removing him from contact with the electricity,
immediately apply mouth-to-mouth artificial
respiration.
If there is no pulse, immediately apply heart
massage. Don't waste precious seconds carrying
the victim from a cramped, wet, or isolated
location to a roomier, dryer, frequented location.
If desired, breathe into victim's mouth through a
cloth or a handkerchief placed over his face. If
assistance is available, take turns breathing into
victim and in massaging his heart (fig. 2-3 A,
Effective only on Class A
includes
fires. Not recommended
for electrical fires as
compound is pod conductor of electricity. Not
effective on burning com-
pounds, such as oil and
the like.
Foam
Very effective on burning
compounds, such as oil
and similar materials.
Not satisfactory for electrical fires, as compound
is a good conductor of
electricity.
B, C).
Table 2-2.
140.114
Types of Fire Extinguishers.
Cardiac Arrest
(Loss of Heartbeat)
If the subject has suffered an electric shook
and has no heartbeat, he has cardiac arrest.
This is demonstrated by finding a complete absence of any pulse at the wrist or in the neck.
WARNING
DO NOT attempt to administer first aid
or come in physical contact with an electric
shock victim before the victim has been re-
Associated with this the pupils of the eye will be
dilated, and respiration will be weak or stopped.
The subject may appear to be dead. Under these
circumstances, severe brain damage will occur
in four minutes unless circulation is reestablished by cardiac massage.
moved from the live conductor.
When attempting to administer first aid to an
electric shock victim, proceed as follows.
1. Shut off the high voltage.
Closed Chest Cardiac Massage.
2. If the high voltage cannot be deactivated,
remove the victim immediately, observing the
This method has been adopted as practical and
can be administered by anyone who is properly
instructed. The object in closed chest cardiac
massage is to squeeze the heart through the chest
wall, thereby emptying it to create a peripheral
pulse. This must be done about 60 times each
minute.
Place the subject on his back; a firm surface,
such as the deck, is preferred. Expose subject's
chest.
Kneel beside victim; feel for lower end of
subject's sternum (breastbone); place one hand
following precautions;
a. Protect yourself with dry insulating
material.
b. Use a dry board, belt, dry clothing,
or other available nonconductive material to free
the victim from the live wire, DO NOT TOUCH
the victim.
c. After removal of the victim from the
live conductor, proceed with the administration
across breastbone so heel of hand covers the
lower part; place second hand on top of the
of artificial respiration as described below.
20
Chapter 2 SAFETY
ARTIFICIAL RESPIRATION
MOUTH-TO-MOUTH OR MOUTHTONOSE
RESCUE BREATHING
-8-0 CLEAR THE MOUTH
1O PLACE CASUALTY ON SACK IMMEDIATELY
AND THROAT
DON'T WASTE TIME MOVING TO A BETTER PLACE OR
LOOSENING CLOTHING
OQUICKLY CLEAR MOUTH AND THROAT
REMOVE MUCUS, FOOD AND OTHER OBSTRUCTIONS.
®TILT HEAD BACK AS FAR AS POSSIBLE
THE HEAD SHOULD BE IN A "CHIN-UP" OR "SNIFF" POSITION AND THE NECK STRETCHED.
TILT HEAD BACK
AND LIFT JAW
@LIFT LOWER JAW FORWARD
GRASP JAW BY PLACING THUMBINTO CORNER OF MOUTH.
DO NOT HOLD OR DEPRESS TONGUE.
(DPINCH NOSE SHUT OR SEAL MOUTH
PREVENT AIR LEAKAGE.
PINCH NOSE
(OR SEAL LIPS)
@OPEN YOUR MOUTH WIDE AND BLOW
TAKE A DEEP BREATH AND BLOW FORCEFULLY (EXCEPT
FOR BABIES) INTO MOUTH OR NOSE UNTIL YOU SEE CHEST
RISE.
GLISTEN FOR EXHALATION
WICKLY REMOVE YOUR MOUTH WHEN CHEST RISES. LIFT
JAW HIGHER IF VICTIM MAKES SNORING OR GURGLING
BLOW
SOUNDS.
()REPEAT STEPS SIX AND SEVEN 12 TO 20 TIMES
PER MINUTE
CONTINUE UNTIL VICTIM BEGINS TO BREATHE NORMALLY.
FOR INFANTS SEAL BOTH MOUTH AND NOSE WITH YOUR
MOUTH
BLOW WITH SMALL PUFFS OF AIR FROM YOUR CHEEKS.
B
A
/7O
4.224
Figure 2-3. Artificial respiration and cardiac massage.
22P
IC ELECTRICIAN 3 & 2
first so that the fingers point toward neck as in
and decrease in the size of the chest, internally
or externally, will move air in and out of a nonbreathing person.
figure 2-3 C.
With arms nearly straight, rock forward so
that a controlled amount of your body weight is
transmitted through your arms and hands to the
breastbone. The amount of pressure to apply will
The mouth-to-mouth or (mouth-to-nose)
technique has the advantage of providing pressure to inflate the victim's lungs immediately.
It also enables the rescuer to obtain more accurate information on the volume, pressure, and
timing of efforts needed to inflate the victim's
vary with the subject. It should be applied as
smoothly as possible. With an adult subject, the
chest wall should be depressed 2 to 3 inches
with each pressure application.
Repeat application of pressure about 60 to 80
times per minute.
lungs than are afforded by other methods.
An assistant should be ventilating the subject's lungs preferably with pure oxygen under
intermittent positive pressure; otherwise with
mouth-to-mouth resuscitation. However, closed
chest massage will cause some ventilation of the
lungs. Therefore, if you are alone, you mustconcentrate on the massage until help can arrive.
Direct other assistants, when available, to
keep checking the patient's pulse. Use the least
pressure that will secure an effective pulse beat.
The pupils will become smaller when effective
cardiac massage is being performed.
Pause occasionally to determine if a spontaneous heartbeat has returned.
When a person is unconscious and not breathing, the base of the tongue tends to press against
and block the upper air passageway. The procedures described below should provide for an open
air passageway when a lone rescuer must
perform artificial respiration.
First, if there is foreign matter visible in the
mouth, wipe it out quickly with your finger or a
cloth wrapped around your finger. Tilt the head
back so the chin is pointed upward (fig. 2-4A).
Pull or push the jaw into a juttingout position
(fig. 2-4B and C). These maneuvers should
relieve obstruction of the airway by Moving the
base of the tongue away from the back of the
PRECAUTIONS: Make every effort to keep the
hands positioned as described in order to prevent
throat.
injuries to the liver, ribs, or other vital organs.
Since the heart cannot recover unless supplied
with oxygen blood, it is necessary to accompany
cardiac massage with mouth-to-mouth artificial
respiration. When there is only one operator, the
cardiac massage must be interrupted every halfminute or so to institute rapid mouth-to-mouth
breathing for three or four respirations.
Open your mouth wide and place it tightly over
the victim's mouth. At the same time pinch the
victim's nostrils shut (fig. 2-4D) or close the
nostrils with your cheek (fig. 2-4E). You may
close the victim's mouth and place your mouth
over the nose (fig. 2-4F).
Blow into the victim's mouth or nose. Air may
be blown through the victim's teeth, even though
they may be clenched. The first blowing efforts
The mouth-to-mouth (or mouth-to-nose) tech-
nique of artificial respiration is the most ef-
should determine whether or not obstruction
exists.
Remove your mouth, turn your head to
fective of the resuscitation techniques.
The mouth-to-mouth (or mouth-to-nose)
technique of artificial respirations is the most
the side, and listen for the return rush of air that
indicates air exchange. Repeat the blowingeffort.
Blow vigorously at the rate of about 12 breaths
per minute.
If you are not getting air exchange, recheck
the head and jaw position. If you still do not get
air exchange, qUickly turn the victim on his side
and administer several sharp blows between the
shoulder blades in the hope of dislodging foreign
matter (fig. 2-4G).
Again sweep your finger through the victim's
mouth to remove foreign matter. Those who do
not wish to come into contact withthe person may
hold a cloth over the victim's mouth or nose and
breathe through it. The cloth does not greatly affect the exchange of air.
practical method for emergency ventilation of an
individual .of any age who has stopped breathing,
in the absence of equipment or of help from a
second person, regardless of the cause of cessation of breathing.
Persons who are trained in first-aid do not
usually have the experience, training, and essential equipment to determine whether or not lack
of breathing is a result of disease or accident.
Therefore, some form of artificial respiratidn
should be started at the earliest possible moment.
Any procedure that will obtain and maintain
an
open air
passageway from the lungs to
the mouth and provide for an alternate increase
8
22
Chapter 2SAFETY
A
B
C
D
E
F
G
4.224
Figure 2 -4,
Mouth -to -mouth respiration.
When radio or radar antennas are energized
by transmitters, workmen must not go aloft unless advance tests show positively that no danger
exists. A casualty can occur from even a small
spark drawn from a charged piece of metal or
rigging. Although the spark itself may be harm-
If you work near a stvic, draw and wear the
oxygen breathing apparatus.
Among other toxic substances, stack gas contains carbon monoxide. Carbon monoxide is too
unstable to build up to a high concentration in
the open, but prolonged exposure to even small
quantities is dangerous.
Observe these safety precautions when you
as those on stations ashore or aboard a ship
munications Watch Officer and 00D.
WORKING ALOFT
recommended
less, the "surprise" may cause the man to let
go his grasp involuntarily. There is alsc shock
hazard if nearby antennas are energized, such
are going aloft:
1. You must have permission of the Com2. You must have the assistance of another
moored alongside or across a pier.
man along with a ship's Boatswain's Mate qualified in rigging.
Danger also exists that radar or other ro-
tating antennas might cause men working aloft
to fall by 'mocking them from their perch. Motor
safety switches controlling the motion of radar
antennas must be tagged and locked open before
anyone is allowed aloft close to such antennas.
3. Wear a safety belt. To be of any benefit,
the belt must be fastened securely as soon as you
reach the place where you will work. Some men
have complained on occasion that a belt is clumsy
23
29
IC ELECTRICIAN 3 & 2
and interferes with movement. It is true the job
may take a few minutes longer, but it is also true
that a fall from the vicinity of an antenna is
usually fatal.
4. Do not attempt to climb loaded with tools.
Keep both hands free for climbing. Tools can be
raised to you by your assistant below. Tools
should be secured with preventer lines to avoid
dropping them on your shipmate.
5. Ensure yourself of good footing and grasp
PERSONNEL ARE CAUTIONED TO GUARD
AGAINST POISONOUS EFFECTS OF SMOKE PIPE
GASES WHILE SERVICING EQUIPMENT ALOFT.
WHEN SERVICING EQUIPMENT IN THE WAY
OF SMOKE PIPE GASES USE OXYGEN BREATHING
APPARATUS AND A TELEPHONE CHEST OR
THROAT MICROPHONE SET FOR COMMUNICATION
WITH OTHERS IN WORKING PARTY.
OBTAIN NECESSARY EQUIPMENT BEFORE
at all times.
6. Remember the nautical expression of old
seafarers: HOLD FAST
7. Ensure that the boiler safety valves are
not being set by checking with the engineer
officer.
o GOING ALOFT.
o
WARNING SIGNS, PLATES, AND TAGS
Warning signs and suitable guards shall be
40.67(26D)
provided to prevent personnel from cnming into Figure 2-6. Smoke pipe gases warning sign.
accidental contact with dangerous voltages, for
warning personnel of possible presence of explosive vapors, for warning personnel working warning signs not listed should be ordered on a
aloft of poisonous effects of stack gases, and for separate requesting document.
warning of other dangers which may cause inDrawings of the standard warning signs most
juries to personnel. Equipment installation should frequently used have been prepared by the Naval
not be considered completed until assurance Ship Systems Command.
has been posted in full view of operating perFigure 2-5 is a High Voltage Warning Sign
sonnel.
Certain types of standard electronics warning
signs are available for procurement for the
Commander, Philadelphia Naval Shipyard. A list
of signs that are available has been distributed to
all ships, commands, and shore activities. Any
(NavShips Drawing No. RE 10 B 608B). This sign
is to be displayed at all locations where danger
to personnel exists, either through direct contact
with high voltage or through high voltage arcover. Appropriate guards should also be installed
at these locations.
Warning Sign for Personnel Working Aloft in
Way of Smoke Pipe Gases (NavShips Drawing No.
RE 10 AA 529A) is to be displayed at the bottom
and top of access ladders to electronic equipment
in
the way of smoke pipe gases (fig. 2-6).
RF Radiation Hazard Warning Sign (NavShips
Drawing No. RE 10 D 2282). These signs are of
the following four types and are included in the
same drawing (fig. 2-7a through d).
1. Type a. To be located on radar antenna
pedestals.
2. Type b. To be located on or adjacent to
radar set controls.
3. Type c. To be located at eye level at the
foot of ladders or other accesses to all towers,
masts, and superstructures which are subjected
to hazardous levels of radiation.
4. Type d. To be located in radio transmitter
40.67(31) rooms in suitable locations in full view of operFigure 2-5. High voltage warning sign.
ation personnel.
1414
col"
Chapter 2SAFETY
kWARNINGA
R F RADIATION HAZARD
A HAZARD TO PERSONNEL EXISTS IN THE
ANTENNA SEAM OF HIGH POWERED RADARS
NONIRON WE DISTANCI rim
swomm
WWI
fun HAN *CANN*.
NOTATOIS "0 NOTATIM
1
b.
oi
.37.)1
WARNING
WARNING
RF RADIATION HAZARD
R F RADIATION HAZARD
A RADIATION HAZARD TO PERSONNEL EXISTS IN THE
00 NOT HAKE A DIRECT VISUAL EXAMINATION
ANTENNA BEAM OF HIGH POWERED RADARS
CHECK WITH RADAR PEfriONNEL
OP ARV MICROWAVE RADIATOR, REFLECTOR,
WAVERIJIDE OPENING OR WAVEGUIDE
BEFORE PROCEEDING
MORN DURING PERIODS OF
TRANSMISSION
BEYOND THIS
POINT
TM t
IMC
WARNING
a.
C.
R F. RADIATION HAZARD
\..TRAIN
WITH POWER OUTPUTS OP *WI WATTS ON MN
WILL NOT DE MOAT'S WREN IINIDUINIC0111114TIOLIS ON
ILIC T ORALLY INITIATES ONDINUICR WINOS SOFT Or ASINP
CIATIO ANTENNASMANSIIITTENS WITN POPES
OUTPUTS If NONE THAN 05 WATTS mu.
OCT OR RPM? ED WNEN NiVIDUNIII
ANT OP TICE Agra MENTIONINI
ITEMS WITHIN 100 IT
SI ASSOCIATED
ANTENNA
ME
d.
40.67(76)
Figure 2- 7.--RF radiation hazard warning signs.
displayed in all spaces where there is a
possibility of the accumulation of explosive vapors
(fig. 2-8).
Warning Plates for Electronic Equipment
Installed in Small Craft (NavShips Drawing No.
RE 10 A 589). This sign is a warning against the
energizing of electronic equipment until ventilation blowers have been operating a minimum of
5 minutes to expd explosive vapors. Althoughthe
drawing title indicates this warning plate is to be
Warning Tags for Marking Open Position of
Switches and Cutout Circuits (NavShips 3950
(3-63)-GPO: 1963-0-674658 (on reverse side of
tag). This tag is used to indicate a switch which
must be left in the OFF or OPEN (safe) position
installed in small craft, it may and should be
25
74
IC ELECTRICIAN 3 & 2
operations afloat and ashore are observed. Subjects for consideration are listed below:
WARNING
1. Wear loose clothing tight clothing and
foot gear restrict blood circulation and invite
00 NOT ENERGIZE ELECTRONIC EQUIPMENT
UNTIL VENTILATION BLOWERS HAVE BEEN
OPERATING A MINIMUM OF FIVE MINUTES
TO EXPEL EXPLOSIVE VAPORS
frostbite or trench foot.
Wear dry clothingouter layers should be
water repellent and impervious of rain, snow,
and sleet.
2. Avoid overheatingexcessive sweating
dampens clothing, resulting in poor insulation.
40.67(140)
'
Figure 2 -8. Warning plate for electronic equipment installed in small crafts.
Perspiration cools the body even more as it
during repairs. These tags are available for
evaporates. It is better to be slightly chilly
than excessively sweaty.
COLD WEATHER SAFETY PRECAUTIONS
allow removal as body heat rises.
4. Work in pairs check each other for frostbite, since a person can become frostbitten
ship and shore personnel through normal supply
channels (fig. 2-9).
3. Wear several layers of thin clothing to
and not realize it. Frostbitten skin becomes
whitish or grayish, and the parts feel numb
Careful instruction and indoctrination of all
personnel are necessary to ensure that safety
precautions peculiar to cold weather and arctic
rather than painful.
5. Wear sun glasses or goggles with tinted
lenses to protect from snow blindness and eye
strain.
6. Never touch metal objects with bare hands
although seemingly dry; they will freeze to very
cold metal.
7. Be very careful when working with fuels
and volatile liquidsgasoline will freeze flesh
in a matter of seconds.
8. Use wind shields or screens whenever
working on exposed equipments.
9. Frequent rest, hot drinks, and food are
necessary for efficiency of personnel working
on exposed equipment.
WORKBENCHES
As an IC Electrician, you will be doing a
great deal of equipment testing and repairing
on a workbench in the IC room. To avoid getting
shocked while working there, you must be careful, and your workbench must be insulated properly.
Figure 2-10 shows the construction features
of a safe electric or electronics workbench. Its
work surface, or top, is usually 30 inches wide
and 4 feet long. The bench must be fastened
securely to the deck.
The joints of surrounding portable deck plates
wsso,9300.°S1.04511
S.° Cr 101
OP°. t VA °
ON
must be insulated with epoxy fiberglass strips
Wit"
(MIL-P-18177, type GEE) and secured with nylon
sorews as delineated in NAVSHIPS Drawing
05-2104467, if the deck plates have vinyl deck
40.67(67B)C
Figure 2-9.-Warning tag for marking open position of switches and cutout circuits.
covering. Where vinyl deck covering is not used,
matting (not less than 3-foot widths) will be
26
32
Chapter 2SAFETY
be installed for every 4 feet of workbench length
to ensure positive grounding of the equipment
being tested. The grounding leads installed on
ships with wooden hulls should be the same as
those installed on ships having stclel hulls except
that the leads should be secured to the ship's
electrical grounding system. A bare solid copper
conductor, not less than 83,690 circular mils,
must be used for the main internal grounding
wire.
Test bench receptacle panels should be installed on test benches where power at various
voltages and frequencies (other than ships service) are needed for testing equipment. In addition, ore symbol 730.1 (or alternate symbol
730.4) receptacle must be installed within 5 feet
of each workbench.
IIIWorking area (top, top edge, front of doors & drawers)
The illumination requirements vary between
those for general purpose workbenches andwork-
insulated with 3/8nich Ilene lex 401 (FSN 9Q.
5640.256-5194).
benches for the repair of instruments, such as
typewriters and meters. A warning plate which
171 All other exposed metal surfaces in the working area
(bench front and sides, kneehole sides, underside of top,
insulated with 118.inch Benelex 401,
reads, ELECTRIC SHOCK DANGER DO NOT
TROUCH ENERGIZED CIRCUITS must be installed over the workbench. Artificial respiration
Rubber matting may be either grey (FSN 9Q-7220.2674630) or green I FSN 9Q-7220-913-87511. but a minimum
of 3 feet in width.
instructions and a description of an approved
method of rescuing personnel in contact with
energized circuits must also L posted.
A dunimy outlet should be installed near the
140.116
Figure 2-10.
workbench for checking the grounding conductor
on portable tools.
Typical electric workbench.
BURNS
installed over the minimum area necessary to
prevent electrical shock. Additionally, a 3-foot
width of rubber matting will be installed to insulate the walkway in front of insulated workbenches where vinyl sheet is not specified.
The top and front surfaces of an electric or
The principal dangers from burns are shock
and infection. All casualty care measures must
be directed toward combating shock, relieving
the casualty's pain, and preventing infection.
electronics workbench must be insulated with 3/8-
CLASSIFICATION OF BURNS
inch Benelex 401. In addition, exposed ends of
the workbench and kneeholes under auxiliary
work tables must be insulated with 1/8-inch
insulation of the same material. Don't defeat the
Burns may be classified according to their
cause as thermal, chemical, or electrical.
Thermal burns are the direct result of heat
purpose of the insulation by attachingvises, locks,
hasps, hinges, or other hardware with metal
throughbolts to the metal parts of the workbench.
The workbench must have grounding leads
that are 4 feet long and of type D, size 10 (in
such as fire, scalding, sun or explosion blast.
Chemical burns are produced by chemical action such as battery acid on tissues. Electrical
burns may be caused by electrical current passing through tissues or the superficial wound
caused by electrical flash.
Bruns may also be classified as first, second,
at
(fig. 2-11). First-degree burns are character-
When mounting hardware items, insulate them
from the workbench.
or third degree, based on the depth of skin damage
accordance with MIL-W-16878). The ground loads
must be secured to the ship's structure
CT
ized only by reddening of the skin. Second-degree
the back of the workbench and equipped at the
free end with a 50-ampere power clip (type PC)
burns are characterized by blistering of the
skin, either early or late. They are the most
painful type of burn. The complete thickness
and insulated sleeving (both conforming to Federal
Specification W-C -440). One grounding lead should
27
33
IC ELECTRICIAN 3 & 2
INIRD-DEGREE
BURN
W.COND-DEGREE
BURN
FIRST-DEGREE
BURN
Figure 2-12.
136.32
First, second, and third degree
burns.
is not as painful as a second-degree burn because the sensory nerve endings have been
destroyed.
Emergency Treatment
The degree of the burn, as well as the skin
area involved, determines the procedures used
in treatment of burns. Large skin areas requires a different approach than small areas.
To estimate the amount of skin area affected,
18%
use fig. 2-12.
As a guideline, consider that burns exceeding
20 percent of the body surface endanger life;
the old or the very young patient will not tolerate
burn injuries well; without adequate treatment,
burns of more than 30 percent are usually fatal
to adults.
If time and facilities permit caring for patients
with superficial burns, the area should be cleaned
with soap and water. A simple sterile dressing
of fine-mesh, dry gauze is then applied over the
area to protect it from infection.
Based on field level casualty treatment conditions, superficial burns include first-degree
burns and lesser second-degree burns, which
136.31
Figure 2-11. Rule of Nines for estimating percentage of burned area.
need little attention beyond self-care.
When emergency treatment of the more serious second-degree burns and third-degree burns
of the skin is not destroyed. Third-degree burns
is required, treat the patient for shock first.
Make the patient as comfortable as possible,
and protect him from cold, excessive heat, and
are characterized by complete destruction of
the skin with charring and cooking of the deeper
tissues. This is the most serious type of burn,
for it produces a deeper state of shock and
more permanent damage and disfigurement. It
rough handling.
The loss of body fk ds is the main factor
in burn shock. Start oral therapy gradually at
28
Chapter 2 SAFE TY
first by giving him small amounts of hot coffee,
tea, fruit juice, or sugar water. Give the drinks
frequently but only if the patient is conscious,
able to swallow, and has no internal injuries.
To enable trained personnel to determine the
kind of treatment required, no medication should
be applied to burns during emergency treatment.
Pain is closely allied to the degree of shock,
and should be relieved as soon as possible. When
available, ice water is an effective pain reducer.
Flooding with lots of clean, cool freshwater helps
also provided that not too much force is used. In
electric shock cases, burns may have to be ignored temporarily while the patient is being revived.
After the patient has been treated for pain and
shock, a compress and bandage may be applied to
protect the burned area. If a universal protective
dressing is not available, fine mesh gauze may be
substituted. Constricting articles of clothing and
ornaments should be removed, and the burned
area should be elevated and immobilized.
Patients with extensive deep burns must be
evacuated to a medical facility for treatment
as rapidly as possible. Pain should be alleviated and shock must be controlled before and
a shower and let the water run as long as necessary.
In order to make the washing process effective, you will of course have to remove all
clothing which has come in contact with the
chemical. Strip it off as quickly as possible;
or, if shears are available, cut it off.
If it is not possible to put the casualty under
rtum4ng water, immerse the affected areas in
the lulest available amount of water, or pour
great quantities of water over him.
It is important to use a large quantity of
water, so that the chemical will be diluted and
weakened; but you should not apply it forcefully.
The skin and tissues which are injured by the
action of the chemical will suffer additional
damage if the water is applied with too much
force.
2. Neutralize any chemical which remains
on the skin, by the following applications: for
ACID burns, apply a solution of sodium bicarbonate (baking soda) or some other mild alkali.
DO NOT ATTEMPT TO NEUTRALIZE ANY
CHEMICAL UNLESS YOU ARE SURE THAT YOU
KNOW WHAT IT !S A..isID WHAT SU_STANCE
WILL EFFECTIVELY NE U TRA LIZ E IT!
3. Wash the affected areas again with fresh
during evacuation.
water, and dry gently with sterile gauze. Be
careful that you do not break the skin or open
any blisters. Take all possible precautions to
Debris and loose clothing must be removed
from burned areas to prevent irritation while
the patient is bring treated and transported.
Clothing that sticks to a burn may be cut around
avoid infection.
4. Do whatever you can to relieve the cas-
the burn and the adhering cloth allowed to remain
ualty's pain and to treat him for shock. extensive
chemical burns, like extensive heat burns, cause
extreme pain and shock.
until it can be removed at the medical facility.
Tne area of the burn is usually sterile; therefore,
care should be taken not to contaminate it.
From this point on, it is usually safe to
treat a chemical burn as though it were a true
Chemical Burns
burn, except that petrolatum gauze should not be
applied unless you are certain aa of the chemical has been removed. Get medical attention
for the casualty as soon as possible.
When acids, alkalies, or other chemicals
come in contact with the skin or other body
membranes, they may cause injuries which are
generally referred to as CHEMICAL BURNS.
For the most part, these injuries are not caused
by heat but by direct chemical destruction of the
body tissues. Chemicals which often cause this
Chemical Burns of the Eye. Chemical burns
of the eye should be treated as follows:
sulphuric acid, hydrochloric acid.
1. Flush the eye IMMEDIATELY with large
quantities of fresh, clean water. A drinldng
sists of the following measures:
of water; hold the casualty's head in position
kind of injury are acids, such as nitric acid,
fountain may be used to supply a steady stream
First aid treatment for chemical burns con-
so that the water flows from the INSIDE corner of
his eye toward the OUTSIDE corner. Do NOT let
the water fall directly on the eyeball, and do NOT
1. WASH OFF THE CHEMICAL WHICH IS
CAUSING THE INJURY! This must be done
IMMEDIATELY. Flood the affected areas with
large amounts of waterpreferably water which
is clean, fresh, and cool. The best way to get
rid of the chemical is to put the casualty under
use any greater force than is necessary to keep
the water flowing across the eye.
If you are not near a drinkAng fountain, have
the casualty lie down with his head turned slightly
29
25
IC ELECTRICIAN 3 & 2
to one side; then pour water into the INSIDE
corner of his eye and let it flow across the eyeball to the OUTSIDE corner. Remember that the
water-ma-St not fall directly upon the eyeball, and
that it must not be poured with any greater
force than is necessary to sustain the flow across
the eyeball.
NOTE: Because of the intense pain, the
casualty may be unable to open his eyes.
If this occurs, you must hold the eyelids
apart so that the water can flow across
the eyeball.
Another way to wash chemical substances
from the eye is to have the casualty open and
u6
30
close his eyes several times while his face is
immersed in a pan or bucket of fresh water.
2. Cover the eye with a small, thick com-
press; fasten the compress in place with a bandage or an eyeshield.
3. Get medical care for the casualty as soon
as possible.
CAUTION: Do not use anything except water
in treating chemical burns of the eye. Do not
attempt to neutralize the chemical which has
caused the injury. Do not apply any ointment,
grease, oil, or salve.
CHAPTER 3
SWITCHES, PROTECTIVE DEVICES, AND CAMS
indicates the number of places at which the operating device (toggle, plunger, etc.) will come
As an Interior Communications Electrician,
you will be working with sophisticated circuitry,
consisting of complex equipment, multiconductor
cabling, and a variety of switching and protecting
to rest.
Another means of classifying switches is
devices. The material which follows will give
you a basic understanding of the hardware
(switches, protective devices, and cable) of
interior communications. You will be able to
recognize installations, and with limited super-
method of actuation; that is, knife, toggle/ push,
or rotary. Further classification includes a description of switch action, such as on-off, momentary
on-off,
and on-momentary off.
Momentary contact switches hold a circuit closed
or open only as long as the operator deflects the
actuating control.
vision you will be capable of installing this
hardware on board ship after studying the
material presented. Not every component used
in the Navy is covered, but rather the common
installations.
KNIFE SWITCH
The knife switch (fig. 3-1) is the basic power
switch from which most modern switches
have been developed. A single-pole, single-
SWITCHES
throw knife switch consists of a single copper
blade hinged at one end and designed to fit
tightly between two copper jaws, or clips, at
the other end. An insulated handle is fastened
A basic understanding of switches and their
uses is a necessity for the IC Electrician. The
Navy uses hundre:.'s of different types of
switches.
to the copper blade to open and close the switch.
Terminals are provided for connecting the leads.
A switch may be described as a device used
for making, breaking, or changing connections
A two-pole, single-throw knife switch (fig.
3-1A), has two blades with one set of clips for
each blade and an insulated handle that operates
in an electrical circuit. Switches are rated in
amperes and volts; the rating refers to the
maximum allowable voltage and current of the
circuit in which the switch is to be used. Since
it is placed in series, all the circuit current will
pass through the switch; because it opens the
circuit, the applied voltage will appear across
the switch in the open circuit position. Switch
contacts should be opened and closed quickly to
minimize arcing; therefore, switches normally
utilize a snap action.
both
blades
simultaneously. Double-throw
switches (fig. 3-1B) have two sets of clips (one
set at each end) so that the blades can be thrown
Many types and classifications of switches
have been developed. A common designation is
by the number of poles, throws, and positions.
The number of poles indicates the number of
terminals at which current can enter the switch.
The throw of a switch signifies the number of
circuits each blade or contactor can complete
through the switch. The number of positions
31
37
1.102
Figure 3-1. Knife switches.
IC ELECTRICIAN 3 & 2
0
-*-_--.:::---->
0.--/.
0
"MAKE"
;..
e
V,
"BREAK"
A
A
...
Ito.
---'
Figure 3-3.
,cl
Pushbutton switch.
1.99
.,,...;--.
The following types of switches are also
used: 3-pole,
single-throw (3PST); 3-pole,
(3PDT); 4-pole, single-throw
(4PST); and 4-pole, double-throw (4PDT). The
'4.
double-throw
0
voltage ratings range from 20v to 600v, and
the amperage ratings range from 1 ampere to
o
30 amperes.
C
D
PUSHBUTTON SWITCH
Figure 3-2.
1.98
Toggle switches.
The normal contact arrangement of a push-
button switch is either "make" or "break" as
shown in figure 3-3. The make-type of switch
is usually a start switch; the break-type, a stop
switch. Either switch may be locking or non-
into either set of clips to shift from one circuit
to another.
locking. There is also a break-make pushbutton
TOGGLE SWITCH
switch (not shown).
Representative examples of toggle switches
are shown in figure 3-2. In part A is shown a
ROTARY SNAP SWITCH
rates at 20v and 20 amperes, and having 2
solder terminals. The schematic diagram is
that opens or closes a circuit with a quick
single-pole, single-throw (SPST) toggle switch,
The rotary snap switch (fig. 3-4) is a device
motion. A type SR rotary snap switch consists
of one or more sections, each of which has a
rotor and a stationary member. Movable contacts are mounted on a bushing and stationary
shown beneath the switch. This switch is used
to open or close an electric circuit.
Part B shows a single-pole, double-throw
(SPDT) switch, rated at 250v and 1 ampere,
and having 3 screw terminals. One of the uses
contacts are mounted on insulated discs, which
are arranged one beneath the other in "pan-
of this switch is to turn a circuit on at one
cake" style along the switch shaft. This type of
construction has the advantages of shockproof-
place and to turn if off at another place. It is
sometimes called a 3-way switch.
A double-pole, single-throw (DPST) switch
ness, compactness, flexibility of circuit ar-
rangements, and protection to the operator. The
operator, by rotating the switch handle, triggers
a spring and cam arrangement, which, in turn,
operates the switch contacts. If the spring should
break, further rotation of the handle will eventually cause a projection on the handle's shaft to
is shown in part C. It has 4 solder terminals
and is rated at 250v and 1 ampere.
A double-pole, double-throw (DPDT) switch
is shown in part D. It has 6 solder terminals
and is rated at 125v and 3 amperes.
32
ai
Chapter 3SWF:TRES, PROTECTIVE DEVICES, AND CABLES
HANDLE
CAP
SNAP
MECHANISM
MOUNTING
SPACER
12.69
Figure 3-4.
PANCAKE
Type SR rotary snap switch (10
ampere size, 1SR).
contact a projection on the operating shaft to
ROTARY
CONTACT
operate the switch. However, the switch-driving
shaft and handle will be misaligned from its
normal position, and the characteristic snap
action will not be apparent.
Snap switches are available in a wide variety
of amperage ratings (from 10 to 200), poles, and
mountings (bulkhead or panel mounting).
STA1 IONARY
CONTACT
The switch type designation indicates its
current rating (15It is 10 amp, 3SR is 30 amp,
and so on); number of poles (3SR3 is 30 amp,
3 pole); switching action (1SR3A is single throw,
that is on-off); mounting style (1SR3A1 is frontmounted, back-connected); and enclosure for
type switches (3SR4B1-3 is watertight). An ex-
ploded view of a type 6SR snap switch is illustrated in figure 3-5.
Most snap switches are suitable for 450 volt, 60-hertz, a-c and 250-volt d-c operation.
Present 10-ampere switches are suitable for
120-volt operation only, although the switches
are sometimes used at higher voltages where
the currents are very small. Care must be
exercised in the application cf multithrow
(double-throw and triple-throw) switches. The
movable blade, in some cases, is so wide that
in moving from one stationary contact to a second, the two stationary contacts will be momentarily bridged by the arc and movable blade,
causing a short circuit. Therefore, each time
a multithrow switch is to h.4 installed, a careful check should be made on both the switch and
140.1
Figure 3-5. Type SR snap switchexploded
view (60 ampere size 6SR).
the intended circuit to make sure that a switch
of the proper current and voltage ratings is
used.
PILE SWITCH
Pile switches are constructed so that they open
or close one or more electrical circuits.
sliding motion.
33
39.
The
contacts are arranged in leaf, or pileup, fashion
and may be actuated by a rotary, pushing, or
IC ELECTRICIAN 3 & 2
01111
FORM F
FORM A
"MAKE-MAKE"
"MAKE"
FORM B
FORM 6
"BREAK"
"BREAK-BREAK"
FORM C
FORM H
"BREAK-MAKE"
"BREAK-BREAK-MAKE"
W-1
FORM 0
"MAKE BEFORE-BREAK"
FORM .1
"MAKE-BEFOREBREAK-MAKE"
0.--------A
FORM E
"BREAK -MAKE-
BEFORE- BREAK"
0"---54
FORM l
"BREAK-MAKE-MAKE"
B
I
Figure 3-6. Pile type switches.
The various basic forms of the contact ar-
1.99: 104
used in relays, key switches, and jacks in lowvoltage signal circuits.
rangements in pile switches are shown in figure
3-6A. These basic forms are used by themselves
or in combination to make up the contact assembly
ROTARY SELECTOR SWITCH
of a pile switch. Figure 3-6B shows a contact
assembly made by combining two"break-make/'
A rotary selector switch may perform the
to form C, contact arrangements. This switch
functions of a number of switches. As the knob
or handle of a rotary selector switch is rotated,
it opens one circuit and closes another. In figure
3 - ?, the contact is from A to E. If the switch is
rotated clockwise, as viewed, the circuit from
is therefore designated 2C. When the armature
is moved upward by the rotary motion of the cam
lobe (fig. 3-6B), two circuits are opened and two
are closed. This type of switch is commonly
34
40,
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
12.68
Figure 3-7. Rotary selector switch.
A to E is opened and the circuit from A to D is
completed. Some rotary switches have several
layers of pancakes or wafers. By means of
additional wafers, the switch can be made to
operate as several switches. Oscilloscope and
and pancake sections. The number of sections
required in the switch is determined by the
individual application. A shaft with an operating
handle extends through the center of the rotors.
The movable contacts are mounted on the rotors,
voltmeter selector switches are typical examples
of this type. These switches are more common
in civilian equipment than in military hardware.
and the stationary contacts are mounted on the
pancake sections. Each section consists of eight
Type J
Each movable contact is arranged to bridge
two adjacent stationary contacts. The switch
The type J multiple rotary selector switch
(fig. 3-8) consists of an equal number of rotors
contacts, designated A to H, and a rotor with
two insulated movable contacts spaced180° apart.
eight positions. A detent mechanism
is provided for proper alignment of the contacts
in each position of the operating handle. In one
position, the rotor contacts bridge segments
A-B and E-F; in the next position, the
has
rotor contacts bridge segments B-C and F-G.
Diagonally opposite pairs of contacts are subsequently bridged for the remaining positions.
Type JR
The type JR switch (fig. 3-9) is installed on
recent IC switchboards. This switch is smaller
in size and more rapidly disassembled than the
J switch. These features result in a saving in
switchboard space, and facilitate repairs. The
JR switch is of the 1JR, 2JR, 3JR, or 4JR
type.
The 1JR switch has only one movable contact per section. This movable contact bridges
two adjacent stationary contacts.
The 2JR switch has two movable contacts
per section, 180° apart. Each movable contact
12.70
bridges two adjacent stationary contacts.
Figure 3-8. Type J switch.
35
41
IC ELECTRICIAN 3 & 2
The designations of JR switches are determined by the type of section (rotary and stationary contacts) followed by the number of
sections in the switch. For example, a 2JR10
PANCAKES
switch denotes a JR switch with ten 2JR sections.
The JR switch is stocked in multiples of 5
sections (up to 25 sections). In some cases, a
switch with a number of sections (not a multiple
of five) has been installed. If this switch must
be replaced, a switch with the next largest number of sections that is a multiple of five should
be installed if space permits.
Type JR switches are rated at 120 volts, 60
hertz, and 10 amperes. The switch should not be
used on d-c circuits because of the possibility of
severely burned contacts when operated slowly
(teased). The switch is of the nonshorting type.
Although the blade bridges two adjacent contacts
simultaneously (for example, contacts 1 and 2
DETENT/
STOP
PLATE
MECHANISM
A
Figure 3-9.
Type 4JR switch.
when the switch is operated), the blade breaks
contact 1 before making the next alternate contact 3. For example, in the 2JR switch alternate
terminals may be connected to an inuependent
source of a-c power without danger of short
circuit during movement of the switch blade.
Barriers are also provided between sections
to prevent terminals from turning and shorting
to adjacent terminals.
If the sections are not uniform the switch
will be designated by JRSP followed by the
12.71
number of sections.
The JR switch has a stop deck, which permits setting the switch to the number of positions desired. Pins or screws inserted in the
stop deck immediately after the desired last
position, will limit the switch movement to the
The 3JR switch utilizes one of the stationary
contacts as a common terminal. This stationary
contact is connected, in turn, to each of the
other stationary contacts of the section by a
positions between these points.
single-wiper contact. The 3JR-type is used for
selecting one of several (up to seven) inputs.
Type JL
The 4JR switch is designed as an "either or
both switch" with two movable contacts per
section. Each movable contact bridges three
adjacent stationary contacts (fig. 3-9B). This
switch is used to select either or both of two
indicators or synchros. The positions for ener-
The JL switch is identical to the JR, except
in size, mounting facility, and electrical rating.
The diameter of the JL deck is approximately
1 3/4 inches; whereas the diameter of the JR
deck is approximately 2 1/4 inches. The rating
of the JL switch is 120 volts, 60 hertz, 5 amperes. Standard types are available in 3, 5, and
10 sections. The JL switch has a threaded bush-
gizing two indicators are:
90° right both indicators energized.
45° right indicator 1 energized only.
ing for single-hole mounting.
0° off.
Type JA
45° leftindicator 2 energized only.
The JA switch (fig. 3-10) was developed pri-
When the 4JR switch is in the OFF position,
both indicators are connected together, but are
marily for circuit selection in sound-powered
telephone applications. It provides a greater
number of selections and is a smaller switch
disconnected from the power supply.
36
H
42
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
A
ill'
II
&
3
I
I
4
III ®III III
5
6
65.75
Figure 3-11.
Type A switch contacts.
insulating film form:, over the contacts which
is only broken down if appreciable voltage and
power are available in the circuit. However, in
sound-powered telephone circuits, there is insufficient power to break down the film, and
relatively high resistance results. The silverto-silver contacts of the JA switch consist of
pure silver welded to beryllium copper. Silver
1
I
I
®1
3
1
1
1
I
1
1
1
1
4
1
1
6)
5
1
1
1
1
1
1
1
I
6
7
140.2
Figure 3-10. Type JA switch and detent mechanism.
than the JR switch. The JA switch is furnished
only wit!, common rotor sections as shown in
figure 3-11. Sixteen-position and 30-position JA
switches permit selection of 16 and 30 circuits,
respectively. With the JR switch the maximum
number of possible selections is 7.
The JA switch also provides lower contact
140.3
resistance by using either silver or silveroverlay contacts. With brass or copper, an
Figure 3-12.
37
4.3
Type JF switch.
TC ELECTRICIAN 3 & 2
or silver-coated contacts are now being utilized
for latest type JR switches and other low-current
switches. In larger switches, silver (unless
alloyed with other metals) is unsatisfactory
because it vaporizes too readily due to arcing.
The JA switch is available in 2, 6, and 10
sections. An example of the switch designation
outside of the mounting bushing to give a watertight seal against the panel in which the switch
is mounted. These features have eliminated the
need for a watertight cover over the switch.
The JF switch is satisfactory for 120 volt,
a-c applications up to 1 ampere. It is being
is J A6C (16) for a 6-section, 16-position switch;
used in sound-powered telephones, loudspeakers,
microphone stations, and similar low-current
equipment.
positions.
CAUTION: The switch decks are made of
molded nylon material. Be careful in soldering
here the first number designates the number of
sections, the C indicates common rotor, and the
number of parentheses indicates the number of
leads to the switch contacts. Too much
the
Type JF
The JF switch (fig. 3-12), was developed
primarily to replace toggle switches in the 10
and 20 switch boxes for sound-powered telephone
applications.
Because of the problems in making toggle
switches watertight, it was necessary to provide
a gasketed cover for the 10- and 20-switch boxes,
which contained the toggle switches. The cover
had to be open when the switches were operated.
Therefore, the switch box was not watertight,
leading to possible malfunctioning of the
switches. In addition, the lack of a strong contact wipe action in toggle switches and the low
voltage and current of sound-powered circuits
resulted in the formation of an insulating film
on the contacts. This film resulted in open
circuits or it required several operations of
the toggle switch handle before the circuit was
initially made.
The JF switch replacement utilizes silverto-silver conact surfaces and provides a strong
heat passing back to the switch deck will destroy
the switch deck or damage the insulation between
adjacent contacts.
LEVER-OPERATED SWITCH
Many types of lever-operated switches are
used in Navy alarm and warning systems to complete an electric circuit to various types of
and visual alarm signals. The type
audible
depends upon the circuit in which it is installed.
Most lever-operated switches utilize JR interiors (fig. 3-13). These switches are bperated
by a lever with suitable locking plate. In the interests of standardization, two types of interiors
are available, each containing three 2JR sections. One type is the JRM-300, which has a
spring return 'mechanism; and the other type is
the JR-304, which has
a positive detent
mechanism. Through slightly different arrangements of pins, lever, and locking plate, various
types of switches can be obtained.
wiping action in moving between positions. Open
circuit problems have been eliminated in this
manner. The blade arrangement provides for
a circuit between two adjacent contacts, such
as in the 2JR switch previously discussed. The
type 2JF has two such blade arrangements per
switch deck. The standard switches have 1, 3,
ft
d
and 5 switching decks, which are indicated in the
type designation by the number following JF.
The original production of the switches had
a detent to limit the switching action to two
positions. The present design has a 12-position
detent arrangement with adjustable stops. The
stops can be adjusted by removing the four
screws on the back plate and arranging the stop
arms mounted on the switch shaft to give the
number of positions desired.
An 0-ring on the switch shaft within the
mounting bushing prevents water from entering
the switch. An 0-ring is also provided on the
Figure 3-13.
38
44
140.4
Lever- operated switch (manual
contact maker).
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
Special switches are used where the standard switches cannot. For example, the diving
alarm switch on the submarine bridge must
be pressure proof. For submarine service, a
distinctive shape is used for the operating lever
knob or heads of alarm switches in conning
tower and control room (where illumination is
low) to avoid the possibility of confusion in
operating the proper switch. A square-shaped
knob is used for the diving alarm switch a
star-shaped head for the collision alarm switch,
and a standard rounded head for general alarm.
Lever-operated switches are available in
1-, 2-, and 3-ganged types. These switches
are used in such systems as the fireroom
emergency signal, general alarm, chemical-
attack alarm, steering emergency signal, whistle
operation, lifebuoy-release, and flight-crash
signal.
PRESSURE SWITCH
Pressure-operated switches are normally single-pole, single-throw, quick-acting
switches. Each contains either a bellows or a
diaphragm that works against an adjustable
spring. The spring causes the contacts to close
automatically when the operating pressure falls
below a specified value. The pressure at which
the switches operate is adjustable within ranges,
such as 0 -15, 15 -50, and 50-100. Make this
adjustment at the screw marked, higher (fig.
3-14). These switches can be used also to
77.119(140)
Figure 3-14.
Pressure switch type IC/L.
which the switches operate is adjustable at x
(fig. 3-15).
Temperature-operated switches are used
with the circulating-water, high-temperature
determined point.
alarm system; cruising-turbine exhaust alarm
system, and generator-air, high-temperature
alarm system.
Pressure-operated switches are used with
the lubricating oil, low-pressure alarm system;
MECHANICAL SWITCH
indicate an increase in pressure above a pre-
air-pressure alarm system; and booster-feed
pressure alarm system.
Mechanically operated switches are used in
many types of installations, such as wrong
direction alarms and valve-position indicators.
Widely used because of their small size and
excellent dependability, they are commonly called
Microswitches. (Microswitch is a trade name for
the switches made by the Microswitch Division
THERMOSTATIC SWITCH
or temperature-operated,
Thermostatic,
switches are usually single-pole, single-throw,
quick-acting, normally open switches. Each
switch contains a bellows that works against
an adjustable spring y (fig. 3-15). The spring
causes the contacts to close automatically when
the operating temperature exceeds a specified
value. The bellows motion is produced by a
sealed-in liquid that expands with rising temperature. The sensitive element containing this
liquid may be built into the switch or located
in a remote space and connected to the switch
by a capillary tube. The temperature range at
the Minneapolis
of
Company.)
Honeywell
Regulator
These switches will open or close a circuit
with a very small movement of the tripping device. They are usually of the pushbutton variety,
and depend on one or more springs for their
snap action. For example, the heart of the Microswitch is a beryllium copper spring, heattreated for long life and unfailing action. The
simplicity of the one-piece spring contributes
39
IC ELECTRICIAN 3 & 2
140.5
Figure 3-15. Temperature-operated switch.
to the long life and dependability of this switch.
The basic Microswitch is shown in figure 3-16.
The types of mechanically operated switches
are the push-action (type A-S) and the camaction (types P and P1). The push-operated
switch, provided for bulkhead mounting, is a
single-throw or multiple-throw, momentary acaction mechanism utilizes a straight-line
movement of the shaft to operate the electrical
contacts.
The cam-action switch consists of two singlepole, double-throw Micraswitches operated by
two adjustable cams mounted on the rotor shaft
(fig. 3-17). The cam-action mechanism utilizes
a rotary motion of the shaft to move cams,
tion, normally open push switch. The push-
SW SW
CONTACTS
ES,
CLOSED
CONTACTS
OPEN
ADJUSTABL
CAMS
Figure 3-16.
Microswitch.
12.72
140.6
Figure 3-17. Cam-action mechanical switch.
40
46
Chapter 3 SWITCHES, PROTECTIVE DEVICES, AND CABLES
LS Submersible steering-gear alarm
which in turn operate sensitive switches. The
points of operation of the sensitive switches
are varied by adjusting the angular positions
of the cams with respect to the shaft on which
they are mounted. Mechanical switches are used
with the following systems:
QA Air-lock indicator
PW Clutch-position indicator
SP Shaft-position alarm
DW Wrong-direction alarm
TR Hull-opening indicator
VS Valve-position indicator
WATER SWITCH
Water switches consist of a pair of terminals
mounted in an insulated base within a cast fitting (fig. 3-18). There is a 7000-ohm, 5-watt
rmr4 pm,
r,,A
0
B
10*
11.111111r4
orb fry,
H
Aire;
.D4).
.,-4111541un
600,3NYu
0
0
Fit
0 SPACER
0 I/8 STD. PIPE PLUG
0 CONTACTS
0 CLAMP
® "0" RING GASKET
0 RESISTOR 7000 OHMS 5 WATT
SUGGESTED METHOD OF MOUNTING WATER SWITCH
SPRINKLING
CONTROL VALVE
WET SIDE
INSTALL WATER SWITCH ON
UNDERSIDE OF PIPING ON THE
DRY SIDE OF THE SPRINKLING
CONTROL VALVE
WATER SWITCH
140.7
Figure 3-18. Water switch.
41
47
IC ELECTRICIAN 3 4z 2
resistor connected across the two terming s,
which limits the current to the required value
for the supervisory circuit when the switch
casting is dry. The switch is mounted in the
magazine flooding system, and a sprinkling control valve is installed between the switch and
the fireman. When the sprinkling control valve
is opened, water floods the switch casting and
shorts out the 5-watt resistor. With the supervisory resistor shorted, a current of sufficient
value to operate the alarm will flow in the circuit.
Water switches are used principally in
sprinkling alarm systems (circuit FH).
LiguidLevel Float Switch
A relatively new development in indicating
alarm and control functions, the liquid level
float switch (fig. 3-19) is replacing the float and- switch combination found in tank and bilge
level alarms. This float switch has doughnut-
shaped, floatable, magnetic core operating over
an encapsulated reed switch. The entire assembly
can be mounted at any predetermined level, and
the switch can be male normally open or closed
by reversal of the core. Level conditions are
indicated as normal, above normal, or below
normal.
IL
The switch is capable of being connected to
the standard alarm unit discussed later.
MAINTENANCE OF SWITCHES
Switches should be checked periodically to
ensure that all electrical connections and mechanical fastenings are tight. Lockwashers must
be in place. Avoid overtightening the packing
gland nut on watertight rotary switches as excessive pressure on the switch shaft will cause
Figure 3-19.
Float switch.
140.63X
When replacing a switch, great care must be
taken in tagging leads to ensure proper replacement. Close supervision and proper checkout by
improper positioning of the switch.
Remove dirt and grease from switch and relay contacts with a cloth moistened with an approved solvent. No lubricants of any kind should
be applied to the contacts. Use a burnishing tool
for dressing small light contacts.
Clean burned copper contacts with fine sandpaper. Do not use emery cloth. Badly burned
contacts should be replaced. Always replace
contacts in pairs, rather then replacing a single
contact.
Silver contacts require very little maintenance. Removal of the tarnish that forms on
silver contacts due to arcing is no longer recommended, as this blackened condition improves
the operation of the contacts.
an electrical petty officer can ensure against
personal injury and equipment damage.
SOLENOIDS
A solenoid is an electromagnet formed by
a conductor wound in a series of loops in the
shape of a helix (spiral). Inserted within this
spiral or coil is a soft-iron core and a movable
plunger. The soft-iron core is pinned or held
in position and therefore is not movable. The
movable plunger (also soft iron) is held away
from the core by a spring when the solenoid is
deenergized. (See fig. 3-20.)
42
48
Chapter 3 SWITY.:FIES, PROTECTIVE DEVICES, AND CABLES
spring action. It is interesting to note that the
effective strength of the magnetic field on the
plunger varies with the distance between the
CORE
two. For short distances, the strength of the
field is strong; and as distances increase, the
strength drops off quite rapidly.
Solenoids are used for electrically operating
PIN
hydraulic valve actuators, carbon pile. voltage
regulators, power relays, and mechanical
COIL
CEENERGIZEO
clutches. They are also used for many other
140.147
Figure 3-20. Solenoid action.
When current flows through the conductor, a
magnetic field is produced. This field acts in
every respect like a permanent magnet having
both a north and south pole. The total magnetic
flux density produced is the result of the generated magnetonwtive force and the permeability
of the medium through which the field passes.
In
much the same way that electromotive
force is responsible for current in a circuit,
magnetomotive force is responsible for external
magnetic effects. The magnetomotive force
(mmf) which produces the magnetic flux in a
solenoid is the product of the number of turns
of wire and the current through the coil. If the
current is expressed in amperes, the magnetomotive force is expressed in ampere turns.
From this it can be seen that a prescribed
magnetomotive force can be produced by using
either a few turns of large wire (high current)
or many turns of small wire (low current).
The soft-iron core will also influence the
strength of the magnetic flux produced by the
coil. The strength of the field is greatly increased by the use of a soft-iron core due to
the greater permeability of iron in respect to
air. Consequently, by using an iron core a
purposes where only small movements are required. One of the distinct advantages in the
use of solenoids is that a mechanical movement
can be accomplished at a considerable distance
from he control. The only link necessary between the control and the solenoid is the electrical wiring for the coil current.
MAINT3NANCE
The first step to be taken in checking an improperly operating solenoid is a good visual in-
spection. The connections should be checked
for poor soldering, loose connections, or broken
wires. The plunger should be checked for
cleanliness, binding, mechanical failure, and
improper alinement adjustment. The mechanism
that the solenoid is to actuate should also be
checked for proper operation.
The second step would be to check the ener-
gizing voltage by use of a voltmeter. If this
voltage is too low, the result would be less current flowing through the coil and thereby a weak
magnetic field. A weak magnetic field can result in flow, ineffective operation. It could also
possibly result in chatter or inoperation. If
the energizing voltage is too high, it will in
all probability damage the solenoid by either
overheating or arcing. In either case the voltage should be reset to the proper value so that
further damage or failure will not result.
greater flux density can be produced for a given
number of ampere turns.
The magnetic flux produced by the coil will
The solenoid should then be checked for opens,
shorts, grounds, and correct resistance with an
ohmmeter. If, when you check the resistance of
the solenoid the ohmmeter indicates infinity,
the solenoid is open circuited and should be
result in establishing north and south poles in
both the core and the plunger. These poles have
such a relationship that the plunger is attracted
along the lines of force to a position of equilibrium when the plunger is at the center of the
coil. As shown in figure 3-20,. the deenergized
position of the plunger is partially out of the
coil due to the action of the spring. When voltage is applied, the current through the coil produces a magnetic field which draws the plunger
within the coil, thereby resulting in mechanical
motion. When the coil is deenergized, the
plunger returns to its normal position by the
replaced. If the ohmmeter reads zero or less
than the specified resistance, the coil is shorted
and should be replaced. However, if the resistance
of the coil is higher than specified (but not
infinity) look for a poor contact or a damaged
conductor. If the fault cannot be found or corrected, replace the solenoid. Another check possible with the ohmmeter is to determine if
the coil is grounded. If the coil is grounded,
reinsulate the solenoid.
43
. 49
iC ELECTRICIAN 3 & 2
RELAYS AND CONTACTORS
are also classified as open, semisealed, or sealed.
A RELAY is a magnetically operated switch.
The operating coil can be connected in series
with a supply line to the load or shunted across
the line. A CONTACTOR, like the relay, is a
magnetically operated switch, except that the
main contacts are designed to carry the heavier
current of the load device.
The coil design is influenced by the manner
in which the relay is used. When the relay is designed for series connection, the coil is usually
wound with a fairly small number of turns of
large wire because the load current will be
flowing through the winding. When the relay is
designed for shunt connection, the coil is wound
with a large number of turns of small wire,
which will increase the resistance and thus
lower the current through the coil.
Because the contacts of relays and contactors
may open or close when energized, they can be
used as protective devices or control devices or
both simultaneously. The basic difference between
a-c and d-c relays lies in the armature and magnet core construction.
The armature and magnet cores of an a-c
relay are made up of laminations, and those of
a d-c relay are of solid material. The use of
laminations in an a-c relay reduces the heating
due to eddy currents. In addition, a copper strap
or ring (called shorted turn) is placed near the
end of the pole piece of an a-c relay to reduce
"chatter" during operation. Because the alter-
nating current is going through a peak, dropping
to zero, and going through a peak in the opposite
direction and then dropping to zero again during
each complete cycle, the coil tends to release the
armature each time the current drops to zero and
The clapper relay (discussed later) is an open
relay. Semisealed relays are covered to protect
the contacts against the effects of dust, moisture,
and foreign matter. A hermetically sealed relay
is encased with glass, plastic, or metal. Besides
not being affected by changes in temperature and
humidity, hermetically sealed relays are tamperproof.
The function of a control relay is to take a
relatively small amount of electrical power and
use it either to signal or to ttontrol a large
amount of power. Where multipole relays are
used, several circuits may be controlled simultaneously. In automatic relaying circuits, a small
electric signal may set off a chain reaction of
successively acting relays, which then perform
various functions. Control relays can also be
used in so-called "lockout" :lotion to prevent
certain functions. In some equipment, control
relays are used to ."sense" undervoltage and
overvoltage, reversal of current, excessive currents, phase and amplitude, polarity, etc.
The relay permits the operator to control
large amounts of current at other locations in
the equipment, the heavy power cables need
to be run only to the point of use. Only lightweight control wires are connected to the control switches. Safety is also an important reason for using relays, since high power circuits
COMMON
PIVOT
attracts the armature each time it reaches a
peak. The SHORTED TURN acts as the secondary
of a transformer, the primary of which is the
relay operating coil. The current in the shorted
turn is out of phase with the current of the
operating coil because the copper ring has lowinductive reactance. Thus, when the operating
coil flux is zero, the flux produced by the shorted
coil is different from zero, and the tendency cf
the relay to "chatter" is reduced.
RELAYS
Relays are classified according to their use
RE!.AY COIL TERMINALS
as control relays or power relays. Control relays
are usually known simply as relays; power relays
are called contactors. Pawlr relays control the
heavy power circuits of an electric system. Relays
Figure 3-21. Relay construction.
44
50
140.148
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
mounting. Figure 3-21 illustrates the fundaPUSH ROD
NONMOVABLE
CONTACTS
mental construction of a relay. When the circuit is energized, the flow of current through
the coil creates a strong magnetic field which
pulls the armature to contact Cl whichcompletes
the circuit from the common terminal to Cl. At
the same time it has opened the circuit to contact C2.
MOVABLE
CONTACT
The clapper relay (fig. 3-22) contains the
same components but has multiple sets of con-
tacts. As the circuit is energized, the clapper
is pulled to the magnetic coil. Pulling the arm
of the clapper forces the movable contact up-
ffiv\k\\\*Ot
I10`""
ward to move the push rod and the upper movable contact. This action could be repeated for
as many sets of contacts as required. Thus it
..
t \\\\00\\\\00
is possible to conrol many different circuits
COIL
type of relay can be a source of trouble. The
simultaneously. To the maintenance man, this
CI APPER
140.149
Figure 3-22. Clapper type relay.
can be switched remotely without danger to the
operator.
In general, a relay consists of the following
a magnetic core and associated
components:
coil, the contacts, springs, armature, and the
motion of the clapper arm does not necessarily
assure the tandem movement of all the movable
contacts. If the push rod was broken, the clapper
arm would push the lower movable contact upward but would not move the upper movable
contact, thereby not completing the circuit.
Time Delay Relay
A thermal time delay relay (fig. 3-23) is
constructed to produce a delayed action when
energized. Its operation depends or a thermal
action such as thLt of a bimetallic element being
heated. The eleniz.nt is made by welding together two strips of different metals having
different thermal expansion rates. A heater is
mounted around, or close to, the element with
the contacts mounted on the element itself. As
the heat causes the element to bend (because of
the different thermal expansion rates), the contacts close to operate a relay. The delay time
of the bimetallic strips is usually from 1/2 to
1 1/2 minutes and is varied by using metals
with different expansion rates or by increasing
or decreasing the distance between the fixed
and moving contacts.
One common form of time delay relay utilizes a lag coil, which is usually a large copper
slug located at one end of the winding or a tubular
sleeve located between the winding and the core.
The lag coil (slug) acts as a short-circuited secondary for the relay coil. The counter magnetomotive force due to the current induced in the
coil by the changing coil current, delays the
flux buildup or decay in the airgap and hence
the closing or opening of the armature. A short
140.150
Figure 3-23.
Thermal time delay relay.
45
51,
IC ELECTRICIAN 3 & 2
slug near the armature end of the core has relatively more effect on the operating time, and
one at the heel end has more effect a the release time.
Latch-In Relay
Another type of relay is the latch-in relay.
This relay is designed to lock the contacts in
the deenergized position until the relay is either
manually or electrically reset. Two windings
are used, one is the trip coil, and the other the
reset coil. When the trip coil is energized it
acts on a spring-loaded armature. The relai's
movable contacts are mounted on this armature.
After the contacts open they are held in the
open position by a mechanical latch. The mechanical latch is unlatched when the reset coil
is energized, thus allowing the relay's contact
to close again.
SHUNT TYPE CONTACTORS
The SHUNT type contactor (connected across
to line) operates when line voltage is applied
to its operating coil 2 (fig. 3-24). The main
1. Magnetic frame.
2. Operating coil.
3. Armature.
4. Main contacts.
Figure 3-25. A-c shunt relay.
140.9
contacts, 4 , are arranged to complete or interrupt an electric circuit. In the arrangement the
contacts are connected in series with the voltage
supply to the controlled circuit. When voltage is
applied to the coil, a magnetic pull attracts the
armature. 3 , which closes the main contacts.
When the voltage supply to the coil is interrupted,
the magnetic pull on the armature is removed,
and the armature spring pulls it away from the
magnet. This action opens the contacts and deenergizes the controlled circuit.
1. Magnet fr1/2me.
2. Operatinkcoii.
3. Armature.
4. Main contacts.
140.8
Figure 3-24. Shunt type d-c contactor.
140.10
Figure 3-26. Adjustment of a-c shunt relay.
542
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
In addiAn a-c SHUNT relay is illustrated in figure collect as readily on a curved surface.
film
tion,
a
ball-shaped
contact
can
penetrate
3-25. The basic function of the relay is to make
Avoid
flattening
more
easily
than
a
flat
contact.
or break an electrical control circuit when the or otherwise altering a contact's rounded surrelay coil is energized. To do this, voltage is faces. Relays similar to the shunt relay, figure
applied to the operating coil, 2 (connected 3-25 have replaceable contacts that should be
across the line), which attracts the armature, maintained similar to switch contacts. See main3 . When the armature is pulled down, it closes
tenance of switches at the beginning of this
the main contacts, 4 .
chapter.
values
The PULL-IN and DROPOUT current
Many relays have been damaged or ruined
may be adjusted. In figure 3-26 the various ad- because
the contact points were cleaned with
justment points of the a-c shunt type relay are
sandpaper
or emery cloth instead of a burnishing
the
setscrew,
E,
indicated. The spring, A, and
tool.
The
use
of sandpaper and emergy cause
values.
Before
the
control the pickup and dropout
bending
of
the
contact springs and other damage.
relay is adjusted, screw F should be set to clear Attempts to straighten
the contact springs with
in
the
closed
the armature when the armature is
pliers cause further damage, eventually
position. The pull-in value can be raised by in- longnose
requiring
replacement of the relays. Burned and
creasing the spring tension or by increasing the
pitted
contacts
cannot be repaired by burnishing;
armature gap.
the relay should be replaced. Figure 3-27
illustrates a burnishing tool being used on a relay.
SERIES TYPE CONTACTORS
Burnishing tools are stocked in supply activit.
ties
and may be obtained through normal supply
operated
by
The SERIES type relays are
channels.
When using this tool, be sure to clean
circuit current flowing through the coil or coils.
it
thoroughly
with alcohol; do not touch the tool
This feature makes it possible to use the relay
with the fingers prior to use.
as a field failure relay, or for any application surface
Another useful tool in relay maintenance is a
where the relay operation is in response to point
bender (fig. 3-28) for straightening bent
changes in circuit current flow.
contact springs. It can be fabricated locally
There are two adjustments on the two-coil relay
from
0.125-inch diameter rod stock shaped as
relay. One adjustment sets the difference 113- indicated
in the figure, or it may be obtained
current
values.
tween the opening and closing
normal supply channels.
The other adjustment sets the range of operating through
Potential relay trouble can be spotted by
values. Usually, the operating adjustment is the checking
for charred or burned insulation on the
only one required.
relay and for darkened or charred terminal
MAINTENANCE OF RELAYS
The relay is one of the most dependable
electromechanical devices in use, but like any
other mechanical cr electrical device it occasionally wears out or becomes inoperative.
When current flows in one direction through
a relay, the contacts may be subjected to an
effect called "cone and crater." The crater is
formed by the transfer of the metal of one
contact to the other contact, the deposit being
in the form of a cone.
Under normal operating conditions, most relay
contacts spark slightly: this will cause some
minor burning and pitting of the contacts. Contact clearances or gap settings must be main-
tained in accordance with the relay's operational
specifications. Relay contact surfaces must be
kept clean and in good operating condition. Some
relays are equipped with ball-shaped contacts
which, in many applications, are superior to the
flat cmtacts. Dust or other substances do not
140.151
Figure 3-27.
47
53
Burnishing tool.
IC ELECTRICIAN 3 & 2
current. The most common types of protective devices are fuses, circuit breakers, and
overload relays.
FUSES
A fuse is a protective device used to open an
electric circuit when the current flow exceeds
a safe value. Fuses are made in many styles
and sizes for different voltages and currents,
but they all operate on the same general principle. Each fuse contains a soft metal link that
melts and opens the circuit when overheated by
excessive currents,.
Plug Fuse
Figure 3-28. Point bender.
140.152
A plug fuse has a piece of zinc-alloy wire
mounted in a porcelain cup with a metal cover.
A threaded contact base similar to a lamp socket
is provided so that the fuse can be screwed
into a socket in the fuse block. Plug fuses are
leads coming from the relay. Both of these indicate overheating. If there is any indication that
a relay has overheated the cause of overheating
should be determined. An experienced senior
petty officer should determine whether the relay
requiree. repls_iment. An occasional cause of
relay trouble, not due to the relay itself, is
overheating caused by loose power terminal
connectors.
used on small-capacity circuits ranging from 3
through 30 amperes at not more than 250 volts.
Some plug fuses have small mica windows so
that the fusible link can be observed. The plug
fuse is not normally used in naval vessels and
is seldom used in commercial applications;
however, they can be found in older buildings
and houses.
Cartridge Fuse
It is recommended that covers not be removed from semisealed relays in the field. Removal of a cover in the field, although it might
give useful information to a trained eye, may
result in entry of dust or other foreign material
which may cause poor contact or an open circuit.
Removal of the cover may also result in loss of
or damage to the cover gasket.
Should an inspection determine that a relay
has exceeded its safe life, the relay should be
A cartridge fuse consists of a zinc-alloy
link enclosed in a fiber, plastic, ceramic, or
glass cylinder. Some fiber and plastic fuse
cylinders are filled with nonccnducting powder.
The smaller fuses are used in circuits up to
60 amperes and are made in the FERRULE, or
round-end cap type. Large sizes with short
flat blades attached to the end caps are rated
from 65 through 200 amperes. Ths,:se blades
fit tightly into clips on the fuse block
to knife-switch clips.
removed imirsedlately and replaced wih another
of the same tyue. The replacement relay must have
Cartridge fuses are made in capacities of 1
through 1000 amperes for voltages of 125, 250,
the same characteristics or ratings, such as
voltage, amperage, type of service, number of
500, 600, and 1000 volts. Fuses intended for 600and 1000-volt service are longer and do not fit
contacts, continuous or intermittent duty.
the same fuse holders as fuses intended for
lower volt service. Fuses of different ampere
capacity are also designed fov different sizes
of holders. For example, fuses of 1 through
30 amperes fit one size of holder, and fuses
with capacities of 35 through 60 amperes fit a
PROTECTIVE DEVICES
Most protective devices are designed to interrupt the power to a circuit or unit under
abnormal conditions, such as short circuits,
overloads, high or low voltage, and excessive
different size holder.
48
54
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
Cartridge fuses in IC equipment are of various
sizes, such as the miniature F02 or F03 (1 1/4-
by 1/4-inch) fuse rated from 0.1 through 30
amperes at 125 volts and the midget F09 (1 1/2by 13/32-inch) fuse rated for 0.1 through 30
greater. Where the circuit incorporates branch
fuses, such as those associated with the firecontrol switchboards, the rating of the fuses on
the IC switchboard should be 20 percent above
the maximum connected load to provide sufficient
amperes at 125 volts. The standard 2- by 9/16 inch fuse is rated from 1 through 30 amperes,
500 volts for a-c service and 250 volts for d-c
service. Fuses above 60-ampere capacity have
knife-blade contacts and increase in diameter
and length as the capacity increases.
ma :gin so that branch fuses will always blow
capacity are pulled, the switch for the circuit
Fuse Holders
Before fuses of greater than 10 ampere
should be opened. Whenever possible, this pre-
caution should be taken before any size fuse
is pulled or replaced. Approved fuse pullers
must be used for removing fuses. Fuses should
never be short circuited or replaced with fuses
of larger current capacity.
before the main fuses. In no case should the fuse
rating be greater than two and one-half times
the rated capacity of the smallest cable in the
circuit. If too large a fuse were used, a fire
hazard would exist.
The type EL-1 fuse holder consists of a base
and a plug, as shown in figure 3-29. The base
extends behind the panel, and into it is screwed
the plug containing the fuse. Behind a hole in the
plug cap is small neon lamp which serves as a
Time Delay Fuse
Time delay fuses are used in motor supply
circuit, for example, where overloads and
motor-starting surges of short duration exist.
Common trade names for these fuses are rusetron
and Slo-Blo. A conventional fuse of much higher
rating would be required to prevent blowing of
the fuse during surges. Because of its high rating,
this fuse could not provide necessary protection
for the normal steady state current of the circuit.
The time delay fuse is rated as to its time
lag characteristic with a minimum blowing time
at some overload current. A typical rating is
"12 seconds minimum blowing time at 200 percent
rated current."
Selection of Proper Fuses
Individual fuses are provided on the IC switch-
boards for each associated circuit. A separate
fuse in each line of each circuit has the effect
of considerably increasing the maximum short
circuit current that the fuses can safely interrupt.
It also provides greater protection to the re-
maining circuits energized from the same bus in
case of a possible defect in one fuse.
In general, fuse ratings should be approximately 10 percent above the maximum continuous connected load. In circuits, such as call
bell systems and alarm systems where only a
small portion of the circuit is likely to be
operated at any one time, the fuse rating should
be 10 percent greater than the load of one associated group of signals operated, or 15 percent of the total connected load, whichever is
140.12
Figure 3-29. Fuse holder, type EL-1.
49
IC ELECTRICIAN 3 & 2
fuse holder provides a third terminal connected
to a 28-volt incandescent lamp in the cap. By
insertion of a suitable resistor between the load
terminal and the added terminal, the lamp will
be energized by a sufficient voltage to become
visible when the fuse has blown. In some lowvoltage fuse holders the resistor and lamp are
included within the clear plastic cap. Lowvoltage fuse holders should not be used in sensitive, low-current equipment. Where an overload condition occurs and the fuse blows, the
low resistance indicator circuit may pass sufficient current to damage the equipment.
Due to the design of certain fuses and in
cases where space does not permit indicator
Figure 3-30.
140.13
fuse holder, type FHL12U.
blown-fuse indicator, lighting when the energized
circuit through the holder is interrupted by the
blowing of a fuse. Series resistors of different
values are used with the lamp on 125- and 250volt circuits, except for the MIDGET holder,
which is rated for 125 volts only.
The types FHL1OU, FHL11U, and FHL12U
(fig. 3-30) consist of fuse holder body and a fuse
carrier. The body is mounted on the panel, and
the earner with the fuse placed in the clips is
inserted into the body in a manner similar to
inserting a bayonet type lamp into a socket.
Removal of the fuse is accomplished by pushing
and turning the fuse carrier in a counterclockwise direction, again similar to the removal of a
bayonet base lamp. The types FHL1OG and
FHL1IG accommodate 1 1/4- by 1/4 inch
fuses. The type FHL1OG will hold two fuses and
can therefore be used to fuse both sides of the
line, or, in conjunction with a type FHL11G, will
fuse a three-phase line. Type FHL12G will accommodate
1 1/2- by 13/32-inch fuses.
When these fuse holders are mounted in a
dripproof enclosure they maintain the dripproof
integrity. They also possess the ruggedness and
the vibration and high-impact shock resistance
necessary for shipboard use.
The extensive use of low-voltage power supplies has required the use of incandescent lamps
in place of neon glow lamps in some indicator
light circuits. A modification of the FHL1OU
Figure 3-31.
50
73.32(I40B)
Voltage tester.
Chapter 3 SWITCHES, PROTECTIVE DEVICES, AND CABLES
total current of its several branches. This reduces the possibility of one circuit failure in-
type fuse holders, separate indicator light circuits are mounted on a panel and connected in
parallel with separately mounted fuses and fuse
terrupting the power for the entire system. The
feeder distribution boxes and the branch dis-
clips. In some cases an alarm circuit in the
tribution boxes contain fuses to protect the
form of a bell or buzzer takes the place of the
various circuits.
The distribution wiring diagram showing the
indicator light.
Voltage Tester
connections that might be used in a lighting
The most commonly used voltage tester now
available to the fleet is the multifrequency type
shown in figure 3-31. This tester has electronic
cuits through branch distribution boxes.
system is illustrated in figure 3-32. An installation might have several feeder distribution
boxes, each supplying six or mare branch cirFuses F1, F2, and F3 (fig. 3-32) protect the
main feeder supply from heavy surges such as
short circuits or overloads on the feeder cable.
circuitry and glow lamps to indicate voltage,
frequency, and polarity. One, two, or three lamps
are used to indicate the a-c or d-c voltage. The
other lamps identify the a-c frequency (60 or
400 hertz) or whether the d-c circuit being tested
has negative polarity applied to either the red
probe or the black probe. This tester is designed
Fuses A-Al and B-B1 protect branch No. 1.
If trouble develops and work is to be done on
branch No. 1, switch Si may be opened to isolate
this branch. Branches 2 and 3 are protected and
isolated in the same manner by their respective
fuses and switches.
for operation on 28 to 550 volts a-c or 28 to
600 volts d-c.
Branch Circuit Tests
Before being taken from the shop and used
on a circuit, a voltage tester must be tested for
proper operation on a known voltage source,
Usually, receptacles for portable equipment
and fans are on branch circuits separate from
lighting branch circuits. Test procedures are
the same for any branch circuit. Therefore, a
such as the electric shop test panel.
If your voltage tester is inoperative, turn
it in to your leading petty officer for repair
or replacement.
Never use a lamp in a "pigtail" lamp holder
as a voltage tester. Lamps designed for use on
description will be given on the steps necessary
to (1) locate the defective circuit and (2) follow
through on that circuit and find he trouble.
Assume that, for some reason, several of the
lights are not working in a certain section. Because several lights are out, it will be reasonable to assume that the voltage supply has been
interrupted on one of the branch circuits.
To verify this assumption, first locate the
distribution box feeding the circuit that is ii operative. Then make sure that the inoperative
low voltage (120 v) may explode when connected
across a higher voltage (440 v). In addition, a
lamp would only indicate the presence of voltage,
not the amount of voltage. Learn to use and rely
on standard test equipment.
TROUBLESHOOTING
FUSED CIRCUITS
circuit is not being supplied with voltage. Unless
the circuits are identified in the distribution box,
An electrical system may consists of a com-
the voltage at the various circuit terminations
paratively small number of circuits or, in the
larger systems, the installation may be equal
will have to be measured. For the following pro-
cedures, use the circuits shown in figure 3-32
to that of a fair sized city.
Regardless of the size of the installation,
an electrical system consists of a source of
power (generators or batteries) and a means
as an example circuit.
To pin down the trouble, connect the voltage
various loads (lights, motors, and other elec-
these terminals indicates a blown fuse or a
failure in the supply to the distribution box.
tester to the load side of each pair of fuses in
the branch distribution box. No voltage between
of delivering this power from the source to the
trical equipments).
From the main power supply the total electrical load is divided into several feeder circuits
To find the defective fuse, make certain SI is
closed, then connect the voltage tester across
A-Al, and next across B-B1 (fig. 3-32). The
full-phase voltage will appear across an open
fuse, provided circuit continuity exists across
the branch circuit. However, if there is an open
and each feeder circuit is further divided into
several branch circuits. Each final branch circuit is fused to safely carry only its own load
while each feeder is safely fused to carry the
51
57
IC ELECTRICIAN 3 & 2
11M
FEEDER SUPPLY
FEEDER SUPPLY
O
F3
.1111
FEEDER CABLE
FEEDER DISTRIBUTION BOX
11111.10111
A
Ai X
X1
SIB
BI Y
BRANCH
NO.1
YI
BRANCH
LEGEND
NO.2
01%0 DOUBLE
BRANCH
NO.3
ICZLOr.,
o
POLE
SWITCH
ri -FUSE
BRANCH DISTRIBUTION BOX
Figure 3-32. Three-phase distribution wiring diagram.
circuit at some other point in the branch circuit,
this test is not conclusive. If the load side of a
pair of fuses does not have the full-phase volt-
65.57
is in good condition. To test fuse B-B1, place the
tester leads on A and B, and then move the lead
from B to Bl. No voltage between these terminals
indicates that fuse B-Bl is open. Full-phase voltage between A and B1 indicates that the fuse is
age across its terminals, place the tester leads
on the supply side of the fuses. The full-phase
voltage should be present. If the full-phase voltage is not present on the supply side of the fuses,
the trouble is in the supply circuit from the feeder
distribution box.
good.
This method of locating blown fuses is preferred to the method in which the voltage tester
leads are connected across the suspected fuse
terminals, because the latter may give a false
Assume that you are testing at terminals
A-B (fig. 3-32) and that normal voltage is present. Move the test lead from A to Al. Normal
indication if there is an open circuit at any point
between either fuse and the load in the branch
circuit.
voltage between Al and B indicates that fuse A-Al
52
58
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
for either manual local closing or electrical remote closing. It has an open metallic frame con-
CIRCUIT BREAKERS
Circuit breakers have three fundamental pur-
struction mounted on a drawout mechanism and is
poses: (1) to provide circuit protection and to
perform normal switching operations; (2) to
normally used to supply heaq loads and protect
the equipment from high short circuit currents.
isolate a defective circuit while repairs are
switch gear groups, and in distribution panels.
Type ACB circuit breakers are used to connect ship's service and emergency generators
to. the power distribution system. They are also
used on bus ties and shore connection circuits,
The types installed on naval ships areACB,AQB,
AQB-A, AQB-LF, NQB-A, ALB and NLB. They
and on some feeder circuits from the ship's
service switchboard. In these applications, they
are called air circuit breakers because the main
current carrying contacts interrupt in air.
operate usually in conjunction with a pilot device,
such as a relay or switch. An electrically operated
may not provide protective functions. Some types
may be operated both ways, while others are restricted to one mode.,
causes the breaker contacts to open. The energy
being made, and (3) to help start large motors
in manual and automatic bus transfer.
Air circuit breakers are used in switchboards,
Circuit breakers are available in manually circuit breaker has an electromagnet which acts
or electrically operated types which may or as a solenoid to trip a release mechanism that
to open the breaker is derived from a coiled
spring. The electromagnet is controlled by the
contacts in the pilot device.
AC B
Circuit breakers designed for high currents
have a double-contact arrangement. The com-
Figure 3-33 shows the exterior of a type ACB
circuit breaker. This circuit breaker is designed
plete contact assembly consists of the main
bridging contacts and the arcing contacts. AU
current carrying contacts are high-conductivity, arc-resisting silver or silver alloy inserts.
ARC QUENCHERS
CONNECTION
Each contact assembly has a means of holding the arcing to a minimum and extinguishing
the arc as soon as possible. The arc control
section is called an arc chute or arc runner.
The contacts are so arranged that when the
circuit is closed, the arcing contacts close
first. Proper pressure is maintained by springs
rt,
to ensure the arc contacts close first. The
main contacts then close.
When the circuit opens, the main contacts
open first. The current is then flowing through
the arc contacts, which prevents burning of the
main contacts. When the arc contacts open, they
pass under the front of the arc runner, creating
a magnetic field that blows the arc up into the
arc quencher and quickly opens the circuit.
Type ACB circuit breakers are either hand
operated or electrically operated. The high interrupting types of ACB breakers are electrically
operated from a remote location, making it un-
necessary for personnel to approach them in
order to open or close the circuit.
No circuit breaker, regardless of type,
should be worked on without opening the circuit.
OVERCURRENT TRI
Remember that certain termivals may have
voltage
applied to them even though the breaker
is open. Aboard ship, power may be supplied
27.73
Figure 3-33. Type ACB circuit breaker.
to either end of the circuit breaker.
53
59
IC Ei2CTRICIAN 3 & 2
They are designed or front or rear connections
as required and may be mointed so as to be
remogable from the front without removing the
circuit breaker cover. The voltage ratings of the
AQB-A250 are 590 volts a-c, 60 hertz or 250
volts d-c.
The 250 part of the circuit breaker type
designation indicates the frame size of the cir-
cuit breaker. The current carrying parts of a
250-ampere frame size circuit breaker have a
continuous rating of 250 amperes. Trip units
(fig. 3-35) for this breaker are available with current ratings of 125, 150, 175, and 250 amperes.
4
3
1. OPERATING HANDLE SHOWN
IN LATCHED POSITION
2. AMPERE RATIt'G MARKER
3.MOUNTING SCREWS
4. COVER SCREWS
5. BREAKER NAMEPLATE
6. COTTER KEY HOLE
77.241
Figure 3-34. AQB-A250 circuit breaker complete, front view.
AQB
Type AQB circuit breakers (fig. 3-34) are
7
mounted in supporting and enclosing housings of
insulating material and have direct-acting automatic tripping devices. They are used to protect
single-load circuits and all feeder circuits
II 7
3
II
7
3
II
ARC
SUPPRESSOR
) STATIONARY CONTACT
IX) ARC SUPPRESSORS
(3) TERMINAL STUD NUTS AND WASHERS
(4) TRIP UNIT LINE TERMINAL SCREW-OUTER POLES
IS) TRIP UNIT LINE TERMINAL SCREW- CENTER POLE
coming from a load center distribution panel.
(S) TRIP UNIT NAMEPLATE
(7) TERMINAL BARRIERS
Where the requirements are low enough, the
type AQB may be used on generator switchboards. When it becomes necessary to replace
one of the older type circuit breakers, it should
(8) SHUNT TRIP OR UNDERVOLTAGE DEVICE
(9) AUXILIARY SWITCH
(IC) HOLE FOR SHUNT TRIP OR uNCCRvOLTAGE
RELEASE PLUNGER
be replaced by the newer AQB-A101, AQB-A250,
AQB-A400, AQB-A600, or AQB-A800 as required.
AQB -A250.
3
In) INSTANTANEOUS TRIP ADJUSTING WHEELS
1121
COTTER HEY HOLE
The newer AQB type circuit
breakers such as the AQB-A250 have several ad-
vantages over the older types. The outside di-
77.242
mensions of these new breakers are the same for
both the two-pole and three-pole circuit breakers.
Figure 3-35. AQB-A250 circuit breaker front
view, cover and arc suppressor removed.
54
60
Chapter 3 SWITCHES, PROTECTIVE DEVICES, AND CABLES
The trip unit houses the electrical tripping
mechanisms, the thermal element for tripping
the circuit breaker on overload conditions, and
the instantaneous trip for tripping on short
circuit conditions.
In addition 100, 160, and 250 ampere rating
trip units with a special calibration are available
for use with generator circuit breakers. Regardless of the trip unit used the breaker is
still a 250 ampere frame size. The automatic
trip devices of the AQB-A250 circuit breaker
and "trip free" of the operating handles; in
other words the circuit breaker cannot be held
closed by the operating handle if an overload
exists. When the circuit breaker has tripped
due to overload or short circuit, the handle rests
in a center position. To reclose after automatic
tripping, move the handle to the extreme OFF
position which resets the latch in the trip unit,
then move the handle to the ON position.
The AQB-A250 circuit breaker may have
auxiliary switches, shunt trip (for remote tripping), or undervoltage release attachments when
so specified. However, a shunt trip cannot be provided in the same. breaker with an under-voltage
III TM). UNIT LATCH PIN
(1) SHUNT TR P TUIRIL AR CORE
12) AUXILIARY SWITCH
13) AUXILIARY SWITCH MOUNTING SCREwS
111) SHUNT TRIP MOUNTING SCREwS
IQ AUXILIARY SWITCH LEVER
15) AUXILIARY SWITCH MOUNTING 'RACKET
(9) TUIBUL AR CORE LOCK NUT
001 HOLE FOR SHUNT TRIP PUSH
PIN
IC SHUNT TRH.
(III SHUNT TRIP PLUNGER
A
release since in all cases the shunt trip coil is
ms:;mentary rated and must be connected in series
with a circuit breaker auxiliary switch. Figure
3-36 shows a trip unit with shunt trip and a trip
unit with undervoltage trip. The coil for a shunt
trip has a dual rating for a-c and d-c voltages
whereas the undervoltage trip coils are wound
for a specified voltage such as 450 a-c or 250
d-c and have rated pickup and dropout values.
The instantaneous trip setting of the AQB -A250
trip units may be adjusted by the instantaneous
trip adjusting wheels shown in figure 3-35.
Though not shown in the figure these trip adjusting wheels are marked for five positions,
LO-2-3-4-HI, the trip unit label (not shown)
will list the instantaneous trip value obtainable
for each marked position. Identical settings
must be made on each pole of the circuit
s... ....
breaker. NEVER remove a circuit breaker cover
to perform adjustments while the circuit breaker
is in the closed (ON) position.
Terminal mounting block assemblies used in
conjunction with the circuit breaker (fig. 3-37)
for drawout mounting, consist of terminal studs
, URE TRAVEL ADJUSTING SCREw
li ) uNDERWLTAGE RELEASE
IS)
12) AUXILIARY SWITCH
131 AUxiLAARF SWITCH MOUNTING SCREwS
IS) SET SCREW FC1 ARMATURE TRAVEL
ADJUSTING SCREW
110) ARMATURE - MAGNET AIR GAP
14) AUXILIARY SWITCH LEVER
15) AUXILIARY SWITCH MOUNTING @RACKET
110 uNDERVOLTAGE RELEASE PUSH ROD
IS) UNOERvOLTACIE RELEASE MOUNTING SCREWS
1?) UNCIERvOLTAGE RELEASE MAGNET
OD LOCK NUT FOR PUSH ROD
451 UNOERVOLTAGe RELEASE ARMATURE
CC ARMATURE RETAINING SPRINGS
B
in terminal mounting blocks of insulating material. The terminals of the circuit breaker
have slip type connectors which engage the
terminal studs as shown in figure 3-37. Two
77.243:.244
Figure 3-36. AQB-A250 trip unit: (a) with
shunt trip and auxiliary unit; (b) with under-
mounting blocks are usually required for each
circuit breaker. This method of connecting a
circuit breaker to a bus or circuit is known as
voltage release and auxiliary switch.
55
.
61
IC ELECTitt 3tkii 3
2
ATTACHMENT WIRING 18" LONG
DRILL OUT FOR LEADS
4
(I) TERMINAL MOUNTING BLOCKS (2 NEW:
)
IP SLIP TYPE CONNECTOPIS
(3) TERMINAL STUDS
(4) TERMINAL MOUNTINS BLOCK INSERTS FOR BREAKER MOUNTING BOLTS
(5) TERMINAL STUD NUTS
Figure 3-37. AQB-A250 circuit breaker rear view, with terminal mounting blocks.
a "back connected circuit breaker." Circuit
unit when the circuit breaker is in the closed
position will automatically trip the breaker.
The AQB-LF250 circuit breaker is inter-
breakers which have solderless connectors attached to their terminal are commonly called
"front connected circuit breakers." The interrupting rating of the AQB-A250 circuit breaker
is 20,000 amperes at 500-volts a-c to 15,000
amperes at 250-volts d-c.
AQB-LF
250.
The AQB-LF 250 circuit
breaker (fig. 3-38), combines the standard AQB
circuit breaker and a current limning fuse unit
which interrupts the circuit when the current is
in excess of the interrupting rating of the breaker.
Constructed as one compact unit, the AQB-LF
circuit breaker incorporates the current limiting
fuses (fig. 3-39) as integral parts of the circuit
breaker. The common trip features of the AQBA250 circuit breaker are retained and trip units
from 125 to 250 amperes are available for use
77.245
changeable with the AQB-A250 circuit breaker
except a larger cutout is required in the switchboard front panel to accommodate the fuse unit
of the AQB-LF250.
The AQB-LF250 circuit breaker is a 250
ampere frame size, however, the circuit breaker
has an interrupting rating of 100,000 amperes
at 500-volts a-c whereas the AQ3 -A250 circuit
breakers interrupting rating is 20,000 amperes
at 500-volts a-c.
While the AQB-A250 circuit breaker could be
either front or back connected, the AQB-LF250
is designed only for back (drawout type) connection, using the same type of slip connectors
terminal studs as shown in figure 3-37.
in the AQB-LF 250.
NQB
The current limiting fuse unit is designed so
The NQB-A250 circuit breaker (fig. 3-41) is
similar to the AQB-A250 circuit breaker except
that it trips the breaker and opens all poles if
any current limiting fuse (fig. 3-40) is blown.
the NQB-A250 has no automatic tripping devices.
After a fuse has blown, the circuit breaker
cannot be reclosed until the blown fuse
This type of circuit breaker is used for circuit
isolation and manual transfer applications. This
is replaced. Any attempt to remove the fuse
NQ13 -A250 is still a 250-ampere frame size as
56
62
Chapter 3 SW/ fC, 'IRS, PROTECTIVE DEVICES, AND C tiBLES
drawout type connectors, and nonremoveable
and nonadjustable thermal trip elements.
This circuit breaker is a quick-make, quick-
break type. If the operating handle is in the
tripped (midway between ON and OFF) position,
indicating a short circuit or overload, the operating handle must be moved to the e.treme
off position, which automatically resets the overunit
closed.
load
and
the
breaker can again be
NLB
Circuit breakers type NLB are identical to
ALB types except that they have no automatic
tripping device and are used only as on-off
switches.
Maintenance
Metal locking devices are available that cane
be attached to the handles of AQB type circuit
breakers to prevent accidental operation. All
breaker handles are now provided with a 3/32 inch hole permitting fastening the locking device
( II OPERATING HANDLE SHOWN
IN LATCHEO POSITION
(21 AMPERE RATING MARKER
(31 BREAKER MOUNTING SCREWS
(41 COVER SCREWS
(5) BREAKER NAMEPLATE
with a standard cotter pin. NavShips Technical
Manual, Chapter 9600, lists the stock numbers
for three different sizes of breaker handle locking
devices.
Circuit breakers require careful inspection
(61 FUSE UNIT ASSEMBLY
(7) FUSE UNIT MOUNTING
SCREWS
(8) FUSE UNIT NAMEPLATE
(91 BREAKER COVER
and cleaning at least once a year (more fre-
(JO) COTTER KEY HOLE
quently if subjected to unusually severe service
conditions). The special inspections follow.
No work should be undertaken on circuit
breakers without first obtaining approval Of
77.246
Figure
the electrical or engineer officer.
Before working on a circuit breaker be aware
of its time delay characteristics, whether short
3-38. AQB-LF250 complete circuit
breaker, front view.
time, long time, or instantaneous trip are provided. The adjustments for tripping of the/cir-
the current carrying parts of the breaker are
cuit breakers are made and sealed at the factory;
no unauthorized changes shOuld be made to their
capable of carrying 250 amperes. Technically
this circuit breaker is simply a large on and
trip settings because these changes may completely disrupt their intended functions of protection. Improper tripping action is corrected
best by replacement of the entire breaker as-
off switch. Some types of AQB and NQB breakers
ars provided with electrical operators mounted
on the front of the breaker. These are geared
motor devices for remote operation of the breaker
handle.
sembly, especially where trouble is encoun-
tered in the contact assemblies.
A special inspection should be carefully made
ALB
of each pair of contacts after a circuit breaker
has opened on a heavy short circuit. Before
working on a circuit breaker, deenergize all
control circuits to which it is connected; the
procedure differs somewhat with the type of
mounting which is employed. For example,
before work is performed on drawout circuit
Type ALB circuit breakers ere designated
low-voltage, automatic circuit breakers. The
continuous duty rating ranges from 5 through
200 amperes at 120 volts a-c or d-c. The
breaker is provided with a molded enclosure,
57
63
IC ELECTRICIAN 3 41 2
(1) BREAKER OPERATING HANDLE SHOW IN
TRIPPED POSITION
(2) AMPERE RATING MARK ER
(3) BREAKER MOUNTING SCREWS
(4) COVER SCREWS
(5) CURRENT LIMITING FUSES
(6) FUSE UNIT ASSEMBLY
(7) FUSE UNIT INTERLOCK PIN
(8) TRIP LEVER
(9) FUSE SLIPON CONNECTORS
(10) FUSE RETAINING BLOCK SCREWS
(11) INSTANTANEOUS TRIP ADJUSTING WHEELS
10
Figure 3-39. Complete circuit breaker, front view with fuse unit removed.
breakers, they should be switched to the open
position and removed. Before working on fixedmounted circuit breakers, open the disconnect-
ing switches ahead of the breakers. If disconnecting switches are not provided for isolating
fixed-mounted circuit breakers, deenergize the
supply bus to the circuit breaker, if practicable,
before inspecting, adjusting, replacing parts, or
doing any work on the circuit breaker.
Contacts are the small metal parts especially selected to resist deterioration and wear
from the inherent arcing. The arcing occurs in a
77.247
discolored (blackened during arcing) with silver
oxide. The blackened condition, therefore, requires no filing, polishing, or removal. As with a
silver contact, silver oxide is formed during
arcing and it has been found that the addition of
cadmium oxide greatly improves operation of the
contact because it minimizes the tendency of one
contact to weld to another, retards heavy transfer of one material to another, and inhibits
erosion.
circuit breaker while its contacts are opening
and carrying current at the same time. When
Usually, a contact containing silver is serviceable as long as the total thickness worn away
does not exceed 0.030 inch.
stant research, resulting in various products,
is another matter. It may require some filing
firmly closed, the contacts must not arc.
Contact materials have been subjected to con-
Severe pitting or burning of a silver contact
ranging from pure carbon or copper, to pure .silver, each being used alone and also as alloys with
other substances. Modern circuit breakers have
(with a fine file or with fine sandpaper, No. 00)
to remove raised places on surfaces that prevent intimate and overall closure of the contact
surfaces. If of cessary, use a CLEAN cloth
contacts coated with silver, or silver mixed
with cadmium oxide, or silver and tungsten.
The two latter silver alloys are extremely hard
moistened with INHIBITED methyl chloroform
Be very certain to provide ample ventilation
to remove all DEADLY and TOXIC fumes of
and resist being filed. Fortunately, such contacts
made of silver or its alloys conduct current when
the solvent.
58
64
,
Chapter 3 SWITCHES, PROThCTIVE DEVICES, AND CABLES
(1)
FUSE RETAINING BLOCK
(2, 3 & 4) CURRENT LIMITING FUSES
(8)
FUSE UNIT TRIPPER BAR
(9)
FUSE UNIT TRIPPER BAR LEVER
(5)
EXTENDED PLUNGER OF BLOWN FUSE
(10)
FUSE INTERLOCK PIN
(6)
RETRACTED PLUGER OF UNBLOWN FUSE
(11)
FUSE UNIT HOUSING
(7)
FUSE PLUNGER LEVER
77.248
Figure 3-40. Current limiting fuse unit assembly.
When cleaning and dressing copper contacts,
maintain the original shape of each contact surface and remove as little copper metal as
possible. Inspect and wipe the copper contact
surfaces for removal of the black copper-oxide
film and, in extreme cases, dress and clean only
with fine (No. 00) sandpaper to prevent scratching
the surfaces.
NEVER use emery cloth or emery pw.asr.
the contact pressure should be checked with that
of similar contacts. When the force is less than
the designed value, the contacts either require
replacing because they are worn down, or the
contact springs should be replaced. Always
replace contacts in sets; not singly, and replace
contact screws at the same time. Do not use
emery paper or emery cloth to clean contacts,
Because this copper-oxide film is a partial
and do not clean contacts when the equipment is
energized.
with a clean cloth moistened with inhibited
mechanism, particularly the insulation surfaces,
insulator, follow the sanding procedure by wiping
chloroform solvent. Provide VERY
LIBERAL ventilation by means of exhaust fans
or with portable blowers to entirely remove all
traces of the deadly fumes of the solvent.
methyl
Calibrati n problems on circuit breakers
should be huadled in accordance with chapter
9600 of NavShips Technical Manual.
The function of arcing contacts is it necessarily impaired by surface roughness. Re-
move excessively rough spots with a fine file.
Replace arcing contacts when they have been
burned severely and cannot be properly adjusted. Make a contact impression and check
the spring pressure in accordance with the
Clean all surfaces of the circuit breaker
with a dry cloth or air hose. Before directing
the air on the breaker, be certain that the water
is blown out of the hose, that the air is dry,
and that the pressure is not over 30 psi. Check
the pins, bearings, latches, and all contact and
mechanism springs for excessive wear or
corrosion and evidence of overheating. Replace
parts if necessery.
Slowly open and close circuit breakers manually a few times to be certain that trip shafts,
toggle linkages, latches, and all other mechanical parts operate freely and without binding. Be
certain that the arcing contacts make before
and break after the main contacts. If poor
alignment, sluggishness, or other abnormal con-
manufacturers' instructions. If information on
ditions are noted, adjust in accordance with
the correct contact pressure !s not available,
59
65
IC ELECTRICIAN 3
2
relays, and other control equipment, and should
not be used at all unless called for in the manu-
facturer's instructions or unless oil holes are
provided. If working surfaces or bearings show
signs of rust, disassemble the device and care-
fully clean the rusted surfaces. Light oil can
be wiped on sparingly to prevent further rust-
ing. Oil as a tendency to accumulate dust and
grit, which may cause unsatisfactory operation
of the device, particularly if the device is delicately balanced.
Arc chutes or boxes should be cleaned by
scraping with a file if wiping with a cloth is not
sufficient. Replace or provide new linings when
they are broken or burned too. deeply. Be certain
that arc chutes are securely fastened and that
there is sufficient clearance to ensure that
no interference occurs when the switch or contact is opened or closed.
Shunts and flexible connectors, which are
flexed by the motion of moving parts, should
be replaced when worn, broken, or frayed.
( I ) CONNECTOR STRAPS
(SI LATCH MOUNT INS SCREWS
(2) LATCH POST
It) TRIP UNIT LATCH PIN SLOT
IS) TERMINAL STUD NUTS* WASHERS
(1) MECHANISM T RISSER
(4) TRIP UNIT LINE TERMINAL
NI MECHANISM TRISSER LATCH
If) COTTER KEY HOLE
SCREWS - OUTER POLES
Operating tests that consists of operating the
circuit breakers in the manner in which they
are intended to function in service should be
conducted regularly. For manually operated circuit breakers, simply open and close the
breaker to check the mechanical operation. To
check both the mechanical operation and the
control wiring, electrically operated circuit
breakers should be tested by means of the
operating switch or control. Exercise care
not to disrupt any electric power supply that
is vital to the operation of the ship, or to endanger personnel by inadvertently starting
77.249
Figurc.. 3-41. NQB-A250 circuit breaker front
view, cover removed.
Instructions for the particular circuit breaker.
Before returning a circuit breaker to service, inspect all mechanical and electrical conthe manufacturer's
motore and energizing equipment under repair.
OVERLOAD RELAYS
nections, including mounting bolts and screws,
drawout disconnect devices, and control wiring.
Tighten where necessary. Give the breaker a
final cleaning with a cloth or compressed air.
Operate ma 'ivally to be certain that all moving
parts function freely. Check the insulation resistance.
The sealing surfaces of circuit-breaker contactor and relay magnets should be kept clean
and free from rust. Rust on the sealing surface
Overload relays are provided in motor con-
trollers to protect the motor from excessive
currents. Excessive motor current causes normally closed overload relay contacts to open
which break the circuit to the operating coil of
the main contactor, and disconnects the motor
from the line (fig. 3-42). Overload relays are of
the thermal or magnetic type.
Thermal Relay
The thermal overload relay has a heat-
decreases the contact force and may result in
overheating of the contact tips. Loud humming
or chattering will frequently warn of this condition. A light machine oil wiped sparingly on
the sealing surfaces of the contactor magnet
sensitive element and an overload heater connected in series with the motor circuit as shown
in figure
will aid in preventing rust.
Oil should always be used sparingly on cir-
3-42. When the motor current is
excessive, heat from the heater causes the heatsensitive element to open the overload relay con-
cuit breakers, contactors, motor controllers,
tacts. As it takes time for the heat-sensitive
60
66
Chapter 3 SWITCHES, PROTECTIVE DEVICES, AND CABLES
heater cnsists of a coil in the motor circuit and
a copper tube inside the coil. The copper tube
acts as a short-circuited secondary of a trans-
former, and is heated by the current induced in it.
This type of overload relay is used only in a-c
controllers, whereas the previously described
types of thermal overload relays may be used
in a-c or d-c controllers.
Magnetic Relay
The magnetic overloal relay has a coil con-
nected in series with the motor circuit and a
tripping armature or plunger. When the motor
current is excessive, the armature opens the
overload relay contacts. Magnetic overload
relays may be of the instantaneous or time delay
type.
INSTANTANEOUS TYPE.
OVERLOAD
INELNI
CONTACT
This type oper-
ates instantaneously when the motor current be-
comes excessive. The relay must be set at a
tripping current higher than the motor starting
current to prevent ripping when the motor is
124.249
Figure 3-42. Schematic diagram of motor controller with thermal type overload.
started. This type of overload, relay is used
mostly for motors that are started on reduced
element to heat up, the thermal type of overload
relay has an inherent time delay. Thermal lverload relays may be of the solder-pot, bimetal,
single metal, or induction type.
ly the same as the instantaneous type with the
addition of a time delay device. The time delay
SOLDER-POT TYPE.
voltage then switched to full line voltage after the
motor comes up to speed.
TIME DELAY TYPE. This type is essential-
device may be an oil dashpot with a piston
The heat sensitive
attached to the tripping armature of the relay.
The piston has a hole through which oil passes
when the tripping armature is moved due to excessive motor current. The size of the hole can
be adjusted to change the speed at at which the
piston moves for a given pull on the armature.
For a given size hole, the larger the current, the
faster the operation. This allows the motor to
element is a solder pot which consists of a cylhaler inside a hollow tube. These are normally
held together by a film of solder. In case of ex-
cessive motor current, the heater melts the
solder, breaks the bond between the tube and cyl-
inder, and releases the tripping device of the
relay. After the relay trips, the solder cools and
soldifies, and the relay is ready to be reset.
BIMETAL TYPE. The heat-sensitive elen.ent is a strip or coil of two different metals
carry a small overload current for a longer
period of time than a large overload current.
ELECTRICAL CABLES
fused together along one side. When heated, one
metal expands more than the other causing the
Shipboard electrical and electronic systems
require a large variety of electric cables. Some
circuits require only a few conductors having a
high current-carrying capacity; others require
many conductors having a low current-carrying
capacity; still oth-- may require cables with a
special type of insulation, the conductors may
have to be shielded, or in some cases the conductors may have to be of a metal other than
copper.
strip or coil to bend or deflect, and open the
overload relay contacts.
SINGLE METAL TYPE. The heat-sensitive
element is a metal tube around the heater. The
tube lengthens when heated and opens the overload relay contacts.
INDUCTION TYPE.
ment
The heat-sensitive ele-
is usually a bimetal strip or coil. The
61
67
IC ELECTRICRN 3 ti 2
The proper installation ant maintenance of
the various electrical systems aboard ship are
very important to the IC Electrician. The repair of battle damaTs. accomplishment of ship
alteratic-- , and some electrical repairs may
require that changes or additions to the ship's
cables, control and protective devisees, be made
by the IC gang. Additionally, during shipyard
and tender availabilities, you may be required
to inspect, test, rnd approve the new installations.
To perform these tasks you must first have
a working knowledge of the various types, sizes,
capacities, and uses of shipboard electrical
cable. The IC Electrician must also be capable
of selecting, installing, and maintaining cables
in such a manner as to ensure their adequacy.
items for replacement of obsLhete items. Cable
items are listed in the guide by general classifica-
tions as to construction and service conditions.
These broad groupings are broken down into types
and sizes and indicerd as being current (C), discontinued (D), or obsolete (0), as shown in the
first column of Table
The term "watertight cable," designated by
an asterisk (*) in the cable guide and in Table
3-1, indicates standard cables in which all
spaces under the impervious sheath are filled
with material to eliminate voids and to prevent
the flow of water through the cable by hose
action in the event that an open end of cable is
exposed to water under pressure.
Finally, you mist know the purpose, construction,
installation, and testing procedures of control
and protective devices in order to maintain an
electrical system properly.
CABLE COMPARISON GUIDE
The IC Electrician needs to have a working
knowledge of the Cable Comparison Guide, NavShips 0981-052-8090. This guide fills a need for
information on the use of electric shipboard cable,
particularly for the selection of substitute cable
.Table
3-1.
3-1.
of the varied service conditions
Beca Ise
aboard ship, the cable must have the ability to
withstand heat, cold, dampness, dryness, bending, crushing, vibration, twisting, and shock. No
one type of cable has been designed to meet all
of these requirements; therefore, a variety of
types are employed in a shipboard cable installation.
cable types are grouped under the general
classifications of: (1) cables for nonflexing
service (table 3-1), (2) cables for repeated flexing service, and (3) cables for special purposes.
Cables for Nonflexing Service
rStuffing
Tub. Size
Outside Deck
Cur
No
Strands Diem
Dl'
Diem
and
of
Per
Obs Type & Silt
Cats Cdr
Cable
Mos
Bulkhead
Copper Area
Cdr
Cdr
Inch
Cirmils
,-Maximum
Equip, Voltmint age
Volts
Inch
nns
r
TA m
bep
:tut.
ne
40"C
Radius
of
50% Bend
Amperes
Inch
Federal
Est Wt Stock
Per Ft No
Lbs.
GX6145
1927195
LIGHTING AND POWER -Cont.
C
C
C
C6441.400
2
127
.742
413,600
DIMA-400
2
127
,742
413,600
127
.742
413,600
2.119
2.508
2.508
.457
157,600
198,700
2.010
2.250
65GA-150
65GA-200
6
61
6
61
.514
V
8
1000
Y
9
600
Y
9
W
9
600
492
492
492
453
453
453
13.0
15.5
15.5
4.28
4.75
4.75
1000
1000
326
369
300
340
12.0
13.5
4.17
5.19
184.5897
192.7221
Maximum ratings for 6SGA cables are for 400 hertz power circuits only.
Watertight Construction
77.1
62
GS
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
employs silicone rubber and glass as primary
insulation, making it heat and flame resistant.
CABLE TYPE AND SIZE
DESIGNATIONS
Shipboard electrical cables are identified according to type and size. Type designations consist of letters to indicate construction
and/or use. Size designations consists of a num-
The construction of a DSGA. cable is shown in
figure 3-43. The insulated stranded copper con-
ductors are enclosed in an impervious sheath,
braided metal armor, and paint. The cable has
depending upon the type of cable.
been made watertight by the application of waterproof sealing compound to all voids of the conductors and cable core. DSGA cables are designed
to have a minimum outside diameter and weight
In most cases the number of conductors in a
cable, up to and including four conductors, is in-
newer cable saves on space and weight which is
at a premium on combatant naval vessels.
ber or numbers to indicate the size of the conductor(s) in circular inn area, number of
conductors, or number of pairs of conductors
as compared to older type cable. Using the
dicated by the first type letter as follows: S-
The numerals (table 3-1) immediately follow-
single conductor; D-double conductor; T-three
conductor; and F-four conductor. For cables with
more than four conductors, the number of conductors is usually indicated by a number following the type letters. In this latter case, the letter
M is used to indicate Multiple Conductor. Examples of common shipboard cable designations are
ing the type letters indicate the cross-sectional
area of a single conductor and expressed in
thousands of circular mils. For example, 6SGA150 indicates approximately 158 thousand circular mils conducting area.
Table 3-1 also lists the sizes of stuffing
as follows:
tubes (metal or plastic tubing containing the
cable) used with particular types and sizes of
cable. Metal stuffing tubes are used generally
DSGA-3-Double conductor, Shipboard, Gen-
eral use, Armored, conductor size approxi-
for deck and bulkhead installations.
mately 3000 circular mils.
FHFA-4-Four conductor, Heat and Flame resistant, Armored, conductor size approximately
4000 circular mils. Type FIFA cable has been re-
Type and Size Exceptions
By analyzing the designations for cable types
and sizes, you will notice that some letters have
placed by type SGA.
DCOP-2-Double
conductor, Oil resistant,
Portable conductor, size approximately 2000
more than oae meaning. The letter T, for example,
usually means THREE. In the designation
circular mils.
conductor, Shipboard,
MSCA-30-M ultiple
Control, Armored, with 30 conductors.
MDGA-19 (6)-Multiple conductor, Degaussing, Armored, 19 conductors, conductor size approximately 6000 circular mils.
TTHFWA-10, however, the double T stands for
twisted-pair, telephone. The T in TRXF means
Also included in this lighting and power group
is the DSGA type cable. The DSG type cable
conductors or sizt; of copper conductor or number
STRANDED COPPER CONDUCTOR
tough jacket.
Similarly, there are exceptions regarding
the use of numerals in size designations since
the numerals ir ay indicate number of copper
and size of a conductor or size and number of
BINDER
GLASS FIBER BRAID
(COLOR CODED)
EXTRUDED SILICONE RUBBER
FILLER
IMPERVIOUS SHEATH
BRAIDED METAL ARMOR AND PAINT
29.226(77)A
Figure 3-43.
Type DSGA shipboard nonflexing servi3e
63
69
IC ELECTRICIAN 3 & 2
strands per conductor or number of twisted
pairs or maximum rms rated voltage.
Example: MSCA-7
The 7 stands for the number
of conductors, not the con-
ductor area as in the case
of DHFA-400 (table 3-1).
Example: TTHFWA -10
The 10 indicates the
number
of
A
twisted
pairs; that is, 20 conExample: SS5P
IRON
ductors.
*
TYPE MDU CABLE
#millostailig
The 5 is an indication of maxi-
CONSTANTAN
mum rms rated voltage, 50n0
in this case.
g TYPE PBJX CABLE
NONFLEXING SERVICE
i
1
Nonflexing service cable designed for use
aboard ship is intended for permanent installation and is commonly referred to as such. The
cables that are described in the previous paragraphs for use with lighting and power circuits
are intended for this nonflexing service. This
nonflexing service can be further classified according to its application and is of two types
general use and special use.
C TYPE TTHFWA CABLE
Figure 3-44.
General Use (Nonflexing Service)
29.226(77A)B
Nonflexi ng service cable for spec-
ial use.
Nonflexing service cable is intended for use
in nearly all portions of electric distribution
systems, including the common telephone circuits and most propulsion circuits. Special
cases occur in d-c propulsion circuits for surface ships. In those cases where the impressed
voltage is less than 1000 volts, an exception is
permitted.
essary requirements, yet be economically impracticable. For these reasons, there are many
different types of nonflexing service cable for
specialized use, such as degaussing, telephone
The previously described DSGA cable is one
type usually found in this general use, nonflexing
Type MDU (fig. 3-44A) is a multiconductor
cable .ised in degaussing circuits. Type PBJX
(replaled by type TCJA-mil-C-2194 on new
constrsic'ion) cable (fig. 3-44B) consists of one
radio, and casually power. Some of these cables
are shown in figure 344.
service. Also in this classification is the type
MSCA 'able. This cable is nothing mor: fain
".var..?.rtight cable for use in interior commulica-
conductor of constantan (red) and one conductor
tions, as well is in fire control circuits.
of iron (pay), and is used for pyrometer base
leads. Type TTHFWA (fig. 3-44C) is a multi-
Special Use (Nonflexing Service)
conductor, twisted-pair cable used for telephone
circuits.
There are many shipboard electrical circuits
where special requirements of voltage, current,
frequency and service must be met in the cable
REPEATED FLEXING SERVICE
installation and other circuits where general
Repeated flexing service cable designed for
use, nonflexing service cable ma/ meet the nec-
use aboard ship is commonly referred to as
64
70
Chapter 3 SWITCHES, PROT:XTIVE DEVICES, AND CABLES
IMPERVIOUS SHEATH
SEPARATOR
CONDUCTOR
COTTON TAPE
SYNTHETIC RUBBER
FILL ER
RUBBER)
A TYPE MHFF CABLE
BINDER
29.226(77)C
Figure 3-45.
Type DHOF shipboard repeated
flexing service cable.
being portable because it is principally used as
leads to portable electric equipment. It is also
of two types general use and special use.
General Use (Flexing Service)
29.226(77)D
Figure 3-46. Repeated flexing service cable for
special use.
Repeated flexing service cable is designed
for use as leads to portable equipment and
permanently installed equipment where cables
are subjected to repeated bending, twisting,
mechanical abrasion, oil, sunlight, or where
maximum resistance to moisutre is required.
Its letter designation is HOF (heat and oil resistant, flexible). This cable contains stranded
copper conductors that are insulat, ' with butyl
rubber, covered with a tape or braid. The designated number of conductors are twisted together, held by a binder, and covered with an
equipment) cables having from 2 to 44 individually insulated conductors within a common
protective sheath. For example, all single- conductor cables are black; all 2-conductor
cables consist of 1 black, 1 white, and all 3-
conductor cables consist of 1 black, 1 white, and
1 red, etc., up to a 44-conductor cable, where all
the color combhations listed in table 3-2 would
be included. In cables with more than one layer
of conductors, the numbering shown in the table
is from the innermost to the outmost. For
impervious sheath (fig. 3-45).
Repeated flexing service cable designed for
general use is of four different types, depending
on the number of conductors. Type SHOF cable
example, the No. 1 conductor will be the center
designated as types SHOF (single conductor),
d-c portable equipment and tools is black, white,
and green. The green conductor is used to ground
the metal case of the equipment to the ship's hull.
is available in various conductor sizes
conductor
and
DHOF (two conductor), THOF (three conductor),
and FHOF (four conductor).
Individual conductors and pairs in twistedpair telephone cables are color coded by pairing
the solid colors in sequence as shown in table
Special Use (Flexing Service)
There are many different types of repeating
flexing service cable designed for special requirements of certain installations, including
type TTOP and casualty power cables. Two of
3-3.
CABLE MARKING
these types are shown in figure 3-46 type MHFF,
Rcady identification for maintenance and repairs of IC circuits is provided by cable designations embossed on the cable tags (fig. 3-47).
These cable designations include (1) service
letter, (2) circuit letter(s), and (3) cable number.
The SERVICE is denoted by the letter C, which
is the designation for all cables and circuits that
comprise the IC system in naval ships. Each
(fig. 3-46A) is used for control circuits in re-
volving structures, and type TRF (fig. 3-46B) is
used for arc-welding circuits.
COLOR CODES
The color code given in table 3-2 applies to
all multiple conductor (except twisted-pair or 3-
conductor commercial for portable tools
(or one of the center conductors
where two or more are used as a center) of the
concentric lay. The color coding of 3-conductor
flexible cable for single-phase a-c and 2-wire
circuit is distinguished by a single letter or
and
65
IC ELECTRICIAN 3 & 2
Table 3-2. Color Coding of Multiple Conductors Cables
Conductor No.
1
2
3
4
5
6
7
8
9
10
ll
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Base color
Tracer color
Black
White
Red
Green
Orange
Blue
White
Red
Black
ft
Green
Orange
ft
ft
ft
Blue
Black
Red
White
ft
ft
Green
ft
Blue
Black
White
Red
ft
Orange
ft
Blue
Red
Orange
Black
White
Red
ft
Green
ft
White
Black
White
36
37
38
39
40
Orange
ft
ft
White
ft
Red
White
Red
White
Brown
ft
ft
ft
43
ft
ft
ft
Green
ft
-
ft
Orange
Green
Orange
ft
,,
Blue
ft
Black
White
Red
ft
41
ft
ft
ft
Black
Blue
42
White
Red
Green
Orange
Black
ft
ft
Blue
Black
White
Red
35
Red
ft
ft
ft
Green
Orange
32
33
34
44
Tracer color
Green
Orange
Blue
140.64
it
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
Table 3-3. Color Coding of Twisted Pair Telephone Cable
Telephone Pair
1
2
3
4
5
6
7
8
9
10
One Wire
White
Red
Green
Orange
Blue
Brown
Gray
Yellow
Purple
Tan
11
Pink
12
13
14
15
16
17
18
19
20
Red
-21
22
23
24
Green
Orange
Blue
Brown
Gray
Yellow
Purple
Tan
Pink
Green
Orange
Blue
A typical cable designation is C-MD-144. The
letter C denotes the service (the IC system).
The letters MB denote the circuit, engine-order
system, which may actually include wires of
circuits 1MB, 2MB, 3MB, etc. The number 144
denotes cable number 144 of circuit MB.
Other Wire
Black
Black
Black
Black
Black
Black
Black
Black
Black
Black
Black
Permanetly installed ships' cables are tagged
as close as practicable to each point of con-
nection, on both sides of decks, bulkheads, and
other barriers. Cables located within a single
compartment in such a manner that they can be
readily traced are not tagged.
TERMINAL MARKING
single-letter circuits and d-c supply
circuits the positive terminal is designated by
a single letter, as M. Similarly, an arbitrarypolarity of single phase a-c circuits is designated
by a single letter, as M (assumed instantaneous
positive). The other side (representing the opposite polarity) of both d-c and a-c circuits is
In
White
White
White
White
White
White
White
White
White
White
designated by the double letter, as MM.
Double-letter circuits have supply lead
markings assigned as for single letter circuits,
except that the second letter of the negative is
doubled; for example, positive M 3, negative
Red
Red
Red
MBB.
TERMINAL
BLOCK
140.146
double letters. These letters identify the cable
as a part of one of the numerous IC circuits. If
two or more circuits of the same system are
contained in a single cable, the number preceding the circuit letter or letters is omitted. The
cable number is the number of the cable of the
particular circuit.
c)
3EPS /C -E -53
3EP/C-E-52
3 EPP/C-E-52
Ci 3EPT /C -E-53J
3EP6/C-E-54
3 EP3 /C-E-52011
CI3EP9/C-E-54
Lur 3EP4/C-E-52 lea
SECURE 746 70 CABLE
3EPIO/C-E-54
SHOWN
ITV
3EP5/C-E-52
111.41111
TYPICAL
MARKING
140.14(140B)
12.74
Figure 3-48. Wire terminal markings.
Figure 3-47. Cable tag.
67
73
IC ELi.:C'fi-tICIAN 3 & 2
All IC terminals are identified by insulated
sleeving that is stamped with the lead number
CABLE MAINTENANCE
and cable number the lead belongs to (fig. 3-48).
The purpose of cable maintenance is to keep
the cable insulation resistance high. Cables
should be kept clean and dry, and protected from
mechanical damage, oil, and salt water.
The wire terminals 3EP and 3EPP, respec-
tively, are the pusitivc and negative supply
terminals from cable C-E-52, which emanates
from the IC switchboard and leaves from cable
Testing Cables
C-E-53. The wire terminals, 3E1)3, 3EP5, 3DP6,
and 3EP8, from cable C-E-52 are the positive
terminals of pushbutton stations 3, 5, 6, and 8,
respectively. The functions of these wires art
found on the elementary and isometric drawings
of the SEP (protected E call) circuit for your
Insulation resistance tests (ground tests) must
be made periodically on IC cables to determine
the condition of the cable. In addition, tests
should be made when cables have been damaged,
when cables have been disconnected for circuit
or equipment changes, when there is evidence
ship.
that a cable has been subjected to oil or salt
Numbers following the circuit letter indicate
a serial number assigned for the station, followed by the section wire number designating
the function of the circuit. On systems containing synchros, the numberals, 1, 2, and 3, are used
for the connections to secondary windings. Where
more than one synchro is employed in a single
instrument, the numberals 4, 5, and 6, apply to
the second synchro, and 7, 8, and 9 to the third
synchro. For example, 1-MB14 should be interpreted as follows:
starboard circuit
MB-engine-order system
1 station number, such as pilot house
4connection to secondary windings of the
1
No.
ment
2 synchro receiver in the instru-
If corresponding portions of a circuit are
energized from the forward and aft IC switchboards, the suffix letters, F and A, are added to
the ends of wire markings to indicate the switchboard from which the wire originated.
All terminals in a circuit that may be connected without a break (in the electrical sense)
shall be assigned the same wire marking. A fuse,
switch, or instrument is considered a break in
the circuit and requires a change in the wire
marking.
Signal contacts should be connected to the
positive (single-letter connection) in the instruments. The section-wire markings for bell or
visual signal circuits should be assigned the next
higher number after assignment of numbers to
secondary windings of all synchro receivers in
the instruments. For example, in an instrument
containing two synchro receivers the signal circuits
should be assigned section wires
No. 7, 8, etc.
water, and after shipboard overhauls.
Interior communication cables may be tested
with a 500-volt megger if they are disconnected
at the equipment or load end. In some cases,
when it is not practical to disconnect the cable,
an ohmmeter, or 50-volt tester must be used as
described in NavShips Technical Manual,
chapter 9650.
GROUND TESTS. To ground test a multi-
conductor IC cable, proceed as follows:
1. Check to see that the cable armor is
grounded by measuring between the cable armor
and the metal structure of the ship; normally,
grounding has been accomplished by means of
cable straps. If a zero reading is not obtained,
ground the cable armor.
2. Select one conductor to be tested, and connect all other conductors in the cable together
and ground them by means of temporary wires
or jumpers.
3. Measure the resistance of the conductor
being tested to ground. The test voltage should
be applied until a constant reading is obtained.
Hand-driven generator type meggers should be
cranked for at least 30 seconds to ensure a steady
reading.
4. Repeat steps 2 and 3 as necessary to test
each conductor to ground..
A reading equal to, or above the accepted
minimum for the cable concerned (discussed
liter), indicates that the conductor under test is
satisfactory. A reading below the accepted minimum indicates that the insulation resistance of
the conductor under test to ground, or from one
or more of the grounded conductors, or both, is
low. The grounded conductors must then be disconnected from ground, and each conductor tested
68
74
Chapter 3 swirciiEs, PROTECTIVE DEVICES, AND Cto.1:,ES
individually
to
isolate
the
of type MSCA-7 cable (7-conductor cable) connected to 200 feet of MSCA-24 cable (24-con-
low reading
conductor( s) .
ductor cable) represents a total cable length of
An alternate method of ground testing multiconductor cables is to connect all conductors
together and measure the insulation resistance
from all conductors to ground simultaneously.
If this reading is equal to or above the accepted
minimum, no other reading need be taken. If the
reading is below the accepted minimum, the conductors must be separated and tested individualto isolate the low reading conductor(s).
ly
400 feet.
TYPE OF CABLE.Insulation resistance
will vary considerably with the nature of the insulating materials employed and the construction
of the cable. Therefore, it is possible to determine the condition of a cable by its insulation
resistance measurements only when they are
considered in relation to the typical characteristics of the particular type of cable. The min-
Factors Affecting Insulation Resistance
imum safe insulation resistance for types DSGA,
HF, DG, SCA, TTHFA, and TTHFWA cables is
Factors that aff'sct cable insulation resistance measurements are the length, type,
temperature, and the equipment connect in the
circuit. Each of these factors must be evaluated
to reliably determine the condition of the cable
indicated on the reverse side of the Resistance
Test Record Card, NavShips 531-1, (fig. 3 -49).
TEMPERATURE OF CABLE. With nonflexing service cables, the highest permissible
from the measurements obtained.
operating temperature (85° C at the sheath) and
The insulation resistance of a length of cable is the resultant of a
number of small individual leakage paths or reLENGTH OF CABLE.
sistances between the conductor and the cable
sheath. These leakage paths are distributed along
the cable. Hence, the longer the cable, the greater
the number of leakage paths and the lower the insulation resistance. For example, if one leakage
path exists in each foot of cable, there will be 10
such paths for current to flow between the conductor and the sheath in 10 feet of cable, and the
total amount of current flowing in all of them
would be 10 times as great as that which would
flow if the cable were only 1 foot long. Therefore, to establish a common unit of comparison,
cable-insulation resistance should be expressed
in megohms (or ohms) per foot of length. This
is determined by multiplying the measured in-
sulation iesistane, of the cable by its total
length in feet.
When measures insulation resistance is converted to insulation resistance per foot, the total
length of cable to be used is equal to the length
of the cable sheath for single conductor cable and
for multiple conductor cable in which each con-
ductor is used in one leg of a circuit. For example, in a TSGA cable with a cable sheath of 100
the nature of the insulating material makes it
essential that temperature of the cable be considered in conjunction with the insulation reTherefore, fairly
sistance measurements.
accurate estimates or measurements of the
temperature of the sheath of the cable must be
made to permit proper use of the Resistance
Test Record Card.
EQUIPMENT CONNECTED.When insula-
tion resistance measurements are made with
equipment connected, always record the exact
equipment included, and the type of tester used,
so that accurate comparisons can- be made with
similar past or future measurements.
CABLE REPAIR
AND INSTALLATION
Electrical cables installed aboard Navy vessels must meet certain requirements determined
by the Naval Ships Systems Command. These
requirements, published in the General Specifications for Ships of the U.S. Navy, are too numerous to cover in detail in this training manual;
hence, only the more basic ones are included.
The job of installing nonflexing service cable
may be performed by the IC gang whenever
necessary to repair damage or to accomplish
feet in which the three conductors are phases
A, B, and C of a 3-phase power circuit, the total
length of the cab.e is 100 feet, not 300 feet. The
reason for this is that each conductor is mea-
ship alterations. Before work
is begun on a new cable installation, cableway plans should be available. If repairs to a
damaged section of installed cable are to be
authorized
sured separately. If this cable is connected,
either in series or parallel, to a similar cable
that has a sheath length of 400 feet, the total
effected, information on the original installation
can be obtained from the plans of the ship's
length is 500 feet. As another example, 200 feet
69
75
IC ELECTRICIAN 3 & 2
ROE
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(NO, 0A. *AI
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NO.
WAILS= Se-
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A
RESISTANCE TEST RECORD CARO
NASHIPS $31.1 ((0.031 'FRONT)
TOO
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MINNS. ALLOW111.1 INMEATION RESISTANCE
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70.1
COLD CLIMATE
SINTER 04 AGAINST
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NON1C-J1n .OR OBTAINING RESISTANCE PER. FT.
RESISTANCE TEST RECORD CARO
Ire sot
110.151
I00
SAO
(POINT 01
(POINT (:))
5500
2200
(POINT (:))
(POINT (:))
I
mo
0-111114
Figure 3-49 Resistance test record card.
electrical system, which are normally on file
1.3
above the main deck, except where necessary
in the engineering department office (log room)
aboard ship. If a ship alteration is to be accomplished, applicable plans not already on board,
can be obtained from the naval shipyard listed
because of the location of the equipment served,
or because of structural interferences or avoidance of hazardous conditions or locations. Where
practicable, route vital cables along the inboard
side of beams or other structural members to
afford maximum protection against damage by
flying splinters or machine gun strafing.
Where practicable, avoid installing cable in
locations subject to excessive heat, and never
install cable adjacent to machinery, piping, or
on the authorization for the alteration (SHIP ALT)
at the planning yard for the ship.
Wireways
Before installing new cable, survey the area
to see if there are spare cables in existing
other hot surfaces having an exposed surface
temperature greater than 150° F. In general,
cables shall not be installed where they may be
wireways and spare stuffing tubes that can be
used in the new installation. The cable run must
be located so that damage from battle will be
minimized, physical and electrical interference
subjected to excessive moisture.
Selecting Cable
When installing cable, use all reference data
with other equipment and cables will be avoided,
and maximum dissipation of internally generated
heat will occur. Do not run cables on the ex-
available. Table 3-4 is a typical cable char-
terior of the deckhouse or similar structures
acteristics chart for TTRSA, while table 3-5
70
76
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND Cita: tS
Table 3-4. Cable Characteristics
CABLE TYPE: TTRSA
Telephone and RF, Non-Flexing Service.
DESCRIPTION: Twisted shielded pair, radio, armored. Conductor insula
tion: Polythene over each conductor with an inner cotton braid over a
braided copper shield on each pair. Cable insulation: Braided metal
armor of aluminum alloy over an impervious sheath.
USE:
la
N 0z
5 :a
Lu z
-J (-0
a2 7,
5
(1
u)
ct
CC
L1-1
Ct°-
w5
CO 0
2z
ct
o
I--
on
Z
4 z0
c M. AREA
OF
ILJ
w0
co ILI co
a0 0
ao
2 oz
CONDUCTOR
-
,.. w
cl
LLI 0
4
2 Ic..) <)
0
0
Z0
NO.
NO.
NO.
C.M.
INCH
INCH
2
4
6
4
7
7
7
7
7
7
7
1113
1119
1119
1119
1119
1119
1119
0.038
0.038
0.038
0.038
0.038
0.038
0.038
0.740
0.800
0.940
1.050
1.140
1.160
1.250
<
0
'Li
8
10
12
16
8
12
16
20
24
32
Ct 0
I-- 0
MAXIMUM
RATING
50° C
u_
0
0
VRMS
AMPS
300
300
300
300
300
300
300
- - -- - -- - -- - -- - -- - --
----
140.61
dripproof through stuffing tubes or cable clamps
sealed with plastic sealer.
is an installation data chart from EIMB. Ackli-
tional information is available in NavShips 0967000- 0110 Section 4, Interconnection Cabling and
Wiring.
Below the main deck, stuffing tubes are used
fpr cable penetrations of watertight decks,
watertight bulkheads, and watertight portions of
bulkheads that are watertight only to a certain
height. Above the main deck, stuffing tubes are
used for cable penetrations of (1) watertight or
airtight boundaries; (2) bulkheads designed to
withstand a waterhead; (3) that portion of bulkheads below the height of the sill or coaming of
compartment accesses; (4) flametight or gastight, or watertight bulkheads, decks, or wiring
trunks within turrets or gun mounts; and (5)
structures subject to sprinkling.
Stuffing Tubes
Stuffing tubes (fig. 3-50A, B, and C) are used
to provide for the entry of electric cable into
splashproot, spraycight, submersible, and explosion-proof equipment enclosures. Cable
clamps, common!y called box connectors (shown
in figure 3-51), may be used for cable entry into
all other types of equipment enclosures, except
that top entry into these enclosures shall be made
71
77
Table 3-5 -Installation Data
CABLE TYPE: TTRSA
Telephone and RF, Non-Flexing Service.
DESCRIPTION: Twisted shielded pair, radio, armored. Conductor insulation: Polythene over each conductor with an inner cotton braid over a
braided copper shield on each pair. Cable insulation: Braided
metal
armor of aluminum alloy over an impervious sheath.
USE:
la z
NO
0_
Vi F:
Q.
4 2
w2
_i 0
co Fj
ct la
00
-ca2n
D
i
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ri
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w
w
D
CZ
CO
W
_iN
4
I- Cr;
w
2
NO.
INCH
NO.
2
5.0
5.0
6.0
6.5
7.0
E
4
6
8
10
11
16
7.0
7.5
F
J
K
K
L
M
0
>cI-0 w
OWN
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Z
00
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>-
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(-0
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(7)
z
Z
NO.
MS NO
INCH
INCH
4
4
16179-5
16179-7
16189-3
16189-4
16189-7
16189-8
16190-1
3/4
3/4
1
1
1
1
1-1/4
1-1/4
1-1/4
1-1/4
1-1/2
3/4
1S
1S
5
5
1-1/4
1-1/4
1-1/4
1-1/4
5
5
6
Stuffing tubes are made of nylon, steel,
brass, or aluminum alloys. Nylon tubes have
0
1-1/4
1-1/4
1-1/4
140.62
the entrance to the enclosure and nylon body of
the stuffing tube is made with a neoprene "0"
ring, which is compressed by a nylon locknut.
A grommet type, neoprine packing is compressed by a nylon cap to accomplish a watertight seal between the body of the tube and the
cable. Two slip washers act as compression
washers on the grommet as the nylon cap of the
very nearly replaced metal tubes for cable
entry to equipment enclosures. Cable penetration of bulkheads and decks using nylon stuffing
tubes is limited for use above the watertight
level of a vessel. The watertight level is the
highest expected water level (determined by the
Naval Ship Systems Command studies of stability and reserve buoyancy) and is indicated on
the applicable ship's plans. The nylon tube is a
lightweight,
positive-sealing, noncorrosive
stuffing tube is tightened. Grommets of the same
external size, but with different sized holes for
the cable, are available. This allows a single-
maintenance for the preservation of watertight
integrity (fig. 3-52). The watertight seal between
cable sizes, and makes it possible for nine sizes
of nylon tubes to replace 23 sizes of aluminum,
steel, and brass tubes.
size stuffing tube to be used for a variety of
stuffing tube, which requires only minimum
72
78
Chapter 3SWITCHES, PROTE:.;TIVE DEVICES, AND CABLES
Sealing plugs are available for sealing nylon
stuffing tubes from which the cables have been
removed. The solid plug is inserted in place of
the grommet, but the slip washers are left in
the tube (fig. 3-52B).
A grounded installation that provides for
cable entry into an enclosure equipped with a
nylon stuffing tube is shown in figure 3-53. This
type of installation is required only when radio
interference tests indicate that additional
grounding is necessary within electronic spaces.
In this case, the cable armor is flared and
trimmed to the outside diameter of the slip
washers. Ori2 end of the ground strap is inserted
through the cap, and one washer is flared and
trimmed to the outside diameter of the washers.
Contact between the armor and the strap is maintained by pressure of the cap on the slip washers
and the rubber grommet.
Tables listing the correct size for deck, bulkhead, and equipment stuffing tubes for lighting
and power cables are found in the Cable Comparison Guide, NavShips 0931-052-8090.
TAPERED THREAD
Watertight integrity is vital aboard ship in
peacetime or in combat. Just one improper cable
installation could endanger the entire ship. For
example, if one THFA-4 cable (.812 inches in
diameter) is replaced by the newer TSGA-4 cable
(.449 inches in diameter) but the fittings passing
through a watlrtight bulkhead are not changed to
CSTRAIGHT
(IPS THREAD)
II 90
BEND
12.78
Figure 3-50. Nylon stuffing tubes.
the proper size, the result could be two flooded
spaces in the event of a collision or enemy blt.
Deck Risers
The nylon stuffing tube is available in two
parts. The body "0,, ring, locknut, and cap
comprise the tube; and the rubber grommet,
two slip washers, and one bottom washer comprise the packing kit.
A nylon stuffing tube that provides cable
entry into an equipment enclosure is applicable
V> both watertight and nonwatertight enclosures
(11g. 3-52A). Note that the tube body is inserted
from inside the enclosure. The end of the cable
armor, which will pass through the slip washers,
is wrapped with friction tape to a maximum
diameter. To ensure a watertight seal, one coat
of neoprene cement is applied to the inner surface of the rubber grommet r 1 to the cable
sheath where it will contact Ulf ommet. After
the cement is applied, the gn let is immeaint must be
diately slipped onto the cable. '1
Where one or two cables pass through a deck
in a single group, kickpipes are provided to protect the cables against mechanical damage. Steel
pines are used with steel decks, and aluminum
pipes with aluminum and wooden decks. NOTE:
When stuffing tubes and kickpipes are installed,
care must be taken not to install two different
metals together, an electrolytic action may be
set up. Inside edges on the ends of the pipe and the
inside wall of the pipe must be free of burrs to
prevent chafing of the cable. Kickpipes including
the stuffing tube shall have a minimum height of
9 inches and a maximum of 18 inches. Where the
height exceeds 12 inches, a brace is necessary
to ensure rigid support. Where the installation of
kickpipes is required in nonwatertight decks, a
conduit bushing may be used in place of the
stuffing tube.
When three or more cables pass through a
cleaned from the surface of the cable sheath
deck in a single group, riser boxes must be used
before applying the cement.
73
79
6
IC ELECTRICIAN 3
2
TONGUE
MACHINE SCREW
PLASTIC SEALER
SHEET METAL
OR CAST
ENCLOSURE
SIDE VIEW
END VIEW
BODY MEMBER
CLAMPING MEMBER
LOCKNUT
CABLE
PLASTIC
SEALER
MACHINE
SHEET METAL
OR CAST
SCREW
ENCLOSURE
SIDE VIEW
END VIEW
Figure 3 -51. Cable clamps.
provide protection against mechanical dam-
77.3
watertight decks.
Cable Supports
secure cables to bulkheads, decks, cable hangers, fixtures, etc. (fig. 3-54). The one-hole cable
strap (fig. 3-54A) may be used for cables not
exceeding five-eighths of an inch in diameter.
The two-hole strap (fig. 3-54B) may be used for
cables over five-eighths of as inch in diameter.
The spacing of simple cable supports, such as
those shown in figure 3-54 must not exceed 32
inches center to center. A more complex cable
support is the cable rack, which consists of the
cable hanger, cable strap, and hanger support
The single cable strap is the simplest form
of cable support. The cable strap is used to
Banding material is five-eighths of an inch
wide, and may be zinc-plated steel, corrosion
age. Stuffing tubes are mounted in the top of
riser boxes required for topside weatherdeck
applications. For cable passage through watertight decks inside a vessel the riser box may
cover the stuffing tubes if it is fitted with an
access plate of expanded metal or perforated
sheet metal. Stuffing tubes are not required
with riser boxes for cable passage through min-
(fig. 3-55).
74
80
Chapter 3SWITCHES, PROTEC rIVE DEVICES, AND CABLES
SIRRS STRUCTURE
war END or um ARMOR
ENCLOSURE
WITH rocrioN not TO A
MAX DIAMETER *HIGH %mu.
RIMS TH*CmGH THE sus
RASHERS
vcLosure
Cg CABLE
1407
REQUIRE:, TO BE
wiTH
g-u
ENZ)
'NKOMO PRCRO
444:1! CA4LOSORt
SOTTCRA
CA
MICE ENCLOSuRE
Cc GROMMET
E
MEM
RASA*
BDOTTUBE BODY
INSERTED FROM
S.EAM
Kyr - rum SOD!
R546
GASKET
Mr1 /
OCTTOM
WASHER
GROMMET
SUP
RASHERS
SURFACE COATED
MTH NEoPmREy
COAT SURFACE
INDICATED W'TH \
CEMENT
NEOPRENE calm
A
0 RM10
GROMMt
CAP
CAP
SLIP
WASHERS
FLRE
ARAMOR D
OCKNuT
CABLE
SUP
PODy
WASHERS
77.11
Figure 3-53. Nylon stuffing tube grounded installation.
CAP
BD4OLDSURE
R.NG
Not more than one row of, cable shall be in-
SEALNO PLUG S0L10
stalled on a single hanger.
Modular cable supports (fig. 3-56) are being
installed on a number of naval ships. The modular method saves over 50 percent in cable-pulling time and labor. Groups of cables are now
passed through wide opened frames, inst...ad of
being inserted Individually in stuffing tubes. The
77.10
Figure 3-52. Representative nylon stuffing tube
installations.
resistant steel aluminum, depending on the requirements of the installation. For weatherdeck installations, use corrosion resistant steel
band with copper armored cables; zinc-coated
frames are then welded into the metal bulk-
heads and decks for cable runs.
The modular method of supporting electrical
cables from one compartment to another is de-
steel with steel armor: and aluminum with
aluminum armor.
signed to be fireproof, water- and air-tight.
Modular insert semicircular grooved twin
half-blocks are matched around each cable to
When applying banding material apply one
turn of banding for a single cable less than one
inch in diameter. Apply two turns of banding for
single cables of one inch or more in diameter
and for a row of cables. Apply three turns of
banding for partially loaded hangers where
hanger width exceeds the width of a single cable
or a single row of cable by more than one-half
form a single block. These grooved insert blocks
which hold the cables (along with the spare insert solid blocks) fill up a cable support frame.
During modular armored cable installation
(fig. 3-56B), a sealer is applied in the grooves
of each block to seal the space between the armor
and cable sheath. The sealer penetrates the
braid and prevents air passage under the braid.
A lubricant is used when installing the blocks
inch.
Cables must be supported. so that the sag
between supports, when practicable, will not
exceed one inch, Five rows of cables may be
supported from an overhead in one cable rack,
and two rows of cables may be supported from
a bulkhead in one cable rack. As many as 16
rows of cables may be supported in main cableways, in machinery spaces and boiler rooms.
75
91.
which allow the blocks to slide easily over each
other when packing and compressing them over
the cable. Stay plates are normally inserted between every completed row to keep the blocks
positioned and help distribute compression evenly
throughout the frame. When a frame had been
-I
IC ELECTRICIAN 3 & 2
must be routed inside the enclosure with sufficient extra length allowed for re-termination
at least three times (fig. 3-57B). Excessive
bends or slack in the cable must be avoided
ONE HOLE
CABLE STRAP
in figure 3-57C). The minimum radius of bend for
an electric cable is equal to approximately six
times the diameter of the cable.
BULKHEAD
STRIPPING CABLE. The cable armor may
be removed '33, using a cable stripper of the
type shown in figure 3-58. Care must be taken
not to cut or puncture the cable sheath where
the sheath will contact the rubber grommet of
the nylon stuffing tube. If either a metal stuffing
tube or cable connector is used, allow the cable
(with armor) to extend at least one-eight of an
A
inch through the tube.
Next, remove the impervious sheath, starting
DECK
A
a distance of at least 1 1/4 inch (or as necessary
to fit the requirements of the nylon stuffing
TWOHOLE
CABLE
STRAP
77.15
Figure 3-54. Single cable strap applications.
built up, a compression plate is inserted and
tightened until there is sufficient room to insert
the end packing.
To complete the sealing of the blocks and
cables, the two bolts in the end packing are
tightened evenly until there is a slight roll of
the insert material around the end packing metal
washers. This indicates the insert blocks and
cables are sufficiently compressed to form a
complete seal. The compression bolt is then
backed off about 1/8 turn.
tube) from where the armor terminates. The
cable stripper should be used for this Job. Do
not take a deep cut because the conductor insulation can be easily damaged. Flexing the
cable .gill help separate the sheath after the
cut has been 'ands. Clean the paint from the
surface of the remaining impervious 'Meath
exposed by the removal of the armor. This
paint is conducting. It is applied during manufacture of the cable and passes through the
armor onto the sheath. Once the sheath has
been removed, the cable filler can be trimmed
with a pair of diagonal cutters.
CABLE ENDS. When a cable is terminated
in an enclosed equipment through a metal stuffing
tube, the cable jacket Must be tapered, and any
cavities filled with plastic sealer to prevent
possible water transit, in the event of flooding.
The tapered section is then wrapped with synthetic resin tape, and the end of the tape served
with
eated glass cord.
When a cable is terminated in an enclosed
equipment through a nylon stuffing tube, the
cable jacket is cut square and allowed to protrude through the grommet as shown 4.n figure
3-52A.
Connecting Cable
When a connectm ,s used for cable termination, the armor is cut back and taped, and the
square cut jacket allowed to protrude through
the connector about 1/8" as shown in figure
When connecting a newly installed cable to a
junction box or unit of IC equipment, the length
of the cable must be carefully estimated to en-
3-52.
The ends of cables terminating in open equip-
sure a neat installation (fig. 3-57). Sufficient
cable must be stripped for proper routing and
termination of the conductors. The conductors
82
ment are tapered, taped, served /Rh cord and
varnished, as shown in figure 3-59.
76
Chapter 3 SWITCHES, PROTECTIVE DEVICES, AND CABLES
DECK OR BULKHEAD
II
7./AMIZAMEIMIZI711ZINIZA1741EVAMPV
BANDING BUCKLE
rd
1
.
C ABL E
iAN
_
ci
---
..I._.w.
1.
A.
.1.111:/'
aIrmrmrA
AU WM I WWI FA M .WAIr_
iiiii-vere
TEFL
/4//AMPVAMPF/411/ZaWe
I PAO
lz msoilmUM
_
.111.31atio
TUBULAR HANGER-STEELi
- .. - 15 MAXIMUM ON DECKS
9 MAXIMUM ON BULKHEADS
77.16
Figure 3-55. Cables installed in a mble rack.
CONDUCTOR ENDS. Wire strippers (fig.
3-60) are used to strip insulation from the conductors. Care must be taken to avoid nicking
the conductor while removing the insulation.
Side, or diagonal, cutters should not be used for
manufacturer, and with wiring boxes or equipment in which electrical clearances would be
reduced be!ow minimum standards by the use
of the solderless type terminal.
vidual strands thoroughly and twist them tightly
For connection under a screwhead where a
standard terminal is not practicable, an alternate method can be used. Bare the "onductor
for the required distance and thoroughly clean
the strands. Then twist the strands tightly together, bend them around a mandrel to form
a suitable size loop (or hook where the screw
terminal for fitting either approved clamp-type
solder. Remove the end, shake off the excess
lugs or solder type terminals. If the solder
type terminal is used, tin the terminal barrel
solder, and allow it to cool before connecting it.
After the wiring installation has been com-
and clamp it tightly over the prepared conductor
(before soldering) to provide a solid mechanical
joint. Conductor ends need not be soldered for
use with solderless type terminals applied with
a crimping tool. Do not use a side, or diagonal,
pleted, the insulation resistance of the wiring
circuit must be measured with a megger or
similar (0-100 megohm, 500 volt d-c) insulation
resistance measuring instrument. Do not ener-
stripping insulation from conductors.
Conductor surfaces must be thoroughly
cleaned before terminals are applied. After baring the conductor end for a length equal to the
length of the terminal barrel, clean the indi-
together. Solder them to form a neat, solid
cutter for crimping solderless type terminals.
Solderless type terminals may be used for
all lighting, power, interior communications,
and fire control applications, except with equipment provided with solder type terminals by the
is not removable), and dip the prepared end into
gize a newly installed, repaired, or modified
wiring circuit without first ascertaining (by
insulation tests) that the circuit is free of short
circuits and grounds,
LACING CONDUCTORS. Conductors within
equipment must be kept in place in order to
IC ELECTRICIAN 3 &
Before lacing, lay the conductors out straight
and parallel to each other. Do not twist them
FRAME
together because twisting makes conductor lacing
and tracing difficult.
COMPRESSION
PL ATE
A shuttle on which the cord can be wound
will keep the cord from fouling during the lacing
operations. A shuttle similar to the one showu
in figure 3-61 may easily be fashioned from
aluminum, brass, fiber, or plastic scrap. Rough
edges of the material used for the shuttle should
be smoothed.
COMPRESSION
BOLT
ENO PACKING
SPARE
INSERT
BLOCK
To fill the shuttle for sis'gle lane, measure
the cord, cut it, and wind .1t on the shuttle. For
double lace, proceed as before, except double
SLAY PLATE
GROCVECI
the length t,i ih cord before winding it on the
INSERT
BLOCK
shuttle, and start the ends on the shuttle in order
to leave a loop for starting the lace.
Some installations. huwc.::::, require the use
A
of twisted wires. One example is the use of
"twisted pair:" fc-,r the a-c filament leads of
certain electron tube amplifiers to minimize
radiation of
magnetic field, thus preventing
annoying hum tr: the amplifier output. Yc'. should
duplicate the original layout, when replacing
such twisted leads, and when relacing and wiring
harness.
Single lace may be started with a square
knot and at least two marling hitches drawn
tight. Details of the square knot and the marling
hitch are shown in figure 3-62. Do not confuse
the marling hitch with a half hitch. In the
marling hitch, the end is passed over and under
the strand (step 1). :_fter forming the in ...rling
hitches, draw them tight against the square knot
Figure 3-56.
(step 2). The lace consists of a series of marling
hitches evenly spaced at one-half inch to one:ach Intervals along the length of the group of
conductors, as indicated in step 3.
77.296
Modular cable supports.
present a neat appearance and facilitate tracing
of the conductors when alterations or repairs
are required. When conductors are properly
laced, they support each other and form a neat,
When dividing conductors to form two or
nivre brariches, follow the procedure illustrated
in figure 3-63. Bind the conductors with at
least six turns between two marling hitches,
and continue the lacing along one of the branches
single cable.
(fig. 3-63A). Start a new lacing along the other
branch. To keep the bends in place, form them
in the contkictors before lacing. Always add an
extra marling hitch just prior to a breakout
The most common lacing material is waxed
cord. The amount of cord required to single
lace a group of conductors is approximately
2 1/2 times the length of the longest conductor
in the group. Twice this amount is required if
(fig. 3-63B).
Double lace is applied in a manner similar
to single lace, except that it is started with the
telephone hitch and is double throughout the
the conductors are to be double laced.
78
84
Chapter 3 SWITCHES, PROTECTIVE DEVICES, AND CABLES
140.15(140B)
Figure 3-57.
Connecting cable to a junction box.
length of the lacing (fig. 3-64). Double. as well
as single lace may be terminated by forming
a loop from a separate length of cord and using
it to pull the end of the lacing back underneath
a
serving of approximately eight turns (fig.
active conductors of the cable with a few telephone hitches. When two or more cables enter
an enclosure, each cable group should be laced
separately. When groups parallel each other,
they should be bound together at intervals with
3-65).
telephone hitches (fig. 3-66).
Lace the spare conductors of a multiconductor cable separately, and secure them to
insulation (fig 3-67).
Conductor ends (3000 cm or larger) should
be served with cord to prevent fraying of the
CUTTING BLADE
ALIGNMENT DETAIL
DEPRESSING KNOB
KNOB FOR BLADE
DEPTH ADJUSTMENT
CLAMPINg
LEVER
CUTTING BLADE
bADDLE
CABLE SIZE
ADJUSTING SCREW
77.22
Figure 3-58. Cable strippers.
79
85
IC ELECTRICIAN 3 & 2
STEP 2
STEP I
1*-- VARNISH
I
STEP 4
STEP 3
29.226(140)A
Figure 3-59 Preparing cable ends.
3"
I
1.24
Figure 3-60. M.achanical wire stripper.
5.138
Figure 3-61.
80
86
Lacing shuttle.
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
SQUARE
KNOT
MARLING
'HITCH
6 TURNS
STEP I
r
FORM BENDS
BEFORE LACING
t:"It1111111114)
START
NEW LACE
STEP 2
A
EXTRA
\
MARLING
HITCH
STEP 3
AT LEAST
2 MARLING
HITCHES
8 TLENS
TERMINATE
12.247(77)A
Figure 3-G2.
Applying single lace.
COAXIAL CABLE
Coaxial cable is used to conduct small signal
voltages and to protect these voltages from
radiated radio frequencies (RF) signals. Thv tit'
signals, if induced into the conductor, wol.id re-
B
sult in the distortion of the small signal voltages.
Some of the applications of coaxial and coaxial-type cables include antenna lines for ship's
entertainment systems, ship's TV systems, and
twinax cable that is used to connect the rodmeter
of the electromagnetic underwater log to the amplifier of the indicator transmitter.
Construction of Coaxial Line
The coaxial transmission line has a center
conductor that is separated from, and completely
surrounded by, an outer conductor. The conduc-
tors are separated by a solid or semisolid dielectric, or by air and small insulating spacers
called beads. Figure 3-68 illustrates the makeup of general purpose coaxial cable.
Coaxial lines are small, light in weight,
and will conduct a relatively wide band of frequencies. These lines are of three types flexible, semirigid, and rigid.
12.247(77)B
Figure 3-63. --Lacing branches and breakouts.
Flexible coaxial cables are a simple and
popular means of transmitting radio frequency
energy. They are made in a wide range of sizes
and electrical characteristics.
There are many constructional variations
between the flexible coaxial cables and the rigid
coaxial lines which fall in the broad category
of semirigid, or semiflexible lines. These lines
can be fabricated and shipped in continuous
lengths to 2,000 feet. The outer conductor is
a smooth-drawn or corrugated tubing of ductile
metal which may be covered for abrasion protection or for corrosion resistance. They have
been separated into two main classes airspaced lines and solidudielectric lines. The di-
electric material of the airspaced lines ley be
81
87
IC ELECTRICIAN 3 & 2
r
STEP i
4 MARLING
HITCHES
SERVING OF
8 TURNS
STEP I
STEP 2
5.140.1
Figure 3-65. The loop method of teiminating
the lace.
mechanically crimped or press fitted. Rigid
coaxial lines are designated by the outside di-
COMPLETED
TELEPHONE
HITCH
ameter of the outer conductor and are fabricated
in 20-foot sections with couplings at each end.
COAXIAL CABLE CONNECTORS
Coaxial cables are connected by means of
a plug or receptacle assembly (figure 3-69).
STEP 4
5.139.1
Figure 3-64. Starting double lace with the telephone hitch.
a continupus ribbon, rod, or tube which is
placed between the inner and outer conductor.
The solid dielectric type is fabricated with a
solid or continuous insulating material between
the inner and outer conductor.
The conductors A rigid coaxial lines
are different diameter tubes, one being inserted
within the other. They are usually precision made
tubing of high-conductivity, hard-drawn, copper,
although extruded aluminum or copper-coated
steel has been used. The inner conductor is rigidly supported by some type of dielectric material in the form of a bead or pin which is
5.139
Figure 3-66. Binding cable groups with the
telephone hitch.
82
88
Chapter 3SWITCHES, PROTECTIVE DEVICES, AND CABLES
PLUG BODY --s,
MALE CONTACT
WASHER-,
STEP
GASKET
/
9 .K.
I
NUT-
CLAMP
-/
STEP 2
140.153
Figure 3-69.
5.140.2
Exploded view of a standard BNC
connector.
Figure 3-67. Serving conductor ends.
The details of attaching a connector to coaxial
cable are shown in figure 3-70. The first step
is sliding the nut, washer, anti gasket over the
cable jacket. Notice that the V-groove of the
gasket faces the cable end. Then the braid is
combed and bent out of the way (step 2). As
shown in step 3, the braid wires are tapered
STEP 4
toward the center conductor and the clamp
slides over them and onto the jacket. In step
4, the braid wires are formed over the clamp
and trimmed to proper length; next, the bushing
slides over the dielectric and the contact
(male or female) is soldered to the center
conductor. The connector is then assembled in
STEP 3
140.154
step 5 by tightening the nut after e:Lding the
plug body (male or female) into position and
moving the gasket into contact with the sharp
Figure 3-70.
Installing a connector.
edge of the clamp.
STANDARD SYSTEM OF DESIGNATING
CABLE CONNECTORS
Because there is a wide variety of cable
connector designs it is necessary to use a
standard system of designation to identify them.
Without the designation system it would be dif-
MS 3100
ficult to order replacement connectors. The
SHIELD (OUTER
CONDUCTOR)
MS 3102
DIELECTRIC
MS 3106
OUTER JACKET
MS 3101
MS 3107
MS 31,41
CENTER CONDUCTOR
,
29.226(140B)
Figure 3-71. Connector shells.
Figure 3-68. --General purpose coaxial cable.
83
89
12.76
IC ELECTRICIAN 3 & 2
system uses an alpha-numeric code to indicate
the shell type, shell design, size, and insert
Flow rosin-core solder into the connector terminals. Insert each wire into its
terminal while holding the tip of the
soldering iron against the terminal. As
type, style, and position. An example is the
designator MS3100-A-11PX.
the sol "er melts, push the wire into
the terminal cavity. Remove the heat
source holding the wire steady while
the solder cools. (Be careful to avoid
The letters MS form the prefix and identify the designation system, Military
Standard.
The number 3100 indicates the shell type
and identifies it as being one of he
types shown in figure 3-71.
The
`amaging the connector insulation with
ue soldering iron.) When soldering the
connector, follow a prearranged sequence.
letter A stands for a solid-shell
The recommended sequence is to start
from the bottom connection and work
from left to right, moving up a row at
a time. After soldering the connections,
solder the shields (if any) to a common
terminal or ferrule. Then lace the cable
and reassemble the connector, moisture
connector. Other letters used, with their
meanings, follow:
B
C
E
K
R
split shell
pressurized
environment resistant
fi reproof
lightweight environment
proofing it if necessary.
.Present practice is to use type E, I., or
potted connectors (moistureproof or environment-
The number 11 indicates the type of insert pin arrangement that is used in the
proof connectors). However, conditions sometimes demand that ordinary electrical connec-
connector.
tions on older types of cable installations be
given a moistureproofing treatment. The basis
The letter P means that the insert is
a pin (male) insert. The letter S is used
of moistureproofing is the application of a seal-
to indicate a socket (female) insert.
ing compound which can be obtained in kit
form through the normal supply channels. The
sealant should not be used on connectors located
in areas where the temperatures exceed 200° F
because the sealing clampound deteriorates after
long exposure to such temperatures. .
Moistureproofing reduces failure of electrical connectors by reinforcing the wires at the
connectors against the effects of vibration and
lateral pressure, both of which fatigue the wires
at the solder cup.
The sealing compound also protects connectors from corrosion and contamination by excluding metallic particles, moisture, and liquids.
As a result of its improved dielectric characteristics, the. sealing compound also reduces
the possibility of arc-over between pins at the
back of electric connectors.
A summary of the procedures involved in
sealing (or potting as it is called) a connec-
The letter X designates a nonstandard
contact position or angle that the insert
is rotated from the standard position.
Other nonstandard positions are designated W, Y, or Z. No letter at the end
of the 4esignator indicates the standard
contact position.
FABRICATING A CABLE ASSEMBLY
You may on occasion be required to fabricate a cable assembly. The type of connector to use is normally specified in the maintenaree instructions manual for the particular
xi. To provide a quality connection,
follow a prescribed procedure.
The following is an. outline for attaching a
multipin connector to v'cable:
Disassemble the connector to allow access to the terminals.
tor follows:
Prepare the connector by removing ex-
Cut the cable to correct length.
isting sealants and cleaning. The cleaning
solvent must clean thoroughly, evaporate quickly,
and leave no residue. Remove all sleeving from
Strip away insulation with a wire stripper or knife. When using a knife, avoid
cutting or nicking the wire strands.Tin
wires Re-solder loose or poorly soldered conneenns and add a length of wire approximately
9 inches long to each unused pin. The unused
pins serve to provide emergency connections.
More on this later.) Remove any excess rosin
the baler wire ends.
Run tne wires through the connector assembly and coupling nuts.
See that all contact surfaces are clean.
84
30
Chapter 3SWITCHES, PROTECTIVE 1) VICES. ANT) CABLES
a mold formed from masking or cellophane tape
or equivalent. This mold will retain the sealant
during the curing process. If the back shell is
used, apply a slight amount of oil to the surface
facing the potting compound to prevent the compound from adhering to it. (See fig. 3-72A and B.)
Apply the compound with a spatula, putty
knife, or paddle. Pack it around the base of the
pins. Fill the part being potted completely or at
least to a point that will cover a minimum of
3/8-inch of insulated wire.
Allow the compound to cure.
If it is desired that the entire connector assembly (plug and receptacle) be sealed against
fluid entering or collecting between the two parts,
fit a rubber 0-ring over the barrel of the plug.
This 0-ring will provide a seal when the two
parts are engged and will prevent moist air from
entering due to variations in temperature, alti-
tude, or barometric pressure on the ground..
Rubber packing 0-rings are available for this
purpose through normal supply channels. Due to
the aging of these rings in service, examine them
each time connectors are disassembled. If deteriorated, replace them.
As mentioned earlier, a short length of wire
is soldered to each spare pin. This wire will
enable additional circuits to be included in the
connector and can avoid the need to repair a
single wire which may have failed within potted
connectors. Instead of having to disassemble the
connector it is now possible to have ready access
to a spare pin by making a splice to one or the
spare wires.
If a spare wire is not available in the connector and a single wire must be replaced, the
back shell may be removed. Removal may require
considerable force depending on how well the
sealant adheres. Access to the desired lead may
now be obtained by cutting away a part of the
potting compound with a knife. If a center wire
of a larger connector is defective, and is beyond
140.155
Figure 3-72,
(A) Ma'cing mold from masking
tape: (B) finished potted plug.
easy reach from the side, it may be better to
remove the sealant from the center with long
from around the pins and the insert with a stiff
bristle brush. Now, repeat he cleaning process.
Then separate the wires so the sealing compound
will flow evenly into all spaces.
Prepare the potting compound. Because
nose pliers until enough is exposed to allow the
defective lead to be repered. Obviously a small
soldering gun is require? when working in such
confined places. Complete removal of the com-
or plugs without back shells must be fitted with
to any old compound remaining in the connector.
the ratio of the amount of accelerator to base
compound is critical, the entire quantity of ac- pound may also be necessary. Regardless of
celerator furnished must be added to the base., 'the met'.od used to gain access to the defective
terminal, the plug is returned to its original
compound.
Place the plugs or receptacles on a table, condition by applying sealant to the connector
arranging them so that gravity will draw the in the manner previously described. The new
sealer to the bottom of the plug. Box receptacles compound will seal or vulcanize satisfactorily
85
91
1
CHAPTER 4
POWER DISTRIBUTION SYSTEMS
The majority of interior communications systems on naval vessels receive their power from
the interior communications switchboard; only
The readiness classification (1, 2, 3, or 4)
defines the exitut to which a system contributes
to the operational readiness of the ship. (See
a few of the systems are powered from local
lighting and power sources. The main interior
communications (IC) switchboard on smaller
ships, the only IC board is located in the
table 4-1.
TYPES OF INTERIOR COMMUNICATIONS
SWITCHBOARDS
forward IC and plotting room. There maybe an
after board located in the No. 2 IC room, and
DEAD-FRONT SWITCHBOARDS
smaller local service boards in each engineroom and in the steering gear room.
The dead-front IC switchboard (fig. 4-1)
the most recent types are dead-front, front-
dead-front types switches throughout.
The fuses, except those mounted on the type K
switches, are mounted in plug-in type combination fuseholder-blown fuse indicators. This
type of switchboard has many design features
This chapter describes the various types of
Table 4-1. Circuit Classification by Readiness
The physical construction of IC switchboards
varies greatly. The switchboards installed on
older ships are completely open, eso live-front;
service.
IC switchboards. emphasizing the types installed
on a modern DDC. Also included are topics on
distribution systems for ship's service, emer-
has
Circuit Switch
readi- recogniness
tion Color
gency, and casualty power.
INTERIOR COMMUNICATIONS SYSTEMS
CLASSIFICATION
IC systems are classified according to importance and readiness. The importance, classification (vital, semivital, or nonvital) defines
the extent to which a system affects the
1
Yellow
Semivital IC s;.stems those which, if
disabled, would impair the effectiveness to a
lesser extent than the loss of a vital system.
Nonvital
Essential to ship's safety;
energized at all times.
2
Black
maneuverability or fighting capability of the ship.
Vital IC systems those which, if disabled, would seriously affect the fighting effectiveness and maneuverability of the ship.
Readiness requirement
Essential to ship's control;
energized when ship is preparing to get underway, is
standing by, is underway, or
is anchoring.
3
Red
Essential to complete interior control; energized during battle condition watches.
4
IC systemsthose whir.,.h, if
disabled, would not impair the fighting effectiveness or the maneuverability of the ship.
White
Convenience circuits; energized when required.
140.115
86
92
Chapter 4 POWF.R W3TIII31.1TIJN SYSTEMS
J.,1m 01-
........
27.270
Figure 4-1. Duad-front IC switchboard.
today is the dead-front, front-service board.
It is similar in construction to the dead-front
that serve to make it safe in operation. All
connections are made behind the panel with
only the switch handles accessible to the
operator; fuse holders of the plug-in type are
mounted perpendicular to the panel resulting.
in a more compact board: and all meters, circuit breakers, and bus tie switches are mounted
board, yet has the additional feature of allowing all service requirements to be performed
from in front of the unit. Figure 4-2 is a typical
example of an installation as is currently in
use. The front-service board uses a boxlike
constructon with the front panels hinged for
access. Switches and fuseholders up to 60
amperes, as well as all other lightweight items,
are ,nounted on the hinged door, while the
behind hinged panels.
DEAD-FRONT, FRONT-SERICE
SWITCHBOARD
heavier hardware is mounted on the unit itself.
T3rminal boards are provided within the
switchboard enclosure for termination of all
The most re,ent advance in switchboards
and the unit being installed aboard naval vessels
87
93
IC ELECTRJCIAN 3 & 2
II ;
Ira
00 00t
-A1
5
.CC
K .,La^ 4. 4 N1:44,'
;0
sr
tt
.4 .4.
4004.4.1
04.25.{
A
a:2 `At.
A.41.
444114044.411140
11.011141,4111111
Figure .-2. Main IC switchboard.
ship's cables, which run directly to their associated switches and fuse holders. All wiring
between the terminal boards and the equipment
mounted on the hinged and stationary panels
140.65
1 thru 4, while the action-cutout section is
palels 5 avid 6. These sections are then further
subdIvided into varilus buses, dependent upon
is installed by the manufacturer prior to installation to ensure the free swinging of the
panels without interference from, or damage
to, the wiring.
In order to reduce the rigidity of the switchboard, and to permit separate movement of
panels during shock, cables instead of horizontal
buses are used for connection between or among
board sections. Some vertical buses may be
used, however, to supply sections of individual
panels.
the specific needs of the vessel in which installed.
DISTRIBUTION SECT' DN
The distribution section (fig. 4-3) is typical
of an men distribution units. The various IC
circuits receive power from its seven buses:
430-volt, 403-Hz; 123-volt, 400-Hz, regulated and
unregulated; 450/120-volt, 60-Hz; 120-volt, d-c;
aad 50-Jolt, d-e.
The main advantage of this type of switchboard .s that it can
mounted flush against
a bulkhead, no a.,:cess being required in the
60-Hz Power
The 450-volt, 3-phase, 60-hertz bus is enerfrom one c1 three power sources
through the use of two mechanically interlocked
rear of the bco.rd. This feature results in a
saving of space which is a mc3t important
gized
consideration on board ship.
switches ald an automatic bus transfer (ABT)
switch (fig. 4-4), which selects its feed from
normal, alternate, or emergency supplies. The
normal supply to the main IC board is from the
SWITCHBOARD SECTIONS
The main IC switchboard is broken down
into two major subdivisions. In figure 4-2 the
power distribution section comprises sections
ship's forward switchgear group number 1S. The
alternate supply to the board is from the after
switchgear group number 2S while the emergency
88
94
Chapter 4 POWER DISTRIBUTION SYSTEMS
t
t,
Figure 4-3. Interior view main IC switchboard distribution section.
140.117
portable cable from a remotely located riser
supply emanates from the nearest ship's emergency group, in this case the forward emergency
switchgear 1E. Normal or alternate power is selected by two interlocked switches and becomes
nearby.
Power available indication is provided
through the use of indicator lights connected
via transformers to each power source. The
automatic transfer device, indicator lights, and
"Preferred" power. The bus may also be powered
by a casualty power terminal installed on the
board, which in turn receives its power via
89
95
IC ELECTRICIAN 3 & 2
TERMINAL
BOARDS
450 VOLT
CIRCUIT
SWITCHES
'TEST
LWITCH
im6164ioli
HANDWHEEL
LIGHTS
o
ELECTOR SWITCH
INPUT TO
SIGHT GLASS
450/20 VOL
TRANSFORMERS
POWER TO
-G SETS.
1$ INPUT
2S INPUT
MECHANICAL
INTERLOCK
SHOWING A-3 AV:
140.67
Figure 4-4.
Type A-3 ABT and pr.nel #1.
90
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10 O
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L2
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140.119
Chapter 4 - POWER DISTRIBUTION SYSTEMS
all appropriate switching and instrumentation
are located in panel #1.
The 120-volt, 3-phase, 60-hertz bus receives
its power from panel #1 via a bank of three
450/120-volt, 60-hertz, 15-kva transformers.
remotely located, in panel #2. Refer to figure
4-5. As can be seen in figure figure 4-2, meters
for voltage and current indication are located
on this panel. It is from this bus that these meters
receive their power. (There is also a megohmmeter installed on this panel, however this unit
will be discussed later.) This panel disseminates
units receive their excitation from the 450 volt supply of panel #1 (fig. 4-6). The unit in
operation is selected by a double-pole, doublethrow rotary snap switch located on panel #3.
Indicator lights tell the toperator which of the
two units is in operation.
A 50-volt d-c supply for the weapons control
units is also provided to panel #3 via a separate
set of remotely located rectifiers. The excitation is again the 450-volt supply of panel #1.
Again, indicator lights are provided.
both single- and 3-phase, 120-volt a-c power
Instrumentation
400-Hz Power
Located on panel #2 are an ammeter and
a voltmeter. The former indicates 120-volt,
60-hertz current of phases A 'and C. Current
as required.
A 450-volt, 400-hertz, 3-phase, regulated
bus is located in panel #4 of the board. This
bus is powered by any of three 30-KW motor
generator sets located near the IC room and
controlled from panel #4. The power to these
M-G sets is from the 450-volt, 3-phase supply
of panel #1. Indicator lights are located on
panel #4 for power available indication from
each of the M-G sets. See figure 4-6.
Installed also in panel #4 is a 450-volt,
400-hertz, 3-phase unregulated bus. This bus
is intended to receive its power from the shyn
400-hertz supply, although on most installations
it is at present connected to the regulated source.
To facilitate weapons requirements, a 450 volt,
400-hertz, 3-phase weapons direction
transformers and switching are provided. Phase
B current herein is the vectorial sum of the
other two currents.
The voltmeter can by the use of a selector
switch be used to indicate phases A and B, 13
and C, or A and C.
To indicate the 450-volt, 400-hertz, 3-phase
regulated supply of panel #4, a voltmeter is
installed to indicate phases B and C, and C
and A of the bus, as well as each bus phase to
ground. Additionally, this instrument through
its selector switch indicates phases A to B
of each generator. A 450/115-volt transformer
is employed in conjunction with this voltmeter.
Frequency indication is provided, by meter,
in parallel with the voltmeter.
equipment bus has been installed. Through a
Current indication on the 450-volt, 400-hertz,
triple-throw rotary snap switch this bus may regulated supply is provided by a meter which
receive its power from either of three sources: can, by the positioning of its selector switch,
(1) Weapons Director Equipment Motor Gen- indicate each bus phase as well as phase A of
erator (#3), (2) 450-volt, 400-hertz regulated each of the generators.
bus, or (3) 450-volt, 400-hertz unregulated bus.
In order to permit parallel operation of the
Via a bank of three remotely located trans- generators, a synchroscope and synchronizing
formers, panel #4 also supplies a 120-volt, lights and the necessary switching are provided
400-hertz, 3-phase regulated bus. The primary on panel #4.
voltage supply for these transformers is the
higher voltage regulated supply.
Additionally, a 120-volt, 400-hertz, 3-phase
Additional Switchboard Equipment
unregulated bus is installed. At present it is,
on most installations, conrected to the regulated
bus; however, it was originally intended to be
connected to the unregulated, higher voltage
via a separate transformer bank.
A megohmmeter is installed in panel #2 to
assist in circuit testing. The power supply for
this unit is installed in the switchboard, and the
unit is energized through a single-throw rotary-
D-C Power Buses
a part of the unit are the Bus Failure Alarms.
These units are used to indicate the lose of 120-
snap switch installed on the panel.
Remote from the switchboard but nonetheless
Direct current in the magnitude Of 120 volts
is supplied to panel #3 of the switchboard from
remotely located rectifier supplies. These
volt, 60-hertz; 120-volt, d-c; 450-volt, 400-hertz,
unregulated; 120-volt, 400-hertz, regulated; and
120-volt, 400-hertz, unregulated power supplies.
91
101
IC ELECTRICIAN 3 & 2
55.316
Figure 4-7. Dead-front, front serve section. (A) Front view: (B) Action cutout unit; (C) Rear view,
door open.
ACTION CUTOUT (ACO) SECTION
information suppliers to specific indication or
control units, the ACO section (fig. 47) of the IC
switchboard is installed alongside the power section. Through the use of JR type switches (chapter
3) and synchro overload transformers (explained
In order to facilitate the removal of damaged
portions of certain IC cereults from the main
indicating bus, and to permit the use of alternate
92
10 4
Chapter 4
POWER DISTRIBUTION SYSTEMS
later in this chapter) in drawout units, it is
possible to divide the various included circuits
Fuses are installed on these panels to isolate
the supplies of the gyro compass roll and pitch
synchro signal amplifiers, and the engine room
indicator lights of the General, Chemical, and
Collision Alarms.
into their component legs.
In the typical installation, panel #5 of the
switchboard is used to switch in and out the
repeater and control circuits of the gyro com-
LOCAL IC SWITCHBOARDS
pass system (LC). Through the proper manipulation of switches, either the main or the aux-
In order to facilitate better local control
over circuits vital to the operation of various
iliary compass may be selected as the information-sending device to the many repeaters
spaces, local IC boards have been installed. Such
boards are installed in many enginerooms and
steering gear rooms.
These boards (fig. 4-8) receive their power
from two sources; in the case of the engineroom
boards the normal source of power is the nearest
main IC switchboard, while alternate power is
of the circuit. In addition each of the individual
repeaters in the circuit may be cut in or re-
moved from the circuit without having any adverse effect on the operatior of the remaining
components.
Panel #6 is used in a similar manner in
supplied from a local emergency lighting circuit.
In the case of the steering gear room boards the
conjunction with circuits, such as wind indicating,
propeller revolution, engine order, underwater
log, and propeller order.
Located on the ACO section are a bank of
type SR switches which are used to isolate the
normal source is usually from a local power
panel located in the steering gear room, while
the alternate source is again a local emergency
lighting circuit. Local IC switchboards use as
their primary source of power, 120-volt singlephase or three-phase a-c, dependent upon their
individual requirements. Automatic bus transfer
various speaker groups of the General Announcing System circuit 1MC. The General C hem-
ical and Collision Alarms contact makers may
also be isolated at these panels.
rx
140.66
Figure 4-8. Local IC switchboards.
93
103
IC ELECTRICIAN 3 & 2
TYPE II SWBD
ST GR. RM
I-ID- 450/120V-6CA,
TRANSFORMER
NORMAL SUPPLY
PA. LT
450-G0'1J-1D
111
/OEM.
FROM
STEERING
PAM
PWR SWBD.
DP DT ABT
/KM
120V - GO'L, - ID
Figure 4-9.
Local IC switchbodA, steering gear room.
140.18
devices and indicator lights are included in all
current applications.
alarm, valve position indicator, and turbine
Circuits whiTh may be found on these local
switchboards include the rudder order system,
steering emergency system, rudder angle indicator, salinity indicator system, turbogenerator
A local IC switchboard (fig. 4-9), is usually
installed in each steering gear room to energize
all circuits associated with steering such as
the steering - order and rudder-angle indicator
alarm system.
94
104
Chapter 4 POWER DISTRIBUTION SYSTEMS
"..7=1=1WINAINIIMM=
systems. The normal supply for this switchboard
is from the steering-power transfer switchboard
through a local transformer. An alternate supply
is taken from a local emergency lighting circuit
to provide power if the normal supply is lost, because manual or emergency steering gear is pro-
vided in case of power failure to the steering
power switchboard.
Automatic Bus Transfer Devices
The automatic bus Transfer device installedin the local IC switchboard is designed to trans-
fer a load, in this case the board, from one
source of supply which has failed to an alternate
source which remains energized. The model
A3 and A2 units, described below, are two of
OUTPUT
BIO SSCL3 L2 LiESC 1310
EC
SC
PREFERRED
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SUPPLY
EMERGENCY
SUPPLY
EB
S
TEST
SWITCH
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EA
SA
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V
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(SSL)
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JLIMIT
I
SS-CCW ROTATION OF OUTPUT SHAFT
ES-CW ROTATION OF OUTPUT SHAFT
Figure 4-10. Schematic and wiring diagram of A-3 ABT.
95
105'
SWITCH
(ESL)
140.68
IC ELECTRICIAN 3 & 2
the more recent devices used to perform this
(VR) which opens its normally closed contacts
and closes its normally open contacts, thereby
closing the circuit to the motor from the ship's
service supply (normal). Counterclockwise rota-
function.
AUTOMATIC BUS TRANSFER MODEL A3.
The 300-ampere A3 units is currently being employed on large IC switchboards. The unit,
tion of the motor results in rotation of the
cam and a change in the position indicator.
Presently the Ship's Service Supply Contacts
pictured in figure 4-4, is designed to transfer
a load from a preferred source to an alternate
(SSC) close and the Emergency Supply Contacts (ESC) open. Rotation to a predetermine
source of power in the event of a voltage failure
in the
preferred source, and to further re-
limit results in the opening of the Ship's Supply
Limit Switch (SSL) disconnecting the motor
transfer upon restoration of the preferred source.
With this type of unit the load is connected at all
from the line and completing the retransfer.
times to the preferred source as long as there
is preferred voltage present at that source.
The contactor is motor operated but there
is a means provided for meaual operation of
the unit. In this manner the desired source
or the "off" position may be selected, regard-
Provision is also made for testing the unit
through the manipulation of the Test switch.
AUTOMATIC BUS TRANSFER MODEL A2.
The A 2 Model automatic bus transfer unit is
designed to handle smaller loads and operate
on 120-volt, 60-hertz circuits. Units of this
type are currently being employed on local IC
switchboards of the engineroom and steering
gear room type, previously discussed. This
unit may be used on single- or 3-phase circuits. For purposes of explanation the 3-phase
less of the voltage present.
The unit is designed for 450-volt 3-phase
operation in which the contactor consists of
two three-pole cam-operated contactors for
main line connection, two auxiliary camoperated two-pole switches for control circuitry,
a motor and a reduction gear for automatic
operation, and a handwheel for manual operation.
Manual operation of the unit is accomplished
by positioning the selector switch to the
MANUAL
position which disengages the
motor enabling the operator to engage the
unit will be discussed.
The A2 ABT (fig. 4-11) is designed to transfer
automatically from normal to emergency supply
upon a decrease in voltage to within the
handwheel. The handwheel is pushed in for
engagement and then turned in the proper di-
rection
pointer.
as
81/69-volt range across any two of its three
phases. Upon restoration of the voltage to the
range of 98/109 volts the unit is adjusted to
retransfer to the normal source of supply. An
indicated on the glass-inclosed
Automatic operation of the A3 takes place
intentional time delay is included in the circuitry
when the selector switch is in the AUTOMATIC
position (fig. 4-10). Assuming that the preferred
voltage drops to within the 264/308 volt range,
the voltage relay VR becomes deenerglzed
of
from 0.3 to 0.5 seconds for both transfer
and retransfer to allow for surges in line voltage
and short duration losses in power.
The A2 unit is readied for manual operation
by placing the control disconnect in the manual
position and operating the manual handle (fig.
allowing its contacts to assume their normal
position as shown. This permits the threephase line from the emergELey supply to be
completed to the motor, resulting in a clockwise rotation of the motor and cam assembly.
4-12).
Automatic operation is accomplished when
the normal supply voltage drops to the dropout
This rotation, which opens ehip's service supply
contactor contacts (SCC) and closes emergency
supply contacts (ESC), is visible through the
range and relay 1V, 2V, and 3V drop out.
Contact 1 Val opens disconnecting relay SE. After
a time delay of from 0.3 to 0.5 seconds, re-
sight glass in front of the position indicator.
When the cam has rotated to a predetermined
position, the normally closed contiots of the
Emergency Supply Limit Switch (ESL) open,
lay SE opens closing its SEb1 and SEb2 contacts
and energizing relay 4V from the emergency
source. Contact 4 Val in closing connects the
emergency source to coil TS of the transfer
switch which in turn operates, transferring the
disconnecting the motor from the line and completing the load transfer.
Automatic retransfer is accomplished when
load to the emergency source.
Presently, contacts TSa4 and TSa5 open dis-
the preferred supply returns to the 374/418
vplt range energizing the voltage Relay Coil
connecting coil TS from its operating circuit.
TS is now held in the operated condition
96
106
Chapter 4 POWER DISTRIBUTION SYSTEMS
tt.UxiLtARY
CONTACT
ASSEMBLY
CONTACT
ASSEMBLY
RELAY
1V
DISCONNECT
SWITCH
RELAY
SF
TEST
SWITCH
DRIVE
UNIT T S
MANUAL
SWITCH
CONTACT
ASSY.
RELAY
2v
AUXILIARY
CONTACT
ASSEMBLY
140.70
Figure 4-11. Pictorial view of A-2 ABT.
mechanically, however and the transfer is now
Presently the transfer coil contacts TSb4 and
complete to the emergency supply.
Upon restoration of the normal power to the
cuit. The coil is again mechanically held and
close energizing relay SE. Contacts SEIM. and
SEb2 now open, disconnecting relay 4V from
the emergency source. After the time delay, re-
units to ensure that they do not include in their
lay 4V opens, closing its 4Vb1 contact and completing the normal supply circuit to the transfer
almost instant return of power. As in other
selected range the retransfer is begun by the
energizing of relays 1V, 2V, and 3V which
switch coil, TS, which again operates transferring the load back to the normal supply.
TSb5 open, disconnecting the coil from the cirthe retransfer is now complete.
Care must be exercised when testing the ABT
load vital
and sensitive electronic circuitry
which will be adversely affected by the loss and
tests, IC Electricians must ensure that all other
groups are informed of the tests to be performed.
1107
IC ELECTRICIAN 3 & 2
PREFERRED SOURCE
SB
SC
SA
TEST
IV
2VoI
williiis
orimpteirmino
TSo2
LOAD
TSol
SEM
+
C
_SEo2
2R
To2
E8
A
T So5
4 Vol
4V
TSbI
TSb3
TITSEDI
NOTE:
AUX.CONTACTS TSo6 . TSb6 ARE
SEb2
PROVIDED FOR FUTURE APPLICATIONS
EC
EA
EMERGENCY SOURCE
I
LOAD
DISC
TSo4
r
TSo3
4VbI
TSb5 CONTTsb4
L
CIRCUITS SHOWN WITH BOTH
SOURCES ENERGIZED
PREFERRED SOURCE
1
IR
LOAD
SC
S
EC
---%
jot
LOAD
2V
LOAD
SA
to
EA
R
I
L
EMERGENCY
SOURCE
NORMAL EMERGENCY
MANUAL AUTOMATIC
THIS WIRING SHOWN AS
10
SEEN FROM FRONTOF
FLIP
HANDLE
PANEL
DO NOT USE HANDLE UNLESS
CONTROL DISCONNECT
IS IN MANUAL POSITION CONTROL
DISCONNECT
TEST
Figure 4-12. Schematic and wiring diagram of A-2 AST.
16
140.69
Chapter 4
POWER DISTRIBUTION SYSTEMS
OVERLOAD INDICATORS
by
also
operating the associated switches. It is
necessary in each case to fuse the
Recent designs of ACO sections are provided
with synchro overload transformers. These transformers are in series with the secondary
primary wires. Otherwise, a short in one in-
damaged instruments can be disconnected quickly
of two primary windings, each in series with
connections of selected synchro torque indicators to provide immediate information to operating personnel regarding a casualty so that the
dicator might blow the main fuses of the circuit,
and no power would be available to operate
the overload indicators to show the faulty circuit.
An overload transformer (fig. 4-13) consists
NEON.
LAMPS
OVERLOAD
TRANSFORMERS
L2
LI
3
SIGNAL
BUS
Ti
20-0
T2
30
4
Si
0--052
053
55.317
Figure 4-13. Synchro overload transformer.
99
109
IC ELECTRICIAN 3 & 2
one leg of the synchro stator wires. The secondary winding is connected to a small neon
lamp (fig. 4-13) mounted on the face of the
switchboard. The overload transformer is a
current-sensitive device. It is arranged so that
when the sum of the currents in the stator circuits to a particular synchro exceeds a pre-
neon lamps varies over a wide range. Any
variation in this breakdown voltage is equivalent
to changing a transformer tap. Replacement
lamps, therefore, should be selected by measuring the breakdown voltages until a lamp is
found that conforms approximately to the values
given.
determined amount, a neon lamp glows.
The synchro stator is in series with the
primary coils of the transformer. An increase
of current in the primary winding of the transformer will increase the voltage between the
INDICATOR LIGHTS
The indicator lights on IC switchboards normally use two 6-volt lamps because 120-volt
lamps are not suitable for the vibration and
shock conditions encountered aboard ship. A-c
applications require transformers, whereas d-c
secondary terminals of the transformer.
The secondary oTthe transformer has numerous taps to provide a wide range of voltages for
a given current.
The transformer may be used under different
applications require resistors to furnish the
necessary voltage. The a-c indicator lights are
provided with integral transformers for either
120-volt or 450-volt applications. D-c indicator
load currents. However, the tap used is dependent on the breakdown voltage of the neon
lamp.
lights are provided with separate resistors.
The principal difference between the opera-
tion for IC synchro circuits and for FC circuits is that for IC synchro circuits the overload transformers are usually set to provide a
much greater relative displacement between
transmitter and indicator before the overload
lamp lights. FC synchro circuits are usually
precision systems in which a relatively slight
Globes of various colors are required for
specific applications.
SHIP'S SERVICE POWER
DISTRIBUTION SYSTEM
The ship's service power distribution system
displacement between a transmitter and indicator may involve a serious error. Most IC circuits are generally used for the transmission of a relatively small number of orders,
and a displacement between transmitter and indicator is not serious until sufficiently great to
cause an incorrect order to appear at the indicator.
Operating personnel of IC switchboards
should be very cautious when operating switches
to disconnect indicators, particularly on vital
circuits such as the engine order system. When
practicable, operating personnel should investigate before operating the switch, as the overload
indicatIon may be a result of too low a setting
on the overload transformer.
Energizing a circuit by means of a transfer
Thus, any ship service switchboard can be
connected to feed power from its generators
to one or more of the other switchboards. The
bus ties may also be used to connect two or
more switchboards so that the generators can
be operated in parallel (or the switchboards
sociated overload light, which is caused by the
momentary displacement between the transmetter and receiver. Such indications are normal and show that the system is operating
properly. Continual flashing, however, should
be investigated.
The overload transformers are designed to
operate with neon lamps for which the breakdown voltage is 52.5 volts a-c and 74 volts d-c.
As previously stated, the breakdown voltage of
Power distribution is direct from the ship
service generator and distribution switchboards
to large and important loads, such as the main
IC switchboard, steering gear, the gun turrets, and to loads near the switchboard. In
large installations power distribution to other
loads is from the generator and distribution
switchboards or switchgear groups to load centers, to distribution panels, and to the loads
or directly from the load centers to the
switch generally results in a flash on the as-
is the electrical system that normally supplies
power to thee ship's equipment and machinery.
The switchboards and associated generators are
usually located in separate engineering spaces to
minimize the possibility that a single hit will
damage more than one switchboard.
The ship's service generator and distribution
switchboards are interconnected by switches
and cables, designated bus ties, because they
tie together the buses of different switchboards.
can be isolated for split plant operation).
loads.
100
11.0
1
Chapter 4
POWER DISTRIBUTION SYSTEMS
On certain new construction, such as aircraft carriers, a system of zone control of the
ship's service and emergency distribution is
provided, wherein the ship is divided into areas
generally coinciding with the fire zones of the
damage control system. The system establishes
a number of vertical zones, .each of which contains one or more load center siwtchboards
supplied through bus feeders from the ship's
service switchgear group. A load center switch-
board supplies power to the electrical loads
within the electrical zone in which it is located.
Thus, zone control is provided for all power
the electrical zone. The emergency
switchboards may supply more than one zone,
the number of zones depends on the number of
emergency generators installed.
The majority of a-c power distribution systems in naval ships are 450-volt, 3-phase, 60hertz, 3-wire systems.
The ship service generator and distribution
switchboards are interconnected by bus ties so
that any switchboard can be connected to feed
within
At least two independent sources of power
are provided for selected vital loads. The distribution of this dual supply is accomplished
in several ways: by a normal and an alternate
ship service feeder; normal ship service feeder
and an emergency feeder; or normal and alternate ship service feeder and an emergency
feeder.
A-C SWITCHBOARDS
A-c switchboards may consist of a single
section or of several sections physically separated and connected by cables to form a switchgear group. This arrangement of sections pro-
vides greater resistance to damage. It also
provides a means for localizing damage, and
removal of a damaged section for repairs or
replacement.
BUS-TRANSFER EQUIPMENT
nect tow or more switchboards so that the
Bus-transfer equipment is installed at load
centers, distribution panels, or loads that are
fed by both normal and alternate and/or emer-
In large installations (fig. 4-14a) distribution to
either the normal or alternate source of the
centers, to distribution panels, and to the loads.
or directly from the load centers to some loads.
vided.
power from its generators to one or more of
the other siwtchboards. Th bus ties also congenerator plants can be operated in parallel.
loads is from the generator and distribution
switchboards or switchgear groups to load
On some ships, such as large aircraft car-
riers, a system of zone control of the ship
service and emergency distribution is provided.
Essentially, the system establishes a number
of vertical zones, each of which contains one
or more load center switchboards supplies
through bus feeders from the ship service
switchgear group. A load center switchboard
supplies power to the electrical loads within
the electrical zone in which it is located. Thus,
zone control is provided for all power within
the electrical zone. The emergency switch-
boards may supply more than one zone, the
number of zones depends on the number of
emergency generators installed.
In small installations (fig. 4-14b), the distribution panels are fed directly from the generator
and distribution switchboards. he distribution
panels and load centers (if any) are located
centrally with respect to the loads that they
feed. This arrangement simplifies the installation and requires less weight, space, and
equipment than if each load were connected
to a switchboard.
gency feeders. This equipment is used to select
ship's service power, or to obtain power from
the emergency distribution system if an emergency distribution system feeder is also pro-
Automatic bus-transfer equipment is used
for loads that require two power supplies, except for auxiliaries that are used when lighting
off the engineering plant and fire pumps, which
have manual bus-transfer equipment. On the
steering power switchboard, which is provided
with anormal, alternate, and emergency power
supply, manual bus-transfer equipment is used
to select between the normal and alternate supplies, and automatic bus-transfer equipment is
used to select between the ship service and
emergency supplies.
LIGHTING
The lighting circuits are supplies from the
120-volt secondaries of 450/120-volt trans-
former banks connected to the ship service
power system. In large ships the transformer
banks are installed in the vicinity of the lighting
distribution panels located at some distance
from the generator and distribution switch-
boards. In small ships the transformer banks
101
111
.1.11
to
TRANSFER
SWITCHBOARD
ISTBO)
STE
POWER
(PORT)
TRMtoSYNT
STEERING
11
I
Nn
r
CENTER
! I
tl r-
I(Fa 3
TO DISTRIBUTION
PANELS OR LOADS
PANELS OR LOADS
TO OISTRIBUT/ON
LOAD
CENTER
2
NQ
_J
PANEL
D
LOANTER
INTERIOR
Car#441CAN
PANELS ORR IB LTOAN
DS
CE
LOADS
DISTRIBUTION
CENTER
1
L
r
INDS I - 4
EMERGENCY
RADIO
Figure 4-14A.Power distribution in a large combatant ship.
TTSWITO4BOARD
EMERGENCY
AFT
RADIO
TRANSMITTER
r
II
it
II
1
EMERGENCY FEEDER
BUS TIE
NORMAL FEEDER
ALTERNATE FEEDER
O
SWITCHBARD
DISTRIBUTION
GENERATOR
SHIP SERVICE
(15.54.:2
c
-c
NORMAL FEEDER
MISSILE
LAUNCHER
GEN 2SA
1
L
LOAD
LOAD
T
0 OM LOAD
DISTRIBUTION PANEL
-
LOADS
OR
TO
DIST
PANEL
_{-0 @ LOAD
DEGAUSSING
SWITCHBOARD
DISTRIBUTION,
PANEL
I
i
I.
,
I
i
i
__j
GENIE
1
FT
SWITCHBOARD ,
_J
EMERGENCY
IE
SWITCHBOARD
COMMUNICATION
INTERIOR
)GEN ISA
Figure 4-141:I.Power distribution in a guided missile destroyer.
GEN 2SB
EMERGENCY FEEDER
r--
SWITCHBOARD
2E
EMERGENCY -.-
GEN 2E
-- -- - ALTERNATE FEEDER
--0--..--.-.-- BUS TIE
----
t...
1
1
i
I
1
SWITCHBOARD,
STEERING
_SWITCHBOARD
I
I
1
F
GEN ISB
ASROC
LAUNCHER
65.54.1
_J
1
51 j
MOUNT
IC ELECTRICIAN 3 & 2
are located near the generator control and distribution switchboards and energize the switchboard buses that supply the lighting circuits.
The lighting distribution system feeders,
mains, and submains are 3-phase circuits;
submersible pumps. The multipurpose
power
outlets are of the grounded type and are used with
grounded plugs and cables having a ground
wire that grounds the metallic case and exposed
metal parts of the tool or equipment when the
plug is inserted in receptacle. The ground wire
provides a conducting path of low resistance
between the metai housing of the tool and the
ship's structure. In the event of a casualty
to the insulation of the tool, the ground wire
will shunt the operator, thereby protecting him
from electrical shock.
the branches are single-phase circuits. The
single-phase circuits are connected so that under
operating conditions the single-phase loads
on
the
3-phase circuits are as nearly
balanced as possible.
PHASE SEQUENCE
These outlets are located so that two portable
pumps can be operated in any compartment by
using 75 feet of cable for each pump. The outlets are fed from battle power distribution
panels. A minimum number of outlets are fed
from any one panel to provide as great a di-
Phase identification is denoted by the letters,
A, B, and C, in a. 3-phase system. Switchboard
and distribution panel bus bars and terminals
on the back of switchboards are marked to
identify the phase with the appropriate letters,
A, B, or C.
versity of supply as possible. An adapter is
The phase sequence in naval vessels is
provided with the 75-foot extension cables for
making connections to the casualty power system if power is lost from the outlets.
ABC; that is, the maximum positive voltages
on the three phases are reached in the order: AB,
BC, and CA. Phase sequence determines the
direction of rotation of 3-phase motors. Reversal of the phase sequence reverses the direction of rotations of electric motors. The
D-C POWER
D-c power in ships with a-c power systems is furnished either by oversize exciters
for the ship's service generators, by separate
phase sequence of the power supply throughout
a ship is always ABC, irrespective of whether
power is supplied from any of the switchboards
or from the shore power connection. This con-
motor-generator sets, or by rectifiers. The
principal d-c loads are carbon-arc search-
dition ensures that 3-phase, a-c motors will
lights, degalissing installations, battery charging
always run in the correct direction.
stations, and the interior communications and
fire control system. The use of the 24-inch,
carbon-arc searchlight has been discontinued
aboard most ships with a consequent reduction
in the d-c power requirements. Rectifier power
supplies are used as d -e power sources in the
latest ships provided with a-c power systems.
SHORE POWER CONNECTION
A shore power connection is provided at, or
near a twitable weather deck location to which
portable cables from the shore or from a vessel
alongside can be connected to supply power for
the ship's distribution system when the ship
EMERGENCY POWER DISTRIBUTION
SYSTEM
service generators are not in operation. This
connection also can be used to supply power from
the ship's service generators to a ship alongside. The E'iore power circuit breaker is lo-
The emergency power distribution system is
provided to supply an immediate and automatic
source of electric power to a limited number of
selected vital loads in the event of failure of the
normal ship service power distribution system.
The system, which is separate and distinct from
the ship service power distribution system, in-
cated on the after switchboard on most destroy-
ers. The breaker connects the shore power to
the bus tie system.
MULTIPURPOSE POWER OUTLETS
cludes one or more emergency switchboard is
supplied by its associated emergency generator.
The emergency feeders run from the emergency
switchboards (figs. 4-14a and b) and terminate
in manual or automatic bus transfer equipment
at the distribution panels or loads for which
emergency power is provided. The emergency
Multipurpose power outlets are provided to
supply 450-volts, 3-phase power for portable
hoists; portable tools that require 450-volt power,
portable welding units for repair, maintenance, and damage repair purposes, including
underwater welding and cutting; and portable
104
114
_
Chapter 4
POWER DISTRIBUTION SYSTEMS
.^=10
alternate source of the ship service
power. If both the preferred and alternate sources
of ship's service power fail, the dieseldriven emergency generator starts automatically, and the emergency switchboard is
automatically transferred to the emergency
generator.
the
power distribution system is a 450-volt, 3-phase,
60 hertz system with transformer banks at the
emergency distribution switchboards to provide
120-volt, 3-phase power for the emergency lighting system.
The emergency generators and switchboards
are located in separate spaces from those containing the ship service generators and distri-
located near the centerline and higher in the
ship (above the waterline) than the normal and
alternate ships service feeders. This arrange-
When the voltage is restored on either the
preferred or alternate source of the ship service
power, the emergency switchboard is automatically retransferred to the source that is avail-
ment provides for horizontal separation between
the normal and alternate ship's service feeders
and vertical separation between these feeders
and the emergency feeders, thereby minimizing
the possibility of damaging all three types of
manually shut down. Hence, the emergency
switchboard and distribution system are always
bution switchboards. The emergency feeders are
able or the preferred source if voltage is restored on both the preferred and alternate
sources. The emergency generator must be
energized either by a ship service generator or
by the emergency generator., Therefore, the
emergency distribution system can always supply power to a vital load if both the normal and
alternate sources of the ship service power to
this load fail. The emergency generator is not
started if the emergency switchboard can re-
feeders simultaneously.
When the ship service plants are secured
and shore or tender power is not available, the
emergency generators can "feed back" power
to either switchgear group by means of a bus
transfer selector switch on the emergency
switchboards. The bus transfer selector switch
ceive power from a ship service generator.
when placed in the manual position, allows
manual ()aeration of the circuit breakers on the
emergency switchboards. While the bus transfer
selector switch is in the normal preferred or
FEEDBACK TIE
alternate preferred position, the three circuit
breakers on the emergency switchboards are
A
switch and cable arrangement, designated a feedback tie, is provided in most
interlocked and only one of them can be closed
at a time. The feedback circuits should only be
used in special circumstances such as to supply
ships. The feedback tie feeds power back to the
ship service switchboard, thus a selected portion of the ship service switchboard load may
be supplied from the emergency generator.
This feature facilitates starting up the ma-
power to the ship service bus for starting the
ship service plant. When the feedback provision
is in use, do not overload the emergency generators. The feed-back circuits must NEVER be
used to parallel the emergency generators with
each other, with the ship service generators, or
chinery after major steam alterations and re-
pairs, and provides power to operate necessary
auxiliaries and lighting during repair periods
when shore power and ship service power are
with shore power.
not available.
PREFERRED AND ALTERNATE
SOURCES OF POWER
OPERATION OF A-C GENERATORS
The emergency switchboard is connected by
cables, called feeders, to at least one and
usually to two different ship service switchboards. One of these switchboards is the
PREFERRED, or normal, source of ship service
power for the emergency switchboard and the
other is the ALTERNATE source. The emergency switchboard and distribution system are
normally energized from the preferred source
of ship service power. If this source of power
should fail, bus-transfer equipment automatically transfers the emergency switchboard to
The a-c generator may be operated separately as a single unit or in combination with
other generator units in paralleling operation.
The advantages of having generator sets paralleled together is that more current or power is
available in a system, an electric load can be
transferred without interruption of power, and
that there is greater efficiency under a varying
load condition. The basic requirements for paral-
leling are that the generators must be in phase
with each other, have the same phase rotation
(ABC), and have the same voltage and frequency.
105
115
IC ELECTRICIAN 3 & 2
NONPARALLEL OPERATION
The nonparallel operation of a single a-c
generator consists of connecting the generator
to a non-energized bus for operation. The generator should be inspected before starting for
any machinery derangements that may be caused
by operating or repair personnel. Routine checks
and inspections are made during generator operation according to operating instructions.
The Machinist's Mate and Electrician's Mate
have operating instructions to follow when operating generator equipment. Before starting and
Again, it is very important to follow the operating instructons.
On new construction "synchronizing monitors" are being used on 60-hertz ship service
systems to prevent the paralleling of generators
which are not synchronized. On systems using
this type of monitoring, it is not possible to close
the circuit breaker on the incoming generator
unless the phase angle, frequency, and voltage
are within predetermined limits as follows:
during idling (warmup time), there are many
1. Phase angle between -30° and +40°.
2. Frequency difference less than 0.2 hertz.
3. Voltage difference less than 5%.
positioned all switches in the correct position
before starting the generator. After starting, he
must be met to complete the circuit breaker
checks to be made. The EM must be sure he has
must check his instruments and gages for proper
operation. Before connecting the generator to the
bus he must be sure the generator is running at
operating speed. He then manually adjusts the
voltage and frequency to the correct rating and
places the generator in automatic operation and
again checks the voltage and frequency. When he
is satisfied that all operating conditions are
normal, he closes the generator circuit breaker
connecting the generator to the bus and load. In
some installations, it may be necessary to open
certain power and lighting circuit breakers before connecting the generator to the bus so that
the generator will not pick up the entire load at
one time.
When the a-c generator is operating,
the
man on watch is required to note the
voltage and frequency readings and adjust, when
necessary, check warning lights, gage sight
glasses, steam and vacuum gages, and be aware
of lube oil alarms, unusual generator noises,
vibrations, odors, and other abnormalities. He
may be required to control the voltage manually
during emergency operations.
To secure an a-c generator which is con-
nected along to a bus, reduce the load on the
generator as much as practicable by opening
feeder circuit breakers on the power and lighting circuits. Trip the generator circuit breaker,
turn the voltage regulator control switch to the
manual position, and place the manual voltage
control as far as it will go in the DECREASE
VOLTAGE direction.
PARALLEL OPERATION
Parallel operation of a-c generators consists of connecting a generator to a bus that is
already energized by one or more generators.
On this type of system, the above conditions
closing control circuit.
To synchronize generators for parallel operation, bring the incoming generator up to normal
speed and voltage. Adjust the incoming generator
frequency and voltage to that of the bus. Use the
synchroscope to make the fine adjustment. In
operation the synchroscope will rotate in one
airection or the other. Adjust the speed of the
generator by means of the governor motor
control switch until the synchroscope rotates
very slowly in the clockwise direction. Be certain that the voltages of the bus and the incoming
generator are still equal, and close the generator circuit breaker just before the synchro-
scope pointer passes very slowly through the
zu'o position (pointing vertically upward).
When synchronizing lamps are used instead
of the synchroscope, close the circuit breaker
just before the midpoint of the dark period of
the lamps is reached. The midpoint of the dark
period corresponds to the vertical position of
the synchroscope pointer. Then turn the synchronizing switch to the OFF position.
When a-c generators are operated in parallel, the kilowatt and reactive kva load should
be divided between them in proportion to the
generator ratings. The desired division of the
kilowatt load is obtained by adjusting the governor, which controls the gnerator speed. To
balance the reactive kva load, the generator
line currents should be equal for equally rated
generators and divided in proportion to generator ratings for unequally rated generators.
Where power factor meters are provided, the
power factors for all generators in parallel
should be equal. Equality of power factor or
correct division of generator line currents is
obtained by adjusting the voltage-adjusting rheostats of the voltage regulators.
106
Chapter 4 POWER DISTRIBUTION SYSTEMS
by ev...1ssive current, and the longer you hold
WATC HSTANDING
During watchstanding there at a few simple
operating rules which should be observed on all
installations.
Watch the switchboard instruments. They
show how the system is operating, reveal overloads, improper division of kilowatt load or of
reactive current between generators operating
in parallel, and other abnormal operating conditions. By reading these instruments the watch-
stander can detect the presence of a moderate
over current or a power overload which, if
allowed to remain, would cause the geneiators
to overheat.
Keep the frequency (on a-c systems) and
voltage at their correct values. Departure from
either affects, to some extent at least, the operation of all equipment supplied with electric
power.
Low
or
high
voltage has a pro-
effect on lights since low voltage
results in a marked decrease in illumination,
the circuit breaker closed, the greater is the
chance of permanent damage to circuits or equip-
ment. A circuit breaker should never be held
closed unless there is an emergency which justifies the risk.
Never parallel ship service generators until
they have been brought into synchronism.
Never close the bus tie circuit breakers
to parallel the buses on two energized switchboards until the buses have been brought into
synchronism.
Never close the bus tie circuit breaker to re-
store power to a switchboard which has lost
power because of failure of a local generator
that was supplying power to the switchboard
prior to the generator failure, unless the generator circuit breaker has first been tripped
by hand, or unless it has been definitely established that the generator circuit breaker is in
nounced
the open position.
while high voltage materially shortens lamp
life. The operation of vital electronic, interior
shore
communication, and fire control equipment is
of power
also seriously affected. This sensitive equipment
requires careful ad;204-nent of voltage regulators and prime mover governors to obtain satisfactory performance.
Use good judgment when reclosing circuit
brealr.ers after they have tripped automatically.
If a circuit breaker trips immediately upon the
first reclosure, it is desirable to investigate
Never parallel ship service generators with
power except for the short interval
required to transfer the load from one source
to the other. Never parallel ship
service generators with shore power of a different frequency such as 50 Hz. Never parallel with shore power without the use of synchroscope or synchronizing lights. On ships
where a synchroscope is
provided for synchronizing between shore power and the bus,
the generator breakers shall be opened first and
then the shore power breaker shall be closed.
to the circuit is important and the interrupting
disturbance when the breaker tripped was not
excessive. Remember that repeated closing and
tripping may result in damage to the circuit
breaker and thereby increase the repair or re-
On some ships, shore power may be. connected
to the bus tie with the bus tie breake'rs open and
synchronizing can be accomplished across the
bus tie breakers. When placing the shore power
and the ships service generators in parallel, the
nor'ial synchronizing process is reversed. The
incoming shore power is the controlling source
and the voltage and frequency of the ship service
placement work needed to get tht. circuit back in
operation again.
power voltage and frequency. There are several
before again reclosing. The circuit breaker may,
however, be closed a second time without in-
vestigation if the immediate restoration of power
Use the hold-in device on circuit breakers
only when absolutely necessary. The hold-in
device enables an operator to hold a trip
free circuit breaker closed when the current is in excess of the tripping value. The
circuit breaker will open automatically as soon
as the hold-in device is released if the current
is above the tripping current. In an emergency
it may be vitally important to obtain power even
at the risk of burning out equipment. The hold -in
device makes it possible to do this. However,
when holding a circuit breaker closed, you deprive the circuit of protection against damage
generators must be made to match the shore
precautions to be taken when paralleling with
shore power in addition to the usual ones when
paralleling two ship's service generators. The
shore power connection phase rotation must be
the same as the ship phase rotation. This is
easily determined with a phase-sequence indicator. If there is to be more than one shore
power connection and they are to be paralleled,
the actual phases of the shore power should not
only be in the same rotation but must be connected to match the ship's phases in order to
avoid a short circuit through the ship's system.
When paralleling with shore power for purposes
107
117
IC ELECTRICIAN 3 & 2
of transferring the load, bring the ship's voltage
To secure an a-c generator that is operating
b parallel with another generator or other gener?'ors: (1) turn the governor motor control
up to the shore power voltage or as close
thereto as possible. In some cases, the shore
power voltage may be around 480 volts.
switch of the generator being secured in the DECREASE SPEED direction and the governor
motor control switch (or switches) of the other
generator (or generators) in the INCREASE
Increase the ship's generator to 480 volts.
Now bring the ship's frequency to that of the
shore power. Turn on the synchroscope, syn-
SPEED
direction until all the load is shifted
from the generator being secured, (2) trip the
circuit breaker of the generator bei.ig secured,
ani (3) return the automatic voltage regulator
control to the manual position, and the manual
voltage control rheostat to the decrease voltage
chronize the ship's power with the shore power,
and close the shore power breaker. Quickly
transfer load to the shore power. Trip the ship
service generator breakers.
Always check phase sequence before making
connection to a shore power supply and be sure
to make connections so that the phase sequence
on the shore power will be A, B, C. If the shore
power connection is made so that it gives the
wrong phase sequence on the ship, motors will
run in the wrong direction.
Never parallel an emergency generator with
any other generator except on certain ships
where the emergency generator also serves as
a "standby set" and, as such, provisions have
been made for paralleling with the ship service
power system.
Always observe electrical safety precautions. Never adjust a ventilation opening for
personal comfort of watchstanders to a position
where spray or solid water entering the system
through weather openings can be discharged onto
switchboards, distribution panels, bus bars, or
other electrical equipment.
Always operate switchboards and distribution system equipment as if no automatic protective devices were installed. Trouble will
sooner or later be the inevitable consequence of
careless and slipshod operating practices based
upon the assumption that automatic protective
devices either will prevent incorrect operation
or will prevent damage from incorrect opera-
tion. They will not because they are not designed
or intended to do so. The protective devices
used with the distribution system are intended
to afford protection against damage as a conse-
quence of equipment failure, not of operator
failure. The intelligence which is needed for the
operation of the distribution system is not built
into the system but must be furnished by the
operator. You must, therefore, read and follow
the instructions on warning plates and indicator
lights, must know the system and operate it
correctly, and must never depend upon auto-
matic devices to keep you from making a mistake or to save you from the consequences of a
mistake.
position.
CASUALTY POWER SYSTEM
The casualty power distribui-on system is
provided for making temporary connections to
supply electric power to certain vital auxiliaries
if the permanently installed ship service and
emergency distribution systems are damaged.
The system is not intended to supply circuits
to all the electrical equipment in the ship but
is .confined to the facilities necessary to keep
the ship afloat and to get it away from a danger
area. The system also supplies a limited amount
of armament, such as antiaircraft guns and
their directors, that may be necessary to protect
the ship when in a damaged condition. The casualty power system for rigging temporary circuits
is separate and distinct from the electrical
damage control equipment, which consists of
tools and appliances for cutting cables and
making splices for temporary repairs to the
permanently installed ship service and emergency distribution system.
The casualty power system includes portable
cables, ''alkhead terminals, risers, switchboard
terminals, and portable switches. Portable cables
in
suitable lengths are stowed throughout the ship in convenient locations. The bulkhead terminals are installed in watertight bulkheads so that horizontal runs of portable cables
can be connected on the opposite sides of the
bulkhead terminal to transmit power through the
bulkheads without the loss of water tight integrity.
The risers are permanently installed vertical
cables for transmitting power through decks
without impairing the watertight integrity of the
ship. A riser consists of a cable that extends
from one deck to another with a riser terminal
connected to each end for attaching portable
cables.
108
118
Chapter 4 POWER DISTRIBUTION SYSTEMS
Suitable terminals are provided at switchboards and some distribution panels for connecting portable cables at these points to obtain
power from or supply power to the bus bars.
Casualty power circuit breakers are installed
at switchboards so that the terminals can be
deenergized when the cable's are connected.
The portable switches are stowed in repair
party lockers and are used when necessary for
connecting and disconnecting the circuits. The
locations of the portable cables, bulkhead terminals, and risers are selected so that connec-
Casualty power cables should be tied to the
overhead and high voltage signs should be attached at each connection. Also, itis Conimon
practice to pass the word over the ship's 1MC
system, informing all hands to stand clear of
the casualty power cables after they are energized.
Unrigging casualty power is also hazardous
if not handled correctly. The recommended procedure is for the Electrician's Mate on the
switchboard at the source of the casualty power
supply to open the 225 or 250ampereAQB circuit
tions
breaker behind the switchboard that supplies
emergency generators. Casualty power cables
should be rigged only when required for use,
or for practice in rigging the casualty power
cable nearest the source. After this has been
done, both ends of the last cable in the system
that connects to the load are disconnected and
can be made to many vital electrical
auxiliaries from any of the ship's service or
the system, and to remove both ends of the first
system.
removed. The normal feeder or feeders may now
RIGGING AND UNRIGGING
rigged and restowed on the proper racks.
be reenergized to the equipment, and the remainder of the casualty power cables are un-
CASUALTY POWER CABLES
POWER DISTRIBUTION
SWITCHBOARDS
There are definite procedures that mast be
followed and safety precautions that must be
observed in rigging casualty power. Only qualified personnel should do the actual connecting;
however, the portable cables may be laid out
by other personnel. Safety precautions require
A switchboard may consist of a single section
or of several sections that are physically sepa-
rated and are connected by cables to form a
switchgear group. This arrangement provides
sufficient separation between sections to mini-
the man making the connections to wear rubber
mize damage from shock, to LOCALIZE damage
before making a connecting. Tne portable cable
connections for casualty power should always
plete with a separate front panel and all the
required apparatus, such as the a-c generator
gloves, and to stand on a rubber mat or wear
rubber boots while making connections. He is
further required to test each casualty power
riser or bulkhead terminal with a voltage tester
be made by first connection at the load, then
working back to the source of power. In making
casualty power connections at a load where
there are not circuit breakers or transfer switches
to interrupt the incoming feeder cable, it
must be disconnected or cut at the equipment.
It is quite possible that this cable may be
damaged by the casualty which caused the loss of
power, and such a damaged cable if energized
would probably trip the casualty power cir-
cuit breakers. If not disconnected, this incoming
feeder cable may be reenergized and present
a hazard to personnel handling the casualty
power cables. Care should be exercised
making all connections, to keep the
in
phase sequence correct in a-c systems. If the
load includes motors in either a-c or d-c systems, the connections should be made so as to
include the motor controller in the circuit.
from fire, and to permit easy removal of damaged sections for repairs or replacement.
On dead-front switchboards the equipment
is grouped to form a number of units each comcontrol unit a-c bus-tie unit, power distribution
unit, and lighting distribution unit. The units are
mounted on a common base.
CONTROL BENCHBOARD
A separate control benchboard (fig. 4-15) is
provided in the switchgear groups for cruisers
and aircraft carriers. This benchboard mounts
generator control equipment, measuring instruments, and remote controls for some electrically
operated equipment. This arrangement provides
for a centralized control of the generators and
major svitching operations. The control benchboard in ships equipped with four ship's service
switchaear groups is provided with a mimic
bus (a small switchboard plan) that has indinting
lights to show which generator circuit breaker
and which bus-tie circuit breakers are closed
109
IC ELECTRICIAN 3 & 2
switchgear group and consists of the same
number of corresponding designated panels,
-Generator switchboards are equipped with
meters to indicate the generator voltage, current, watts, frequency, and power factor. Synchroscopes and synchronizing lamps are provided for paralleling generators. Indicator lamps
are provided for visual indication of the operating
conditions of various circuits.
The frequency is controlled by the generator
speed. The speed is automatically controlled
by the governor of the prime mover. The gov-
ernors for large machines can be set to the
required speed by a governor motor controlled
from the switchboard.
To prevent the generator from operating as
a motor when running in parallel with other
generators, the generator circuit breaker is
equipped with a reverse power .lay that trips
the breaker and takes the generator off the line
when power is fed irom the line to the generator
instead of from the generator to the line.
Protection against overspeed is provided in
the governing mechanism of the prime mover.
GROUND DETECTOR LAMPS
A set of three ground detector lan ns (fig.
4-16) is connected (through transformers) to the
27.65.1
Figure 4-15. Control benchboard.
main bus of each ship's service switchgear
group and to the emergency bus, enabling the
switchboard watch to check for grounds on any
phase of the 3-phase bus.
To check for a ground, turn switch S on and
throughout the ship. In ships not provided with observe
brilliancy of the three lights. If
control benchboards the =tering and control the lightsthe
are
bright, no ground exits,
equipments are mounted on the front ponels of and all lights equally
receive
the same voltage. For
the units in the switchboards or switchgear
groups.
SHIP'S SERVICE SWITCHBOARD
The ship's service switchboards in a destroyer
consist of switchgear groups 1S and 2S, located
in
the
forward and after enginerooms,
respectively.
The forward ship's service switchgear group
IS is designated as the control switchboard
because it is provided with instruments and
governor control (for the forward generator)
to allow for dividing the load. All paralleling
of the generators is accomplished at the ship's
service switchboard associated with the incoming
generator.
The after ship's service switchgear group
2S
77.172
is similar to the forward ship's service Figure 4-16. A-c ground
detector lamp circuit.
110
120
al7
t-
ADD
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it
1
L
S US
P0001
SAME
GENERAL
AND
RUDER TO OR
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LUNING
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,
a
EUS
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1
rad
GENERAL
0 C SAS TT
sus
1.=
4S0/11?
IC
CASUALTY FONDER TtRIONAL
G ENE/CENCI GETOUT°, IPA ORCIAT DREADED
It 9000F POwflt COMO SOW_ADEN
A ENEDGEKT GENERAITAt °DWI' IIISEADER
L. AGO CASUALTY POOR MAWR
AC GCN.
400 own
450 WWI,
F. AC DIME E GENERAL PORED ODONT WAKED
0. AC sus re CPILLAT SWAMI
E. AC LAWNS ONZIAT WADER
C D.C. IPAS TE CIRCUIT eatmet
D 0 C GEMDATOR Man WEAKER
A AC GOIEDATOD MOAT VICAKEN
IA
DC
O2
120V
SO ocw
OC MIA
120 v
So Gila
IS
Figure 4-17.Shies service and emergency switchboard interconnection.
-J
22
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Az GIN
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77.169
IC ELECTRICIAN 3 St 2
example, if lame A is dark and lamps a and C
are bright, phase A Is grounded. In this case, the
primary of the transformer on phase A is shunted
by ground and receives no voltage.
abrasive dust, and copper particles are removed
from inaccessible parts by vacuuming (0 blowing
with dry, clean compressed air. Vacuuming is
preferred to blowing. Using compressed air is of
little benefit unless the dust is removed from
the generator. Approved cleaning solvents are to
be used only where necessary to remove grease
and pastelike substances that contain oil or car-
BUS TIES
The connections between the ship's service
and, the emergency generating units and their
associated switchboards and the interconnections between the switchboard are illustrated in
the schematic line diagram In figure 4-17. The
a-c buses on the forward and after ship's service switchboards can be connected together, and
the d-c buses on these switchboards can also
be connected together. This arrangement enables one generating unit to supply power to both
ship's service switchboards when the other unit
is out of service, and also provides for parallel
operations of the two ship's service generating
units (1SG and 2SG). However, when operating
SPLIT PLANT the generators are operated separately, each unit supplying power for its own
Sction of the ship.
bon.
Portable electric lights (with guard) may be
placed inside idle generators not provided with
space heaters to keep the insulation dry. Only
enough heat to keep the temperature- inside the
generator, about 5° to 10° above ambient temperature is required. Measuring insulation resistance of idle generators at sufficiently short
intervals will help to detect moisture absorbed
by the windings.
At least once a year and during each overhaul, each switchboard propulsion control cubicle, distribution panel, and motor controller
should he deenergized for a complete inspection
and cleaning dit all bus work equipment. The
inspection of deenergized equipment should not
be limited to visual examination but should include grasping and shaking electrical connections and mechanical parts to he certain that all
connections are tight and that mechanical parts
are free to function. Be certain that no loose
tools or °thee extraneous articles are left in or
around switchboards and distribution panels.
Check the supports of bus work and be certain that the supports will prevent contact be-
MA/NTENANCE
The purpose of maintaining a power distribu-
tion system is to ensure that the generators,
owitchboards, and transfer equipment are ready
for service at all times. Basic to the maintenance
of this equipment are the procedures and means
for keeping the equipment clean and dry, keeping
electrical connections and mechanical fastenings
tight, and inspecting or testing to determine the
tween bus bars of opposite polarity or contact between bus bars and grounded parts during
periods of shock. Clean the bus work and the
creepage surfaces of insulating materials, and
operating condition of the equipment.
GENERATORS
The main concern in generator maintenance
is keeping the electrical insulation clean and dry
and in good condition (high resistance). If generators are not kept clean, they will tend to
overheat due to the presence of dust, dirt, and
other foreign matter, such as particles of carbon,
copper, and mica. Excessive operating temperatures will result in damage to the electrical
insulation. The windings will eventually short
circuit or ground out because the foreign matter
is abrasive or conducting or forms a conducting
paste (thro:1h absorption of moisture or oil).
Generators can be cleaned with rags, vacuum
cleaner, compressed air, or approved solvents.
Wiping with a clean, lintfree, dry rag ISUCL1 as
cheesecloth) is effective for removing loose
dust or particles from accessible parts. Grit,
be certain that creepage distances (across which
leakage currents can flow) are ample. Check the
condition of control wiring and replace if necessary.
Be certain that the ventilation of rheostats
and resistors is not obstructed. Replace broken
or burned out resistors. Temporary repairs can
be made by briaging burned out sections when
replacements are not available. Apply a light
coat of petroleum to the face plate contacts of
rheostats to reduce friction and wear. Be certain
that no petrolatum is left in the spaces between
the contact buttons as this may cause burning or
arcing. Check all electrical connections for
tightness and wiring for frayed or broken leads.
The pointer of each switchboard instrument
should read zero when the instrument is discon-
nected from the circuit. The pointer may be
112
122
Chapter 4 POWER DISTRIBUTION SYSTEMS
brought to zero by external screwdriver adjustment. Caation: This should not be done unless
proper authorization is given. Repairs to the
switchboard instruments should be made only
by the manufacturers, shore-repair activities,
or tenders.
Be sertain that fuses are the right size;
clips make firm contact with the fuses; lock-in
devices (if provided) are properly fitted; and
that all connections in the wiring to the fuses
are tight.
SWITCHBOARDS
Switchboards and distribution panels should
be deenergized after firing, if practicable, and
thoroughly inspected for tightness of electrical
connections and mechanical fastenings. Emergency switchboards should be tested regularly
in accordance with the instructions furnished
with the switchboard in order to check the operation of the automatic bus transfer equipment
and the automatic starting of the emergency
generator. This test should be made in connection with the weekly operating test of emergency
generators.
Bus bars and insulating materials can be
cleaned with a dry wiping cloth, or a vacuum
cleaner. Be certain that the switchboard or distribution panel is completely dead and will
remain so until the work is completed; avoid
cleaning live parts because of the danger to
personnel and equipment.
The insulated front panels of switchboards
can be cleaned without deenergizing the switchboard. These panels can usually be cleaned by
wiping with a dry cloth. However, a damp, soapy
cloth can be used to remove grease and fingerprints. Then wipe the surface with a cloth dampened in clear water to remove all soap and dry
with a clean, dry cloth. Cleaning cloths must be
wrung out thoroughly so that no water runs down
the panel. Clean a small section at a time and
then wipe dry.
Control circuits should be checked to ensure
circuit continuity and proper relay and contactor
operation. Because of the numerous types of
control circuits installed in naval ships, it is
impracticable to Set up any definite operating
test procedures in this rate training manual.
In general, certain control circuits, such as
those for the starting of motors or motorgenerator sets, or voltmeter switching circuits,
are best tested by using the circuits as they are
intended to operate under service conditions.
Protective circuits, such as overcurrent,
reverse power, or reverse current circuits,
usually cannot be tested by actual operation
because of the danger involved to the equipment.
These circuits should be visually checked, and,
when possible, relays should be operated manually to be certain that the rest of the protective
circuit performs its intended functions. Exercise
extreme care not to disrupt vital power service
or to damage electrical equipment.
BUS TRANSFER EQUIPMENT
Bus transfer equipment should be tested
weekly. For manual bus transfer equipment,
manually transfer a load from one power source
to another and check the mechanical operation
and mechanical interlocks. For automatic bus
transfer equipment, check the operation by means
of the control push-switches. The test should
include operation initiated by cutting off power
(opening a feeder circuit breaker) to ascertain
if an automatic transfer occurs.
113
1..?1,3
CHAPTER 5
TEST EQUIPMENT
As an IC Electrician, youwill find itnecessary
to use a variety of test equipment to help trouble-
shoot and repair the newer, more sophisticated
electrical/electronic gear aboardship. This
chapter provides you with a useful and logical
troubleshooting procedure, and describes the test
equipment that you are likely to operate when
troubleshooting and repairing the installed electrical/electronic gear.
we have available information that indicates it
will not function normally for much longer.
Picture again the watch, but this time the
second hand is stopped. A malfunction has occurred at some previous time. It may be that
someone has forgotten to wind the watch, but
since you recognize that the normal condition is
for the second hand to complete 360 degrees in
1 minute and since it is not moving, you are
aware that a malfunction has occurred. If, how-
TROUBLESHOOTING
ever, when you looked at the watch you noted that
is the art of locating the
problem. Like any art, it requires talent and
Troubleshooting
training before it is developed into truly great
work. Over the years IC Electricians have developed specific theories as to how to go about
their art, and since they are passed on to you
free of charge it will stand you well to use them.
The first step in logical troubleshooting is to
recognize a normal condition; in other words, to
determine that everything is working properly.
For example, the second hand on our watch is
going through 360 degrees in aclockwise direction
every minute, the chances are pretty good that
the second hand on your watch is working properly. If, however, you had never seen a watch
before, you would have no idea that this was the
proper method for the second hand to work and
therefore would have no way of knowing that the
hand was working properly. When you are dealing
with a dead reckoning tracer or cyrocompass,
the problem of recognition of normal conditions
is far more complicated and you may need an
explanation from a senior or from the manufacturer's technical manual. The point is you must
have a fair comprehension of the normalcondition
of a piece of equipment before you can consider
maintenance of it.
A second logical step in the art of troubleshooting is the ability to recognize that a malfunction is occurring, is about to occur, or has
at some time past occurred. Then we assume that
the equipment is not functioning normally, or that
the second hand was moving at a rate of but 10
degrees in a 1-minute period, you could safely
assume that a malfunction was occurring at that
time. The third situation would be in effect that
you find the watch running at the proper rate but
noted a grinding sound from somewhere in its
interior. You could then assume with some reliability that a malfunction was about to occur in
some future time. Again it must be emphasized
that the criterion of step one remains true: you
must be able to recognize a normal condition before
you can determine that there is a
malfunction.
Step three in logical troubleshooting falls
right in place once you are sure of the mal-
function's existence. Collect all available
data regarding the malfunction in order to find
the symptoms. Is the unit running at all? Is it
within the normal temperature and pressure
range? Has this malfunction occurred before? Is
the malfunction occurring only during a specific
set of circumstances? Is the unit noisy? Out of
calibration? Over or under design limits? Don't
overlook anything, as the smallest unit of informa-
tion that you collect may in the final analysis
be the solution to the problem.
Now that you have collected all of the symptoms of the malfunctions, the next step is to list,
mentally or on paper, the possible causes of
these symptoms. Many manufacturer's technical
manuals list the "probable cause" in the corrective maintenance sections. It is often wise at this
point to discuss the malfunction with another IC
r t4
Chapter 5 TEST EQUIPMENT
Electrician. Giving him the symptoms may result
in his coming up with several causes that were not
apparent to you.
Armed with a complete set of symptoms and
with the probable causes of these symptoms, the
troubleshooter now begins the painstaking checks
which will ultimately lead to isolation of the mal-
function. To sectionalize the trouble means to
track it down into one specific area of a piece of
equipment. This may be done by going over the
energizing procedure slowly and determining
when the trouble first appears. It may be done
through the use of a troubleshooter's chart listed
in the manufacturer's technical manual. It also
can easily be performed through the use of the
probable causes that you have listed.
Once it has been determined which section of
a system is malfunctioning, it is usually but a
matter of time before the defective component or
components are isolated and repairs can be
made. During this final step of troubleshooting
it is most important that you, the Interior Communications Electrician, use every method of
isolation. An open resistor can be determined
through the use of a meter, but time is wasted
if you do not note that the component is discolored when you originally open the chassis for
inspection. It is imperative in troubleshooting
that the IC Electrician give full attentionlook,
listen, smell, and feelto ensure good, quick,
trouble isolation.
PRECAUTIONS
Basic electrical indicating instruments
receive extensive coverage in Basic Electricity,
NavPers 10086 (Revised) and in Basic Electronics, NavPers 10087 (Revised) and all that
is needed here is a reminder of certain specific
precautions which are applicable to them and to
all test equipment. The delicate mechanisms of
most test equipment require that you take pains
to avoid rough handling and the possibility ci mois-
ture and dust or fine magnetic particles entering
the case. Other factors which have led to the
ruining of certain pieces of equipment are the
subjection of the unit to an input signal of a mag-
nitude greater than the range which is selected
on the input scale, use of the instrument in close
proximity of strong magnetic fields, and subjecting the meter movement to high potential sources
while attempting to calibrate or service it. When
all is taken into account, you should understand
the specific piece of equipment that you are using
and the circuit upon which you are using it.
MULTIMETERS
Multimeters combine a voltmeter, ammeter,
and ohmmeter in one unit and may be classified
as either the electronic and nonelectronic type.
A discussion of a representative unit of each type
follows.
MULTIMETER AN /PSM- 4(SERIES)
Multimeter AN/PSM-4A (fig. 5-1) is a portable, nonelectronic volt-ohm-milliammeter. It is
designed to measure direct current (up to 10
amperes), resistance (up to 30 megohms), d-c
voltage (up to 5000 volts), a-c voltage (up to
1000 volts rms) or output voltage (up to 500
volts rms). The complete unit includes test
probes which may be used with their prod tips,
or the tips can be fitted with alligator clips
or with a telephone plug to simplify contact
arrangements and connections. A high voltage
probe is also included, which makes it possible
to read voltages up to 5000 VDC. This probe
contains a warning light to indicate the presence
of high voltage.
The Multimeter AN/PSM-4 series comprises
the 4A through 4E meters. Except for minor circuit changes to the basic meter, they are identical. The instrument part of each multimeter contains circuits for measuring current, resistance,
or voltage separately.
D-C Voltmeter Circuits
The block diagram of the circuit in Multimeter AN/PSM-4A which is used for measuring d-c voltages is shown in figure 5-2. The
circuit is selected with function switch S101, in
either its DIRECT or REVERSE DCV position
(fig. 5-1). For voltages up through 500 volts, a
range is selected with range switch S-102 (only
one position shown in figure 5-2). For the 1000 -
volt range, the read test lead connects into the
special 1000 VDC jack (fig. 5-1), and the range
switch is not in the circuit. For the 5000-volt
range the high voltage probe (not shown) connects
the special 5000 VDC jack, and places its resistance in series with the meter movement. For any
range, the total resistance in series with th, meter movement will regulate the meter current to
provide a proportional current to indicate the
amount of voltage in the circuit.
A-C and Output Voltage Circuits
The circuits which measure a-c and output
voltages (fig. 5-3), are selected with the ACV and
115
IC ELECTRICIAN 3 & 2
FUNCTION SWITCH
RANGE SWITCH
4.133
Figure 5-1. Multimeter AN/PSM-4A.
HIGH VOLTAGE PROSE
MULTIPLIER
RESISTORS
4=4 RED TEST LEAD
5101
RANGE
SWITCH
.1.."f
SIOI
REVERSING
METER
MOVEMENT
SLACK TEST LEAD
1.311
Figure 5-2. Functional block diagram of d-c voltage circuits.
116
r
1Z6
Chapter 5TEST EQUIPMENT
MULTIPLIER
RESISTOR3
4==I RED TEST LEAD
CAPACITOR
RECTIFIER
METER
MOVEMENT,
BLACK TEST LEAD 1=
(OUT PUTT
3 101
FUNCTION
SWITCH
1.312
Figure 5-3.
Functional block diagram of a-c and output voltage circuits.
OUTPUT positions of function switch S-101. For
voltages up through 500 volts, a range is selected
Ohmmeter Circuits
range, the red test lead connects the specia11000
VAC jack, and the range switch, S-102, is not in
are selected with function switch S-101. The
ranges are Rxl, Rx10, Rx100, Rx1000, and
tries to send current through the resistance of the
circuit in both directions, but the rectifier allows
Rx13000. An internal battery furnishes the power
for all resistance measurements. For each range,
the circuit is arranged so the meter will
indicate zero ohms, and full scale deflection
when the red test lead and the black test lead are
shorted together. When you connect a resistance
between the test leads, this resistance will be in
with range switch S-102. For the 1000-volt
The ohmmeter circuit (fig. 5-5) and its ranges
the circuit. The a-c voltage impressed across
the circuit between the red and black test leads
only one direction of current flow through the
meter movement. The meter is calibrated to indicate the RMS value of the a-c voltage applied
to the instrument circuit.
Direct Current Circuits
series with the instrument circuit, and less
current will flow through the meter movement.
The amount of reduced meter deflection indicates
how much resistance is between the test leads.
The circuit which measures direct current is
selected with the d-c µ A MA AMPS position of
function switch S-101 (fig. 5-1). For currents up
to 1000 milliamperes, the range is selected with
range switch S-102 (fig. 5-4). For the 10 ampere
range, the red test lead connects the special 10
AMPS jack, and range switch S-102 is not in the
,circuit. Each range provides a parallel shunt resistance for the meter movement, and the circuit
current divides between these two parallel paths.
The proportional part which passes through the
meter movement indicates the total circuit
current.
Function Switch S-101
Function switch S-101, (fig. 5-1) located in the
lower left-hand corner of the front panel, selects
the type of circuit for which the instrument is
connected. There are two positions for d-c volts:
DIRECT and REVERSE. The normal position is
DIRECT. When using the meter to make a d-c
voltage measurement and a connection is made
which causes the meter to read backwards (de-
flection of the pointer to the left), set switch
S-101 to REVERSE and the pointer will be de-
flected up-scale. To read alternating current
METER
MOVEMENT
3 102
RED TEST LEAD
SLACK TEST LEAD
RANGE
SWITCH
SHUNT
1.313
Figure 5-4.
Functional block diagram of d-c circuits.
117
IC ELECTRICIAN 3 & 2
METER
MOVEMENT
MULTIPLIEll
RED TEST LEAD
H
H
ZERO
-
MULTIPLIER
5101
FUNCTION
SWITCH
Figure 5-5.
IMMTERY
+
OLACK TEST LEAD 1==10
COMPARISON
RESISTOR
Functional block diagram of ohmmeter circuits.
voltages, set switch S-101 to the ACV position. A
rectifier within the instru nent rectifies the a -c
voltage to an equivalent d-c value, and the meter
indicates the RMS value of the applied voltage. To
read the a-c portion of mixed a-c and d-c voltages, set switch S-101 at OUTPUT. Set switch
S-101 at d-c g A MA AMPS to read direct current. As mentioned previously, switch S-101 also
serves as a range switch for resistance
measurements.
Range Switch S-102
This eight-position range switch located in
the lower right corner of the front panel permits
the selection of voltage and current ranges. The
full scale value for each range switch position is
marked on the front panel.
Zero Ohms Controls
The ZERO OHMS control is located near the
center of the front panel. Each time the function
switch S-101 is placed in a position to read resistance, short the test leads together and rotate
the ZERO OHMS control knob to make the pointer
read full scale, or zero ohms. If you cannot bring
the pointer to full scale, replace the battery in
the rear of the case.
...
F
OHMS
Test Leads and Test Jacks
There are two test leads, W-101 and W-102,
(fig. 5-6) which are needed for all measurements
except those which require the 5000 VDC range.
Test lead W-101 is red and test lead W-102 is
black. Unless other wise specified, connect black
test lead W-102 in the COMMON jack, J106, and
connect the red test lead W-101 in the + V MA
OHMS jack, J101. For the 1000 VDC range, place
1.314
red test lead W-101 in the 1000 VDC jack, J-103.
For the 1000 VAC range, place red test lead W101 in the 1000 VAC jack, J104. Use the red test
lead to contact the positive side of the source
for d-c measurements and the black test lead to
contact the negative side. For the 5000 VDC
range, use black test lead, W-102 in the COMMON
jack, J-106, and use the highvoltage test lead, W103, screwed on over recessed post J-102, +5000
VDC MULTIPLIER. For the 10 ampere range,
place red test lead, W101, in the special 10
AMPS jack, J105.
Accessories E-101, E-102, and E-103
There are two alligator clips, E-101 and E102, which the operatok may use to screw on over
the end of test leads W-101 and W-102. This is
for the convenience of the operator. There is a
telephone plug, E-103, which may be used to con-
nect both the test leads, W-101 and W-102, to
contacts within a two-contact telephone jack.
This permits easier connection to the jack contacts for any electrical measurement because the
operator can make the measurement directly
through an equipment panel without opening the
case of the equipment. The red test lead W-101,
connected in the red insulated jack (not shown) on
the rear of telephone plug E-103, contacts the tip
of the plug. The black test lead, W-102, connected
in the black insulated jack (not shown) on the rear
of the telephone plug, E-103, contacts the sleeve
of the plug.
ELECTRONIC MULTIMETER AN/USM-116
At times accuracy is a major consideration
in the art of troubleshooting. When working with
the underwater log or the gyrocompass circuits,
Chapter 5 TEST EQUIPMENT
J-I06
J -101
J-105
A - 102
J -104
J-103
W-103
J -102
E -101
MULTIMETER
E -102
ME - 48 A/U
E -103
Figure 5-6. Control, jacks, leads, and accessories.
4.133(ME-48A/U)
the IC Electrician must often adjust to within a Direct current
few millivolts or perhaps a milliampere. To
enable him to maintain close tolerances, the
Navy has developed a series of portable electronic multimeters of which the AN/USM-116 is
a representative model. With a high degree of
accuracy, this instrument measures voltage, cur-
rent, and resistance values, using a relatively
high input impedance to prevent loading the circuit under test.
The values listed below are within the range
of the AN /USM -116:,
A-c volts
D-c volts
0.01 to 300 rms
0.02 to 1000
20 microamps to1000milliamps
Resistance 0.2 ohms to 1000 megohms
The unit pictured in figure 5-7A requires a 115 -
volt a-c power source, and along with its 8-foot
power cord contains 4 permanentlyconnected test
leads.
Two unshielded leads or probes are used to
measure both resistance and current. A third,
red in color, is used in conjunction with the com-
mon of the former two in the measurement of
d-c voltage. This probe contains a 36-megohm
resistor to eliminate the capacitance caused by
interaction with its shield. The fourth lead, used
for a-c voltage, is recognizable by the permanent
119
k:9
IC ELECTRICIAN 3 & 2
RF CABLE
ADAPTER
(COAXIAL TEE
CONNECTOR)
COVER
MULTIMETER
ASSEMBLY
IMPFDANCE MATCHING
NET WORK
\ (COAXIAL TERMINATION PLUG)
HANDBOOK
ALLIGATOR
CUP
GROUND
EAD
POWER
CABLE
\
/ --...--.7,
AC TEST PROD
AC TEST LEAD
1
OHMS-MILS TEST LEAD
DC TEST LEAD
COMMON TEST LEAD
Figure 5-7A.
4.133
Multimeter AN/USM 116.
attachment of an RF type probe for use on highfrequency circuits. When htgn frequency is measured, a ground attachment is employed and con-
nects directly to the a-c probe. The a-c probe
also contains a diode circuit as the meter circuit
is designed for d-c measurement only.
setting of all scales through the use of two singlemounted potentiometers. The Ohms Adjust is used
to precalibrate the meter for any of the ohmmeter
functions. The Function Switch is also used as an
on-off switch with a 15-minute warmup time
being recommended for greater meter accuracy.
be measured, that is current, resistance, a-c
The meter face contains a zero adjustment
screw which can, by mechanical means, preset
the meter to the true zero. This adjustment is
selects the scale of the meter for the chosen
prior to warmup. If it is necessary to re-adjust
The USM 116 has four operating controls. The
Function Switch selects the desired parameter to
voltage or d-c voltage. The Range Switch pre-
parameter. A Zero Adjust permits the accurate
directly below the face glass, and should be made
this control, it should be done with all probes dis-
connected and the function switch in the mils
position.
VACUUM TUBE VOLTMETERS
The a-c rectifier type of voltmeter has several
disadvantages that make it practically useless for
measuring voltages in high impedance circuits.
For example, suppose that the plate voltage of a
pentode amplifier is to be measured. (See fig.
5-7B.) When the meter is connected between the
plate and cathode of the electron tube, the meter
resistance R
is placed in parallel with the
effective platPtesistance R fp thereby lowering
the effective plate
resisthee. The effective
plate resistance is in series with the plate load
Figure 5-7B.
189.52
Loading effect created by meter
resistance.
120
1
resistor, RL, and this series circuit appeas
across the supply voltage, Ebk as a voltage
divider. Since the overall resistance is lowered,
12e
Chapter 5 TEST EQUIPMENT
it follows that current through RL will increase,
the voltage drop across RI., will also increase,
and the voltage drop across Roy will decrease.
The result is an incorrect indication of plate
voltage, the effect of connecting this meter in
the circuit is called loading effect.
A meter having a sensitivity of 20,000 ohms
per volt and a 250-volt maximum scale reading
would introduce an error of about 1 percent.
The lower the sensitivity of the meter, the
greater the error. however, in circuits where
very high impedances are encountered, such as in
grid circuits of electron tubes, even a meter of
20,000 ohms per volt sensitivity would impose too
much of a load on the circuit.
Another disadvantage of the a-c rectifier
type of voltmeter is the shunting effect at high
frequencies of the relatively large capacitance of the rectifier. This shunting effect
may be eliminated by replacing the usual
metallic oxide rectifier with a diode electron
tube; the output of the diode is applied to the grid
of an amplifier in which the plate circuit contains
the d-c meter. Such a device is called an electron tube voltmeter or a vacuum tube voltmeter,
usually abbreviated VTVM. Voltages at frequencies up to 500 megacycles, and sometimes
even higher, can be measured accurately with
this type of meter. The frequency limitation is
may or may not be that of the equipment in which
the tube is to operate. Also, the tester takes no
account of the interelectrode capacity of the tube.
Military specifications allow a wide deviation of
interelectrode capacity which makes an accurate
prediction of tube performance with a tube tester
difficult. The range ci operating frequency
affects performance also.
It is impracticable to design a complete testing instrument that will evaluate the performance
of any tube in any circuit in which it is being
used. A tube may test low on the tester and yet
work perfectly well in the circuit or, on the otl.er
it may check good in the tester and not
function in the equipment. As a rule, therefore,
hand,
only dead, shorted, or extremely weak tubes
should be discarded purely on the basis of a tube
tester check.
The two principal types of tube testers are
the emission tester and the mutual bonductance or
transconductance tester. An emission tester
measures the ability of an electrua tube to emit
electrons from its cathode. A mutual conductance
tester indicates the ability of the grid voltage to
control the plate current. Tube testers are also
capable of detecting short circuits and leakage
between tube elements and showing the presence
of too much gas in electron tubes.
determined by the model of VTVM.
ELECTRON TUBE TEST SET
MODEL TV-10A/U
and therefore the current drawn from the circuit
whose voltage is being measured is small and in
Model TV-10A/U is a typical mutual conductance tube tester. Mutual conductance is defined
as the ratio of the change in plate current
to the change in grid potential producing it, under the condition of constant plate voltage. Mu-
The input impedance of a VTVM is large,
most cases negligible. The main reason for
using a vacuum tube voltmeter is to overcome
the loading effect by taking advantage of the
V TVM's extremely high input impedance. A
VTVM that is used extensively for electronics
maintenance is contained in the AN/USM 116
multimeter described earlier.
The VTVM measures d-c voltages from 0.02
volt to 1,000 volts and a-c voltages from 0.01
volt to 300 volts rms at frequencies from 30
cps to 1 mc. With an adapter it can measure
RF voltages.
TUBE TESTERS
Although rigid controls reduce tube failures
considerably, tube testers provide some means
of determining the condition of tubes that have
been in use for some time, as well as the condition of new tubes that are to be placed in equipment. In general, tube testers do not completely
indicate tube performance because they present a
fixed impedance to the tube grid and plate which
is expressed in micromhos
(symbol Gm) and the condition of the tube is
indicated on the meter scale directly in
tual conductance
micromhos.
Test Set Panel
The TV-10A/U panel is shown ia figure 5 -8.
The tube sockets are grouped along tll.: top edge
and in the upper left-hand section of the panel
as follows: Along the top edge reading from
the left are test sockets for SUBMINIATURE
tubes; 7 pin MINIATURE tubes; 9 pin NOVAL
base miniature tubes; LOCTAL and OCTAL
tubes; a combination large and small radius
socket for standard 7 pin tubes, which also
provides a pilot lamp test i..iceptacle; and sockets
for standard 6, 5, and 4 pin tubes. An acorn
tube socket designed to accommodate all tubes of
this type now in use is located at the right of the
filament voltage switea.
1C ELECTRICIAN 3 & 2
'
.
fi
,as
:151$ 1r4
Tret:
'
'A4t
t!'
ir.rft
rpt.
°
hat4li.".14 ggiPs;Se-4
Figure 5-8. Tube tester panel.
The power switch controls the a-c power input
to the tester. The pilot lamp indicates whether
power is on or off. The cartridge fuse, rated at
1 ampere, protects the a-c line. Overloading the
tester or a tube under test is indicated by the
fuse lamp. The line adjust control enables the
test set operator to vary the input voltage to
a power transformer in order to standardize the
voltage for the test circuits. In this way, proper
test potentials are maintained at all tube elements
under varying conditions of line voltage.
The test set operator consults the roll chart
for the proper settings of the switches, controls,
and selectors on thc' pant. Column headings on
the panel above the index window make it easy to
refer to the tube test data on the roll chart.
20.346(5)
the proper level for testing rectifier and diode
tubes.
The shorts-micromhos switch selects the
proper
range of mutual conductance in
micromhos for the tube under test, as indicated
on the roll chart. The letters (A, 13, C, D, and E)
at the five right-hand positions of this switch
indicate the scale for reading the meter. The
switch alsk, has five left-hand positions for testing
shorts. The neon lamps glows to indicate a short
circuit.
Pushbutton switches located in the center of
panel actuate the final circuit selector
switches for testing as follows:
P1: Line adjust.
the
P2: Diodes (tubes having no grid), such as
The filament voltage switch selects the proper
filament or heater voltages from 0.6 volts through
117 volts, alternating current in 18 steps. Another
6H6.
P3: Mutual conductance of amplifier tubes
only; NEVER RECTIFIER TUBES.
position on this switch, marked BLST provides
P4 and P5: Gas.
for testing ballast tubes. An OFF position is
P6: Cold cathode rectifiers, such as OZ4.
P7: Rectifiers, such as 5Y3, 6X4, 83, etc.
also provided.
The bias control is used to adjust the bias
voltage to the proper value for the tube under
test, Th.,: bias fuse lamp protects this control.
The shunt control is a potentiometer that
controls the sensitivity of the meter circuit to
,
Vt°,"
oerl '
ZiVt.
-
P8: Reversing polarity of voltage applied to
the meter (certain types of tubes).
Proper switching or the internal circuits to
apply correct test voltages to the various pins of
the tube under test is provided by the selectors
122
12
Chapter
5 TEST
EQUIPMENT
TO ELEMENTS OF TUBE
THROUGH SHORT TEST SWITCH
TUBE
TEST
CIRCUIT
SHORT
TEST
CIRCUIT
-aw-
METER
TO
AC POWER
SUPPLY
LINE
POWER
SUPPLY
1.
NOISE - TEST
JACKS
TEST
o'11%b
Sw
RECTIFIER
CIRCUIT
A
SHORT TEST
R
POWER
SOURCE
TUBE
UNDER
TEST
TO
AC POWER
SUPPLY
140.142
Figure 5-9. Block diagram, tube tester.
on the panel (two filaments, one grid, one plate,
once screen, one cathode, and one suppressor).
Fundamentals of Operation
The various circuits of the test act are related
as shown by the block diagram of figure 5-9. The
source of power is 105 to 125 VAC at any frequency between 50 and 1600 hertz. The power
supply has a transformer consisting of the primary winding and seven secondary windings. One
of the secondary windings is tapped at several
points to supply the filament voltage for all
types of tubes. Other secondary windings supply
filament and plate voltages to rectifier tubes in
the tester. The d-c output of these tubes is used
for the electrode supply voltages for tubes under
test.
The line test adjusts the meter indica-
METER
B
RECTIFIER TEST
Figure
5-10.
Simplified short- and rectifiertest circuits.
20.347
The tube test circuit applies the proper a-c
grid and plate voltages to the tube under test.
An a-c voltage is applied in series with the grid
bias to swing the grid in positive and negative
directions frk.m the d-c bias value, thereby
producing the grid voltage required for a dynamic test. The plate voltage is furnished by
L2
METER
the line voltage. Normally, with the
meter pointer over the line test mark, the rms
voltage across the transformer primary will be
tion to
93
volts.
In figure
L3
GAS
93V AC
the shorts test circuit detects short circuits and leakage between tube
L
r.4-
V2
TEST
BUTTON
5-10A,
-GRO BIAS
elements.
VOLTAGE
The rectifier circuit (fig. 5-10B) is used to
test rectifier tubes and diode tubes, which re-
BIAS
CONTROL d +130V DC
+56 DC
quire an emission test only. In this test, the
SCREEN
shorts-micromhos switch is set at position 1%,
which connects a shunt potentiometer into the
rectifier circuit. In positions B, C, D, and E,
fixed shunt resistors are connected across the
meter to provide the proper signal voltage for
the Gm scale that is selected.
LOW ) 124VOLTAGE
PUSH-BUTTON
SWITCH
Figure
123
1133
5-11.
Simplified mutual-conductance
test circuit.
20.348
IC ELECTRICIAN 3 & 2
another full-wave rectifier. The meter is connected in the negative return of this circuit and
indicates the change in plate current (fig. 5-11).
As mentioned earlier, the test set can show
whether or not there is excessive gas in a tube.
In the gas test, normal filament, grid, and plate
groups. Be sure to replace each tube with an
identical replacement.
Maintenance
voltages are applied to the tube to cause a
definite value of plate current to flow, which
It may become necessary to replace fuses,
pilot lamps, rectifier tubes, or the neon short
indicator lamp, in the tester from time to time.
However, the proper use of the tube chart and
take place across the series resistor. This
to tube tester components. The rectifier tubes
in the tester should operate for a much longer
time than the same type of tube used in continuous service. Failure of the type 83 rectifier
shows on the meter. Pressing the gas test button
inserts a resistance in series with the grid circuit. If grid current is flowing because of the
presence of gas in the tube, a voltage drop will
voltage drop will reduce the grid bias, and the
plate current will rise. The rise will be shown
by an increase in meter reading. A slight increase in meter reading (no more than one scale
division) is permissible.
Testing Practices and Precautions
Be sure the tester is connected to a 105- to
125-volt a-c power source, not a d-c power
instruction book will prevent accidental damage
tube can be detected without opening the case of the
test set. This tube supplies plate voltage, and its
failure is indicated if the pointer of the meter
moves sharply off scale to the right when the red
pushbutton P3 is pressed (with no tube in the test
sockets, but the controls set for tube test).
The type 5Y3 rectifier tube furnishes d-c
50 to 1600 hertz.
Do not insert a tube in any test socket without
screen and bias voltages for the tube under test.
The instruction book will show how these voltages can be checked without removing the panel
from the case.
having top grid connections, top plate connections,
MEGGERS
supply line. The frequency of the source can be
first adjusting the controls properly. For tubes
or both, use the test leads supplied with the
tester. Dangerous voltages are present at the
top cap connections for certain tubes when test
pushbuttons are depressed. Be sure to remove
your hands from the test leads before pressing
the pushbuttons. This lead is kept in the case
of the test set.
Check all tubes for shorted elements first.
If a tube is shorted, do not make any other tests.
When testing rectifier tubes, do not depress the
red pushbutton P3; it is used in testing the
mutual conductance of amplifier tubes only.
Turn the power switch off immediately if
the fuse lamp flashes brightly. This lamp is an
overload indicator that will burn out, of course,
under prolonged or excessive overload.
Turn the shorts-micromhos switch to position
No. 5 immediately if the bias fuse lamp glows.
This lamp shows an accidental overload due to
a shorted tube. An excessive or prolonged overload will burn out the lamp.
Furthermore, it is NOT advisable to replace a
large number of tubes especially in high frequency circuits without checking their effect
on the circuit, one tube at a time. In any complicated circuit it is bad practice to arbitrarily
replace a large number of tubes. It is better to
replace them either tube by tube or in small
Meggers (megohmmeters) are used primarily to test insulation resistance. A megger employing a 500-volt d-c generator is described in
Basic Electricity, NavPers 10086 (Rev.). Another
type employing electronic circuitry is the CV60089.
MEGOHMMETER, TYPE CV-60089
Electron tube megohmmeter, Navy type CV60089 (fig. 5-12) is recommended for testing IC
circuits and components that must be tested at
a lower potential than 500 volts. Supplied with
the tester are three test leads, and a leather
carrying, strap. The tester, test leads, and
carrying strap are enclosed in a heavy oak
case.
The rheostat marked ZERO ADJUSTER con-
trols the plate and grid potentials of the ampli-
fier tube. This rheostat is used to adjust the
pointer to the zero or top mark division with
the GROUND and LINE terminals short-cir-
cuited. The right-hand button marked PRESS
TO READ is depressed whenever a reading is
desired. This closes the filament circuit to the
amplifier tube. There is no drain on the internal
batteries unless this button is depressed.
Chapter 5 TEST EQUIPMENT
When circuits or components under test con-
tain a large electrical capacity, the PRESS
SOO
TO READ button must be depressed for a sufficient time to allow the capacitor (fig. 5-13) to
charge before a steady reading is obtained. The
test voltage applied by the megohmmeter to the
unknown resistance is approximately .50 volts
when measuring resistances of approximately
10 megohms. The voltage is slightly greater than
this when measuring higher resistances.
10
IWO _..101.+111
Maintenance
MEats
After considerable use, the test leads may
become worn or frayed, usually where they enter
the hard rubber sleeves of the forked terminal.
When this occurs, the sleeve should be unscrewed and the lead cut off beyond the worn
spot and resoldered to the terminal.
Batteries for supplying voltage for the op-
eration of the CV-60089 megohmmeter are contained in the bottom of the bakelite panel. These
batteries are subject to deterioration either
from use or from age. When the meter pointer
cannot be brought to full scale with the test prods
shorted and the ZERO ADJUSTER rheostat at
maximum right-hand position, the batteries should
be replaced.
1.55
Figure 5-12. Megohmrneter, Navy Type CV60089.
The tube does not normally need replacing
unless mechanically damaged. Never replace
the tube unless all other component parts are
in good working order.
For normal operation, the LINE and GROUND
terminals are used. The LINE binding post is
insulated with polystyrene fittings and is guardringed against leakage current. The guard ring
on this binding post connects to the center post
marked SHIELD. Where surface leakage in-
fluences readings, such as in cable testing, a
guard ring or a leakage shield should be applied
to the surface of the insulation and connected
to the SHIELD terminal.
To operate, connect one test lead to the
ground terminal and one test lead to the line
terminal. Short-circuit the clipped ends of the
leads slid depress the PRESS TO READ button.
The pointer should deflect to the ZERO posi-
tion. if adjustment is necessary, remove the
ZERO ADJUSTER cap and rotate the adjuster
screw bringing the pointer to the ZERO position. Replace the zero adjuster cap nut and
connect the leads across the unknown resistance. Depress the PRESS TO READ button and
note the resistance reading.
125
If during an actin.' resistance testing operation,. with the PRESS TO .-RAD button depressed,
the instrument pointer flut,tuates due to an
intermittent contact, remove the panel and clean
the switch contacts with a piece of crocus cloth.
TACHOMETERS
A tachometer is an instrument which shows
the rate at which a shaft is turning. Tachometer
indicate in revolutions per minute (rpm) the
turning rate of motors, generators, and other
rotating machines. Though tachometers are
installed on Navy machinery, such as ship's
service generators and main engines, an IC
Electrician must often determine the speed of
a rotating machine that is not equipped with a
tachometer. In this case, he uses a portable
tachometer.
Portable hand tachometers measure speed by
direct contact with the shaft of the measured unit.
Each nand tachometer (fig. 5-14) comes with an
assortment of hard rubber tips, one end of which
IC ELECTRICIAN 3
2
RI"
"--"--410tfAM
500 kin
Figure 5-13. Megohmmeter wiring diagram.
is inserted in the instrument the other applied
shaft speed as long as it is in contact with the
to the rotating shaft.
machine shaft under test.
Portable tachometers are for use only during
testing and should not be used continuously. The
tachometer shaft must be aligned to the center
of the shaft of the unit under test; and offcenter
position will yield an incorrect reading. Additionally you should ensure that the design limit
of the tachometer is not exceeded.
The common types of tachometers are the
centrifugal and chronometric.
In
140.143
the centrifugal tyre, (fig. 5-14B) cen-
trifugal force acts upon weights or flyballs which
are connected by links to upper and lower
collars. The upper collar is affixed t-, a drive
shaft while the lower is free to move up and
down the shaft. A spring, which fits over the
shaft, connects the upper and lower collars.
As the drive shaft begins to rotate, the flyballs (or weights) rotate with it.
Centrifugal force tends to pull the flyballs
away from the center, Ur:, the lower collar
rises and compresses the spring. The lower
collar is attached to a pointer and Its upward
motion, restricted by the spring tension, results
in an increase in the indication on the dial face.
The unit when properly used indicates correct
The centrifugal tachometer may be either
portable (single and multiple range) or per-
manently mounted. The portable multi-range
tachometer has three ranges: low (50 to 500
rpm), medium (500 to 5,000 rpm), and high
(5,000 to 50,000 rpm).
Normally, permanently mounted centrifugal
tachometers operate off the governor or speed
limiting assembly. The tachometer continuously
records the actual rotational speed of the machinery shaft.
The shaft, portable/CHRONOMETRIC tachometer, shown in figure 5-15A is a comination watch aril revolution counter. It measures
the average number of revolutions per minute of
a motor shaft, pump shaft, etc. The mechanism of
thic ..chometer is such that its outer drive shaft
runs free when applied to a rotating shaft, until
a starting button is depressed to start the timing
element. Note the starting button beneath the
index finger in figure 5-15B. The chronometric;
tachometer retains readings on its dial after its
drive shaft has been disengaged from a rotating
shaft, until the pointers are returned to zero by
the reset button (u3ually the starting button).
The range of a chronometric tachometer is
126
126
Chapter 5 TEST EQUIPMENT
FIXED
'DOLLAR
alia"
SPRING
POINT R
110
FLY WEIGHTS
-1 -I
,41'
MOVABLE
COLLAR
PIVOT
DRIVE SHAFT -'-
A
B
Figure 5-14. Centrifugal tachometer.
usually from 0 to 10,000 rpm, and from 0 to
a simple but accurate means for measuring
speed and rate of vibration.
3,000 feet per minute (fpm).
Each portable centrifugal or chronometric
tachometer is supplied with a small rubber
covered wheel and a number of hard rubber
tips. The appropriate tip or wheel is fitted on
the end of the tachometer drive shaft, and held
against the shaft to be measured. Portable
tachometers of the centrifugal or chronometric
type are used for intermittent readings only,
and are not used for continuous operations.
The RESONANT REED tachometer, illustrated in figure 5-15B is particularly useful
for measuring high rotational speeds such as
A resonant reed tachometer consists of a
set of consecutively tuned steel reeds mounted
in a case with a scale to indicate rpm of the
shaft and vibrations per minute (vpm) of the
reeds. This tachometer has not pointer only a
set of accurately tuned reeds and it operates
without direct contact with a moving part under
test. It has no gears or couplings, and it requires no oiling and practically no maintenance.
STROBOSCOPIC TACHOMETER
those that occur in urbines and generators.
The stroboscope is an instrument that per-
This type of tachometer is particularly suitable
where it is practically impossible to reach the
moving ends of the machinery shafts. This instrument gives continuous readings and is capable
61.17X: 2.66X
mits rotating or reciprocating objects to be
viewed intermittently and produces the optical
effect of slowing down or stopping motion. For
example, electric fan blades revolving at 1800
of making very rapid, instantaneous ad-
rpm will apparently be stationary if viewed
justments to rotational speed.
Resonance is the quality of an elastic body
which causes it to vibrate vigorously when
subjected to small, rhythmic impu. es at a rate
equal to its natural frequency, or nearly so. In
a resonant reed tachometer, resonance provides
under a light that flashes uniformly 1800 times
per minute. At 1799 flashes per minute, the
blades will appear to rotate forward at 1 rpm
and, at 1801 flashes per minute, they will appear
to rotate backward at 1 rpm.
127
137
IC ELECTRICIAN 3 & 2
...
B
-
* :`,4,-
2.66X:61.16X
Figure 5-15. Additional tachometers. (A) portable chronometric; (B) mounted resonant reed.
Because the human eye retains images for
The normal speed range is from 110 to 25,000
a fraction of a second, no flicker is seen ex- rpm. At speeds below 600 rpm flicker becomes
cept at very low speeds. The apparent slow pronounced because the human eye cannot retain
motion is an exact replica of the original higher successive images long enough to create the
speed motion, so that the action of a high-speed illusion of continuous motion. The flicker and the
machine can be analyzed under normal condi- low average level of illumination set 600 rpm as
tions.
the lower limit of speeds used for slow-motion
studies. If slow speeds are to be checked, it is
When the flashing rate of the light is adjust- necessary to use an external flash with higher
able, the control can be calibrated in flashes intensity than the built-in flash in order to raise
(or revolutions) per minute. The stationary the average level of illumination.
image seen when the flashing rate of the lamp
and the rotational rate of a shaft are equal per- Maintenance
mits very precise speed measurements to be
The life of the strobotron tube is approximade.
mately 250 hours if used at flashing speeds of
The Strobotac is an electronic flash device, less than 5000 rpm or 100 hours if used at
in which the flash duration is very short (on the higher speeds.
order of a few millionths of a second), which
If the Strobotac is operated continuously at
allows very rapid motion to be arrested.
the higher speeds, the strobotron cathode emisFigure 5-16 is a photograph of the Strobotac. sion may eventually be reduced to the point where
The box contains a swivel mount with a the tube is inoperative. When this happens, the
strobotron lamp in a parabolic reflector, an tube usually glows with a dull red color, but will
electronic pulse generator to control the flashing not flash. Flickering is another symptom of low
rate, and a power supply that operates from the cathode emission.
It is sometimes possible to restore operaa-c power line. The flashing rate is controlled
by the large knob (see photo), and the cor- tion, by running the tube at low speeds for sevresponding speed in rpm is indicated on an eral hours. Eventually, however, the tube beilluminated dial viewed through windows in the comes completely inoperative and must be
replaced.
knob.
Chapter 5 TEST EQUIPMENT
the display, the instrument provides calibrated
vertical sensitivities, triggered internal sweeps,
calibrated sweep times, calibrated expanded
sweeps, beam finder, and calibrator.
Oscilloscope AN/USM-105A consists of a
major unit and two plug-in units. The major unit,
Oscilloscope OS-82A/USM-105, contains the power supplies, horizontal amplifier, sweep
generator, main vertical amplifier, cathode-ray
tube (CRT), calibrator, and the controls associated with these circuits. Oscilloscope Subassembly, Vertical Channel, Dual
amplifier MX-2930A/USM-105 is
Trace Pre-
a plug-in
preamplifier to the main vertical amplifier. The
dual trace preamplifier contains two separate
voltage channels each with its own controls. An
electronic switch, controlled from the front
panel, connects one channel or the other to the
main vertical amplifier and thereby determines
the vertical presentation on the CRT. To produce
a dual trace, the electronic switch alternates
channels, either on alternate sweeps, or contin-
uously at a one-megahertz rate. Oscilloscope
Subassembly, Horizontal Channel, Auxiliary
Plug-in Unit MX-3078/USM-105A permits
single-sweep operation and external intensity
modulation.
oN\
The test prods are used to decrease circuit
,s(.44
loading. The one megohm input impedance of the
vertical and horizontal circuits plug the shunt
capacity of a cable connecting the oscilloscope to
the test circuit may degrade the operation of the
circuit under test. The test prod increases input
impedance to 10 megohms shunted by 10
picofarads. The test prod also introduces a 10:1
voltage division which must be considered when
translating waveform deflection on the CRT into
volts.
The test prod has an adjustable compensating
capacitance so the prod can be matched exactly
to a particular input of the oscilloscope. The procedure for matching a test prod to the Channel
A input of the dual-trace preamplifier is given
below. The procedure is similar for matching a
test prod to any other input.
140.31(140B)
Figure 5-16. Strobotac (Type 1531-AB)
1. Connect test prod cable to Channel A INPUT, (fig. 5-18).
OSCILLOSCOPE AN/USM-105A
Oscilloscope AN/USM-105A (fig. 5-17) is a
general purpose, high-speed laboratory type oscilloscope designed for shipboard use. It
produces a graphical display of simple and complex voltage variations which contain frequency
components ranging from zero to 14 megahertz.
To simplify operation and the interpretation of
2. Select CHANNEL A and set Channel A
SENSITIVITY switch to .02 VOLTS/CM.
3. Set SWEEP TIME switch to .5 MILLISECONDS/CM, HORIZONTAL DISPLAY switch
to Xl, TRIGGER SOURCE switch to INT, and
SWEEP MODE control to PRESET.
129
IC ELECTRICIAN 3 & 2
Figure 5-17. Oscilloscope AN/USM-105A.
4. Set CALIBRATOR switch to 1 and touch
test prod to VOLTS terminal of calibrator output. A square wave five centimeters high should
1.86.5
Rotate INTENSITY control fully counterclock-
wise before turning instrument on to prevent
accidental burning of the CRT face during warm-
appear on the CRT.
up.
5. Loosen knurled locknut just behind rear
Use the test prods and other accessories
flange on test prod body.
6. Hold test prod behind locknut and rotate
rear flange to give flat-topped square wave.
7. Tighten knurled locknut without disturbing adjustment. This completes the adjustment.
furnished with the oscilloscope as necessary.
Single Trace Operation-Internal Sweep
1. Connect vertical signal to INPUT of Channel A.
Operation
2. Set
CHANNEL A.
The following procedures give step-by-step
operating instructions for Oscilloscope AN/
USM-105A. The first procedure gives complete
instructions for single-channel operation. The
remaining procedures give instructions peculiar
only to the modes of operation with which they
are concerned.
Vertical Presentation switch to
3. Set SENSITIVITY switch for Channel A as
desired. (Set VERNIER to CALIBRATED for
calibrated sensitivity.)
4. Set input coupling for a-c or d-c coupling
as desired.
5. Set POLARITY switch to + UP or - UP
as desired.
Before making any test or measurements,
allow the instrument about 5-minutes warmup.
130
140
IOU.
IISIOLC
CONNECT VIM MOO
PORT
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IRMTO LOOM Of TIISSIX /' IT Os TROMPS
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MAO IOWA On SIOLZIOUP OPOIATUR
CALIOSIATTO STOPS
Allit/ST nalstOsTAL ICIRMATT WIMP
ULM OCROOKTL IINSITIWO CO OCIIIM Or
OIIpML IOW IIMPOPICATION
WINTS WIN NITTILOOST IS OM
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CALOUTOPI OITPUT L OLUTOLTS
IMITPunOrr 610000
CALORATOR OUTPUT NI VOLTS
!LW Cuseffels cuOvor Arun=
MIS TO LOCATE Of 401E01 man
mem aLonsonos of ~OAT SCALE
ORP/ST HIMONT Of MAO Os OR
MOST POCUS Of MCC OR CRT
Figure 5 -18.
Front panel controls and connectors.
111111111111
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111111111111111111111111
IIMMIll11111111111
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IC ELECTRICIAN 3 & 2
6. Set TRIGGER SOURCE as desired. If external trigger is used, connect it to trigger
source INPUT.
7. Set INTENSITY MODULATION and
SWEEP OCCURRENCE switches to NORMAL.
8. Set HORIZONTAL DISPLAY switch to
INTERNAL SWEEP Xl.
9. Set SWEEP MODE to PRESET.
10. Set TRIGGER SLOPE switch for trigger-
ing on positive or negative slope of trigger
signal as desired.
11. Set TRIGGER LEVEL control to 0.
12. Set SWEEP TIME switch for desired
sweep time (set VERNIER control to CAL for
calibrated sweep time).
13. Set INTENSITY control as desired.
14. Adjust
VERTICAL
POSITION
and
HORIZONTAL POSITION controls as desired.
15. If trace does not appear on screen, press
BEAM FINDER switch and readjust position controls to center trace.
16. Adjust TRIGGER LEVEL control to start
trace at desired level of trigger signal. It may be
necessary to switch SWEEP MODE control from
PRESET and select a better setting for the
particular trigger signal being used.
NOTE: To use Channel B for single trace
operation follow this procedure, substituting Channel B controls and terminals.
Dual Trace Operation
1. Connect one signal to INPUT connector of
Channel A and set Channel A controls as desired.
2. Connect second signal to INPUT of
Channel B and set Channel B controls as desired.
3. Set Vertical Presentation switch to
CHOPPED for display of-both signals on same
sweep, to ALTERNATE for display of signals on
alternate sweeps.
NOTE: For best results, use external triggering.
Differential Operation
1. Connect one signal to INPUT of Channel A.
2. Set SENSITIVITY switch of Channel A as
desired.
3. Connect
Channel B.
second
signal to
INPUT of
4. For best results, set SENSITIVITY of
Channel B to same setting as SENSITIVITY of
Channel A.
132
142
5. Set
POLARITY
to + UP.
switch of Channel A
6. Set vertical Presentation switch to A-B.
7. If vertical adjustment is necessary, use
VERTICAL POSITION control of Channel A.
Internal Sweep Magnification
1. Set SWEEP TIME switch as desired. (Set
VERNIER control to CAL for calibrated sweep
time.)
2. Set HORIZONTAL DISPLAY switch to
INTERNAL SWEEP Xl (unmagnified sweep posi-
tion).
3. Adjust HORIZONTAL POSITION control
to place portion of trace to be magnified under
vertical center line of graticule (lined scale on
the screen of the CRT).
4. Set HORIZONTAL DISPLAY to desired
magnification.
5. Readjust INTENSITY as necessary.
6. If selected sweep time with magnifica-
tion is less than minimum calibrated sweep
time (0.02 microseconds/cm), SWEEP UNCAL
indicator will light indicating that sweep time
is no longer calibrated.
External Horizontal Input
1. Connect horizontal signal to horizontal
INPUT connector.
2. Set horizontal input coupling switch to a-c
or d-c as desired.
3. Set HORIZONTAL DISPLAY to desired external sensitivity.
4. Adjust HORIZONTAL POSITION control
as desired.
Intensity Modulation
1. Set INTENSITY MODULATION switch to
EXTERNAL.
2. Connect modulation signal to external intensity modulation INPUT connector. Positive
signal of 20 volts peak will blank trace from
normal intensity; negative signal will brighten
trace.
Single Sweep Operation
1. Set
NORMAL.
SWEEP OCCURRENCE switch to
2, Set SWEEP TIME switch as desired. (Set
VERNIER control to CAL for calibrated sweep
time.)
Chapter 5TEST EQUIPMENT
4. For single ended input, ground common
signal lead as shown by dashed ground lead in
figure 5-17. For balanced input, leave both sig-
EXTERNAL
INPUT SIGNAL
1
nal leads ungrounded.
4
4- 1000
100
5. Turn oscilloscope on. Use external signal
to trigger sweep.
(000
Maintenance
100
TO JUNCTION
OUTPUT
IM
AMPLIFIERS
TO JUNCTION
OUTPUT
AMPLIFIERS
( NOT SHOWN)
( NOT SHOWN)
11111
111'
03
CRT SHIELO
Preventive maintenance for oscilloscopes
consists of periodic cleaning and inspections.
No lubrication is required. Use dry compressed
air, or a dry cloth arid a soft brush for cleaning.
It may be necessary to use a dry-cleaning
solvent to clean the ceramic insulators, but care
should be taken not to remove the special paint.
Do not use solvent on the chassis as it may
124.224
Figure 5-19. Direct connection to deflection
plates of cathode-ray tube.
3. Set TRIGGER SOURCE switch according to
trigger signal used.
4. Set SWEEP MODE as desired.
5. Set TRIGGER SLOPE as desired.
6. Adjust TRIGGER LEVEL as desired.
7. Set SWEEP OCCURRENCE to SINGLE.
8. To arm sweep circuit, switch SWEEP
MODE just out of PRESET and back to PRESET,
or apply pulse 1 to 4 microseconds long and +15
to +25 volts peak to ARMING INPUT connector.
9. SWEEP ARMED indicator will light. After
sweep, indicator will extinguish, and sweep circuit will remain disabled until rearmed.
Connecting Signal Directly
to CRT Deflection Plates
soften the tropicalizing paint. Compressed air
or a brush is best for cleaningthe electron tubes.
Keep all tubes that operate at a high temperature
clean, as a layer of dust will interfere with heat
radiation and raise the operating temperature.
Remove all tubes from their sockets periodically and inspect the pins and sockets. Remove
any corrosion from the pins with crocus cloth.
Check the plate connections of the high-voltage
rectifier tubes to ensure that they are clean and
tight. Remove all fuses and check for looseness
and corrosion.
Inspect the AN/USM-105A air filter frequent-
ly and clean if necessary. Check the fan motor
brushes at least monthly.
SIGNAL GENERATORS
Signal generators are test equipments that
generate a-c signals. They are used for signal
tracing, aligning tuned circuits, making sensitivity measurements, and frequency measurements. Audio frequency signal generators (audio
oscillators) have a frequency range of from 20
CAUTION
to 20,000 hertz (up to 200 kHz to 10,000 mHz. As
an IC Electrician, you will be concerned with
audio oscillators.
Do not contact CRT deflection plate terminals
with instrument turned on. These terminals
AUDIO OSCILLATOR TS-382D/U
are normally operated about +200 volts.
1. Turn oscilloscope off and remove access
plate on top of cabinet.
2. Remove leads from vertical deflection
plate terminals D3 and D4 (fig. 5-19).
3. Connect components as shown in figure
5-15. Use capacitors with good high-frequency
response. Front-panel VERTICAL POSITION control remains effective.
A representative audio oscillator, the TS382D/U (fig. 5-20) generates a-c voltages ranging
from 20 to 200,000 hertz at amplitudes which may
be varied continuously from zero to 10 volts. The
set contains thermostatically controlled heaters
which reduce the time required for the instrument to reach a stable operation temperature.
The heaters also permit satisfactory operation
in arctic climates. The audio oscillator operates
133
IC ELECTRICIAN 3 & 2
RANGE
FREQUENCY
HAIRLINE
OUTPUT
SWITCH
METER
OUTPUT
INDICATOR
LEVEL
LEVEL
METER
CONTROL
ft"
POWER
PLUG
HEATER
SWITCH
MAIN
TUNING
ATTENuATOR
SWITCH
DIAL
Figure 5-20. Audio oscillator TS-382D/U.
from a 115-volt a-c source, at a line frequency of
5 hertz to 1600 hertz.
The circuit (fig. 5-21) consists of an oscillator section which generates the audio voltage,
METER
VI03- V104
OUTPUT
fier which is caused to oscillate by the use of
CATHODE FREQUENCY
FOLLOWER
METER
OUTPUT AMPLIFIER. The output section
consists of a two-stage resistance coupled am-
OUTPUT LEVEL
CONTROL ft
positive feedback.
AT TEN uATOR
II5V AC.
POWER
POWER
SUPPLY
INPUT
V I05
Figure 5-21.
ELECTRONIC VOLTAGE
REGULATOR
V106, v IOT V 109
The oscillator section (fig.
5-22), includes tubes V101 to V102 and consists
basically of a two-stage resistance coupled ampli-
uutPuT LEVEL
V101-002
20.338.1
isolates it from the remainder of the circuit.
OSCILLATOR.
AMPUFIER
PLUG
an amplifier which isolates the oscillator from
the external circuit and amplifies the audio voltage, an output level metering circuit with an attenuator, a power supply, an electronic voltage
regulating system, and a cathode follower which
Major Sections
OSCILLATOR
OUTPUT
V 10B
20.338.2
Block diagram of TS-382D/U.
plifier employing tubes V103 and V104. Negative
feedback is used to minimize distortion and
provide uniform output. The output is constant
within two db, over the frequency range covered
by the instrument.
134
144
i
0
la
V
EII3
V
i
0 52
0
01
RISO
S
C4- 1000
r
I
G
;
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,
DUMMY LOAO DA-3SAJ
1000 OHMS)
CAGLE
2A
F102
rio1-211
FRONT VIEW
LSHOWN FOR 20-2001CC
10
000
1-
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0
SI
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a
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V
4...
7
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C105
TO T11ANS
IT6-11
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006
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RI59
4
ICINIIF50.
1:1430
22K 1/109
R145-5114K
V1011
4- L AAP, INCANDESCENT,6.3V 0.15A,E110,E11/.
2- LAAIP, INCANDESCENT, 120 V, 3 W,R115
10-FUSE, CARTRIOGE, 2A, F101,F102.
1-01.11111Y LOAD 0A-35/U.
I-ADAPTER CONNECTOR US-514/U
I- TRANSIT CASE CY-0011/U
AND 011E SET OF OPERATING SPARE PARTS CONSISTAG OF:
1-CORD C11-409A/U (5FTr0 IN )
1-CORD CX- 237A /U (5FTrO IN 1
en
109.9
122.1:
h1530
1234 I,P,
R15211
a
a
a
I,
_
,...../
-, J104
-
.1
+ 290 v
r-
S5C-11
REAR V!!
Z
SHOWN IN 10IH POSITION
L- - - - - .
THE FOLLOWPOG ARE PART OF AND ARE INCLUDED Si AUDIO OSILLATON TS-302 /U.
6
+1115V
Figure 5-22.Audio oscillator TS-382D/U, schematic diagram.
11
0
V
V101
13 6SJ 7
5Y3 -6T
TO 41A-0
U0-514/U
7
0
10
100 NOW
C104
cmcctoot
ADAPTER CONNECTOR
GALE 1-
....,
T101
uaJI03
0
ia
as
a
0112
140.32
INFO
1(
col
INFO
IC ELECTRICIAN 3 & 2
OUTPUT SYSTEM. The output system consists of an output level meter, a gaincontrol, and
a six-section ladder type attenuator, consisting
at the output connector on the lower right-hand
side of the front pane, (fig. 5-20). The output
cable may be used either with the adapter connector (UG-514/U), or the dummy load (DA-
of a series of resistors. The output meter
operates from a full-wave type rectifier circuit
35/U) (not shown) marked 1,000 OHM LOAD, for
high impedances. Use of the dummy load with high
impedance external loads maintains the accuracy
of the metering circuit calibration.
The controls of Audio Oscillator TS-382D/U
and their functions are as follows (fig. 5-20):
in which germanium crystals are used as rectifying elements. The gain control is inserted in the
circuit immediately preceding the output meter
in order to set the voltage level at the input to
the ladder attenuator. The ladder attenuator is
calibrated on the basis of the instrument working
into its rated load of 1,000 ohms.
Control
POWER SUPPLY. The power supply is designed to deliver filament voltage to all the tubes
and to supply well-filtered d-c voltage to the
plates and screen grids. The power transformer
supplies all filament voltages in addition to high
The fil-
tive type voltage regulator employing tubes V106,
V107, and V109. The regulator is designed to
supply a constant voltage of 230 volts to the plate
circuit of the various tubes.
FREQUENCY METER. -A vibrating reed type
meter has been factory adjusted to an accuracy
of three-tenths of one percent. This meter, is
stand-by
Selects frequency range
Selects frequency within
each range
OUTPUT LEVEL
(METER)
Indicates voltage input to
attenuator
OUTPUT LEVEL
Adjusts voltage input to
attenuator
Reduces output voltage
in sub-multiples of ten.
STARTING PROCEDURE. -Plug the female
end of the power cable into the power socket in
the lower left-hand corner of the front panel.
isolated from the second oscillator tube V102 by
a cathode follower stage V108 to prevent shifts
in frequency when the frequency meter is in
operation.
With the OSC switch and HEATER switch in OFF
positions, plug the male end of the power cable
into a 115 volt a-c source. Check the line voltage with a voltmeter to be sure that it is correct.
Throw the OSC switch to ON position and check
Five strip heaters
are used to decrease the time required for the
unit to reach stable operation and to permit satisfactory operation incolder climates. These
strip heaters are controlled by a built-in thermostat, calibrated to maintain the temperature
at 20° C. An ON-OFF switch and an indicator
Audio Oscillator TS-382D/U should be allowed
for
Main Tuning Dial
(Hairline Indicator)
ATTENUATOR
output
frequency of the oscillator at 60 and 400 Hz. The
a warmup period of at least 15 minutes, in order
to reach a stable operating temperature. Audio
frequency output is taken from the oscillator
Switch
(CONTROL)
meter permits accurate check of the
Operation
HEATER: On, Off.
X1, X10, X100, X1000
tered direct current is regulated by a degenera-
light are included in the heater circuit.
Oscillator Power Switch
RANGE
moved.
STAND-BY HEATER.
OSC: On, Off
heater
voltage to the full-wave :'ectifier V105, which
converts the a-c voltage to pul3ating direct current. The rectified wave passes through a single
section pi filter where the a-c component is reVOLTAGE REGULATING SYSTEM.
Function
to see that the pilot lamp directly above the
switch lights. Allow the instrument to warm up
for at InF...ast 15 minutes. At low ambient temperatures, it is advisable to turn the HEATER switch
to the ON position.
SELECTING FREQUENCY. Any frequency
from 20 to 200,000 Hz may be selected by setting the main tuning dial and the range switch so
that the two readings, when multiplied together,
equal the desired frequency. For example, to
select an output frequency of 52,000 hz, set the
main tuning dial to 52 and the range switch to
X1000. Do not force the main tuning dial beyond
136
146
Chapter 5 TEST EQUIPMENT
output voltage level. For example, to obtain an
output voltage of 0.04 volts, set the meter by
means of the OUTPUT LEVEL control to read
4 volts, and set the ATTENUATOR switch to the
.01 position. The output voltage will then be the
meter reading multiplied by the attenuator setting, or 0.04 volts.
STOPPING PROCEDURE. The oscillator is
turned off by throwing OSC switch to OFF position. If the heaters have been used, they should
also be turned OFF. Remove the power plug
first from the supply line and then from the front
panel, remove the output cable, and replace the
unit in its transit case.
Maintenance
The following periodic inspections are recommended for Audio Oscillator TS-382D/U at
the intervals indicated:
Weekly:
Inspect front panel of Audio
Oscillator, check fuseholders,
indicator lamp assemblies,
power plug, output plug, cables,
dummy load, and adapter connector.
Monthly:
Semiannuall-:
Check tight:less of knobs.
Inspect front panel, tubes, and
tube socket, switches, variable
capacitors, thermostat contacts, terminal boards, and
chassis.
To check that the Audio Oscillator is operating properly, set the main tuning dial to 60,
140.144
Figure 5-23. Model 200CD wide range oscillator.
its normal travel as it may destroy the calibration of the instrument.
SELECTING OUTPUT VOLTAGE. Voltages
from zero to 10 volts may be selected by using
the OUTPUT LEVEL control in conjunction with
the attenuator switch. The attenuator is calibrated in seven decade steps so that with the
output meter set to 10 volts, output voltages of
10 volts to 10 microvolts can be obtained by
simply switching the attenuator. For intermediate values of output voltage, the OUTPUT
LEVEL control is varied so that the output
meter reads the desired voltage. The attenuator
switch is then set so that its value, multiplied
by the output meter reading, gives Cie desired
and the range switch to X1 (the lowest frequency
range). This sets the frequency of the oscillator
at 60 Hz. Turn the tuning dial back and forth
slightly until the reed in the Frequency Meter
marked 60 hertz vibrates with maximum
amplitude. This point should be correct within
one division.
Similarly, the output at 400 Hz may be check-
ed by setting the main tuning dial to 40 and the
range switch to X10. The main dial settingshould
be correct within 1 1/2 divisions when the 400
hertz reed vibrates with maximum amplitude.
Turn FREQ. METER switch to OFF position
after checking the frequency calibration.
Use a clean, dry lint-free cloth or adry brush
for cleaning. AU control knobs should be tightened using an Allen wrench. Do not loosen the
three setscrews on the main tuning dial plate behind the knob on the main dial as the frequency
calibration of the instrument will be destroyed.
137
147
IC ELECTRICIAN 3 & 2
AIM
Figure 5-24. Digital voltmeter, model 481.
Snould the contacts of the RANGE switch or
the ATTENUATOR switch become covered with
a heavy accumulation of dust, dry compressed
air of not more than five pounds pressure may
be used, followed by careful cleaning w:th a small
can,cdis hair brush. Care must be exercised when
using the brush, not to damage any of the resistors
mounted on these switches.
No lubrication of any kind is required for
Audio Oscillator TS-382D/U. The main tuning
capacitor and the associated panel bearing have
been lubricated at the factory and do not require
further lubrication.
151.104
Do not tamper with any of the alignment adjustments as these will affect the frequency calibration of the instrument. Removal of any tube
other than those in the power section involves
recalibration of the oscillator. Tubes V105, V106,
V107, and V109 may be replaced without re-
calibrating the instrument.
Audio Oscillator (200CD)
At times the IC Electrician may have to
substitute another audio oscillator for the TS382D/U. When it becomes necessary to do so,
VARIABLE
VOLTAGE
DIVIDER
VARIABLE
VOLTAGE
DIVIDER
+ REFERENCE
GAL vANOMET ER
VOLTAGE
REFERENCE
VOLTAGE
UNKNOWN
UNKNOWN
INPUT
VOLTAGE
INPUT
VOLTAGE
STD
CELL
LALIORATE0 DIAL
Figure 5-25.
151.105
Basic operation principles of a
digital voltmeter.
138
148
REFERENCE
SUPPLY
151.106
Figure 5-26. Potentiometer with calibration
rheostat.
2
GROUND
SIGNAL
100
DEC
MID
RANGE
SW
Figure 5-27.
RANGE
ATTENUGTOR
TRIMMERS
SIGNAL
INPUT
\
%
\
"
OvouGTTPXGTE
RANGE
TYPE CHOPPER
*MARE !MIRE SPEAK
\
\
CALM
1.......1
PULSES
'UP.
200 4 EACH
0 4 EACH
DECADE 3
4344V
0
4.1141 V
1
1
1
i 40240v
I
READOUT
ASSEM SLY
.--A.------.
SWITCHING LOGIC
20,1
21 V
0
0
.22V
I0
1
14 2GIV
0
.2V
.23V
0
0-
2G3V
°
0-
,424V
i 00
I
I .2SV
I
Io
I
100
ETV
4.11V
0
I 2112V
1
1
1
°
1 .2114V
1.213V
I
I
1
I
1
1
2GIV
211V
l
1
OV
1 .2
I
3V
V
M/
.81/
TV
w
SV
REFERENCE
VOLTAGE
10-13V
,,,......"....--.,
/....-..--.".--/....."___....). 30V
0
3.0V
1000a EACH
11 RESISTORS
12v
1 3V
I
Sv
Tv
!V
10V
Maw
oo OnosTCIll
.
151.263
ACIJ
CALIG
NI.
0,
cs,....
POLARSW ITY
KM 4 EACH
Simplified circuit diagram, multirange digital voltmeter, for measuring absolute d-c voltages.
R
DEC
\\
CHOPPER *
FEEOGACX
VOLTAGE
OCC411* 2
II RESISTORS
DECADE I
ID RESISTORS
IC ELECTRICIAN 3 & 2
he should borrow, from the Electronic Material
Officer (EMO), a Model 200CD Audio Oscillator
(fig. 5-23).
Ri
Unknown voltage = l
If the polarity of the unknown voltage is
reversed, the polarity of the reference voltage
must also be reversed in order to obtain balance. The galvanometer pointer will then travel
in the opposite direction, increasing its displacemeht from zero (center position) as the
magnitudr, of the unknown voltage increases.
To nieasure the absolute value of the unknown voltage, the reference voltage must be
known. Instead of accurately measuring the reference voltage directly, it can be adjusted to
the proper value it an accurately known voltage
is available for use as a calibration reference.
Therefore, a standard cell (fig. 5-26) of known
This oscillator is simple to operate, having
only two switches (off/on and range), and two
controls (frequency and amplitude) located on
the face of the unit. There are also output
terminal provisions for either 600 ohms balanced
or unbalanced conditions. The 200CD oscillator
weighs less, is smaller, and has a wider fre-
quency output (5 Hz to 600 kHz) than the more
advanced TS0382D /U.
DIGITAL VOLTMETER, MODEL 481
When measuring voltage with an instrument
that contains a meter movement, the IC
voltage is connected in place of the unknow voltage.
Electrician may find it impossible to get a precise reading. Present-day meter movements do
not measure as accurately as digital voltmeters,
whose internal circuits select ranges automatically and switch upscale or downscale, as necessary, to give a precise readout. Model 481 (fig.
5-24) Is typical of the digital voltmeters used
aboard ship, although there are other kinds. But
if your digital voltmeter is not a Model 481, its
basic operation will be essentially the same as the
481's.
The model 481 Digital Voltmeter measures
d-c voltages and presents the measured value
directly in numerical form on a self-illuminated
4-digit readout. The digital voltmeter is eFsentially a self-balancing potentiometer. Range
changing is automatic. The polarity sign and
decimal point are also automatically displayed.
Accuracy is ± 0.01 percent over the three ranges
which ar.:3 0 to +9.999. +10.00 to ±99.99, and
+130.0 to +999.9 volts. The digital voltmeter
is designed to operate from 105-to-125 or 210 to -259 volt, 60 Hz power sources. Its primary
power requirements are satisfied by most nominal
115 - or 230-volt, 60 Hz power line input sources.
PRINCIPLES OF OPERATION
Consider the basic potentiometer circuit shown
schematically in figure 5-25. If an unknown
voltage is applied at the input terminals and a
variable divider adjusted until the voltage E
is equal in magnitude to the tinknow, voltage.,
zero current will flow through the galvanometer.
This condition is called balance. Note that in
the balanced condition no current is drawn from
the input (circuit under test). The unknownvoltage
can be computed from the formula:
+ R2 x reference voltage.
The variable voltage divider dial reading (not
shown) is set to this known voltage, and the
voltage across the variable voltage divider is
adjusted by means of rheostat, R f I obtain
balance. The potentiometer is now calibrated,
or standardized, and ready for use as an ab-
solute voltage-measuring device.
Basically, the operation of the digital vmt-
mater is the same as the operation of the balanced
potentiometer. The main difference is that instead of the balance being achieved manually it
is done automatically through the use of an error
detection circuit which controls the operation of
a series of stepping relays or switches.
There are five stepping relays (fig. 5-27). One
automatically selects the proper range (attenuation) and polarity (reference voltage polarity),
depending on the amplitude and polarity of the
input (unknown) voltage. The other four relays
automatically select the proper magnitude of
feedback voltage so as t( achieve a balance
between it and the range output voltage.
The error detection circuit consists of an
electromechanical chopper which, in conjunction
with a phase-sensitive amplifier, is used to
compare the feedback voltage with the range
output voltage and produces an error signal
if the two voltages are different from each
other.
NOM: The amplifier sensitivity and gain
are normally adjusted to produce an error
signal if the difference is greater than 0.001
volt.
The error signal will consist of a series
of pulses on the amplifier's up-pulse output
line if the feedback voltage is less positive than
the range output voltage, or a series of pulses
140
150
4
Chapter 5 TEST EQUF MENT
vs
Y1- -vii
Vii
Vt
K1
TEST
POINTS
VS
Y2
Ki
R23
R13
151.108
Figure 5-28.Digital voltmeter, model 481, top interior view.
on the amplifier's down-pulse output line if
the reverse condition is true.
Because of mechanical limitations, wiper
blade action on the stepping relays is unidirectional; that is, they can rotate in one direction
only. Thus, to select the proper range, polarity,
and magnitude of feedback voltage to achieve a
balance, the error signal on the amplifier's
up-pulse or down-pulse output lines must be
routed through the switching logic. This is done
in such a fashion as to cause the stepping relays
to start at their rest positions, and sequentially
cycle through all possible connections until the
proper combination is selected.
141
Is'
1
IC ELECTRICIAN 3 & 2
Whenever a balance is achieved that is,
whenever feedback voltage and the range output
voltage are qual in polarity and magnitude all
switching action stops. The readout device then
gives an illuminated digital readout of the magnitude and polarity of the unknownvoltage, accurate
to within ± 0.01 percent.
adjustment is proper, the instrument may be ac-
curately standardized as described in the next
paragraph.
While holding the operate-calibrate switch in
the CALIBRATE position, slowly turn the cali-
brate adjust control in the clockwise direction
until the meter reads 1019, then stop. The meter
is now standardized.
NOTE: The decimal point may appear in any
To eliminate unnecessary switching when the
magnitude of the unknown voltage is such as
to cause the X10 or X100 range to be selected,
a lockout device is incorporated into the switching logic. This causes the most sensitive range
to be selected first, and prevents the leftmost
readout from registering a zero.
FRONT PANEL CONTROLS
AND INDICATORS
1
The front panel controls and indicators' for
the Digital Voltmeter Model 481 are shown in
figure 5-24.
In the OFF position, the off standby-on switch
disconnects primary power from the voltmeter.
The STD BY (standby) position permits the in-
strument to remain warmed up while stepping
switches are turned off to prevent needless operation. This position also permits locking the read-
ing (so that the displayed information remains
indefinitely) at any time. The ON position of the
switch fully enables the meter after a 15- to
30-second operation delay, controlled by a
thermal timer (not shown).
The operate-calibrate switch selects either
an operating or calibrating mode of operation
for the digital voltmeter.
The calibrate adjust control (located behind
a metal protective cap on the front panel) is
used to standardize the digital voltmeter as
follows:
1. Set the sensitivity control to its full clockwise position.
2. Ensure that the error amplifier gain of
the instrument is properly set. To do so, hold
the operate-calibrate switch in the CALIBRATE
position and slowly turn the calibrate-adjust
control in the counterclockwise direction, stop-
ping each time the meter changes reading.
The meter reading should change by one digit
each time. If the reading changes -by more' han
one digit, or exhibits instability, adjust the internal gain control. (The gain setting procedure is
described later.) Repeat turning the calibrate
adjust control counterclockwise until ten steps
have been satisfactorily completed. Once the gain
location during the standardization procedure
because the d-c voltage range change circuits
(which determines the position of the decimal
point) become deenergized during this operation.
The sensitivity control varies the gain of the
digital voltmeter. When measuring unstable
voltages, turn the control counterclockwise until
the meter settles at a fixed reading. This reading
will be as accurate as the unstable signal
measurement will anew. Always turn the sensitivity control fully clockwise for proper operation with stable d-c voltages.
GAIN SETTING
For best results, the digital voltmeter should
be operated with the amplifier gain set for advancement in single digit steps. If the amplifier
gain is not high enough, the resolution of the
meter will 136 too low. On the other hand, excessively high amplifier gain setting may cause
instability of the readout display. To set the
amplifier gain, proceed as follows:
1. Remove the cover over the calibrate ad-
just control on the front panel. Hold the operatecalibrate switch in the CALIBRATE position.
2. After the usual readout has become stable,
use a screwdriver to slowly turn the calibrate
adjust control, R13 (fig. 5-28) in a counterclockwise direction. Observe the magnitude of
the decrease in the readout display. If the
value displayed decreases in steps of one digit
ar.-1 does not become unstable, no adjustment
of amplifier gain is necessary. If slowly rotating
the calibration control in a counterclockwise
direction results in a decrease of two or more
digits in the rightmost' window, the amplifier
gain should be increased by slightly turning
the amplifier gain control, R20 (fig. 5-28) in
a clockwise direction. Again, observe the number
of digits by which the readout display decreases
when the calibrate adjust control, 1113, is slowly
turned counterclockwise. Repeat the amplifier
gain adjustment, if necessary, to obtain a readout
display decrease of one digit in the rightmost
windown. If instability develops in the readout
142
152
Chapter 5TEST EQUIPMENT
digit to another. If the error exceeds this amount,
display, turn the amplifier gain control, R20,
counterclockwise until the instability just disappears and the readout display decreases in
there are two possible sources of trouble: (1)
excessive hum pickup and (2) excessive grid
current drawn by the input amplifier tube (not
shown). Check all shield and ground leads.
Replace the input amplifier tube (type 5751).
steps of one digit in the rightmost window as the
calibrate adjust control, R13, is slowly turned
counterclockwise.
NOTE: Do not substitute any other type tube.
HUM CONTROL ADJUSTMENT
Improper adjustment of the hum control will cause considerable error in calibration
accuracy. The hum control is accurately set at
STANDARDIZATION ADJUSTMENT
The following standardization procedure is
necessary to ensure accurate readout (measurements). Before making any adjustments, make
sure that the gain and hum controls are properly
set and that the digital voltmeter is connected
to ground. Calibrate the voltmeter as described
in the calibrate adjust procedure treated earlier.
Connect a bank of nine standard cells, each of
which has an accuracy of at least 0.01 percent,
to the input. The meter reading should be correct to within one digit.
NOTE: Be sure to take into account the in-
the factory and should not be reset until it is
definitely determined to be out of adjustment.
Changing the input tubes can cause the hum con-
trol to become incorrectly adjusted. Be sure
that the input tube has been aged before resetting the hum control. To adjust hum control,
R53, (fig. 5-28) located on the amplifier chassis,
proceed as follows:
1. Connect the chassis to ground (the third
pin on the power cord is connected to the
chassis). Turn on the digital voltmeter and ternal resistance of the standard cells. The
allow a warmup of 15 minutes. Connect an digital voltmeter has an input resistance of 10
oscilloscope between either of the two test megohms, and a 9-volt signal will draw 0.9
microamperes. If the reading is not correct,
adjust potentiometer, R11, is located slight-
points (fig. 5-28) and ground. Calibrate the
oscilloscope in terms of one digit error. To do
this, turn the operate-calibrate switch (fig. 5-24)
to CALIBRATE and slowly turn calibrate
adjust control, R13, (fig. 5-28) counterclockwise. Note the amount of error signal on the
oscilloscope. This error is equivalent to one
digit if the gain is properly set (as described
in the gain setting procedure), and the sensi-
ly above and to the right of the calibrate adjust
control, R13, shown in figure 5-28).
FEEDBACK VOLTAGE
LINEARITY TEST
One of the several factors which may affect
the accuracy of digital voltmeters is the linearity
tivity control is advanced fully clockwise.
of the reference voltage divider (fig. 5-27).
2. With the operate-calibrate switch (fig.
5-24) set to OPERATE, short the input leads to
obtain a reading of +0.000. Set the off-standby-on
switch to STD BY. Remove the stepping switch
cover. Step range-polarity switch, K5 (fig. 5-28)
by hand until the meter reads +00.00. Re
place the stepping switch cover. Adjust num
control, R53, for zero error signal as displayed on the oscilloscope. It is necessary that
This reference voltage divider supplies the feed-
back voltage which is compared to the range
output voltage in order to get a readout. Thus,
any change in its linearity (or accuracy) will
affect the accuracy of the readout. While several
methods have been devised for testing the linearity of reference voltage dividers, the one
described below is found to be most satisfactory.
(It is assumed that the error amplifier gain is
properly adjusted before the test is started.)
To perform this test, use as the standard
the stepping switch cover, bottom plate, and
front panel be in position. The hum control is
now properly set.
3. Check the error signal for all ranges
-000.0, -00.00, -0.000, and
+000.0), each time removing the stepping switch
(+00.00, +0.000,
cover, stepping range-polarity switch, K5, (fig.
5-28) by hand, and replacing the cover. Do not
readjust hum control, R53. The error signal
for all range positions should be less than
one-half that allowable in changing from one
precision voltage divider having a resistance of
1 megohm and an accuracy 5 to 10 times that of
the reference voltage divider.
The high resistance is necessary to prevent
excessive current drain from the reference
supply.
Connect the input of the external precision
voltage divider to the input of the reference
143
153
IC ELECTRICIAN 3 & 2
5102
J102
-.1103
J101
R133
3101
F101
Figure 5-29.
Phase sensitive voltmeter.
voltage divider in the digital voltmeter. Disconnect the wire from the arm of the operate-
One advantage of this method of testing
voltage divider linearity is that reasonably large
(20 percent) diviations in reference voltage from
the
nominal value of reference voltage
have no significant effect upon test accuracy.
calibrate switch. Connect the output of the external
precision voltage divider to this terminal. (Observe proper shielding and grounding rules.)
Adjust the standard divider at 00000. The visual
readout should display a zero in each window.
Adjust the standard voltage divider for 99990.
The visual readout display, should display a 9 in
This is true because the same voltage is fur-
nished to the input of the reference voltage divider as well as the input of the external standard
voltage divider. Hence, for equal settings of
the two voltage dividers, the output voltages
should be equal.
each window. These two readout displays must be
obtained for the indicated standard divider settings. If the voltmeter displays digits other than
those indicated above for these two end points,
an improper circuit condition exists and must
be located and corrected before preceeding with
this test.
Now set the standard divider for various
readings such as: .89990, .7990, .6990, - - -.08990,
.00080,
.0790,
----,
00890, .00790,
.00070. The digital voltmeter readout
should be equal to the standard divider setting
+ 1 digit.
140.145
RANGE UNIT ADJUSTMENT
The range unit will require scale factor readjustment only if the range unit resistors
change their ohmic value, or if the internal
electrical loading of the unit output taps changes.
The adjustment method requires several accurate voltage dividers and a stable d-c source.
This method permits accurate range unit scale
factor adjustment regardless of the inaccuracies
144
154
Chapter 5 TEST EQUIPMENT
present in the digital voltage divider because
the voltage divider is always brought .back to
the same position (same numerical display on
the voltmeter, ignoring decimal point location)
when the correspondence of scale factors on
Adjusting the 1000-Volt
Range Scale Factor
The following procedure is used:
1. Connect the input terminals of a 100-to-1
voltage divider to a stable source of d-c voltage
each range is checked.
as close to 999 volts as practicable: (Lower
voltages, no less than 200 volts, can be used,
As in any other test, proper shielding and
grounding techniques must be followed to prevent electrical noise pickup from interfering
with the stability and resolution of the digital
but accuracy will not be as good as when higher
voltages are used.)
voltmeter. Also, each range is checked most
accurately when the test voltage is as close
to full scale for that range as is practicable.
2. Connect the input terminals of the voltmeter under test to the input terminals of the
voltage divider. Observe the readout display
The precision voltage divider in the range unit
adjustment procedure must be compensated for
the electrical loading effect of the digital voltmeter. The accuracy of the external voltage divider should be five to ten times better than the
accuracy to which the range unit is to be adjusted.
and waveform at the error amplifier test points.
3. Connect the input terminals of the digital
voltmeter to the output terminals of the 100-to-1
voltage divider. Observe the readout display
and error amplifier waveform.
4. The 1000-volt range is properly adjusted
when the readout display in step 3 is exactly
one-hundredth of the readout display observed
in step 2, (for example: 982.3 in step 2, compared with 9.823 in step 3) and when the error
amplifier waveform amplitude and phase are
similar to that observed in step 2. If this cor-
Access to the range trim potentiometers
referred to in the following paragraphs is gained
by removing the left-hand protective cap on the
front panel (fig. 5-24). These potentiometers
are identified by 1000v and 100v on the printed
circuit range board.
respondence is not present, adjust the 1000 volt range trim potentiometer, R2.
PHASE SENSITIVE VOLTMETER,
ME-111/U
Adjusting the 100-Volt
Range Scale Factor
The ME-111/U voltmeter (fig. 5-29) is de:-
The following procedure is used:
signed to measure output voltage, in-phase voltage
relative to a reference voltage, and 90° out-of1. Connect the input terminals of a 10-to-1
precision voltage divider to a stable source of
phase voltage relative to a reference voltage. The
main uses of this voltmeter are for observing
and correcting phase relationships and for zeroing
synchros in gyrocompass systems.
The phase sensitive voltmeter is connected to
a system by means of a 5-pin plug and two test
d-c voltage, approximately 95 to 99 volts.
2. Connect the input terminals of the digital
voltmeter under test to the input of the voltage
divider. Observe the readout display and waveform at the error amplifier test points.
3. Connect the input terminals of the volt-
jacks, or by the 5-pin plug only. With just the
5-pin plug, there is only one connection for both
the reference voltage input and the signal voltage
input. When the test jacks and the 5-pin plug are
meter to the output terminals of the voltage
divider. Observe the readout display and the
connected to the voltmeter, the test jacks are
used for the signal voltage input and the 5-pin
error amplifier waveform.
4. The 100-volt range is properly adjusted
when the readout display in step 3 is exactly
equal to one-tenth of the readout display observed in step 2, (for example: 95.93 in step 2,
plug is used for the reference voltage input. The
multiple-connection hookup is preferred since
it eliminates the pickup problems which are likely
to result with the single-connection hookup where
the signal and power leads are near each other.
compared to 9.593 in step 3) and when the error
amplifier waveform amplitude and phase are
similar to that observed in step 2. If this cor-
The reference switch has three positions:
scale A, scale B, and total. With this switch
respondence is not present, adjust 100-volt range
trim potentiometer R4.
in either scale r,osition, you can check the phase
145
155
IC ELECTRICIAN 3 & 2
relationships of the reference and signal voltages.
When the reference switch is in the TOTAL
position, the ME-111/U acts as a vacuum tube
146
156
voltmeter (VTVM) to indicate voltage level ir-
respective of a reference signal. The voltage
range is controlled by the volts selector switch.
CHAPTER 6
SOUND-POWERED TELEPHONES
Telephones provide a rapid and efficient
means of communication between the many
stations aboard ship. A satisfactory telephone
system must be reliable and not susceptible to
damage during battle; it must make possible
rapid completion of calls; and it must be easy
to maintain. The sound-powered telephone fulfills these requirements. As the name implies,
the sound-powered telephone requires no outside
power supply for its operation. The sound waves
produced by the speaker's voice provide the
energy necessary for the reproduction of the
armature, a driving rod, a diaphragm, and a coil.
The armature is located between four pole tips,
one pair at each end of the armature. The spac-
ing between the pole tips at each end is such
that an air space remains after the armature is
inserted between them. This air space has an
intense magnetic field, which is supplied by the
two magnets that are held in contact with the
pole tips.
The armature is clamped rigidly at one end
near one of the pairs of poles and is connected
at the other end to the diaphragm by the drive
rod. Hence, any movement of the diaphragm
voice at a remote location.
causes the free end of the armature to move
toward one of the pole pieces. The armature
passes through the exact center of a coil of
wire that is placed between the pole pieces in
In addition to sound-powered telephones, some
ships are provided with automatic dial-
type telephones. The dial telephone system is
used for administrative purposes and is not
depended upon under battle conditions. The dial
the magnetic field.
telephone system is discussed in chapter 9 of
this training manual. This chapter discusses
sound-powered telephones and associated cir-
PRINCIPLES OF OPERATION
cuits and equipment.
Upon completion of this material you should
be able to distinguish between the various com-
Sound waves are compressions and rarefactions of the medium in which they travel. When
a diaphragm is placed in the path of a series of
sound waves, the waves cause the diaphragm to
vibrate. The armature of a transmitter unit,
ponents of a complete sound powered system.
You should further be able to perform maintenance on all circuits in the sound powered group
when there are no sound waves striking the
be they switchboard, switchbox, or string.
diaphragm, is shown in figure 6-1A. Note that
As an IC Electrician 3 or 2 you will be
the armature is centered between the pole pieces
required to indoctrinate personnel in the uses
and capability of the sound-powered system.
This chapter will be an aid in that indoctrina-
with the magnetic lines of force passing from
the north to the south pole and that there are
no lines of force passing lengthwise through
tion.
the armature.
When sound waves strike the diaphragm and
cause it to vibrate, the vibrations are impressed
SOUND-POWERED UNITS
upon the armature by means of the drive rod,
as shown in figure 6-1B, and C. During the
compression part of the wave this action
causes the armature to bend and reduce the
air gap at the upper south pole. The reduction
of the air gap decreases the reluctance between
the upper south pole and the armature, while
increasing the reluctance between the armature
and the upper north pole. This action reduces
The sound-powered transmitter (microphone)
and receiver units in some telephones are identical and interchangeable. Other telephones have
sound-powered units that differ physically. The
principle of operation, however, is the same
for both transmitter and receiver,
As illustrated in figure 6-1, a unit consists
of two permanent magnets, two pole pieces, an
147
157
IC ELECTRICIAN 3 & 2
MAGNET
/DIAPHRAGM
ie
fee
DRIVING ROD
1
4.
L
eie
.\
Nit
e
i\
I
NI
S
1/
A
C
27.287
Figure 6 -1.
Sound - powered
the lines of force that travel between the two
upper pole pieces. There is no large change
in the reluctance at the lower poles; however,
the armature has less reluctance than the lower
air gap and a large number of magnetic lines of
force will follow the armature to the upper south
pole. Thus, an emf is induced in the coil by the
lines of force that are conducted along the
armature and up through the coil.
When the sound wave rarefaction reaches
the diaphragm, it recoils, as shown in figure
6-1C, thus causing the armature to bend in the
opposite direction. This action reduces the
air gap between the armature and the north
pole.
Note
that the
reluctance between the
armature and upper north pole is decreased
and that the lines of force are reestablished
through the armature, this time in the opposite
direction. Thus, an emf is induced in the coil
by the lines of force that are conducted along
the armature and down through the coil. This
emf is in the opposite direction to that of the
emf induced when the lines of force are established, as shown in figure 6-1B.
Sound waves striking the diaphragm cause
vibrate back and forth. The armature
bends first to one side and then to the other,
causing an alternating polarizing flux to pass
it to
through it, first in one direction and then in the
other. These lines of force passing through the
armature vary in strength and direction, de-
pending upon the vibrations of the diaphragm.
This action induces an emf of varying direction
transmitter unit.
and magnitude
that is, an alternating voltage
in the coil. This alternating voltage has a frequency and waveform similar to the frequency
and waveform of the sound wave striking the
diaphragm.
When this unit is used as a receiver it operates in a similar manner. The alternatingvoltage
generated in a transmitter unit is impressed
upon the receiver coil, which surrounds the
armature of the receiver unit (fig. 6-2). The
resultant current through the coil magnetizes
the armature with alternating polarity. An induced voltage in the coil of the transmitter (fig.
6-2A) causes a current to flow in the coil of the
receiver (fig. 6-2B) magnetizing the free end
of the armature, arbitrarily with north polarity.
The free end of the armature, therefore, is repelled by the north pole and attracted by the
south pole. As the direction of the current in the
receiver reverses, the polarity of the armature
reverses. Thus the position of the armature in
the air gap reverses, forcing the diaphragm inward. Hence the diaphragm vibrates in unison
with the diaphragm of the transmitter and generates corresponding sound waves.
EQUIPMENT
The two types of sound-powered telephones
installed in Navy ships are handsets and headsets. All telephones of a given type are built to
the same military specifications regardless of
the manufacturer.
148
158
Chapter 6SOUND-POWERED TELEPHONES
across the line in series with a 3-db padding re-
sistor. When receiving the receiver unit is directly across the line.
The sound-powered transmitter and receiver
units are not interchangeable; however the receiver units are interchangeable with the type
H-203/U sound-powered units.
HEADSETS
The type H- 200 /U headset is designed for
A
Figure 6-2.
general use. The set consists of two soundpowered receiver units with protective shells
8
27.288
Operation of sound-powered transmitter and receiver units.
HANDSETS
The type H203/U handset is designed for gen-
eral use, primarily one-to-one talking. The
sound-powered transmitter and receiver units
(fig. 6-3) are interchangeable. A nonlocking,
normally open, spring return, push switchS1 disconnects the sound-powered units from the line
in the open position, and connects the units to the
line in the closed (depressed) position. Capaci-
tor Cl, is connected in parallel with the soundpowered units for tone compensation.
The type H-204/U handset (not shown) is
specially designed for use on a line loaded with
other handsets or headsets. The switching arrangement keeps the set off the line when it
is not in use. When transmitting, the transmitter
unit is across the line and the receiver unit is
and ear cushions, one sound-powered transmitter
unit with protective shell provided with a pus hswitch, one mouthpiece, one chest plate assembly
with junction box provided with capacitors and
terminal facilities, one headband assembly and
neck strap, and one cord assembly and plug. The
receivers are mounted on the headband; the
transmitter on the chest plate. Closing the pressto-talk switch 51, (fig. 6-4), connects the soundpowered transmitter unit across the line. The
receiver units are permanently connected across
the line when the set is plugged in.
When a sound-powered telephone set in used
on the output side of a sound-powered telephone
amplifier, a small d-c voltage is placed across
the set. The purpose is to provide an amplifier
squelching circuit to avoid acoustical feedback
when the local set is transmitting. Capacitor Cl
(fig. 6-4), blocks the d-c from the receiver units.
The press-to-talk switch allows the d-c to flow
when transmitting, and operates a sensitive
switch in the amplifier. The two capacitors are
in series across the line. The sound-powered
PAIR
-- --- TWISTED
LINE CORD
SOUND-POWERED
RECEIVER UNIT
...-
--...
\
/
\\\
\_. --
I
/
SOUNO-POWEREO
/ TRANSMITTER
UNIT
3.198
Figure 6-3. Sound-powered telephone handset wiring diagram.
149
159
IC ELECTRICIAN 3 & 2
physical strain is put on the electric conductors.
If the talker must remove the telephone set from
his head, he should hang the set by the head band
and the neck s...ap not by any of the connecting
S......1
0---
MICROPHONE
RECEIVER
wires. Figure 6-5 shows a properly made up
RECEIVER
headset and several properly stowed sets.
The unit is made as waterproof as possible,
but it should not be exposed unnecessarily to
the weather. Moisture and good telephone service
do not go hand-in-hand. Remember that several
5
conductors, which actually carry the messages
to and from the telephone, lie underneath the
rubber covering on the various electric cords
on the set. Although these cords are quite flexi-
f
7
ble, they should not be dragged over sharpedges,
7
pulled too hard, or allowed to kink. The cords
are especially susceptible to damage because
of their small size. If you instruct other men on
how to handle telephones, emphasize the importance of handling the set with care so that
the set will not be out of order in an emergency.
Telephone headsets used in exposed areas
are stowed in boxes located on weather decks.
Those sets used in protected areas are stowed
on bulkhead hooks located in various compartments. The set must be made up properly for
either means of stowage. Use the following procedure to make up a sound-powered telephone
LINE CORO
140.33
Figure 6-4. Sound-powered telephone headset
type H-200/U wiring diagram.
transmitter and redeiver units are not interchangeable.
The type H-201/U headset (not shown) is a
specially designed set for use by plotters, con-
headset for stowage.
sole operators, etc. The transmitter is sus-
1. Remove the headband and hang the headband over the yoke of the transmitter.
pended from the headband by a boom. The boom
may be adjusted to place the transmitter in
2. Remove the phone jack and secure the
jack box cover to keep out moisture and dirt.
Lay the line out on the deck and remove any
kinks. Begin coiling from the end that attaches
to the chest plate. Coil the line with the right
front of the wearer's mouth. The junction box
with terminal facilities, capacitors, and the
normally open, spring return, push switch, is
fitted with a clip that allows it to be attached
to the wearer's belt. The sound-powered units
hand, making the loops in a clockwise direction.
The loops should be about 10 inches across.
3. When the lead is coiled, remove the ear
pieces from the transmitter yoke and hold the
are not interchangeable.
The type H-202/U headset is a specially designed set for use in areas having high noise
levels. The receiver units are housed in noise
attenuating shells consisting of plastic caps
headband in the same hand v, Ith the coil.
4. Fold the transmitter yoke flat so that the
transmitter mouth piece lays flush against the
breast plate connection box, using care not to
lined with sound absorbing material. The soundpowered units are not interchangeable.
pinch the transmitter cord.
5. Holding the headband and coil in the left
hand, unhook one end of the neck strap from the
chest plate.
6. Bring the top of the chest plate level with
HANDLING AND STOWAGE
The connecting wires secured to the various
portions of telephone sets have but one purpose
to transmit electric current. They are not pro-
the coil and headband. Secure the chest plate
vided as straps for supporting the equipment nor
should they be suliiected to a jerk or fall. When
a plug is removed from a jack, the BODY of the
in this position by winding the neck strap around
the coil and headband just enough times so that
there will be a short end left over. Twist this
end once and refasten it to the chest plate. The
plug should be pulled- never the CORD. Connections should be made so that a minimum of
headset is then made up in a neat package ready
150
160
Chapter 6SOUND-POWERED TELEPHONES
3.205:.206
Figure 6-5. Properly made up and stowed headset.
for stowing. A set properly made up fits into
its stowage box without forcing. Never allow
the proper methods of testing and repairing them.
Many of the larger ships have a telephone shop
loose cord to hang out of the box because it may
be damaged when the lid is closed.
Stow only b"ttle telephones in telephone stow-
that ie devoted entirely to the repair of sound-
these boxes. Rags give off moisture, which may
ruin the phone, and soap powder gives off fumes
that rapidly oxidize the aluminum diaphragm.
Tools and other loose gear may prevent getting
the phone out quickly, or may damage the phone.
talk:; is to exchange it for a good one at the
repair shop. This procedure provides each
station with properly operating sets at all times
r.nd concentrates the repair of these sets in one
location. The shop maintains a log of all sets
turned in and the station from which they are
receivAd. This practice aids in locating faulty
circuits or talkers who continually abuse their
sets.
powered telephones.
When trouble develops in a sound-powered
headset, the usual procedure followed by the
age boxes newr put cleaning gear or tools in
Sound-powered handsets are fastened to a
connect_on box by a coiled cord. A stowage hook,
or handset holder, is provided for each handset,
and the set must be properly replaced in the
holder at all times when not actually in use. A
handset left in the bottom of the holder provides
Inspection
an excellent lever for breakage. No special
care, other than intelligent handling, is needed
for handsets as they are much less subject to
trouble than are headsets.
A routine inspection of sets should be made
before repairs are begun to determine whether
physically defective parts should be replaced.
Many troubles may be located by inspecting the
set for damaged cord or insulation; cords pulled
out of units; loose units; defective or broken
,;ushbuttons; and broken or damaged parts, such
as unit covers, neck strap, chest plate, junction
REPAIRS
As an IC Electrician, you will be required to
service sound-powered telephones. Because a
great deal of time is devoted to the repair of
box, plug, and headband.
these sets, you should be thoroughly familar with
151
161
IC ELECTRICIAN 3 & 2
Precautions
is not necessary to press the talk button because
In repairing sound-powered telephones observe the following precautions:
Do not repair telephones on a dirty
workbench. The magnets in the units may attract
iron fillings, which are difficult to remove.
o
Never alter the internal wiring of sets.
Before disassembling a unit, make a
wiring diagram showing the color coding, polarity,
or terminal numbers of the lead connections.
the transmitter and receiver are permanently
connected in parallel. If no sound is heard,
eith..i the transmitter or the receiver is cl.'-
fective. The easiest method to determine whether
the transmitter or the receiver is defective is
to have someone talk into another phone on the
line and to listen to both the transmitter and
the receiver of the handset. If the talker's voice
is heard on one of the units but not the other,
the unit on which the voice is not heard is the
defective one and should be replaced. If the
talker's voice cannot be heard on either unit,
were before disassembly.
and the telephone circuit being used for the test
is known to be free of trouble, the fault may be
traced to the line cord, switch, or internal
handset circuits.
Open and Short Circuits
Replacing Cords
Use a low voltage ohmmeter to test for opens
and shorts to avoid damage to the sound-powered
When it is necessary to replace a defective
cord between the junction box and the transmitter or receivers of headsets, tinsel cord
should be used. Stocks of tinsel cord cut to the
Always replace parts exactly as they
units. Continuity tests may be made from the
chest plate sanction box on the types H-200/U,
and H-202/U headsets. The normal d-c resistances of the sound-powered transmitter and
receiver units are 10 ohms and 62 ohms re-
spectively. A short circuit in a single unit
renders an entire telephone circuit inoperative
because it parallels all of the other units.
Loss of Sensitivity
Loss of sensitivity, or weakening of the transmission sound, is a gradual process and seldom
is reported until the set becomes practically
inoperative. When a sound-powered telephone is
in good condition electrically yet the sound is
weak, the transmitter unit should be replaced.
If this procedure does not remedy the trouble,
the receiver units should be replaced.
Headsets may be tested for loss of sensitivity by depressing the talk switch, and blowing
into the transmitter. If the set is operating
properly, a hissing noise is heard in the receiver units caused by the air striking the transmitter. One receiver unit is listened to, and then
the other. In most cases, the loss in sensitivity
is in the transmitter unit and might be caused
by a displacement of the armature from the
exact center of the air gap between the pole
pieces.
Each sound - powered handset is tested on
location because it is connected permanently to
a box. The simplest test is to blow air into the
transmitter. To test each individual handset it
proper lengths for use with the various types of
headsets and fitted with terminals are stocked
at supply depots and should be requisitioned for
use. Bulk tinsel cordage is also stocked at
supply depots as standard stock. Always use
prepared cords if possible.
If prepared cords are not available, you can
make them from bulk tinsel cord by the following procedure:
1. Strip about 2 in. of the outer layer of
insulation from one end of the cord.
2. Remove about one-fourth of an inch of
insulation from the ends of the conductors,
exercising caution not to damage the tinsel wire.
3. Wind a single layer of 32-gage tinned
copper wire over the tinsel wire and extend
the tinned copper wire about one-eighth of an
inch over the rubber insulation.
4. Dip these whipped conductors into melted
solder and flatten them slightly when cool.
5. Solder the whipped conductor to a lug or
cord tip as required (fig. 6-6).
If tinsel cord is not available, use standard
DCP-1/2 cord between the junction box and the
receivers and transmitter. Use DCOP 1 1/2
cord between the junction box and the plug.
To replace a cord:
1. Open each unit connected to the cord that
is to be replaced.
152
162
Chapter 6 SOUND-POWERED TELEPHONES
damage control, and maneuvering of a typical
CVA.
2. The auxiliary battle telephone system
circuits XJA to XJZ includes circuits duplicating certain primary battle telephone circuits
as alternates in case of damage. The wiring
of the auxiliary circuits is separated as much
as practicable from the wiring of the corresponding primary circuits to prevent battle
damage to both circuits.
3: The supplementary telephone circuits X1J
X61J, consists of a group of outlets
connected together on a single line or "string,"
with no provision for cutting out a single outlet.
through
A supplementary circuit may be one that is
required for use at all times or at times when
battle telephones are not manned. Some "string"
circuits are equipped with call-bell systems.
140.34
Figure 6-6. Preparing a new tip on a tinsel
cord.
2. Before disconnecting the cord make a
diagram showing the color coding of the wires.
3. Disconnect both ends of the cord.
4. Remove the screw that holds the tie cord
or untie the cord if it is secured to an eyelet.
5. Unscrew the entrance bushing, if pro-
vided, and pull the cord through the port.
6. Place the threaded entrance bushing, metal
washer, and rubber gasket on the new cord and
insert the cord into the entrance port (fig. 6-6).
The cord should be long enough to allow slack
after it is connected.
7. Secure the tie cord so that it takes all
the strain off the connections; otherwise the
wires might be pulled from their terminals.
8. Connect the wires to their terminals.
9. Screw the entrance bushing on the en-
trance port, drawing the bushing up tightly to
secure the cable and to seal the port.
10. Close the unit after all connections have
been visually checked.
11. Test the completed unit for operation.
SOUND - POWERED TELEPHONE
SYSTEMS
There are three types of sound-powered
telephone systems:
1. The primary battle telephone system-circuits JA to JZ (table 6-1) includes all circuits used for the main channels of communications in controlling the armament, engineering,
The various sound-powered telephone sys-
tems are classified further into switchboard
circuits, switch-box
type circuits.
circuits,
and
string-
SWITCHBOARD CIRCUIT
A switchboard circuit is a circuit having
cutout switches on a sound-powered telephone
switchboard. (Table 6-2 is a glossary of terms
for telephone switchboards and circuits.) Most
large combatant ships have several sound-powered telephone switchboards installed in different
centrally located and protected control stations,
such as IC rooms and plotting rooms. Smaller
combatant ships usually have only one soundpowered telephone switchboard; it is normally
located in the IC room. Each switchboard (fig.
6-7) usually has several switchboard circuits
and
a line-disconnect switch for
each lice. The older type (fig. 6-7A) is
replaced with the newer switchboard (fig.
6-7B) which has a switchjack (fig. 6-7C) at each
position. The switchjack consists of a line
switch and jack. The purpose Jr the line switch is
either to connect or disconnect a station from
its circuit. The jack either parallels that phone
with another circuit or parallels two circuits.
Paralleling
. accomplished by means of a
PATCHING LORD, which is a short length of
portable cord having a jack plug at each end.
Primary and auxiliary circuits can be connected
either through the switchboard or through switch-
boxes located at the controlling station for each
circuit. On smaller ships only the most vital
primary circuits are backed up by auxiliary
circuits. When an auxiliary circuit is controlled
IC ELECTRICIAN 3 & 2
Table 6-1. Sound-Powered Telephone Circuits
Primary Circuits
Circuit
JA
JC
Title
JL
Captain's battle circuit
Weapons control circuit
Missile batter) control circuit
Target detectors circuit
Flag officer's circuit
Aircraft control circuit
Aircraft information circuit
Aircraft strike coordination circuit
Aircraft strike requirement and reporting circuit
Aircraft information circuit CATTC direct line
Aircraft service circuit
Aviation fuel and vehicular control circuit
Aviation fueling circuit forward
Aviation fueling circuit aft
Aviation ordnance circuit
Aviation missile circuit
Arresting gear and barricade control circuit
Aircraft handling circuit
Airborne aircraft information circuit
Optical landing system control circuit
Switchboard cross connecting circuit
Lookouts circuit
JI.
Double purpose fuse circuit
JM
Mine control circuit
Illumination control circuit
Switchboard operators' circuit
Dual purpose battery control circuit
Heavy machine gun control circuit
Light machine gun control circuit
Torpedo control circuit
ASW weapon control circuit
Rocket battery control circuit
Guided missile launcher control circuit
IOJC
JD
JF
1JG
2JG
2JG1
2JG2
2JG3
33G
4JG1
43G2
43G3
5JG1
5502
630
930
103G
11JG
JH
JN
JO
2JP
4JP
5JP
6JP
8JP
9JP
10JP
27.337.1
154
164
Chapter 6SOUND-POWERED TELEPHONES
Table 6-1. Sound-Powered Telephone CircuitsContinued
Primary Circuits
Circuit
1 OJP1
1 OJP2
11JP
JQ
JR
JS
1JS
2JS
3JS
.20JS1
20JS2
20JS3
20JS4
21JS
22JS
23JS
24JS
25JS
26JS
31JS
32JS
33JS
34JS
35JS
36JS
61JS
80JS
81JS
82JS
JT
1JV
2JV
Title
Starboard launcher circuit
Port launcher circuit
FBM checkout and control circuit
Double purpose sight setters circuit
Debarkation control circuit
Plotters' transfer switchboard circuit
CIC information circuit
NTDS coordinating circuit No. 1
NTDS coordinating circuit No. 2
Evaluated radar information circuit
Evaluator's circuit
Radar control officer's circuit
ti
Weapons liaison officer's circuit
Surface search radar circuit
Long range air search radar circuit
Medium range air search radar circuit
Range height finder radar circuit
AEW radar circuit
Radar information circuit
Track analyzer No. 1 air radar information check
Track analyzer No. 2 air radar information check
Track analyzer No. 3 air radar information check
Track analyzer No. 4 air radar information check
Raid air radar information circuit
Combat air patrol air radar information circuit
Sonar information circuit
ECM plotters' circuit
ECM information circuit
Supplementary radio circuit
Target designation control circuit
Maneuvering and docking circuit
Engineers' circuit (engines)
155
27.337.2
IC ELECTRICIAN 3 & 2
Table 6-1.Sound-Powered Telephone CircuitsContinued
Primary Circuits
Circuit
3JV
Title
6JV
Engineer's circuit (boiler)
Engineer's circuit (fuel and stability)
Engineer's circuit (electrical)
Ballast control circuit
11JV
Waste control circuit
JW
Ship control Dearing circuit
Radio and signals circuit
Damage and stability control
Main deck repair circuit
4JV
5JV
JX
2JZ
3JZ
4JZ
5JZ
6JZ
7JZ
8JZ
9JZ
10JZ
11JZ
Forward repair circuit
After repair circuit
Midships repair circuit
Engineer's repair circuit
Flight deck repair circuit
Magazine sprinkling and ordnance repair circuit forward
Magazine sprinkling and ordnance repair_ circuit aft
Gallery deck and island repair circuit
Auxiliary Circuits
XJA
X1JG
XIJV
XJX
X2JZ
Auxiliary captain's battle circuit
Auxiliary aircraft control circuit
Auxiliary maneuvering and docking circuit
Auxiliary radio and signals circuit
Auxiliary damage and stability control circuit
Supplementary Circuits
X1J
X2J
X3J
X4J
X5J
X6J1
X6J7
X6J11-14
X7J
Ship administration circuit
Leadsman and anchor control circuit
Engineer watch officer's circuit
Degaussing control circuit
Machinery room control circuit
Electronic service circuit
ECM service circuit
NTDS service circuits
Radio-sonde information circuit
27.337.3
1E6
166
I
r
Chapter 6SOUND-POWERED TELEPHONES
Table 6-1.Sound-Powered Telephone CircuitsContinued
Supplementary Circuits
Circuit
Title
XI 4J
Replenishment-at-sea circuit
Radar trainer circuit
Cargo transfer control circuit
Cargo transfer circuit-Lower decks
Cargo transfer circuit -Upper decks
Captain's and admiral's cruising circuit
Capstan control circuits
Aircraft crane control circuits
Missile handling and nuclear trunk crane circuit
XI 5J
SINS information circuit
XI 6J
Aircraft elevator circuit
5-4ich ammunition hoist circuit
X8J
X9J
X1 0J
X1 0J1
XI 0J10
X1 1J
XI 2J
XI 3J
XI 7J
XI 8J
X19J
X20J
X2I J
X22J
X23J
X24J
X25J
X26J
X28J
X29J
X34J
X40J
X4 1 J
X42J
X43J
X44J
X45J
X50J
X6I J
Macnine gun ammunition hoist circuits
Missile component elevator circuit
Weapons elevator circuits
Catapult circuit
Catapult steam control circuit
Stores conveyor circuit
Cargo elevator circuit
Sonar service circuit
Jet engine test circuit
Dumbwaiter circuit
Timing and recording circuit
Alignment cart service circuit
Casualty communication circuit
Special weapons shop service circuit
Missile assembly and handling circuit
Weapons system service circuit
ASROC service circuit
Special weapons security circuit
Fog foam circuit
Nuclear support facilities operations and handling circuit
27.337.4
167
157
IC ELECTRICIAN 3 & 2
Table 6-2. Sound-Powered Telephone Systems Glossary
GLOSSARY
BUS--The
common
connection
between
a group of line
cutout switches. It may be in a single section or divided;
it may be connected to a jack outlet or be free.
BUS TIE SWITCH--A
e .n- cting
switch
separate parts of
the same circuit or similia. circuits on a switchboard
or switchbox.
PLOTTERS' TRANSFER SWITCHBOARD--A radio-type transfer
switchboard performing the function of selector switches.
SELECTOR SWITCH--A
switch
lines to a single jack outlet.
TIE LINE--A
line
connecting
one
of several
two switchboards, two switch-
between
boxes, or a switchboard and a switchbox. It connects
two circuits and is terminated by a switch at each
end.
TIE PLUS SWITCH--A normally closed switch at the opposite
end of a tie lire from the tie switch. It may be opened to
clear a damaged circuit.
TIE SWITCH--A switch at one end of a tie line, usually the
end connected to an auxiliary circuit. It is normally open
unless the ship's doctrine requires that it be closed.
switch for connecting the lines of one
circuit group to one of several other circuit groups.
TRANSFER SWITCH--A
140.156
through a switchbox, the circuits can be crossconnected to the primary circuits on the main
board by means of a tie line.
SWITCHBOX CIRCUIT
A switchbox circuit consists of several line
cutout switches mounted in a switchbox. Usually,
there is only one switchbox for each circuit.
Telephone switchboxes function primarily as
small ACO switchboards. The switchboxes are
located at the principal station on the circuit,
and contain either 10 or 20 switches used for
connecting incoming lines to a common circuit
bus (fig. 6-8). Each station on the circuit is
158
168
connected to one of the line switches. Some of
the switches may be used as tie switches connected to .the circuit bus in other switchboxes.
When these tie switches are closed, the circuits
in the two boxes are paralleled.
All primary circuits are provided with a
tie line for cross connection with their auxiliary
circuits. The tie lines are fitted with a tie switch
at one end and a tie + (tie plus) switch at the
other end. The tie + switch is different from the
tie switch only in that the tie + switch is always
closed to ensure that the tie line may be used at
all times. With this arrangement the two circuits
can be tied together or separated by closing or
opening the tie switch. In case of a casualty to
Chapter 6 SOUND-POWERED TELEPHONES
44,
Amagutogill
comirommrsimmirewnwisis
t0000000000)
eimmeramplukawrimmwme
,O 0 0()Cipolosimmi)c0
it
Q000'000000
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9000000 0 0
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m140000000000 0
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IC ELECTRICIAN 3 & 2
the tie switch end of the tie line the tie + switch
is opened to disconnect the defective circuit or
tie line.
Connecting Primary and
Auxiliary Circuits
A ship's sound-powered telephone system
is designed so that there are backup circuits
for all vital circuits. On large combatant ships,
many primary circuits are paralleled by auxiliary
circuits; on other ships, only a few. However,
all important stations aboard ship are served
by more than one primary circuit.
Auxiliary circuits are normally connected to
their primary circuits when all tie switches on
the auxiliary switchboard are left closed. Connecting or tying of circuits results in paralleling
as many headsets as there are manned stations.
In an extensive telephone system, paralleling of
circuits has both advantages and disadvantages.
One advantage is that it allows a controlling
station to extend supervision over many stations,
using fewer talkers. Also, if communications is
lost to one of the primary stations, paralleling
enables the talker at the station to re-establish
easily communications with the control station
by pulling the plug of his headset from the primary jackbox and inserting the plug into the
auxiliary jackbox. However, paralleling all the
auxiliary lines with the primary lines makes it
harder to locate and isolate a casualty that results in loss of contact or reduced sound caused
by too much of the transmitted energy being
dissipated. There is another disadvantage to
paralleling circuits where some tie switches
are located on switchboards and some in rather
inaccessible switchboxes. In this case, the control
station operator may have trouble locating the
proper tie switches when required to separate
the circuits quickly or to change the setup.
An increase in the number of paralleled
circuits tends to make the system more troublesome and to lower its traffic-handling capacity.
More paralleled circuits could mean more repeats
and garbles, overloaded transmitters, and more
difficulty in locating and clearing faulty circuits.
The problems are not too severe if all equipment
is in good condition and operators use proper
techniques. Because of the advantages and disadvantages, the doctrine of closing all tie switches
Figure 6-8.
A.C.O. switchboxes. Top new;
27.291X
bottom old.
may be best for some circuits, but not all. Your
ship's doctrine will determine whether the
switches are to be kept closed or open.
160
170
Chapter 6SOUND-POWERED TELEPHONES
CIC SECT
FLAG PLOT SECT.
3))
O-NV-I
u) cn NN til
UM t/1 V!
..27-J-2-2
-NM./ -
NO161610)
6.16.16.16.17
JSt
JS 31
JS 2
JS 3
JS 4
JS 5
JS 32
JS33
JS34
JS35
JS36
JS6
JS 7
JS 8
JS 9
JS37
JS38
JSIO
C.OT.P SECT.
JS11
JS12
JS13
JS14
JS15
JS16
JS17
JS18
JS19
JS 26
JS60
JS 61
JS 62
JS63
JS64
JS65
MI
INPUTS
JS21
JS22
JS23
JS24
JS 25
JS 26
J11
TO STRING
CIRCUITS
TO JL
5
TO
CIRCUITS PLOTTERS
JS27
JS28
INPUTS
A
EL.
ITEB-'
TO STRING
CIRCUITS
TO8IJS
SWBOX
0
PLOTTERS TRANSFER
SWITCHBOARD (5)
CROSS- CONNECTION DIAGRAM
TO
PLOTTERS
B
36.69
Figtu e 6-9.
Plotters transfer switchboard, type SB-82/SRR. (A) External view; (B) Wiring diagram.
Circuits may ,lso be parallel with the com; in CIC. Telephone circuits
may be connecte- in multiple by operation of
the paralleling switches on each console. Since
each circuit is routed to a number of plotters'
positions, care must be taken to avoid overmunication cons
loading the transmitter.
STRING TYPE CIRCUIT
A string type circuit consists of a series of
jack boxes connected in parallel to a single line.
There are no action cutout switches for individual
stations. However, some string circuits (21JS
to 24JS) are connected to communication
consoles, selector switches, and plotter transfer
switchboards (fig. 6-9).
Some string tyre circuits, such as X1J
Captains and Admirals cruising, may be equipped
with call bells, armunziators, or magneto call
stations.
SELECTOR AND TRANSFER
SWITCHES
Selector and transfer switches are of the
rotary type. Selector switches are located in
the most important stations throughout the ship
to enable the officer in charge, or his talker,
to connect his telephone at will to any one of a
group of circuits without having to change from
one jack outlet to another.
Transfer switches are usually installed at
switchboards and are used lc
the telephone
connect the lines of one group of circuits to one
of several other groups of circuits.
Circuit Connections Under
Conditions of Readiness
Under normal operating conditions, telephone
circuits are usually paralleled to reduce the
number of talkers required since a relatively
IC ELECTRICIAN 3 & 2,
small amount of traffic is carried on any one
circuit. A talker on the bridge can be connected
with main control and after steering through the
1JV circuit, with the lookouts through the JL
circuit, with CIC through the 1JS circuit, and with
sonar through the 61JS circuit. As conditions of
greater readiness are set, more talkers are
assigned to the bridge and fewer circuits are
paralleled. Few, if any, primary circuits are
cross-connected under the highest condition of
readiness.
Circuit Connections for
Casualty Control
It is most important .to have fast and reliable
internal communications when a ship is being
damaged. In case of extensive damage, considerable cross-connecting and patching may be
Figure 6-10. 2(40J circuit risers.
communications. You must be ready to apply
with the rest of the JL circuit. Run a patch
cord between a "live" jack on the JL part of
140.187
required to restore an effective degree of internal
your ship's doctrine for casualty control of
the sound-powered telephone system.
the board, and the jack on the 1JV circuit that
you are going to use. That line is now a part of
the JL circuit; when the bridge talker plugs into
Damaged lines must always be cut out until
repaired. A cut or damaged line may short
and interrupt an entire circuit. If a compart-
it, he is back in communication.
ment is abandoned because of fire or flooding,
you must isolate all telephone lines in the space
CIRCUIT X40J CASUALTY
switchboxes.
When a telephone line to one talker is damaged,
it is cut out at the IC switchboard. Communi-
Circuit X40J is a means of emergency communications between the bridge, central control
station, IC rooms, machinery rooms, and steering
gear rooms in case extensive casualties disable
normal communications. Installation of the cir-
COMMUNICATIONS
by cutting them out at the switchboard and
cations with the talker can be restored by patch-
ing from his circuit to a workable line having
a jackbox near his station. If a usable line having
an outlet by the station is found, the talker will
plug into its outelt. If the line to be patched in
is on an auxiliary circuit, the switch to the new
line is closed at the auxiliary switchbox. The
tie line between the switchbox and the damaged
line is cut out at the IC switchboard. The talker
is now back on his circuit, using an auxiliary
line.
You can substitute a line in another primary
circuit for a damaged line by patching at the IC
switchboard. With old switchboards, you parallel
two primary circuits by using the transfer
switch. With new boards having switch jacks for
each line, you connect a line into another circuit.
As an example, assume that the JL line to the
starboard wing of the bridge is 'damaged, but
there is still a workable outlet on the 1JV circuit at the station. You disconnect the 1JV line
from the rest of the 1JV circuit by using the
switch jack. You disconnect the damaged JL line
with the switch jack, so it will not interfere
cuit will vary from ship to ship. Aboard
one
ship, circuit X40J is made up of (1) permanently
installed risers (fig. 6-10) from major control
spaces below the waterline to scattered main
deck locations and (2) portable patch cables
which may be plugged into the permanent outlets
in any combination required by the extent of
damage to the regular sound-powered telephone
system. The portable patch cables, each 200 feet
long, and portable dOuble jackboxes are stored in
each repair party locker. The cables are equipped
with telephone jack plugs at each end; the jack-
boxes are used to couple lengths of the cable,
as necessary.
HIGHLINE CIRCUITS
The IC Electricians are responsible for maintaining the sound-powered telephon6 portion of
the bridge-to-bridge phone/distance line and the
station-to-station phone lines. During transfer
1 (-3 2
17Z
Chapter 6SOUND-POWERED TELEPHONES
CALL-BELL SYSTEMS
at sea, ships communicate over the bridge -tobridge line. The station-to-station line is used for
communications between each delivery and receiving ship transfer station. Each line is at least
350 feet long, being made of 1 1/2-inch-circumference, 3-strand, lightweight, polypropylene.
Each strand of the line has one wire interwoven
Call-bell systems provide a means of signaling between stations in a ship. These systems consist of circuits E and A.
CIRCUIT E
in it. Both lines have identical sound-powered
telephone connections. Double-gang jack boxes
are attached to both ends of each line; the boxes
are labeled either BRIDGE-TO-BRIDGE phone
Circuit E provides a means of signaling
between stations on sound-powered telephone
or STA.-TO-STA. phone.
circuits and between outlets on voice tubes. In
large ships this circuit may be designated as
markers are attached to this line at 20-foot
intervals. These markers tmnsists of colored
cloth squares for daytime use and red flashz
EM Self-contained circuits with magneto
call-bells. Stations at all calling and some receiving stations provide for selective calls over
The bridge-to-bridge phone/distance line is
made up by 'the ship's deck division. Distance
follows:
lights for nighttime use. Except for the markers
which it doesn't have, the station-to-station line
is identical to the bridge-to-bridge line. After
a new line is made up, the IC gang installs the
common talk circuits.
as possible since the line is handled roughly.
MJ Self-contained circuits with magneto
call-bells. Stations at all calling and some
receiving stations provide for selective calls
over selective talk circuits.
EP Protected call circuits with cable runs
protected behind armor.
MAINTENANCE
an EP circuit through separate protected fuses
jack boxes and makes the sound-powered telephone
connections. These connections must be as secure
Preventive maintenance for sound-powered
telephone circuits consists of routine tests and
inspections, and cleaning. All circuits should
be tested at least weekly to ensure that they are
working properly. Cleanliness is essential to
the proper operation of sound-powered telephone
switchboards due to the low voltages and currents involved. Dirt and dust between closely
EPS
at the calling station.
E PL Unprotected circuits supplied from an
EP circuit through a protected local cut-out
switch at the station called.
EXExposed call circuits with cable runs
not protected behind armor.
In addition, circuit E has the following functional designations:
spaced contacts can cause cross-talk. Use a
portable blower or vacuum cleaner to clean
1E Cruising and miscellaneous.
2E Ship control.
switchboards and switchboxes at least monthly.
Insulation tests should be made periodically
on all sound-powered telephone cables. In testing
insulation, keep all line switches closed and all
tie switches between circuits open. The pushbuttons on handsets must be open. Unplug the
headsets and remove the sound-powered telephone amplifiers from their cases.
A separate insulation test should be made for
each circuit. Measure the resistance between
each conductor and ground, and between each
pair of conductors.
The minimum allowable insulation resistance
reading depends upon the length and temperature
3E
Engineering.
4E Aircraft control.
5E Fire control.
11E through 15E
Turrets I through V.
For example, a circuit that is designated as
3EP is an engineering call-bell circuit with
cables protected behind armor.
Circuit E includes bells, buzzers, or horns
installed at selected sound-powered telephone
stations and at some voice tubes. Watertight
and nonwatertight pushbuttons, or turn switches,
are provided at all signaling stations to complete
circuits to the station called. Annunciators are
installed at stations where several circuits have
outlets.
The EM and MJ circuits may have as many as
of the cable. Lengthy cable runs on large ships
may read as low as 50,000 ohms and be satis-
16 ringing stations (fig. 6-11). These stations
factory.
163
173
Unprotected signal lines supplied from
IC ELECTRICIAN 3 & 2
r
B
Figure 6-11.Magneto ringing station. (A) External view; (B) Internal view.
164
74.66X
Chapter 6SOUND-POWERED TELEPHONES'
STATION
STATION NO.1
STATION NO.3
NO.2
GENERATOR-1
1
1
16 POSITION I
DOUBLE DEOC1
SELECTOR
1
SWITCH
I
1
1
1
1
I
i
HOWLER
60n
I
I
AT TENUATOR
1
1
L
IW
2W _3_
3W
w
_j LI 0I_ 01)2 _2W
N WO
3
IW
3W
J 21
1W
2
-
2W
3
3W
J
2E M3I
2EM M31
2EM32
2EMM32
2EM33
2EMM33
140.35
Figure 6-12. Sound-powered magneto call system.
are of cast aluminum with all of the equipment
on the cover, except for the terminal board for
the connections. Assembled on the cover are the
rotary selector switch, a hand-operated magneto
generator, a howler unit, and an attenuator to
control the volume of. the howler. The telephone
circuit may be of the string or switchboard type.
The operator simply turns the selector
switch to the station to be called and cranks the
generator handle. The howler (a modified soundpowered telephone receiver unit at the selected
station) will give a high distinctive howl. The
attenuator may be used to adjust the sound level
respective station.
of individual I'owlers at tl.
agrams
(figs. 6-12
The elementary wiring
'city of the circuit.
and 6-13) illustrate the si
CIRCUIT A
Circuit A is for the convenience of the ship's
officers in calling pantry attendants and orderlies. Calls are provided from all cabins; staterooms, except those equipped with ship's service
telephones; and wardrooms to the respective
pantries and orderlies. Circuit A calls are provided also from all sick-bay berths and isolation
wards to the attendant's desk in the sick bay.
Circuit A consists of bells and buzzers at the
orderly and pantry stations and nonwatertight
pushbuttons in the various cabins, staterooms,
and messrooms. Where a station is to be signaled by more than one pushbutton, a drop-type
annunciator is installed in addition to the bell
or buzzer.
Three simplified call-bell circuits are shown
in figure 6-14. These simplified circuit connections apply to circuit A as well as to circuit
E.
The upper branch circuit, with one bell and
one pushbutton in series with each other, is
used to call a single station from one location.
The center branch circuit, with two pushbuttons in parallel with each other and in series
with the bell, is used to operate one bell from
two remote locations.
165
175
4I1 I
.=
OOOOO MEMO.
4
1
1
I
al
ma
r
IONIMIMUU
s
MINNMMIMMMO
PM
IN MNO
MINIM
N
immounmor
mom
.....m.
um".
Chapter 6SOUND-POWERED TELEPHONES
RELAY
DROP COILS
PUSH BUTTON
-r-...N7
O
IL
o 1EX1
o 1EX2
o 2EX1
PUSH BUTTONS
I
o 2EX2
S
BELL
a 1EXX
o 2EXX
0
aBELLS
115V
0
PUSH BUTTON
27.293
_n....
_
Figure 6-15. Two-circuit, four-drop annunciator.
I
ANNUNC aTORS
1.C. SWBO
Call-bell stations that have several soundpowered handsets, each on a different circuit,
are provided with annunciators to identify the
circuit of the station that originates the call.
Annunciators used with E-call circuits are
120 VOLTS
EE I
LINE
IE
of the drop type. The drop, or target,, is embossed
L
with the circuit letter and is held mechanically
in the nonindicating position. When the circuit
is energized by operating a pushbutton at the
FUSES
_
_ -_I
27.292
Figure 6- 14. Simple call-bell system.
The lower branch circuit, with two bells in
parallel with each other and in series with one
pushbutton, is used to operate two bells from one
location.
Note that the bells or signaling devices (fig.
6-14) are connected to the side of the line bearing the negative designation, EE. This arrangement is used on a-c circuits that have no polarity but in which one side of the line arbitrarily
is designated as EE for convenience.
calling station, an electromagnet causes the
target to drop to the indicating position. The
drops are returned to their normal, or nonindicating, positions by a hand-operated reset
button.
Annunciators used with A-call circuits are
similar to those used with E-call circuits ex-
cept that in A-call circuits the drop is embossed with the number of the stateroom, or
location of the calling station, instead of the
circuit letter.
A simple diagram for a 2-circuit, 4-drop
annunciator is shown in figure 6-15. When a
pushbutton is operated, the proper annunciator
drops and the bell rings. The alarm bell rings
only while the pushbutton is closed. One side
of each drop and one side of an audible-signal
relay are connected together so that when the
167
177
IC ELECTRICIAN 3 & 2
external circuit is closed by the p, shbutton,
the current flows through the drop and the relay.
The relay is energized and closes its contacts
to the audible signal. The annunciator may be
equipped with one or more relays as required
by the number of associated circuits, but utilizing a common audible signal.
SOUND-POWERED TELEPHONE
AMPLIFIER AM-2210/WTC
In high noise level areas such as engineering
control, _ Gering engine rooms, and gun mounts,
it is often difficult if not impossible to hear
telephone conversations, even over the best
maintained circuits. Recognizing this, the Navy
developed the sound-powered telephone ampli-
fier to assist communications in these vital
areas. The transistorized AM-2210/WTC, one
of the more recent designs presently in wide
use throughout the fleet, meets the following
requirements with a high degree of reliability:
..
1. Amplify one-way communications in a
two-way sound-powered system using existing
sound-powered headsets. (That is, amplify the
140.71
Figure 6-16. Audio frequency amplifier
AM2210/WTC.
voice to the gun mounts but not the voice from it.)
2. Supply six outlet headsets and two loudspeakers.
3. Be fail-safe on power loss or component
failure. (Allow normal level. conversation.)
4. Operate on 115-volt 60-hertz a-c power.
When operating under normal conditions, the
AM-2210/WTC (fig. 6-16) receives signals from
the remote telephone line, amplifies them, and
transmits the amplified signal to as many as six
headsets and two loudspeakers. Direct talk-back
between any of the six headsets and the remote
line is carried out at normal sound-powered
level, the amplifier being disconnected upon the
actuation of any of the six talk switches.
When the amplifier is deenergized or certain
predetermined casualties occur, direct two-way
communications between local and remote sta-
components. One relay (K1) is employed in the
switching circuit.
AUDIO AMPLIFIER
The amplifier consists of a low level, threetransistor amplifier, (Q1 thru Q3), and a power
amplifier (Q4 and Q5), with negative feedback
employed throughout. The output transformer T3
(not shown) has two secondaries; the first is used
with the loudspeakers and the latter, a tapped
winding is
SWITCHING Ca.CUIT
tions are not interrupted. They are however,
conducted at a normal sound-powered level.
Electrically the unit consists of an audio
amplifier, a switching circuit, and a power
supply, with all possible circuitry being static
in nature. The incorporation of transistors in
the audio and switching circuits as well as
silicon junction diodes in the power supply,
creates a high reliability static condition. Figure
6-17 gives a functional display of the varied
used for as many as six sound-
powered telephone outlets.
The switching circuit is activated when the
amplifier is energized. With power available
and neither heal nor remote talk switches
closed, the relay K1 is operated. When operated,
the depression of a remote talk switch will have
no effect upon Kl, that is, it will remain operated.
When power is available and one of the six local
talk switches is depressed, however, the circuit
to K1 is changed and K1 restores (as discussed
later in this chapter).
168
178
Chapter 6SOUND-POWERED TELEPHONES
-1
SPEAKERS
1
TI
2
REMOTE
VOLUME
SWITCH
1(1
6
LINE
AMPLIFIER
01-05
3
02
S
1
CI
12
LOCAL
NEAr1SE TS
I
SWITCHING
CIRCUIT
06
9
NOTE Si SHOWN IN
POSITION
SHOWN IN Of-ENERGIZED
(RESTORE()) POW**,
POWER
SUPPLY
115V
60 CPS
L
-
P
Si
140.72
Figure 6-17. Functional diagram of AM2210/WTC.
Figure 6-18 is a functional representation of
the K1 switching circuit showing K1 in an energized and operated condition. The receiver element of the local headset is in series with a d-c
blocking capacitor, thereby presenting a high
resistance when the talk switch is open. Closing
the talk switch connects the headset across the
line, giving the headset a d-c resistance of approximately 4.8 ohms. It is the function of the
switching circuit to sense this change from high
impedence to low resistance that takes place
with the depression of one of the six heathet
talk switches.
Resistor R31 provides a bias to the baie of
Q6, which normally holds Q6 in a saturated state,
maintaining K1 in an operated cc.ndition.When the
local talk switch is closed, the base of Q6 is
connected to ground through the 4.8 ohms of the
Presently the voltage across Q6
from base to ground becomes less than the
emitter bias voltage provided by the divider
while the intent of CR1 is to protect Q6 from
surges while it is in the cutoff state.
As can be seen from the foregoing, the
restoration of Kl will result on normal" communications at sound powered level between all
stations; the amplifier being effectively by-
passed. The advantage of this circuitry is that
any casualty, such as a loss of power, will al:ow
normal sound-powered communications.
POWER SUPPLY
The power supply is basically a full-wave
rectifier receiving its power through switch 51
(fig. 6-17) and the fuses on the face of the unit.
A neon glow lamp and a volume control potentio-
meter are also located on the unit's face.
mouthpiece.
R32 and 1133; therefore the transistor becomes
reverse biased and Q6 becomes nonconductive,
deenergizing and restoring Kl.
The incoming and outgoing voice F = finals are
coupled through capacitor Cl of the amplifier
MAINTENANCE
Although by no means trouble frA., the AM2210/WTC is a highly reliable unit. When trouble
does occur it often is cauetd by improper
operating procedures by personnel, or a failure
169
IC ELECTRICIAN 3 & 2
Figure 6 -18. Switching circuit of AM2210/WTC.
in external circuitry. Often personnel who oper-
140.73
ate the unit are not aware of the operational
integrity will result in K1 being continually
restored and bypassing the amplifier system.
practice of taping close the talk button of one
of the local headsets. This violation of circuit
tors Q4 and Q5 were found subject to grounding.
Authorized modifications will correct the difficulty.
capabilities of the unit ind a brief indoctrination
will clear an apparent trouble. One procedure
wMch has caused some failures in the unit is the
In earlier models of the amplifier, transis-
170
180
CHAPTER 7
ALARM AND WARNING SYSTEMS
Although they often constitute little more than
a power soiree, a switch, and an alarm device,
the alarm and warning systems of the various
Interior Communications systems are extremely
vital to any ship's operation. One would not operate
his automobile with the low oil pressure or high
engine temperature alarm glaring. Sc. A is with
the machinery and other components of any ship's
alarm and warning system. It just doesn't make
sense to operate a turbine when the bearings are
overheating or the oil pressure is low.
Alarm and warning systems installed in Navy
ships provide audible and/or visual signals when
abnormal or dangerous conditions occur. The
principal components of alarm and warning sys-
tems are switches or contact makers, relays,
thermostats, and audible and visual signals.
The systems, and their circuit designations and
classifications are listed in table 7-1.
or watertight explosion-proof construction, with
circular or cowbell shape gongs.
Alternating-current bells have 4 types of
gongs: Circular 3-inch diameter, type IC/B8S4;
Circular 4-inch diameter, types IC/B5DSF4
and IC/B5S5; Circular 8-inch diameter, types
IC/B2S4 (watertight), and IC/B2S4 (watertight
explosion-proof); and cowbell type IC/B3S4 (fig.
7-1).
Direct-current bells have 3 types of gongs:
Circular 2 1/2-inch diameter, type IC/B1D4;
Circular 8-inch diameter, type IC/B2D4 (fig.
7-2); and cowbell type IC/B3D4.
Buzzers are used only in relatively quiet
spaces. Buzzer, type IC/Z1D4 (fig. 7-3), is d-c
operated and has make and break contacts.
Buzzer, type Tr /Z154, is a-c operated and has
no contacts.
Horns and Sirens
SWITCHES AND aELAYS
Switches used with alarm and warning systems include manual switches, pressure and
thermostatic switches, mechanical switches,
and water switches as discussed in chapter 3 of
this training manual. Relays are used to open
and close circuits that may operate indicating
lights, annunciator drops and/or audible signals.
AUDIBLE SIGNALS
There are many types of audible signals in
use aboard Navy ships. The type of signal used
depends upon the noise level of the location, and
the kind of sound desired. The principle types
of audible signals are bells, buzzers, horns,
and sirens. Electronic sirials are being used
for some applications on .. ,w construction ships.
Bells and Buzzers
Bells used with alarm and warning systems
may be either a-c or d-c operated, watertight
Nonresonated horns
H4D2,
IC/H4D3)
(types IC/H1D4, IC/
utilize
a diaphragm
actuated by a vibrating armature to produce
sound of the required intensity.
Resonated horns (fig. 7-4A), types IC/H2S4
and IC/H2D4, also use diaphragms, and in addi-
tion, have resonating projections to give the
sound a distinctive frequency characteristic.
The resonated horn is designed in a variety of
types, differing as to intensity, frequency, or
power supply.
Motor-operated horns (fig. 7-4B), types IC/
H8D3, IC/H8D4, and IC/H8S3, utilize electric
motors to actuate the sound producing diaphragms.
Sirens are used in very noisy spaces or to
sound urgent alarms. Ile sound is produced by
an aectric motor driving a multiblade rotor
past a series of ports or holes in the housing
(fig. 7-5). The air being forced through the
ports gives a siren sound, the frequency of
which depends upon the number of ports, the
numl.e.r of rotor blades, and the motor speed.
ie.
VII11.-sIM!
and
IC ELECTRICIAN 3 & 2
Table 7-1. Alarm and Warning Systems
Circuit
BZ
System
Importance
Readiness Class
Brig cell door alarm and lock operating
NV
4
BW
Catapult Bridle Arresterman safety Ind.
NV
1
CX
Bacteriological Lab. & Pharmacy Comb. Refer
NV
1
Secure communications space door position
NV
1
V
2
NV
1
SV
2
SV
1
SV
1
Oxygen-nitrogen generator plant low tem-
NV
1
EF
Generator bearing high temperature alarm
SV
1
EG
Propeller pitch control, hydraulic oil system
low pressure alarm
SV
2
EH
Gas turbine exhaust high temperature
alarm
SV
1 (aux. machinery)
2 (prop. machinery)
EJ
Feed pressure alarm
SV
1
LEK
Pneumatic control air pressure alarm
NV
2
3EK
Catapult steam cut'ff and alarm
NV
2
EL
Radar cooling lines temperature and flow alarm
NV
1
EP
Gas turbine lubricating oil high temperature
SV
1 (aux. machinery)
2 (prop. machinery)
Desuperheater high temperature alarm
SV
1
Catapult steam trough high temperature
alarm
SV
2
Failure
DL
alarm
DW
Wr -rig direction alarm
EA
Reactor compartment or fireroom emergency
alarm
Lubricating oil low pressure alarmpropulsion machinery
IEC
2EC
LED
2ED
Lubricating oil low pressure alarmauxiliary machinery
Generator high temperature alarm
perature alarm
,
alarm
IV,'
2EQ
27.352.1
172
g4
1 81"
Chapter 7ALARM AND WARNING SYSTEMS
Table 7-1. Alarm and Warning Systems Continued
Circuit
System
3ES
Reactor till alarm
ET
Importance
Readiness Class
V
1
Boiler temperature alarm
NV
1
EV
TO3ZiC vapor detector alarm
SV
1
1EW
Propulsion engines circulating water high
temperature
SV
1
2EW
Auxiliary machinery circulating water high
temperature
SV
1
EZ
Condenser vacuum alarm
SV
2
F
High temperature alarm
SV
1
4F
Combustion gas and smoke detector
SV
1
9F
High temperature alarm system-ASROC
launcher
SV
1
11F
FBM storage area temperature and humidity
SV
1
12F
Gyro ovens temperature and power failure
alarm
SV
1
FD
Flooding alarm
NV
1
Fli
Sprinkling alarm
SV
1
FR
Carbon dioxide release alarm
NV
1
FS
Flight Deck Ready light Signal system
NV
2
FZ
Security alarm (CLASSIFIED)
V
1
4FZ
Torpedeo alarm (CLASSIFIED)
V
1
HF
Air flow indicator and alarm
SV
1
LB
Steering Emergency Signal system
NV
2
IS
Submersible steering gear alarm
SV
2
MG
Gas turbine oversneed alarm
SV
1 (aux. machinery)
2 (prop. machinery)
NE
Nuclear facilities air particle detector alarm
NV
1
alarm
27 .352.2
173
a
°3
IC ELECTRICIAN 3 & 2
Table 7-1. Alarm and Warning Systems Continued
Circuit
System
Importance
Readiness Class
NH
Navigation Horn Operating System
NV
2
QA
Air lock warning
NV
1
QD
Air filter and flame arrester pressure differential alarm, or gasoline compartment exhaust
V
1
Qx
Oxygen-nitrogen plant ventilation exhaust alarm
SV
1
RA
Turret emergency alarm
NV
1
RD
Safety observer warning
NV
2
RW
Rocket and torpedo earning
SV
3
4SN
Scavenging air blower high temperature alarm
V
2
SP
Shaft position alarm
NV
2
TD
Liquid level alarm
NV
1
1TD
Boiler water level alarm
NV
1
2TD
Deaerating feed tank water level alarm
NV
1
5TD
Reactor compartment bilge tank alarm
SV
1
6TD
Primary shield tank, expansion tank level alarm
NV
1
IN
1
blower alarm
7TD
-..-/-
-.--". Reactor
plant fresh water cooling expansion tank
level alarm
STD
Reactor secondary shield tank level alarm
NV
1
9TD
Lubricating oil sump tank liquid level alarm
SV
1
11TD
Induction air sump alai m
SV
1
12TD
Diesel oil sea water compensating system tank
liquid level 'larm
SV
1
14TD
Auxiliary fresh water tank low level alarm
NV
1
16TD
17TD
Pure water storage tank low level alarm
Reserve feed tank alarm
SV
NV
1
1
18TD
Effluent tanks and contaminated laundry tank
high level alarm
V
1
27,3E1,3
174
184
Chapter 7ALARM AND WARNING SYSTEMS
Table 7 -1. Alarm and Warning Systems Continued
Circuit
Importance
System
Readiness Class
Sea water expansion tank low level alarm
Gasoline drain tank high level alarm
SV
1
20TD
SV
1
21TD
Moisture separater drain cooler high level alarm
NV
1
24TD
Reactor plant on board discharge tank level alarm
V
1
25TD
Crossover drains high level alarm
SV
1
29TD
Sonar dome fill tank low level alarm
SV
1
30TD
JP-5 fuel drain tank high level alarm
SV
2
TW
Train Warning system
NV
1
W
Whistle Operating System
NV
2
19TD
Legend:
SV-6emivital NV-Nonvit9.1.
V-Vital
1-Continuously energized-supply switch color code yellow.
2-Energized when preparing to get underway, while underway, and until the ship is securedsupply switch color code black.
3-Energized during condition watches -supply switch color code red.
4-Energized only when required-supply switch color code white.
All electronic type alarm systems formerly designated as circuits CA, FC, FW, G, GD, GJ, GN,
and FP are now classified as a portion of the respective announcing system with which they are
associated.
27.352.4
system. The unit contains a solid state oscilL nor
Electronic Signal Units
which generates three distinct tones; a steady
siren; a siren wail; and a siren yelp tone.
The type IC/E1D1 electronic signal unit (fig.
7-6) is designed as a bus failure alarm. The
unit contains an electronic solid state oscillator
which drives a 2-inch howler unit to provide an
audible signal upon loss of power on the supervised bus. The unit also provides a visual signal
VISUAL SIGNALS
Visual signals are used in a great many
alarm and warning systems to provide an addi-
tional means of identifying the alarm being
sounded. Audible and visual signals are often
used together. In noisy spaces audible signals
are supplemented by v,aual signals, and in
brightly lighted spaces visual signals are sup-
upon loss of power.
The power for the oscillator is provided by
a small nicke'.- cadmium battery which is maintained on a low charge when the supervised bus
is energized. The unit will operate on 115 volts,
plemented by audible signals. In many instruments the same audible device is used in combination with several visual indicators. The
d-c or a-c (60 Hz or 400 I:z) without modification.
The IC/E3D2 electronic signal unit (fig. 7-7)
is designed for use with Navy standard alarm
175
185
IC ELECTRICIAN 3 & 2
Figure 7-1.IC/B3S4 bell.
27.297
principal types of visual signals are lamp type
indicators and target drum type alarm indi-
cators.
Lamp Type Indicators
**N. Figure 7-3.IC/Z1D4 buzzer.
Standard watertight, lamp type indicators
are designed as single-dial, 2-dial, 3-dial,
27.299
a
4-dial, and 6-dial units (fig. 7-8A). Two 115-
volt lamps are connected in parallel and mounted
behind each dial. The use of two lamps in parallel
provides protection against the loss of illumina-
tion in case one lamp burrs out. A colored-
glass disk and sheet-brass burns out. A coloredglass disk and sheet-brass target engraved with
the alarm identificatior. :re illuminated from tlie,
rear by the two lamps. Glass disks are furnished
in eight standard colors, depending upon the
application.
The 115-volt lamps are in parallel with the
audible signal. When the audible signal sounds,
the lamps illuminate the colored glass and brass
target of the indicator and identify the alarm
being sounded. This type of indicator is used
Figure 7-2.
27.298
IC/B2D4 bell.
with various alarm systems
Standard watertight lamp type indicators are
designed also as 2-dial variable-brilliancy, (fig.
7-8B), 2-dial fixed-brilliancy, and 4-dial variable-brilliancy unit. Two 6-volt lamps are connected in parallel and mounted behind each dial.
A colored jewel disk and sheet-brass target are
illuminated from the rear by the two lamps.
176
186
Chapter 7ALARM AND WARNING SYSTEMS
Bk.
r
4
A114,
Figure 7-5. Siren.
27.301.
A
- .........
h.
"I-
Ltr
;*;
1
if
. -7:1
..-,--;i'
,:,....",.
;'
.7
POWER
ILENcE
61.7'1
0
0
0
0
0 BEARING,REAR OILITE
0
r.00-0R hOuSING
C) moroR
SuPPORi REAR
O MOTO P SUPPCRT,
;Pow'
® IEP
;
:",
INSULATOR
RATT.J.E t
***
Is
vctlf
lave.__evats..44,*
Mr
ANVIL
,s
0 ARi.RAGM
calmer i,:vArmer".
CI)
B
27.300
27.302
Figure 7-4.Motor operated and resonated
Figure 7-6.
horns.
177
Electronic signal unit type IC/E1D1.
IC ELECTRICIAN 3 & 2
for the audible alarms by moviag roller (3).
However, the supervisory target relay is
designed to be normally operated; its alarm
contact is closed when the relay is deenergized.
The alarm drum has a red section that rolls
into view when the alarm target relay is operated. The supervisory drum shows a yellow
section when it is deenergized.
The two relays are in series with the alarm
device, which is a mercury thermostat in the
.140.120
Figure 7-7. Type 1C/E3D2 electronic signal
unit.
Special lamp type indicator pal:csls are de-
signed to give good visibility at all viewing
angles. These panels contain rows of prismshaped red and green jewels. Each indicator
has two 6-volt lamps in parallel. This type of
indicator is used in the main ballast tank and
hull opening indicator system.
Another special lamp-type indicator consists
of two indicator lights (red and green). Six
115-volt lamps in parallel are provided for each
indication. This type of indicator is used in the
traffic control ready light system on aircraft
carriers.
Alarm Indicators
Each two-line alarm unit provides complete
equipment for supervising two circuits. Each
circuit requires an alarm-target relay, a
supervisory-target relay, and a three-position,
toggle type test switch. The two-line unit (fig.
7-9), has two alarm relays mounted side by
side at the rear and near the bottom of the unit
panel. Each relay has an indicator drum that
projects into square openings in the face of the
panel. The two test and cutout switches are
mounted above the alarm relays. The two super-
visory relays, with their indicator druns, are
mounted above the test and cutout switches.
The relays (fig. 7-10) are of similar con-
struction. However, the number of turns on the
coils and the contact arrangement are different.
Note that when the armature (1) of the alarm
relay operates, it rotates the target drum (2B)
through an eccentric, and closes the contacts
high-temperature alarm (fig. 7-11).
As the operation of a relay is dependent on
the ampere-turns, the current can be limited
so that there will be the required ampere-turns
to operate one coil and insufficient ampereturns to operate a second coil with fewer turns.
The supervisory resistor (fig. 7-11) is in series
with both relays under normal conditions and
acts as a current-limiting device.
Under normal conditions the current that
flows in the supervisory circuit (fig. 7-11),
is supplied by a transformer and rectifier.
The current flows from the negative side of
the rectifier through the operated sui,ervisory
target relay, the supervisory resistor, the lower
section of the mercury thermostat or alarm
device, the energized but not operated alarm
target relay, and back to the rectifier. The
total resistance of the circuit supplied by the
rectifier is 9675 ohms. When the temperature
rises at the alarm device, and the mercury
reaches the upper contact, the 7000-ohm super-%
visory resistor is shunted out of the circuit.
This reduces to 2675 ohms the total resistance
of the circuit supplied by the rectifier. This
increase in current is enough to operate the
alarm target relay. The alarm-target relay in
operating rotates its red target into position
and closes the contact that completes the circuit
to the extension relay, which is supplied power
from the primary side of the transformer.
When the extension relay operates, it closes the
contacts to complete the circuit to the bell. The
bell fu..hishes the audible alarm and the target
drum the visual signal, to indicate which circuit
has the high-temperature alarm.
A loss of current in the supervisory circuit
will cause the supervisory-target relay to release its armature. When the amature drops
down it closes the alarm contact to complete
the circuit from the primary side of the transformer to the buzzer. The target drum furnishes
the visual signal of the circuit in trouble.
An open circuit in either side of the transformer, the rectifier, or the supervisory circuit will cause the :Rizzer to sound.
178
iris
Chapter 7ALARM AND WARNING SYSTEMS
if ?1'
Figure 7-8.
Lamp type indicator.
179
189
T
27.303.1
IC ELECTRICIAN 3 & 2
27.304
Figure 7-9. Two-line alarmunit
Each electromagnet actuates contacts for
energizing common audible signals. A nameplate is provided on the panel to identify the
alarm being sounded. A switch is provided to
test the circuit and to cut off the alarm.
ship to detect and warn of fires or overheated
conditions
spaces.
in
important compartments
and
All alarm systems used in Navy Ships are
closed-circuit supervisory type. Each
circuit of the system consists primarily of one
trouble-alarm relay, one cutout key, one alarm
signal, and one thermostat or group of thermostats.
of the
FIRE ALARM SYSTEMS
There are three indications of fire; heat or
temperature rise, smoke or combustible gases,
and flame. The Navy uses two methods of detection in its circuit F fire alarms. The temperature-rise method, wiich uses a mercury
thermostat, is found on the older naval ships.
On new construction, conversions, and ammunition ships, in awlition to the temperature rise
system, there is a combustion gas and smoke
detector system (circuit 4F).
Alarm Panels and Switchboard
The alarm switchboard is installed in a station, which is continuously manned while both
underway and in port. The alarm switchboard
operates on 120-volt, a-c 60-hertz or 120-volt,
d-c service supplied from the main IC switchboard. The alarm switchboard consists of an
upper section and a lower section.
The UPPER section comprises the alarm
HIGH-TEMPERATURE ALARM SYSTEM
The high-temperature alarm system (circuit
an electrical system installed aboard
F) is
panel (fig. 7-12)., This panel contains an alarm
bell, a test light, a trouble buzzer, two grounddetector lamps, a pilot lamp, a trouble test
180
1 90
Chapter 7ALARM AND WARNING SYS'2EMS
ALARM RELAY
lamp, an alarm test lamp, and a test key. An
extension signal relay, capable of operating up
to four fire alarm bells located at other stations
on the ship, is mounted at the rear of the alarm
panel. As long as the power supply to the
switchboard is maintained, the pilot light at the
center of the panel glows.
.
The LOWER section consists of as many
10-line or 20-line panels as are necessary to
accommodate the total number of high-temperature, circuit F, or water-sprinkling cir-
cuit FH stations aboard the ship. Six 10-line
panels capable of accommodating 60 lines are
shown in figure 7-11. The switchboard apparatus for each two lines is mounted together in a removable alarm unit. Five or
ten of these 2-line units are arranged to
make up a 10-line or a 20-line panel. Each
line supervises one thermostat or one group
of thermostats. Each circuit is provided with
a separate test key with a drum trouble-
SUPERVISORY RELAY
indicator target ubove, and a drum fire-indicator
target below. A nameplate located above the
test key identifies the compartment or the spaces
served by that line.
TYPE IC/B11 ALARM SWITCHBOARD.
The
type IC/SM Supervisory Alarm switchboard provides for centralized monitoring of remotely lo-
cated sensors by means of compact modular
plug-in units. The switchboard (fig. 7-13) houses
the audible speaker, speaker control switch,
lamp dimmer, up to 50 individual display modules,
0
0 ARMATURE
0 ROLLER
0 ECCENTRIC ARM
0 COIL
the power supply, fuses, and ground detector.
The alarm module (fig. 7-14) has a manual
selector switch for placing the module in either
@ TARGET DRUM
NORMAL, STANDBY, CUTOUT or TEST modes
27.305
Figure 7-10.Alarm and supervisory relays.
III
I
0
and a divided, lighted display, either half of
which can show a steady or flashing red light or
no light as required.
1350 OHM
UPERV1SORY
5 OHMS
TARGET RELAY
FF
120 VOLTS
60 Hz
I49V
0
BUZZER
)44V
142V
EXTENSION
RELAY
SUPERVISORY
RESISTOR
*
BELL
h
I
4/4
20
ALARM
TARGET RELAY
0 13259
F
p
150°,125°
OR 105 °F
-I6°F
ALARM
DEVICE
1
27.306
Figure 7-11. High-temperature alarm circuit.
181
191
IC ELECTRICIAN 3 & 2
ALARM
ALARM
TEST KEY
BELL
TEST LIGHT
TROUBLE
BUZZER
,
TROUBLE
TEST LAMP
ALARM
TEST LAMP
GRD. DETECTOR
LAMP, P05.
GRD. DETECTOR
LAMP, NEG.
BLOWN FUSE
INDICATOR FOR
EXTENSION
SIGNAL CIRCUITS
PILOT
LAMP
t
TiNs'44
co
l,
co co
co c
4r t,
mipariiiimaririnpo
I
27.307
Figure 7-12. Alarm switchboard.
182
Chapter 7ALARM AND WARNING SYSTEMS
GROUND DETECTION
LAMPS (+ 8)
AUDIBLE SILENCE
INDICATOR
AUDIBLE SILENCE
CONTROL
AUDIBLE SPEAKER
MAIN POWER FUSE
LAMP DIMMER
INDIVIDUAL D:SPLAY
MODULES,I0 PER LINE
140.121
Figure 7 -13.
IC /SM switchboard showing 50 line with 10 active modules in place.
183
194
IC ELECTRICIAN 3 & 2
Placing the mode selector switch in the TEST
position simulates an alarm condition. For this
position the upper lamp flashes while the lower
lamp is out; a wailing tone alarm sounds just as
it does for an alarm condition in the NORMAL
mode.
The lamp dimmer affects all,the module indiZx
cating lights except for the alarm condition lights
which continue to flash at full brilliance.
Thermostats
As previously mentioned, the detection of
Tres or overheated conditions is accomplished
by means of mercury thermostats (fig. 7-16).
These thermostats are installed at selected
locations throughout the ship. Thermostats are
installed on the overhead and require a free
circulation of air for efficient operation. Barriers that would obstruct the free circulation
of air should never be placed around thermostats
in any compartment. On the other hand, thermostats should not be installed in the path of supply
ventilation.
The thermostats are designed to close their
contacts at temperatures of 105°, 125°, or 150°F.
Except for differences in temperature ratings,
the thermostats are similar. A defective ther-
mostats are similar. A defective thermostat
must be .replaced with one having the same
temperature rating.
140.122
Figure 7-14.IC/M alarm module.
Temperature Ratings
The 125° and 150° F thermostats are normally installed in storerooms, paint lockers,
and similar spaces used to house combustible
In the NORMAL mode, the upper lamp is
"on steady" and the lower lamp is off (fig. 7-15).
During an alarm condition, the upper lamp flashes
and a wailing tone alarm sounds.
To acknowledge an alarm the switch is shifted
to STANDBY and the audible alarm is silenced
stores. The 105° F thermostat is normally
installed in magazines. Because its function is
to detect rises in temperature above the limits
that are safe for magazine spaces, the upper
while both the upper and lower lamps are "on
steady." After the alarm condition is cleared,
the lower lamp flashes while the upper lamp
goes out; a pulsating tone alarm is produced
to inform the operator to return the switch to
contact is located so that the resistor is shorted
out when the temperature reaches 105° F.
As many thermostats as are needed for the
prompt detection of a fire can be connected to
lamp goes out while the lower lamp is "on
any one line. If more than one thermostat is
used in a compartment, only one supervisory
resistor is required, as shown in figure 7-17A
sensor circuit by placing the mode selector
the thermostats in the group is overheated, the
alarm operates. These thermostats or groups
of thermostats are cor.nected to the alarm
NORMAL.
If the sensor circuit should open, the upper
steady ;" a pulsating tone alarm sounds' when
the module is in the NORMAL mode. Then to
work on the circuit safely, you deenergize the
switch to CUTOUT. In this position the lamps
indicate as they do for supervisory failure:
top lamp out, lower lamp "on steady," no
audible alarm.
and R. With such a connection, when any one of
switchboard
by
multiconductor cable.
Each
circuit on the alarm switchboard is marked to
designate one compartment, and the thermostat or group of thermostats, installed in each
184
194
Chapter 7-ALARM AND WARNING SYSTEMS
NORMAL ALARM
NORMAL
OR TEST
771-rj, 7=7
:.::::;:::
STAND-BY ALARM
'-'::::::..
;:;::..
WAILING
STANDBY
ALARM CLEARED
CUTOUT
ar-PULSATING
SUPERVISORY
FAILURE
T'.-PULSATING
140.123
Figure 7-15. IC/SM visual displays and audible outputs.
185
IC ELECTRICIAN 3 8g 2
sTrmr,tv "*,
27.308
Figure 7-16.
Mercury thermostat type IC/J125.
compartment is connected to the circuit marked
for that compartment.
Operation
When conditions are normal, direct current
(approximately 0.0p2 amp) flows from the fullwave rectifier (fig. 7-11), through the super-
visory target relay, the supervisory resistor,
to the intermediate contact of the thermostat,
through its mercury column to the lower contact,
and through the alarm target relay to the rectifier. The current is limited by the 7000-ohm
resistor to a value required to operate the supervisory target relay. This value is smaller than
that required by the alarm-target relay.
In case of fire or other high-temperature
condition the mercury expands and rises in the
thermostat, the supervisory resistor is shorted
out, and the current rises to a maximum value
in the circuit. The increase in current is large
enough to cause the alarm target relay to operate. The relays target is revolved and the alarm
contacts close, to sound the alarm.
When an open circuit occurs, such as in the
secondary of the transformer or a broken
thermostat bulb, the supervisory current no
longer flows in the circuit and the supervisory
relay deenergizes. This action closes its con-
tacts and completes the circuit to the buzzer
and the target is rolled to show yellow.
A switch is provided in each circuit for use
in testing the circuit and for silencing either the
fire bells or trouble buzzer when they sound
an alarm. Complete tests and operating instructions are included on the MRC for the
system and in the manufacturer's technical
manual provided for the alarm equipment installed in your ship.
186
196
Chapter 7ALARM AND WARNING SYSTEMS
chamber. When combustion gases and/or smoke
are present in the air of the outer chamber, the
cold cathode tube fires and supplies the current
to operate the alarm relay.
The air in the inner and outer chamber is
made conductive by a small quantity of radium
(fig. 7-18C). Alpha particles given off by the
7000
radium have the ability to ionize air into positive
ions and negative electrons. If this ionized air is
introduced Into an electric field, a current will
flow. This principle is shown in figure 7-19. A
potential from battery, B, is applied to the plates,
P1 and P2. The air between the plates is
ionized by the radium. The charged par-
OHMS
ticles move in the direction indicated by the
A
arrows. A sensitive galvanometer measures the
current, the value of which depends on the
strength of the radium source, and within limits,
the voltage of the battery. With low potentials,
part of the ions and electrons collide and neutralize each other. It is only when the potential
7000
reaches a certain limit that all of the ions
OHMS
formed reach the plates. This is known as the
saturation point. Beyond this point, the current
remains virtually constant regardless of the
increase of potential. OW.; a change in the gas
in the chamber will cause a change in the current flow when the unit is operating at the saturation point.
Figure 7-17. Thermostat connections.
The presence of combustion gas or smoke
particles between the plates (fig. 7-19), would
cause a sharp decrease in current flow through
COMBUSTION GAS AND SMOKE
combustion gas and smoke particles are many
times larger and heavier than the air molecules,
27.309
the
galvanometer.
This is true because the
and require a stronger radioactive source to
DETECTOR SYSTEM
become ionized. Also, the ionized combustion
gas and smoke particles move much slower in
the electric field, and are practically all neutralized by free electrons before reaching one
of the plates.
The combustion gas and smoke detector sys-
tem, circuit 4F, detects and warns of the presence of combustion gases or smoke. The alarm
circuits are similar to, and operate in the same
manner as the high-temperature fire alarm
circuits. A combustion gas and smoke detector
head is used as the alarm device.
BASIC CIRCUIT
'OPERATING PRINCIPLES
In the basic circuit of the detector system
(fi. 7-20), the normal voltage across chamber
X is 130 volts d-c, and 90 volts d-c across
chamber 0 and tube elements S and K. The
The combustion gas and smoke detector head
(fig. 7-18A), is installed on the overhead
breakdown voltage between the plate, A, and
cathode, K, of the cold cathode tube is greater
than 270 volts. Therefore with 220 volts ap-
in the compartment or space to be protected.
A four-pin polarized plug fits into a socket
base allowing easy replacement (fig. 7-18B).
The major units of the detector head are the
inner and outer chambers and the cold cathode
plied to A and K, the tube will not fire until
triggered by the starter, S. The tube is triggered when the voltage between S and K reaches
110 volts.
tube (fig. 7-18C). The detector compares the air
in the inner chamber with the air in the outer
187
187
IC ELECTRICIAN 3 & 2
X- INNER OR REFERENCE CHAMBER; 0-OUTER OR DETECTING CHAMBER;
;
Ro- RADIUM SOURCES; SA-SENSITIVITY ADJUSTMENT CAP; T SENSITIVITY
ADJUSTMENT SCREW; G- GAS OISCHARGE (COLD CATHODE) TUBE; A-ANODE;
K - CATHODE; S- STARTER ELECTRODE; W-INNER WIRE GRID ELECTRODE;
J - LOCK IN G SHELL; V - 0 RING F- SOCK ET BASE; L - LOCKING SET SCREW;
Y- TERMINAL SCREWS.
Figure 7-18.Combustion gas and smoke dLtector head.
188
138
27.310
Chapter 7 ALARM AND WARNING SYSTEMS
With no smoke or combustion gas present
in the outer chamber, only enough current flows
to energize the supervisory target relay.
The current flow is from the d-c source ( s. full-
wave silicon diode rectifier) through the outer
and inner chambers, the supervisory resistor
R, and back to the d-c source. When smoke or
a combustion gas enters chamber 0, it increases
the resistance of that chamber which- causes
the current to decrease through both chambers.
As the resistance of chamber X is fixed, the
voltage across it decreases. This causes the
voltage across chamber 0 and across S and K
to increase to 110 volts triggering the cold
cathode tube. The tube conducts from K to A
furnishing the required current to operate the
alarm target relay.
SPRINKLING ALARM SYSTEM
The sprinkling alarm system, circuit FH,
is basically the same as the high-temperature
alarm system except that water or pressure
switches are used instead of mercury thermo-
G- ELECTRONS
Ra - RADIUM
q- ALPHA RADIATION
0-IONS
B - BATTERY
stats.
GAM- GALVANOMETER
LUBRICATING-OIL, LOW-PRESSURE
ALARM SYSTEM
P1 AND P2- PLATES OR ELECTRODES
27.311
Figure 7-19. Ionization principle.
The purpose of the lubricating-oil, low-pressure alarm system, circuits lEC and 2EC,
220
VOLTS
+
ALARM
TARGET
RELAY
40,000
OHMS
10
WATTS
B TO 220
VOC
SOURCE
SUPERVISORY
TARGET
RELAY
X INNER OR REFERENCE CHAMBER; 0 - OUTER OR DETECTING CHAMBER,
G GAS DISCHARGE (COLD CATHODE) TUBE; A ANODE; K CATHODE;
S STARTER ELECTRODE; C TRIGGER CAPACITOR;
B ALARM BELL: R. SUPERVISORY RESISTOR.
27.312
Figure 7-20. Basic circuit of detector system.
189
199
IC ELECTRICIAN 3 & 2
is to sound an alarm whenever the pressure in
the lubricating-oil supply line to the main engine and reduction gear, or to the turbine-driven
or diesel-driven generators, and other auxiliary
WHITE
REO
INDICATOR LAMPS
machinery falls below a predetermined minimum
PILOT LIGHT
limit. Where the system is used for the main
engines the circuit is designated, 1EC, and when
CUT
OUT
used for either turbine-driven or diesel-driven
generators and other auxiliaries the circuit is
designated, 2EC. Both circuits are energized
from individual switches on the local IC switch-
NORMAL
4
_4.--:
/TEST:
SWITCH
board.
An EC circuit includes one or more pressure
type switches installed in the lubricating-oil
lines of the associated equipment. A dial-light
indicator, drum typo annunciator, and siren are
LOW.PRESSURE
ANNUNCIATOR
energized when the switch is closed because
of , decrease in oil pressure. The control panel
of the lubricating-oil, low-pressure alarm is
HIGHTEMPERATURE
ANNUNCIATOR
c
located near the operating control board of the
machinery on which the svitch is installed.
r
ANNUNCIATOR
cq
DUSK
CIRCULATING-WATER, HIGHTEMPERATURE ALARM SYSTEM
EC1
ACTUATING COIL
2
:22c
The
circulating-water,
high-temperature
:
alarm system, circuits 1EW and 2EW, automatically indicates when the circulating-water
temperature of the main propulsion diesel en-
0
w
L__
gines or the large auxiliary diesel engines rises
above the predetermined maximum limit. When
AUDIBLE
SIGNAL
the system is used for the main engines the
circuit is designated, 1EW, and when used for
auxiliary engines the circuit is designated,
2EW. The circulating-water, high-temperature
alarm system is usually combined with the lubricating-oil, low-pressure alarm system (fig.
7-21), and consists of temperature-operated
switches located in the circulating water lines
of the engines. A rise in temperature above a
predetermined
point
.
TO IC
U
N
0
Ill
N
t.)
Ill
N
SWITCHBOARO
\
[-F1
LT]
PRESSURE
SWITCH
IND GATING
LAMPSREO LENS
THERMOSTAT
SWITCH
closes a thermostatic
switch, which energizes a lamp-type indicator,
drum-type annunciator, and siren, causing the
alarm to sound.
Figure 7-21.--Schematic of 2EC and 2EW circuits.
GENERATOR AND GENERATOR BEARING
HIGH-TEMPERATURE ALARM SYSTEMS
The generator high-temperature alarm system, circuit lED, provides a means of indicating high temperature of the cooling air exhaust
of generator sets rated at 500 kw and above. The
system consists of thermostatic switches located
in
the generator exhaust to the cooler,
which energize visual and audible signals when
the temperature of the circulating air rises
above a predetermined limit.
27.313
The generator bearing high-temperature
alarm system, circuit E F, provides a means of
indicating high temperatures in the bearings
of generato: s' :s of 200 kw and above. Thermostatic switches energize visual and audible signals when a bearing temperature rises above a
predetermined limit.
The visual and audible signals for circuits
lED, and EF are incorporated in the alarm
lanel of circuit 2EC.
190
200
Chapter 7ALARM AND WARNING SYSTEMS
OPERATED POSITION
BODY
END BUTTON
END BUTTON
REMOVE COVER TO MAKE
WIRING CONNECTIONS WHEN
REINSTALLING COVER BE
SURE THAT SWITCH LEVER
ENGAGES IN SLOT OF PLUNGER
LOWER BODY
COVER
SIDE BUTTON
0I
II
II
STUFFING TUBE
GASKET
CO2 GAS SUPPLY
SIDE VIEW
FRONT VIEW
140.124
Figure 7-22.Pressure-operated switch for CO2 release alarm system.
position: See figure 7-22. The plunger then
CARBON DIOXIDE ( CO ) RELEASE
ALARM SYSTEM
carries the switch lever to the ON position,
released into a monitored space. It is used
causing the bell to operate.
The system may be tested for proper operation by (1) pulling "out" the side button and (2)
pulling the plunger "up" to the operated posi-
sists of a pressure-operated switch and an
alarm bell. The switch is installed in the CO2
supply pipe line of the protected space; the
the spring-loaded side button.
The CO2 release alarm, cricuit FR, is an
alarm system that indicates when CO2 is being
primarily in paint lockers and flammable storage
and paint storage compartments. The system con-
tion by the end button. When these steps are
taken the alarm bell should ring. To reset the
system for normal operation, reverse the procedure: push down on the end button and release
CO2.
alarm be/1 in the space serviced by the
The purpose of the alarm is to warn the per-
sonnel in the protected space that the
CO2
system has been actuated so they may evacuate
the space immediately.
Operation of the system is simple and straight
forward. When the CO2 is released, the pressure
of the CO2 forces the plunger into the operated
BOILER TEMPERATURE ALARM
SYSTEM
The boiler temperature alarm system, circuit ET, provides a means of indicating boiler
steam high temperature in ships having separately fired superheat control boilers. A thermostatic switch located in the main steam line
191
201
IC ELECTRICIAN Z & 2
MEIM.+`
from each boiler energizes a 2-dial lamp type
indicator and a horn, when the total steam
temperature at the superheater outlet rises
above a predetermined limit.
SYSTEMS MAINTENANCE
Alarm and warning system are easy to main-
tain since the MRCs outline the checks to be
performed.
Almost any trouble that will affect system
operation gives an audible and/or visual indication. Do not use oil anywhere in the alarm
aaVIIK
units as it may cause flushovers and short
circuits.
The electrodes of all water switches should
be cleaned after the system has operated. Clean
the electrodes with alcohol and rinse them with
distilled water.
Remove all combustion gas and smoke detector heads periodically. Clean the heads aid
conduct a sensitivity check as described in the
manufacturer's technical manual.
Check all indicator lamps frequently, and
replace any burned-out lamps.
CHAPTER 8
ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
If you should look for the source of .4 sound,
you will find that s mnething had been set in
vibratory motion. It may be that someone shouted
or that an object was dropped or struck. In
each case something had been made to vibrate
and cause the sensation of sound. One sound
that human beings produce is voice. Although air
is the usual medium for carrying voice to your
ears, any elastic materia, in the form of a solid,
liquid, oz gas can serve as well or better. Like
any other sound, voice cannot travel in a vacuum.
In today's Navy, announcing and intercommuni-
cations systems anvlify and then transmit the
voice so it can reach and be heard by the men
aboard ship. With these, systems, which are the
heart of interior communications, the "word"
is passed quickly and clearly. This chapter explains the operating principles of installed and
portable sound systems and describes the types
and characteristics of the microphones and loudspeakers in the systems.
to the vibrations of the sound waves, and some
means of changing this mechanical vibration
into corresponding electrica. signals. The most
widely used types of microphones are the (1)
magnetic, (2) dynamic, (3) crystal, and (4) car-,
bon types.
MAGNETIC MICROPHONE. The magnetic,
or moving-armature, microphone (fig. 8-1) consists of a permanent magnet and a coil of wire inside of which is a small armature. Sound waves
impinging on the diaphragm cause the diaphragm
to vibrate. This vibratioa is transmitted through
the drive red to the armature which vibrates in
a magnetic field, thus changing the magnetic flux
through the armature.
When the armature is in its normal position
midway between the two poles, the magnetic flux
is established across the air gap with no resultant
flux in the armature.
SOUND EQUIPMENT
All sound and announcing systems consist
basically of an amplifier, a microphone, and a
loudspeaker. The microphone converts the sound
energy into electrical energy having the same
waveform ar the sound energy. The ouput from
the microphone is applied as a signal voltage to
the amplifier. The output power from the amp-
SOUND WAVES
lifier has the same waveform as the souridenergy
that is applied to the microphone. The loud -
speaker reconverts the electrical energy from
the amplifier into sound energy at a higher volume level than the original sound. In shipboard
installations many loudspeakers are operated
ELECTRICAL
OUTPUT
from the same amplifier. Each loudspeaker produces sound having the same waveform as the
original sound applied to the microphone.
TYPES OF MYCROPHONES
A microphone is a device that converts sound
7.11
energy into electrical energy. All types of mi-
Figure 8-1.Magnetic microphone.
crophones have a metal diaphragm that responds
193
"Oa
g.
IC ELECTRICIAN 3 & 2
SOUND WAVES
CRYSTAL
VOICE COIL
jr
OUTPUT
VOLTAGE
Awoomete..aNgraarzematira
MAGNET
ELECTRODES
A
DIRECTLY ACTUATED TYPE
POLE PIECE
SOUND WAVES
DIAPHRAGM
DIAPHRAGM
Figure 8-2. Dynamic microphone.
CRYSTAL
7.12
,..010/3
When a compression wave strikes the diaphragm, the armature is deflected to the right.
The flux path is direoted from the north pole of
the magnet across the reduced gap at the upper
right, down through the armature, and round to
OUTPUT
VOLTAGE
zme.07, r
ELECTRODES
DIAPHRAGM TYPE
the south pole of the magnet.
20.219
When a rarefaction wave strikes the diaphragm, the armature is deflected to the left.
Figure 8- 3. Crystal microphone.
The flux path now is directed from the north pole
of the magnet, up through the armature through
the reduced gap at the upper left, and back to the
south pole.
Thus, the vibrations of the diaphragm cause
The dynamic microphone requires no external voltage source, has good fidelity, and produces an output voltage of about 0.05 volt when
nating flux cuts the stationary coil wound around
the armature and induces an alternating voltage
(approximately 10 millivolts at a 150-ohm load)
in it. This voltage has the same waveform as the
sound waves striking the diaphragm.
CRYS7AL MICROPHONE. The crystal microphone utilizes a property of certain crystals such as quartz, Rochelli. salt, sugar, or
an alternating flux in the armature. The alter-
The magnetic microphone is the type most
widely used in shipboard announcing and intercommunicating systems because it is more resistant to vibration, shock, and rough handling.
DYNAMIC MICROPHONE.
The dynamic, or
moving-coil, microphone (figure 8-2) consists
of a coil of wire attached to a diaphragm, and
a radial magnetic field in which the coil is free
to vibrate. Sound waves impinging on the diaphragm cause the diaphragm to vibrate. This
vibration moves the voice coil through the magnetic field so that the turns cut the lines of force
in the field. This action generates a voltage in
the coil that has the same waveform
sound waves striking the diaphragm.
as the
spoken into in a normal tone within a few inches .
of the diaphragm.
coal known as the PIEZOELECTRIC EFFECT.
The bending of the crystal resulting from the
pressure of the sound wave pr.;:luces an emf
across the faces of the crystal. This emf is am-
plied to the input of an amplifier.
The crystal microphone (figure 8-3) consists
of a diaphragm that is cemented to one surface of
the crystal. Metal plates, or electrodes, are at-
to the other surface of the crystal. When
sound waves strike the diaphragm, the vibration of the diaphragm produces a varying pressure on tne surface of the crystal and induces
at, .m.f. across the electrodes. This e.m.f. has
the same waveform as the sound waves striktached
ing the diaphragm.
Rochelle salt is most commonly used in
crystal microphones because of its relatively
194
.204
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
The carbon microphone consists of a dia-
phragm mounted against a mass of carbon gran-
SOUND WAVES
.
ules which are contained in a small cup. In
order to produce an output voltage, this mi-
111
DIAPHRAGM
crophone is connected in a series circuit containing a battery and the primary of 'a transformer.
CARBON
GRANULES
When a direct current flows through the
carbon granules, the varying resistance changes
TRANSFORMER
BATTERY
the amplitude of the current and produces an
altei.lating voltage in the secondary of the transformer. This voltage has the same waveform as the sound waves striking the diaphragm.
The current through this microphone may be as
great as 0.1 ampere. The resistance may vary
from about 50 to 90 ohms. The voltage developed
OUTPUT
VOLTAGE
across the secondary depends upon the --ratio --of the transformer primary and secondary turns
and also upon the change in primary current.
Normal output voltage of a typical circuit is
from 3 to 10 volts peak at the secondary ter-
A
SINGLE-BUTTON CARBON MICROPHONE
SOUND WAVES
DIAPHRAGM
minals.
111
411P
OUTPUT
VOLTAGE
The carbon microphone is not used in shipboard announcing equipment because it requires
a polarizing current and has a tendency to amplify certain frequencies more than others.
CHARACTERISTICS OF MICROPHONES
Microphones are rated according to their (1)
frequency response, (2) impedance, and (3) sensitivity.
BATTERY
B
DOUBLE-BUTTON CARBON MICROPHONE
20.218
Figure 8-4.Schematic diagram of carbon
microphones.
high voltage output. The crystal microphone can
produce an output voltage of from 0.01 to 0.03
volt into a load of 1 megohm or more, when
subjected to a sound pressure of a normal tone
within a few inches of the crystal. However,
this crystal microphone is seldom used in naval
announcing and intercommunicating systems because of the sensitivity of the crystal element
to high temperature, humidity, and rough handl-
RESPONSE. Shipboard anFREQUENCY
nouncing and intercommunicating systems are
designed to produce maximum speech intelligibility under conditions of high background
noise. To achieve this objective the overall frequency response characteristic of the system is
altered by cutting off the system response at
some lower limit, such as 500 I,:rtz, and by
employing an EMPHASIZED frequency response
characteristic which rises with increasing frequency at a rate of approximately 6 decibels per
octave. The output sound pressure is doubled
each time the frequency is doubled for a constant level input to the system. The emphasized
ing.
speech tends to sound thin and sometimes harsh,
but when the masking due to background noise is
The carbon microphone (figure 8-4) operates on the principle
almost as high as the speech level, the speech
CARBON MICROPHONE.
that a changing pressure of a diaphragm applied
to a small volume of carbon granules changes its
electrical resistance in accordance with the vi-
brations of the sound waves striking the diaphr
rrvt .
appears to cut through the noise.
For good quality, a microphone must con-
vert sound waves into electrical waves that have
the same relative magnitude and frequency, without introducing any new frequencies. The frequency range of the microphone must be at least
195
Z05
IC ELECTRICIAN 3 & 2
as wide as the desired overall response limits
levels require less gains in the amplifiers used
with them and thus provide a greater margin
over thermal noise, amplifier hum, and noise
of the system with which it is used.
Except in the case of the emphasized system
in which it may be desirable for the microphone
pickup in the line between the microphone and
amplifier.
When a microphone must be used in a noisy
location, an additional desirable characteristic
is the ability of the microphone to favor sounds
to have a rising frequency-response charac-
teristic, the microphone response should be uni-
form or flat, within its frequency range and
free from sharp peaks or dips such as those
caused by mechanical resonances.
coming from a nearby source over random
sounds coming from a relatively greater dis-
IMPEDANCE. Crystal microphones have
impedances of several hundred thousand ohms
whereas the magnetic and dynamic microphones
tance. Microphones of this type tend to cancel
out random sounds and to pick up only those
have impedances that range from 20 to 600 ohms.
The impedance of a microphone is usually mea-
talking into this type of microphone the lips
sounds originating a short distance away. When
must be held as close as possible to the diaphragm. Directional characteristics that favor
sound coming from one direction only, also aid
a microphone is discriminating against back-
sured between its terminals at some arbitrary
frequency within the useful range such as 1,000
hertz.
The impedance of magnetic and dynamic
ground noise.
microphones varies with frequency in much the
same manner as that of any coil or inductance
TYPES OF LOUDSPEAKERS
that is, the impedance rises with increasing
frequency. The actual impedance of the microphone in shipboard applications is of importance
only as it is related to the input load impedance
A loudspeaker is a device that converts
electrical energy into sound energy and radiates
this energy into the air in the form of waves.
All loudspeakers consist essentially of a driving mechanism for changing electrical waves
into mechanical vibrations that are transmitted
to a diaphragm or other vibrating source. This
vibrating source is coupled, either directly or
by means or a horn, to the air and causes sound
to be radiated. The loudspeakers in general use
into which the microphone is designed to operate.
If the microphone is mismatched with the input
impedance, the microphone input is reduced and
distortion occurs. All specifications and accep-
tability tests for naval microphones are based
on the designed input load impedance.
SENSITIVITY. The sensitivity or efficiency
of a microphone is usually expressed in terms
in the Navy are the (1) direct radiator type
delivers to a terminating load the impedaace
which radiates sound directly from a vibrating
member into the air and (2) horn type which
consists of a driving unit combined with a horn
picked up.
anism changes the electrical vibrations into
of the electrical power level that the microphone
of which is equal to the rated impedance of the . to couple the unit to the air.
microphone, compared to the acoustical intensity
level or pressure of the sound field that is being
DRIVING MECHANISMS.
Most systems rate the microphone in the
mechanical vibrations. The dynamic, or moving-
electrical power level (in decibels below 1 milli-
coil, driving mechanism is the basic type used
in Navy loudspeakers. The design of this unit is
similar to that of the dynamic microphone, but
the pinciple of operation is the reverse of that
watt) produced by an acoustical pressure of 1
dyne per square centimeter. For example, a
crystal microphone rated at 80 decibels means
that for an input acoustical pressure of 1 dyne
per square centimeter, the electrical output is
80 decibels below one milliwatt, or 10-8 milli-
watt. Other systems rate the microphone in
terms of the voltage delivered to a specified
terminating load impedance for an acoustical
pressure input of 1 dyne per square centimeter.
It is important to have the sensitivity of the
microphone as high as possible. High sensitivity
means a high electrical power output level for a
given input sound level. High microphone output
The driving mech-
of the dynamic microphone.
A coil of wire is attached to a diaphragm
and rests in a magnetic field. When a varying
electric current flows through the coil, a force
is exerted on the coil causing it to move back
and forth in the magnetic field. The consequent
motion of the diaphragm causes the radiation
of sound waves which correspond to the variations in the electric current. The electrodynamic and the permanent-magnet types are the
two variations in the dynamic loudspeaker. These
196
2C6
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
in an outward direction, a compression wave is
produced by the front surface of the diaphragm
and a rarefaction wave is produced by the back
surface of the diaphragm.
At low frequencies, whete the wavelength is
large compared with the dimensions of the
loudspeaker, the rarefaction wave from the back
of the diaphragm meets the compression wave
from the front of the diaphragm and neutralizes
it because the waves are in opposite phase
relation. Thus low frequencies are not repro-
)
PERMANENT
MAGNET
duced from this type of direct radiator.
At higher frequencies, where the wavelength
of the sound is small compared with the dimensions of the loudspeaker, the sound waves from
the front of the diaphragm have time to travel
an appreciable distance away from the loudspeaker (in terms of wavelength) and the phase
of vibration of the diaphragm changes before
-- - --
DIAPHRAGM
the interfering ware from behind can traverse
the distance around the diaphragm. Hence, a
BAFFLE is necessary only to reproduce low
frequencies from a direct radiator. The purpose of the baffle is to delay the meeting of
the front and back waves by artifically increasing the distance of the sound-wave path from
VOICE COIL
COVER
0
the front to the back of the diaphragm.
7.15
Figure 8-5. Direct radiator loudspeaker.
loudspeaker. This type of baffle is effective down
types differ only in the method employed for
obtaining the magnetic field.
In the ELECTRODYNAMIC LOUDSPEAKER
the magnetic field is established by passing a
direct current through a field coil that is wound
on an iron core. This type requires a source
of filtered direct voltage and two additional
conductors to carry the field current to the
loudspeaker.
In the
PERMANENT-MAGNET DYNAMIC
LOUDSPEAKER the magnetic field is established
by a permanent magnet. All loudspeakers used
by the Navy are of the permanent-magnet dynamic type.
DIRECT RADIATOR LOUDSPEAKER.
The simplest form of baffle is a flat- board
with a hole in the center to accommodate the
The
direct radiator loudspeaker, sometimes called
a CONE LOUDSPEAKER, is the simplest form
of sound loudspeaker. In this type of loudspeaker
(fig. 8-5), the diaphragm acts directly on the
medium, which is air. Both sides of the diaphragm are open to the air so that sound is radiated behind as well as in front of the loud-
speaker. At the instant the diaphragm is moving
to a frequency the wavelength of which is approximately four times the diameter of the
baffle. If the loudspeaker is mounted in a wall
or is completely enclosed, the baffle is called
an INFINITE BAFFLE. When a cabinet is used
as a baffle, it is desirable to line the inside
with a sound-absorbing material to minimize
the effect of cabinet resonances produced by
standing waves within the enclosure.
HORN LOUDSPEAKER.
The use of the di-
rect radiator loudspeaker is limited because of
its low radiation efficiency. When it is necessary
to produce high sound intensities or to cover
large areas with sound, the radiation efficiency
of the loudspeaker must be increased to keep
the size of t'he amplifier within reasonable
limits. Horns with appropriate driver units provide a practical solution to the problem. A horn
may be considered as an impedance matching
device for coupling a relatively heavy vibrating
surface at the horn throat to a relatively light
medium (the air), at the mouth of the horn.
A STRAIGHT-HORN LOUDSPEAKER is shown
in figure 8-6.
197
1...)07
1
IC ELECTRICIAN 3 & 2
SOUND CHAMBER
MAGNET
7.16.1
Figure 8-6. Straight-horn loudspeaker.
A
For a horn to operate effectively, the mouth
must be sufficiently large in comparison with
the longest wavelength (lowest frequency) of
sound that is to be transmitted. Low-frequency
horns often are considered to be useful at
Figure 8-7. Folded-horn loudspeaker.
7.16.2
frequencies above that for which the mouth
The high-frequency response is limited by the
mass of the voice coil and diaphragm.
extent upon the flare or shape of the horn. The
function of the horn contour is to produce a
smooth and continuous increase in cross-
For horn loudspeakers, the low frequency
response is influeneced principally by the (1)
basic horn formula employed, (2) flare, and
(3) mouth dimensions. The high frequency response is limited by the (1) mass of the voice
diameter is about one-third wavelength. The
performance of a horn loudspeaker near the
low-frequency cutoff point depends to a great
sectional area in progressing from the small
throat to the large mouth. The shape most
commonly employed is the exponential horn in
which the diameter icreases progressively by
a fixed percentage for each equal-distance increment along the horn axis. In order for the
horn to be of a practical size and shape, a
FOLDED-HORN LOUDSPEAKER is employed (fig.
8-7) in perference to a straight horn (fig. 8-6).
There is a practical limit to the amount of
power that can be handled by a conventional
driver unit. When extremely high sound intensities
must be produced, multiunit loudspeakers are
employed in which the units are coupled to individual horn sections that are combined mechanically into a common loudspeaker assembly.
CHARACTERISTICS OF LOUDSPEAKERS
FREQUENCY RESPONSE. In the majority
of cases the frequency response of the loudspeaker is the limiting factor in the overall
response of a sound system. For directradiators
the low frequency response is influenced by the
(1) baffle or enclosure, (2) diameter of the
cone, (3) ability of the cone and voice coil to
execute large amplitudes of vibration, and (4)
strength of the magnetic field in the air gap.
198
coil and the diaphragm, (2) phase effects caused
by differences in path lengths due to bends, and
(3) impedance irregularities caused by sudden
changes in cross-sectional areas at folds or
joints in the horn. Vibrations of the horn walls
must be sufficiently damped to avoid introducing
irregularities into the response as well as
transient effects.
DIRECTIVITY. The directivity of a loudspeaker is an important factor in determining
the efficiency of the sound radiation over the
listening area. All practical forms of sound
radiators exhibit some directional effects. If a
radiator is placed in free space wheie the
results are not affected by interfering reflections, the sound pressure at a given distance
is not the same in all directions. The directivity
of a loudspeaker is a function of both frequency
and the size of the horn mouth of the loudspeaker.
Thus, a loudspeaker becomes more directional
with increasing frequency because of the shorter
wavelength and a direct radiator or horn mouth
of large size is more directional than one of
smaller Size. These factors of frequency and
size are interrelated in that the size becomes
a factor relative to the wavelength of the sound
being transmitted. Thus the directional pattern
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
the loudspeaker on the loudspeaker axis using
of a small loudspeaker transmitting a high- various
test frequency signals. These measurefrequency signal (short wavlength) is similar
to that of a large loudspeaker transmitting a
low-frequency signal (long wavelength). In general a horn loudspeaker of a given mouth diameter is more directional than a direct radiator
of the same diameter, particularly at the lower
frequencies.
ments are combined with off-axis sound pressure
measurements to evaluate the relative loudspeaker efficiency.
When satisfactory frequency in a loudspeaker
is limited to a small angle about the axis,
the absolute efficiency at high frequencies is
The directivity of a horn loudspeaker is also
dependent upon the rate of flare that is, the
directivity increases as the flare is made more
gradual (longer horn). If a rectangular horn
having a long narrow mouth (in terms of wavelength) is mounted with the long dimension of
the mouth vertical, the radiation in the horizontal
considerably lower than at low frequencies. The
use of diffusing arrangements with these loud-
speakers to spread out the high frequencies
usually results in spreading out the small amounts
of available high-frequency energy to such an
extent that the response is unsatisfactory at
all locations.
plane corresponds to that of a small radiator
with a broad distribution pattern. The radiation
in the vertical plane acts as a large radiator
with a relatively narrow beam. In other words,
the horn is made relatively much less directional in the horizontal plane than in the vertical
plane. It is obvious that the reverse is true if
the horn is turned so that the long dimension
of the mouth is horizontal. Thus the sound
energy is flattened out in a plane at right
angles to the long dimension of the loudspeaker
mouth. This principle is used to obtain the required directional characteristics for efficient
high-intensity reproduction on the flight decks
of aircraft carriers.
CAPACITY. The load-carrying capacity of
a loudspeaker is usually expressed in terms of
the maximum electrical power that should be
applied to it. This power is limited by heating,
mechanical strength, and the production of nonlinear distortion which is caused by excessive
diaphragm amplitudes or excessive acoustical
pressures in the sound passages. Excessive
power caases the diaphragm to strike portions
of the magnet or supporting frame and may
produce buzzing or rattling.
EFFICIENCY.
The loudness of the sound
IMPEDANCE.
The impedance of a loud-
speaker is usually measured between the voice
coil terminals at some average frequency, such
as 1,000 hertz, in the usable range. This im-:
pedance varies with the frequency, rising with
increasing frequency. The usual value of voice
coil impedance varies from 3 to 15 ohms.
In shipboard announcing and public-address
systems, a matching transformer is built into
each loudspeaker to transform the low voicecoil impedance to a higher value suiteble for
connection to loudspeaker distribution lines.
Because loudspeakers in a system are connected
and operated in parallel, the combined Impedance of a large number of low-impedance voice
coils without matching transformers would be
so low compared with the resistance of the
connecting cables that an appreciable portion
of the amplifier output power would be dissipated in the cables. Thus matching transformers are provided to reduce this loss. These
transformers have several taps in order to
vary the loudspeaker impedance. Changing the
loudspeaker impedance changes the power absorbed by the loudspeaker from the lines and
thus provides a means of varying the loudness
of the loudspeaker.
obtainable from a loudspeaker at any particular
ANNOUNCING SYSTEMS
listening point is not a factor of load-carrying
capacity alone. Other important factors are the
efficiency and the amount that the sound is
Shipboard announcing and intercommunicating systems, circuits 1MC through 54MC, serve
the general purpose of transmitting orders and
information between stations within the ship by
amplified voice communication. This function
is accomplished by (1) a central amplifier system,
spread out. The definition of absolute efficiency
of a loudspeaker is not subject to simple practical interpretation. However, for specification
purposes and for checking the performance of
naval loudspeakers, a specified voltage is applied
to the input terminals and the output sound pressure is measured at a given distance from
when it is desired to broadcast orders or information simultaneously to a number of stations or by (2) an intercommunicating system
199
IC ELECTRICIAN 3 & 2
Table 8-1.
Circuit
*IMC
*2MC
*3MC
4MC
*5MC
*6MC
7MC
8MC
*9MC
*10MC
*11-16MC
*17MC
18MC
19MC
*20MC
21MC
22MC
23MC
24MC
25MC
26MC
27MC
*28MC
*29MC
30MC
31MC
32MC
33MC
34MC
35MC
36MC
37MC
38MC
39MC
40MC
41MC
42MC
43MC
44MC
45MC
*46MC
47MC
48MC
49MC
50MC
Shipboard Announcing Systems
System
Importance
General
Propulsion plant
Aviators'
Damage Control
Flight Deck
Intership
Submarine Control
Troop administration and control
Underwater troop communication
Dock Control (obsolete)
Turret (obsolescent)
Double Purpose Battery
(obsolescent)
Bridge
Aviation Control
Combat Information
(obsolescent)
Captain's Command
Electronic Control
Electrical control
Flag Command
Ward Room (obsolescent)
Machinery Control
Sonar and Radar Control
Squadron (obsolescent)
Sonar Control and Information
Special Weapons
Escape trunk
Weapons control
Gunnery Control (obsolescent)
Lifeboat (obsolescent)
Launcher Captains'
Cable Control (obsolete)
Special Navigation (osbolete)
Electrical (obsolete)
Cargo Handling
Flag Administrative
Missile Control and Announce
(obsolete)
CIC Coordinating
Unassigned
Instrumentation Space
Research operations
Aviation Ordnance and Missile
Handling
Torpedo Control
Stores conveyor (obsolescent)
Unassigned
Integrated operational
intelligence center
200
210:
Readiness Class
1
1
2
1
1
2
2
1
3
3
2
2
1
1
1
1
4
1
1
4
2
2
2
3
3
1
1
4
2
1
4
1
SV
SV
2
NV
NV
1
1
SV
SV
NV
2
2
SV
227.123.0
3
1
Chapter 8ANNOUNCING AND INTERCOMMUNICA MG SYSTEMS
Table 8-1. Shipboard Announcing Systems Continued
System
Circuit
51MC
52MC
53MC
54MC
55MC
56MC
57MC
58MC
59MC
Aircraft Maintenance and
handling control
Unassigned
Ship Administrative
Repair officer's control
Sonar Service
Unassigned
Unassigned
Hanger Deck Damage Control
SAMID Alert
Importance
Readiness Class
SV
2
NV
4
NV
4
NV
4
V
1
SV
3
* - Central amplifier systems.
27.123.0
when it is desired to provide two-way trans-
equipment to provide circuit 1MC functions for
mission of orders or information.
Each announcing and intercommunicating sys-
general announcing, and circuit 6MC functions for
intership announcing. Power for operating the
equipment is obtained from the ship's single-
circuit designation in , he MC series. The Chief
of Naval Operations authorizes these MC circuits
for each class of vessel, based on size, complement, function, and operational employment.
Authorized IC announcing circuits are listed in
phase 115-volt power supply.
tem installed aboard ship is assigned an
IC
Table 8-1, according to important and readiness. These systems, however, are not all
installed in any one ship.
For general announcing, circuit 1MC is installed in all surface ships above 180 feet in
length, except aircraft carriers, amphibious ships
fitted with flight decks, and large combatant
ships. Aircraft carriers, amphibious ships fitted
with flight decks, and large combatant ships are
provided with circuits 1MC and 3MC.
CENTRAL AMPLIFIER ANNOUNCING
SYSTEM
The central amplifier announcing system is
designed to furnish amplified voice conununications and alarm signals to the various loudspeaker groups aboard ship. The system provides for transmitting the spoken word or signal
at any one of several stations, amplifying this
signal at a central amplifier, and radiating the
signal from a number of loudspeakers.
The components of a representative system
on a cruiser are block diagrammed in figure
8-8. The system consists of audio amplifier
ALARM CONTACT MAKERS
Alarm contact makers are located at various
points
in the ship. The closure of an alarm
contact maker will sound any one of four alarm
signals over all circuit 1MC loudspeakers.
Alarm signals are not transmitted over circuit
6MC. The alarm signals in the order of their
priority are: (1) collision, (2) chemical attack,
(3) general, and (4) sonar. The order of priority
is controlled automatically by relays in the
audio amplifier cabinet. Any alarm takes priority over voice announcements.
If an alarm is being sounded and a higher
priority alarm contact maker is closed, relays
in the audio amplifier cabinet operate to cut off
the alarm signal being sounded and cause the
higher priority alarm to be sounded instead.
Conversely, the closure of a low priority alarm
contact maker has no effect on a high priority
alarm that is being sounded.
The oscillator operates
to
generate the
alarm signals as long as the alarm contact
maker is held closed (except for general alarm
which is sounded for a predetermined 15second interval after momentary closure of
the general alarm contact maker). Release
201
.
IC ELECTRICIAN 3 & 2
CIRCUIT I MC
.1
LOUOSPEAKER
GROUPS
T
_
ALARM
CONTACT
00,
CIRCUIT GMC I
LOUOSPEAKER
MAKERS
L
r
I
GROUP
HORN)
CONTROL
RACK
-I
FIVE
CIRCUIT I MC
MICROPHONE
CONTROL
'
ALARM VISUAL
INDICATOR
STATIONS
TYPE IC/mSB2
POWER
RACK
'WE
ICIRCUIT t MC NGMC,
I
MICROPHONE
CONTROL
SHIPS
I
TYPE IC/MS132
I
I ENTERTAINMENT I
STATION
SYSTEM
--J
_j
I
I
AUXILLIARY
I
ANNOUNCING
EQUIPMENT
Figure 8-8. 1MC-6MC Equipmentblock diagram.
of the alarm contact maker causes the equip-
ing the alarm. The visual alarm circuit is
closed continuously during a chemical attack
alarm, and intermittently during a general
CENTRAL AMPLIFIER SYSTEM
Four microphone control stations are located
at various points throughout the ship. The circuit 1MC-6MC microphone control station can
select any one or more of the four 1MC loud-
speaker groups or the circnit,6MC loudspeakers.
The other microphone control stations are wired
to permit the selection of circuit 1MC loudspeaker groups only. The operation of circuit
1MC from any microphone control station has
priority over circuit 6MC operation. Microphone control stations on circuit 1MC do not
140.125
have priority over each other, however, the
ment to be returned to STANDBY after sound-
alarm.
1
bridge station does have priority over all others.
When the press-to-talk switch on the microphone of any microphone control station is
operated for general voice announcements (fig.
8-9), all loudspeakers selected at this control
station (except the loudspeaker in the immediate
area of the control station in use) are connected
to the equipment and reproduce the message
spoken into the microphone. It is possible for
the 1MC-6MC microphone controi, station to
transmit over circuit 6MC loudspeakers at the
same time that a circuit 1MC microphone control station is transmitting over a circuit 1MC
loudspeaker group.
LOUDSPEAKER GROUPS
The loudspeakers associated with circuit 1MC
operation are divided into four groups designated
202
212
Chapter 8 -ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
6MC circuits independently on the two channels
(fig. 8-11). Each channel includes a preamplifier
and a power amplifier. Channel selection is
aocomplished by means of the amplifier channel
selector switch on the audio amplifier cabinet.
BUSY I
LAMP
Normal operation of the system is obtained
with the amplifier channel selector switch set at
IMC on A and 6MC on B. When the switch is
set at 1MCI-6MC on A, channel B is isolated for
troubleshooting and repair, and the announce-
BUSY 2
LAMP
ments and alarm signals are transmitted on
channel A. Conversely, when the switch is set
at 1MC-6MC on B, channel A is isolated and
all transmission is over channel S.
Preamplifiers
The preamplifiers consists of a power supply,
three parallel-connected voltage amplifier
stages, a push-pull-parallel connected power
amplifier stage, a limiter circuit, and a compressor circuit.
7.19
Figure 8-9. Microphone control station.
officers, (2) topside, (3) crew, and (4)
engineers. There is only one circuit 6MC loud(I)
speaker group.
AUDIO AMPLIFIER CABINET
The control circuits for circuit 1MC and
circuit 6MC are contained in the audio amplifier
cabinet (fig. 8-10). In addition to the various re-
lays, indicator lamps, fuses, transfer switches,
and test switches, the cabinet contains two oscil-
lator assemblies, two preamplifier assemblies,
and two power amplifier assemblies.
The oscillators, one of which is a spare, are
used to generate the alarm signals. The pre-
amplifiers are used to increase the microphone
output on voice signals to a level sufficiently high
to drive the power amplifiers. The power
amplifiers are used to increase the level of the
alarm signals from one of the oscillators and
the voice signals from one of the preamplifiers
for reproduction by the loudspeakers.
Two Identical amplifier channels are provided to permit the operation of the 1MC and
The COMPRESSOR circuit provides greater
amplifier gain with low-level signals than with
high-level signals, thus compensating for the
differences in voice inputs at the microphone
control stations. When the compressor switch,
Si (fig. 8-10) is in the ON position, the bias of
the first stage voltage amplifier is reduced,
resulting in a 14 db maAimum increase in amplifier gain for low-level input signals. The
LIMITER circuit provides for a rapid reduction
in amplifier gain when the amplitude 4 the input
signal would overload the amplifier and cause
distortion.
The compressor-limiter circuit consists of
twin triodes, operating as a phase-inverter and
limiter.
Normal operation of the preamplifier can be
checked by measuring the overall output and
plate current of each stage by the meter, IC,
and meter switch S2. The meter switching is
arranged so that normal operation of each stage
is indicated by a midscale meter reading of
0 db ± 2 db.
Power Amplifiers
The power amplifiers consist of a voltage
amplifier stage, a phase inverter stage, two
driver stages, and a final power amplifier stage.
Two tubes (not sections) operate in parallel for
every stage except the final stage which has
two groups of three triodes in parallel and the
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204
7.20
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
OSCILLATOR GROUP
SELECTOR
V
NO 2
NO I
OSCILLATOR
ALARM
GROUP I
:VAC; t
I
OSCILLATOR
GROUP 2
OSCILLATOR
TEST SWITC
AMPLIFIER CHANNEL
SELECTOR
OSC GROUP I OUTPUT
INC A
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ISSIC-11
03C GROUP 2 OUTPUT
INCA
GYPS
ALARM PRIORITY (REACH' OSCI
oommiar(ALARmSluoC)
PRIORITY (ALARMS/ I MC/111W I
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OW
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LOUDSPEAKER GROUP SELECT CONTROL
_t
L_ (51 _1
41"
LISULL HORN!
I
140.126
Figure 8-12.
Simplified system switching diagram.
two groups in push-pull. The parallel connection of the triodes permits circuit operation in
the event of failure or removal of one tube per
of each stage is indicated by a midacale :reading
on the meter with rated input signal and output
load.
stage (two tubes in the final stage).
The power to operate the powar amplifier
is supplied through a 3-conductor polarized
plug, directly to the filament transformer, and
through switch S3 (fig. 8-10) to the plate power,
transformer. A time-delay relay (not shown),
external tc the amplifier chassis, prevents the
application of power to the plate power transformer until approximately 30 seconds after
filament power has been applied.
The operation of each stage of the power
amplifier in addition to the overall audio output
chan be checked by meter M2 and the 7-position
meter switch, S3 (fig. 8-10). Normal operation
Oscillators
Each oscillator is capable of generating a
variety of alarm signals although only four are
used in this application: (1) collision, (2) chem-
ical attack, (3) general, and (4) sonar. Each
oscillator is also capable of generating four
additional alarm signals which can be used in
the event of future expansion of the system.
The additional alarms are (1) simulated motoroperated horn type signal; (2) jump-tone signal
which alternates bahveen 600 and 1,000 Hz at
the rate of 1 1/2 Hz; (3) jump-tone signal which
205
IC ELECTRICIAN 3 & 2
alternates between 600 and 1,500 Hz at the rate
are determined by timing relays and contactors
(not shown) in the audio amplifier cabinet but
However, these alarms are not discussed in this external to the oscillator assembly.
chapter.
The momentary closure of any general
When any alarm :s saunded, the frequency of contact maker completes the control poweralarm
cirrelay operations is similar except that relays cuit to the relay for the general alarm provided
associated with the particular alarm are ener- the relays for the collision alarm and the
chemigized. The function of each individual mlay in cal attack alarm have not operated to establish
the system is explained in the applicable manu- a higher priority signal.
facturer's technical manual furnished with the
The general alarm contactor determines (1)
equipment. The operation of the oscillator for the duration (15 seconds) of the general alarm,
the various alarms is based on the system being and (2) the 90 strokes per minute striking
set up for normal operation using oscillatort 1 cf the gong tone. An additional switch onrate
the
and channel A for 1MC and channel B for cir- oscillator contactor pulses the visual
alarm
cuit 6MC.
(busy lights on the microphone control stations)
The oscillator generates the alarm signals in step with the general alarm signal.
as long as 'the alarm contact maker is held
The SONAR ALARM is a jump-tone signal
closed (except flr general alarm which is
sounded for a predetermined 15-second interval alternating between 600 and 1500 Hz at the rate
aster momentary closure of the general alarm of 1 1/2 Hertz. The closure of any sonar alarm
contact maker). Release of the alarm contact contact maker completes the control power cirmaker causes the equipment to be returned to cuit to the relay for the sonar alarm provided
STANDBY after sounding the alarm. The visual that other alarm relays have not operated to
alarm circuit is closed continusously during a establish a higher priority signal.
Normal operation of an oscillator can be
chemical attack alarm, and intermittently during
checked by masuring the plate current of the
a general alarm.
Closure of any collision alarm contact maker various stages and the overall output by meter
energizes relays in the audio amplifier cabinet, M3 and meter switch S4 (fig. 8-10). The meter
which in turn energizes the collision alarm switching is arranged so that normal operation
contactor associated with the oscillator in active of each stage is indicated by a midscale meter
service to pulse the signal output of the oscil- reading.
lator and produce the collision alarm.
The COLL:SION ALARM is a pulsed 1000 OPERATION
Hz signal. Each cycle of the signal consists
The path of circuits 1MC and 6MC from the
of three pulses of 0.06 second and the third
pulse is followed by an off period of 0.3 second. inputs to the loudspeakers is shown by the block
This cycle is repeated continuously as long as diagram in figure 8-11. The selector switch for
the collision alarm contact maker is actuated. the oscillators and amplifiers is set for normal
The CHEMICAL ATTACK ALARM is a operation with oscillator 1 and both amplifiers
steady-tone signal of 1000 Hz. The closure of in active use. Channel A is normally used for
any chemical attack contact maker effectively circuit 1MC and channel B for circuit 6MC. In
completes the control power circuit to the relay case of failure of a preamplifier or power amassociated with the chemical attack alarm, pro- plifier, both circuit 1MC and circuit 6MC can be
vided the relay associated with the collision switched for operation on either channel A or
alarm has not operated to establish a higher channel B. When both circuits, 1MC and 6MC,
priority signal. The chemical attack signal is are switched to the same channel, circuit 1MC
generated and amplified in the same manner as has priority over circuit 6MC operation.
the collision alarm signal; however, the signal
is not pulsed.
Circuit 1MC Microphone Con:ol
The GENERAL ALARM is a simulated single- Station
stroke cong-tone striking at the rate of 90
strokes per minute- The tone is caused to delay
To make voice announcements from a circuit
between strokes in a natural manner and the 1MC microphone control station, operate
one or
signal strokes are repeated automatically for more of the loudspeaker group selector switches
15 seconds after the alarm has been started. (fig. 8-9) to select the area or areas to receive
The signal-duration and stroke-repetition rate the announcement. Observe the busy indicators.
of 6 Hz; and (4) simulated siren type signal.
206
21 6
Chapter 8 ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
When BUSY 1 ramp is lighted, circuit 1MC
amplifier is in use. Except in an emergency, do
not attempt to use circuit 1MC when BUSY lamp
is lighted. If another microphone control station
When both BUSY 1 and BUSY 2 lamps are
lighted, (1) an alarm signal is being transmitted;
or (2) both circuit 1MC and circuit 6MC ere on
sion from both microphone control stations will
go out to all loudspeaker groups selected by both
microphone stations.
When BUSY 2 lamp is lighted, circuit 6MC
tion. Because circuit 1MC has priority over
selects a circuit 1MC loudspeaker group and
operates the press-to-talk switch, the transmis-
amplifier is in use and will have no effect on
circuit 1MC operation.
When both BUSY 1 and BUSY 2 lamps are
lighted, (1) an alarm signal is being transmitted
one amplifier (during test or in the event of
failure of an amplifier channel) and circuit 1MC
is in use from another mikrophone control sta-
circuit 6MC, it is not possible ix, use cl.cuit
6MC when both the BUSY 1 and BUSY 2 lamps
are lighted. If a circuit 1MC loudspeaker group
is selected and the press-to-talk switch is
operated, the transmission from both micro-
phone control stations will go out to all circuit
1MC loudspeakers selected by both microphone
stations.
irrespective of the amplifier in use: (2) both
circuit 1MC and circuit 6MC are in use, and if
anothdr microphone control station attempts to Alarm Contact Maker
use circuit 1MC the transmission from both
The operation of an alarm contact maker
microphone stations will go out to all loudwill
take precedence over any microphone conspeaker groups selected by both microphone
stations; or (3) both circuit 1MC and circuit trol station. When an alarm is sounded, the
6MC are on one amplifier (during test or in the BUSY 1 and BUSY 2 indicators are lighted at
event of failure of an amplifier channel) and one all microphone control stations and the alarm
signal is transmitted to all circuit 1MC loudor the other circuit is in use.
Circuit 1MC takes priority over circuit 6MC, speakers. With the exception of the general
therefore, if circuit 6MC is in use and a circuit alarm, the alarm signals will be sounded only
1MC loudspeaker group is selected from a iother as long as the contact maker is held in the
microphone control station, circuit 6MC will be operated position. The general alarm signal,
cut off when the microphone press-to-talk switch once started by momenta: operation of the
is operated and the announcement will go out to general alarm contact maker, will continue for
the circuit 1MC loudspeakers only. If circuit 15 seconds. This alarm can be repeated by
1MC is in use and a circuit 1MC loudspeaker again momentarily closing the general alarm
group is selected, the transmission from both contact maker.
microphone stations will go out to all loud- Audio Amplifier Cabinet
speaker groups selected by both microphone
Normal operation does not involve the operstations.
ation or switching of controls at the audio amCircuit 1 MC -6 MC Microphone
plifier cabinet, provided the switcnes and conControl Station
trols are set for norml operation. The meters
To make voice announcements from the 1MC- on each oscillator and amplifier asse;nbly can
6MC microphone control station, operate the be observed for normal operation by placing the
intership selector switch (fig. 8-9). Observe the meter switch in position 1.
During the transmission from a microphone
busy indicators as previously described.
When the BUSY 1 lamp is lighted, circuit control station, normal operation of the pre1MC is in use, but circuit 6MC can be sleeted amplifier and potIvz amplifier in active use is
and used at the same time without interference shown by a meter reading which swings to 0 db on
to the transmission on circuit 1M0. Except in voice peaks. During the transmission of alarm
an emergency, do not attempt to use circuit
1MC when the BUSY 1 lamp is lighted. If a
microphone control station selects a circuit
1MC loudspeaker group and operates the pressto-talk (microphone) switch when the BUSY 1
lamp is lighted, the transmission from both
microphone stations will go out to all circuit
1MC loudspeaker groups selected by both microphone stations.
signals, normal operation of an oscillator in
active service depends on the nature of the
alarm signal. Normal operation of an oscillator
on general alarm is indicated by a reading which
swings from no reading to midscale (0 db). During alarm signals the preamplifier le bypassed.
Normal operation of a power amplifier in active
service is indicated by a reading within 42 db
of the meter reading for the oscillator.
IC ELECTRICIA 4 3 & 2
MA NTENANCE
switch to the OFF position. If the location of the
defective microphone station is not known, oper-
The Planned Maintenance Subsystem :s the
key to Fool Mt: operation and should be scru-
ate all microphone station disconnect switches
on the audio amplifier cabinet (fig. 8-10) to the
OFF position, one at a time mtil the defective
microphone control station is isolated. Leave
this switch in the OFF position until the trouble
pulously followed. Good preventive maintenance
results in less corrective maintenance being
required.
If the entire announcing system is inoperative, the trouble is probably in the ship's power
supply or wiring from the ship's power supply.
has been corrected. Return all other microphone-station disconnect switches to the ON
position.
Check the power available indicator on the audio
amplifier cabinet (fig. 8-10). This indicator, unless it is defective, will be lighted when power is
available at the cabinet.
Check the fuses in the early stages of troubleshooting. All fuses are located on the control
panel of the audio amplifier cabinet in combination fuse holders and blown-fuse indicators, and
Loudspeaker
A short circuit in a loudspeaker or in the
loudspeaker wiring can cause a power amplifier,
which tests normally, to act abnormally when
switched into active service. It will result in a
lower than normal meter reading of the power
are accessible from the front of the cabinet.
Failure of a fuse is indicated when the neon-glow
lamp in the fuse-holder cap is lighted. The
switch controlling power to the circuit (which a
fuse protects), must be in the ON position for
the glow lamp to give an indication of fuse failure. Also, in the case of fuses protecting microphone control stations, the microphone talk switch
amplifier output. If the location of the defective
wiring or loudspeaker is not known, operate the
loudspeaker-group disconnect switches on the
audio amplifier cabinet to the OFF position, one
at a time until the defective loudspeaker group
is isolated. This will be indicated by a return
to normal meter reading (0 db ± 2 db) of the
power amplifier.
give an indication of fuse failure.
microphone
at the microphone station must be operated to
If the trouble persists aad Is not in the
control stations or loudspeaker
gvoups, it is probably in the preamplifier, power
amplifier, or oscillator assembly.
Performance failure of the shipboard an-
nouncing equipment can be corrected most readily
by
first isolating the assembly at fault,
then IFJlating the circuit of that assembly, aad Preamplifier
finally by isolating the particular part causing
the trouble. Lccalization of trouble in the sysNormal output of a preamplifier is 10 volts
tem will be comparatively simple because of the which is indicated by a mldscalc reading of 0
test facilities included in the equipment. Also, db+db on the output meter with the meter
the use of duplicate oscillator, preamplifier, and transfer switch in position 1. Normal
output is
power amplifier assemblies permits the testing obtained from a preamplifier when the
voice
or repair of one assembly while the other assem- signals from a microphone control station are
bly remains in active service, thereby aiolding applied to the input terminals, or when attenuthe necessity for shutting down the system.
ated alarm signals from an oscillator
Trouble in an assembly can be localized readily tested (or being used as a source of test being
signal)
by using the meter :Ind meter switch included in are applied to the same terminals. In normal
each assembly (fig. 8-10). In most cases a faulty system operation, the alarm signals generated
assembly or even the faulty stage of an assembly by an oscillator in active service
bypass the
can be localized by these meters without resort- preamplifier in active service and are
applied
ing to extensive troubleshooting procedures. directly to the input of the
power amplifier in
active service.
Microphone Control Station
To check a preamplifier for normal operation, apply an attenuated signal from the oscilA short etre:kit in the wiring to a microphone lator not in active service to the input
transcontrol station or a defect in a microphone con- former of the preamplifier and observe
the
trol station can, under certain circumstances, output meter readings from each meter switch
prevent normal operation from other microphone position. Operate the test chemical attack alarm
control stations. In the event of such trouble,
switch to the ON
(fig. 8-10) to
operate the microphone station disconnect cause the oscillator notposition
in active service to
208
2 18
Chapter 8 ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
When the meter switch, S3, is rotated to
generate a 1,000 Hz signal. This signal is
attenuatld and fed to the preamplifier on test
positions 1 through 7, inclusive, the output meter,
When the meter switch, S2, (fig. 8-10) is
rotated to positions 1 through 7 inclusive, the
output meter, Ml, is connected to terminals in
the various output stages of the preamplifier.
place the defective component.
M2, is connected to terminals in the various
stages of the power amplifier. If an abnormal
meter reading is indicated, check the voltage
of the stage or stages at fault with the normal
readings listed in the manufacturer's technical
manual. Isolate the trouble and repair or re-
through the test input control. The normal test
signal input to the preamplifier will indicate a
midscale reading of 0 db+2 db for the normal
outputs of the various steps.
If other than a normal reading is obtained, check
Oscillator
the voltage of the stage or stages at fault and
compare the readings with those listed in the
applicable manufacturer's technical manual.
Localize the trouble and replace the defective
part.
Normal output of an oscillator is 10 volts
which is indicated by a midscale reading of 0 db
Power Amplifier
Normal audio output of a power amplifier is
70 volts which is indicated by a readingof 0 db on
the output meter with the meter switch in position
1 (fig. 8-12). In normal 11 eration, alarm signals
with the meter switch in position 1 (fig. 8-10).
On general alarm, collision alarm, and sonar
alarm, this reading swings from no reading to
0 db. The 1,000 Hz test chemical attack alarm
signal is used for adjusting the amplifier. It is
essential that an output of 0 db be obtained from
the oscillator.
from the oscillator in active service drive the
power amplifier to normal output. Likewise, the
amplified voice signals from the preamplifier
will drive a power amplifier to normal output.
During test, the oscillator not in active service is used to drive the preamplifier not in active
service. The preamplifier, in turn, drives the
power amplifier not in active service. The audio
output of the power amplifier is fed to a dummyload resistor combination in the secondary of the
output transformer of the power amplifier.
Switching arrangements in the audio amplifier
cabinet prevent the test signals from reachingthe
loudspeakers.
Normal operation of each stage of an oscillator is indicated by the correct meter reading,
when the meter, M3, is switched into each stage
by meter switch, S4, and the various test alarm
switches are operated. It is important to note
that no reading will be obtained from some positions of the meter switch when alarms (test or
actual) are being sounded. When troubleshooting
an oscillator, be certain that a normal meter
reading is not obtained for the particular stage
before attempting to localize trouble within the
stage. In most cases, trouble in one stage will
also affect the meter reading when measuring
the oscillator output with the meter switch in
In the majority of cases, trouble in any stage
of the power amplifier will also affect the meter
reading when measuring The output signal. Therefore, when an abnormal signal output is
indicated on the meter, localize the trouble by
using the power amplifier meter and meter
switch to check the operation of all the stages.
position 1.
When an abnormal output is indicated, localize the faulty stage by checking the operation of
each stage. Rotate the meter switch, S4, through
its various positions and compare the readings
of meter, M3, with the normal readings listed
To check a power amplifier for normal operation, operate the TEST START switch on the ON
position (fig. 8-10) and observe the output meter
readings from each meter switch position. The
normal test signal input to the power amplifier
should indicate a midscale reading of 0 db for
normal audio output and a midscale meter read-
in the manufacturer's technical manual.
the other stages of the power amplifier.
place the faulty component as necessary.
ing of 0+2 db will indicate normal output for
If any of these readings are above or below
normal (0 db) by more than 2 db or if no reading
is obtained, make a voltage test of the faulty
stage or stages and compare the readings with
the normal readings listed in the technical
manual. Localize the trouble and repair or re-
209
219
IC ELECTRICIAN 3 & 2
AMPLIFIER-OSCILLATOR GROUP
AN/SIA-114
(CONTROL RACK)
AMPLIFIER ASSEMBLY AM-2316/SI A
(POWER RACK)
Figure 8-12.-1MC-6MC announcing system AN/SIA-114.
210
220
140.36
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
01001
Fr7(551-1
I3
J1001
2N297A
CRIO0i
114538
> 30 V NEG.
12
21
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too
150
0
.
.2
I (MA)
200 225
I (MA)
140.37
Figure 8-13. Power Supply pp-2563/SIA, schematic diagram.
control rack behind the front cover are two
1MC-6MC ANNOUNCING SYSTEM,
relay panels. The outer relay panel consists of.
70 relays mounted in rectangular sockets, and
AN/SIA-114
the
The 1MC-6MC announcing system, AN/SIA114 is a later type of shipboard announcing
system designed to perform the same functions
as the system just discussed. The major units
The 8 plug-in assemblies for each channel
of the system are the control rack and the
consists of power supply, PP-2563/SIA; AF amplifiers, AM-2127/SIA, and AM-2506/SIA; and
power rack, (fig. 8-12).
CONTROL RACK
The control rack is
inner relay panel consists of 14 relays
mounted in octal sockets. A relay power supply
is mounted near the top of the inner relay panel.
a bulkhead mounted
enclosure containing a control panel, two relay
panel assemblies, a relay power supply, and
sixteen plug-in assemblies, (eight for each chan-
AF oscillators, 0-718/SIA, 0-721/SIA, 0-722/
SIA, 0-724/SIA, and 0-725/SIA. A handle is
provided on each plug-in assembly to facilitate
removal and installation of the assembly.
nel).
Power Supply PP-2563/SIA
trols, switches, and indicators for system operatesting. At the bottom of the
and
tion
Transistorized power supply PP-2563/SIA
(fig. 8-13), furnishes -30 +2v.d.c. at 100 to 110
The control panel mounts the various con-
211
IC ELECTRICIAN 3 & 2
MICROPHONE
SIGNAL INPUT
EMITTER
AMPLIFIER
AMPLIFIER
FOLLOWER
0801
Q803
Q802
EMITTER
FOLLOWER
Q804
NETWORK
AUDIO FREQUENCY AMPLIFIER AM-2506/SIA
(MICROPHONE PREAMPLIFIER)
BIAS
BIAS
TRANSISTOR 4- TRANSISTOR
Q903
Q902
ALARM SIGNAL INPUT
AMPLIFIER
Q901
418--.
FOLLOWER
0904
V
AMPLIFIER
Q905
L
MICROPHONE-ALARM
SIGNAL OUTPUT
AUDIO FREQUENCY AMPLIFIER AM-2127/SIA
(MICROPHONE AND OSCILLATOR AMPLIFIER)
.-J
Figure 8-14.-- Audiofrequency Amplifiers AM-2506/SIA and AM-2127/SIA block diagram.
ma, and +3n+2 v.d.c. at .2 ilia. The negative voltage is full-wave rectified, and the positive voltage is half-wave rectified.
Tr ansmistor Q1001 and Zener diodes CR1004A
and CR10048 regulate the -30-volt output as
shown by curve A. Zener diodes CR1005A and
CR1005B regulate the +30-volt output as shown
by curve B.
AF Amplifier AM-2506/SIA
Audio-frequency amplifier AM-2506/SIA is a
4-transistor microphone preamplifier, the output
of which drives a 5-transistor microphone and
oscillator umplifier, AM-2127/SIA. See figure
8-14 for a block diagram.
The microphone preamplifier is a common
emitter 4-stage amplifier with a divider network
between the first and second stages, and a feed-
back circuit (which acts as a limiter circuit),
via transistors Q902 and Q993 in the microphone
and oscillator preamplifier.
140.38
AF Amplifier AM-2127/SIA
Audio-frequency amplifier AM-2127/SIA con-
tains two transistor amplifier stages, Q901 and
Q905, an emitter follower stage, Q904, and two
bias transistors, Q902 and Q903, employed in
a limiter circuit (fig. 8-14).
The limiter circuit consisting of Q902 and
Q903, in conjunction with varistoi s RV801 through
RV806 (fig. 8-15 and 8-16) provides signal ampli-
tude control. Transistor Q902 is biased to conduct only on microphone input signals greater
than the maximum amplitude limit. CO' 'luction of
Q902 results in conduction of Q903. Conduction
of Q903 lowers the impedance of the network
(dashed lines in fig. 8-15 and 8-16), resulting
in a decrease in voltage across varistors RV801
through RV806. The voltage decrease on the
varistors causes their resistance to increase,
which reduces the Q802 base emitter bias current,
and thus the gain of Q802.
212
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
.1401
4.:
1-a-
30 V KG
INPUT
OU TPUT
-TI-,
rk* vousrop VAS mac.
1*4
guosroot sus Pos.
Cpl
I
I
4Z
+114
140.39
Figure 8-15.AF aniplifier" AM-2506/SIA, schematic diagram.
Alarm signals require less amplification than
microphone signals and are therefore applied
directly to the base of Q904.
AF Oscillator 0-718/SIA
Collision alarm oscillator 0-718/SIA contains
a transistorized oscillator circuit which generates
a pulsed 1000 hertz signal (fig. 8-17). Each
period consists of three pulses, 50 milliseconds
in duration. Each group of three pulses is followed
by an off time of 0.35 second. This cycle is
repeated continuously as long as power is ap-
plied to the circuit.
AF Oscillator 0-721/SIA
Chemical alarm oscillator 0-721/SIA contains
a transistorized oscillator circuit which generates
140.40
Figure 8-16.AF amplifier AM-2127/SIA, schematic diagram.
213
IC ELECTRICIAN 3 & 2
0'
1000 HERTZ
EMITTER
OSCILLATOR
FCLLOWER
GATED
AMPLIFIER
01101
01102
01103
PULSE WIDTH
TIMER
PULSE WIDTH
01110
01106.01109
PULSED
--111. 1000 Hz
OUTPUT
FLIP-FLOP
TIMING
SYNCHRONIZER
01107
PERIOD ADJUST
TIMER
.-8110,
PERIOD ADJUST
FLIP-FLOP
01101.01105
01106
Figure 8-17. Audiofrequency oscillator 0-718/SIA (collision alarm), block diagram.
a continuous 1000 Hertz signal as long as power
is applied to the circuit. The oscillator also
contains two transistorized circuits which furnish
a timed relay voltage and an interrupted relay
voltage to the general alarm circuits. Figure
8-18 is a block diagram.
140.41
Transistor Q1401 (fig. 8-19), is connected
as a Colpitts oscillator, and generates a 1000 hertz sine wave signal. This signal is coupled
to the base of emitter follower Q1402. From the
emitter of Q1402 the signal is coupled through
GAIN control potentiometer R1407 to the base of
+26.5V DC
RELAY POWER INPUT
1.2/3 Hz
FROM 01507
4
INTERRUPTED
RELAY
VISUAL ALARM
TIMER 01406
K1402
INTERRUPTED
POWCR (4-26.5V DC)
TO RELAY K563
-22V DC
1000 HERTZ
EMITTER
EMITTER
OSCILLATOR
FOLLOWER
FOLLOWER
01101
01402
01403
1000 Hz
OUTPUT
+26.5V DC
RELAY
POWER
INPUT
TIMER
TIMED RELAY
TIMED RELAY
01404
CONTROL 01405
K1401
TIMED POWER
(+26.5V DC)
ALARM RELAYS
-22V DC
-22V DC
140.42
Figure 8-18. Audiofrequency oscillator 0-721/SIA (chemical alarm), block diagram.
214
224
.
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
CR1402
L1401
NVC4
30V NEG
10001.
P1410
P1406
I2%
P1404
2700
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I OUTPUT
2.21
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1100
404
4
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C1406
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2.2
01403
2N434
DI
111401
2.2
P1406
P1407
11140111
3R , GAIN
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220
660
R14I3
CR1403
160
IN270
C1407
R141I
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IOR
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lf tit INPUT
a TIMED RELAY
POWER OUTPUT
a
52
CR 401
C1402
2.2
POWER .PUT
I_4 30V NEG
INTERRUPTED RELAY
'POWER OUTPUT
01404
2N492
IN734A
Ci4i0
47
P1414
It
GENERAL
ALARM
10011/4
47
MAR
R1416
330
.
P1413
230 R
10
No101
01403
2N43A
iCRAOS
CR1404
N270
114270
05
R1417
220
2 N43 A
R1422
P1416
2 700
01406
R14111
1300
,420
11111142t
160
140.43
Figure 8-19.AF oscillator 0-721/SIA, schematic diagram.
amplifier Q1403. The signal output is at pin 3
of connector J1401.
The circuits associated with the general
alarm are discussed along with the general
alarm oscillator discussion.
AF Oscillator 0-722/SIA
General alarm oscillator 0-722/SIA contains
in conjunction with circuits in the chemical alarm
oscillator, produce a simuluted single-stroke.,
gong tone striking at the rate of 90 strokes per
Unijunction transistor Q1508 is used as a
timer to control flip-flop transistors Q1506 and
Q1507. Potentiometer R1534 controls the timing
of Q1508. The output of the flip-flop is a 1 2/3
minute. The signal continues automatically for 15
seconds after power is applied to the circuit.
215
.
1500 hertz signal from Q1501 is coupled to
emitter follower Q1502, and the 1000 hertz signal from Q1504 is coupled to emitter follower
Q1505. The outputs of Q1502 and Q1505 are
mixed at the base of amplifier Q1503, whose
emitter is gated by the timing circuit.
oscillator and timer circuits (fig. 8-20) which
dr. f
A. 1,-,
Transistors Q1501 and Q1504 (fig. 8-21) are
connected as Colpitts oscillators, and generate
sine wave signals at 1500 and 1000 hertz. The
IC ELECTRICIAN N _3 & 2
1500 HERTZ
EMITTER
OSCILLATOR
Q1501
FOLLOWER
Q1502
1000 HERTZ
EMITTER
OSCILLATOR
FOLLOWER
Q1504
Q1505
.--1111-11,
GATED
AMPLIFIER
Q1503
F-
OUTPUT
DIFFERENTIATING
CIRCUIT
t
TIMER
Q15011
pi
FLIP-FLOP
01506, 01507
TO VISUAL
ALARM TIMER
Q1406
140.44
Figure 8-20. Aadiofrequency oscillator 0-722/SIA (general alarm), block diagram.
hert- square wave having a peak-to-peak amplitude of approximately 14 volts. This square wave
is differentiated by R1516 and 01510, and gates
the emitter of Q1503. The output, regulated by
R1512, is at pin 3 of connector J1501.
When the general alarm is actuated, -30 volts
d-c is
applied to pin 6 of J1401 (fig. 8-19)
capacitors C1410 and C1411 begin to charge.
Potentiometer R1415, resistor R1414, and
capacitors C1410 and C1411 are used as an RC
time constant network. Potentiometer R1415 is
set so that 15 seconds aftei the general alarm
is actuated, timer Q1404 sends out a positive
pulse that cuts off Q1405. When Q1405 is cut off,
relay K1401 is deenergized which disconnects
the relay power input circuit from the timed
relay power output, deenergizing the general
alarm relays.
The 1 2/3 Hz signal output of Q1507 (fig.
8-21) is applied through pin 7 ofJ1401 (fig. 8-10),
to the base of Q1406. This pulse turns
Q1406 on and off, energizing and deenergizing
relay K1402. Thus interrupted relay power is
supplied through pins 9 of J1401 and J1501 to
operate control relay K563 and visual alarm
relay K580 (not shown).
AF Oscillators 0-724/SIA and 0-725/SIA
Unassigned alarm "A" oscillator 0- 724 /SIA
contains transistorized oscillator and timer circuits (fig. 8-22) which generates 500 hertz and
1500 hertz sine waves alternating at the rate of
1 1/2 Hz (jump tone).
Unassigned alarm "B" oscillator 0- 725 /SIA
generates a Jump tone of 600 and 1500 Hz sine
waves alternating at the rate of 6 Hz.
POWER RACK
The power rack is a deck-mounted enclosure
containing two identical 500-watt power amplifiers
(AF amplifier AM-2128/SIA), and a ventilation
blower. Each amplifier consists of two units:
the power amplifier, chassis 1; and the power
supply, chassis 2 (fig. 8-23).
The power amplifiers, similar to the power
amplifiers in the 1MC-6MC system discussed
previously, consist of a voltage amplifier stage;
a phase inverter stage, two driver stages, and a
final amplifier stage.
INTERCOMMUNICATING SYSTEMS
Intercommunicating (intercom) systems pro-
vide for two-way transmission of orders and
information between stations. Each intercom
unit contains its own amplifier.
INTERCOMMUNICATING UNITS
(LS-433A/SIC and LS-434A/SIC)
Regardless of their mechanical construction,
intercommunicating units installed in naval ves-
sels are to be connected together electrically
in a system. The electrical characteristics that
must be identical to permit interconnection in
a system are the (1) audio amplifier input and
output power requirements; (2) amplifier output
impedance to the loudspeaker line transformer;
(3) supply voltages and currents; (4) call the
busy signal voltages; and (5) interconnection
circuits.
W54
2.2
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0501 w. 66
CI.22
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01534
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.56
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44527
05506
.022
C15115
45530
33A
04507
25143A
41515
1115516
470
R1530
6200
115526
Figure 8-21.AF oscillator 0-722/SIA, schematic diagram.
5
SW
CR1501
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140.45
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IC ELECTRICIAN 3 & 2
500 HERTZ
OSCILLATOR
EMITTER
FOLLOWER
GATED
AMPLIFIER
01704
01705
01700
1-1,2 Hs
333 MILLISEC
TIMER
FLIP-FLOP
01701, 01702
01703
1500 HERTZ
OSCILLATOR
---111.
01707
EMITTER
FOLLOWER
01708
busy light, call light, volume cntrol, and dimmer control.
The TALK SWITCH, S26 (fig. 8-25), serves
to select the function of the reproducer. When
the switch is depressed, the reproducer fr.nctions as a microphone and the output of the amplifier of the calling station is electrically
connected to the reproducer of the called station. When the switch is released the reproducer
functions as a loudspeaker. The talk switch is
spring loaded and returns to the listen or stand-
,----111.
81-110. 500, 1500 141
OUTPUT
GATED
AMPLIFIER
01709
by position when released.
A HANDSET can be used with the intercom-
municating unit in place of the reproducer. The
operation is the same as that of the reproducer
except that the pushbutton in the handset is used
140.46
Figure 8-22.Audiofrequency oscillator 0-724/
SIA (unassigned alarm "A"), block diagram.
as a talk switch in place of the regular talk
One type of intercom unit, the LS-433A/SIC
(fig. 8-24), can originate calls up to a maximum
of 10 other stations; another, the LS-434A/SIC,
can originate calls up to a maximum of 20
other stations. There is no operatioLal difference
between these units. The schematic chagrant of a
typical intercommunicating unit is illustrated in
figure 8-25.
The ship's power for the intercommunicating
system is controlled by a master switch on the
IC switchboard and is supplied through a TSGA
cable. The TSGA cable interconnects the units
in parallel for the single-phase 115-volt power
supply and the signal circuit common line. The
115-volt power is fused at each unit. The audio
and signal lines (excluding the signal circuit
common) of the units in the system are inter-
switch on the front panel. Incoming calls will be
heard simultaneously in the handset and in the
reproducer. The volume control will control the
level of the incoming call to the reproducer
only.
A PORTABLE MICROPHONE can also be
used with the equipment. The operation is the
same as that of the reproducer, except that the
pushbutton on the microphone is used as a talk
switch instead of the regular talk switch on the
equipment.
The PUSHBUTTON ASSEMBLY, or station
selector buttons, are located .it the top of the
front panel. The locations or designations of the
various units in the system are engraved in the
station designation plate below the associated
selector buttons. When the station selector buttons are depressed they will lock in the operated
connected with a TTHFWA cable.
position until the release pushbutton is depressed
It will withstand shock, vibration, and salt spray,
and will perform under extremes of temperature
of station selector switches, whereas the 20-
the intercommunicating unit is housed in a
steel cabinet designed for bulkhead mounting.
to return them to the nonoperated position.
The 10-station unit is provided with one bank
station unit is provided with two banks of selector
The components consist
essentially of a reproducer, controls, and amplifier.
switches. In the 20-station unit, however, the
latchbar switches and release pushbuttons are
Reproducer
switch mechanism, 11 pairs of spring pile-up
switches, and a latch bar switch. Each pair of
pile-up switches (consisting of an upper pile-up
designated MU, S2U, and so forth, and a lower
and
high
humidity.
The reproducer serves as .. microphone to
transmit sound from the unit lu other units in
the system and as a loudspeaker to reproduce
sound transmitted to the unit by any other unit.
An incoming call can be heard through the loudspeaker because amplification is accomplished
by the amplifier of the calling unit.
Controls
The controls consist of the talk switch, handset and microphone talk, pushbutton assembly,
electrically interconnected.
One bank of selector switches consist of the
pile-up designated S1L, and so forth, is operated
simultaneously by a separate release pushbutton.
During standby periods the release pushis kept in the depressed, or operated
position. When any station selector button is
depressed, the release pushbutton will autobutton
matically return to the nonoperated position and
the release lamp under the pushbutton will be
218
e>f co
4,/40
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
BLOWER
140.47
Figure 8-23. Amplifier assembly AM-2316/SIA (power rack).
zu9
IC ELECTRICIAN 3 & 2
:Me
s-14
"71'
*:*
%To
'100
......
7.25(74)
Figure 8-24.
Intercommunicating unit (LS-433A/SIC).
knob and the illumination increases as the knob
is turned clockwise.
The VOLUME CONTROL, S25, is associated
with a variable impedance output transformer,
T2, inside the unit. As the knob is rotated, the
lighted. At the conclusion of a conversation the
release pushbutton must be depressed to extinguish the release lamp and return any station
selector buttons which were operated, to the
nonoperated position.
electrical energy passing through the transformer to the loudspeaker is increased and
The BUSY lamp is lighted when a station
button is depressed to call another station and
the station being called is busy. Do not leave a
station selector button depressed when the busy
lamp is lighted. Depress the release pushbutton
and call later.
The
the volume of sound output of the loudspeaker
is correspondingly increased. This control has
no effect on the volume of the outgoing sound
from the unit. Thus, each unit in the system can
control the incoming volume to the desired
DIMMER CONTROL, S27, (fig. 8-25)
controls all illumination of the unit. The signal
lights are off when the control knob is in the
extreme counterclockwise position and are
fully lighted for all other positions as the knob
is turned clockwise. The station designation
lights are lighted for all positions of the control
level.
Amplifier
The amplifier is a 3-stage push-pull amplifier consisting of the input transformer, Ti,
220
2:30
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Figure 8 -25. Schematic diagram of
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Chapter 8 ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
double triodes, V1 and V2, beampower tubes,
V3 and V4, output transformer, T2, and the
power supply rectifier twin diode, V5.
The primary of T1 is tapped to match it
either to the internal loudspeaker, LS1, used as
a microphone, or to an external microphone over
a frequency compensating network consisting of
R21, R22, R23, and C12. The secondary of T1
The upper end of resistor, R11, is also con-
nected to terminal 5 of the feedback winding on
T2. Terminal 6 of this winding is connected to
the V2A grid via R4 and terminal 4 is connected
to the V2B grid via R5. The unbalanced voltage
stage, V1.
developed across R11 will be fed back to the
grids of V2A and V2B through R4 and R5 respectively in the proper phase to correct the
unbalanced condition. The cathode circuit of
V2A and V2B is returned to ground through
tween the three stages of the amplifier. The
contacts 3-4 of the talk relay, K1.
Negative feedback is incorporated in the
drives the grids of the first voltage amplifier
Resistance-capacitance coupling is used be-
output of the power stage, V3 and V4, is coupled
through the output transformer, T2, to the voice
design of the Amplifier to lower the apparent
use (when receiving calls), transformer, T2,
acts as a line transformer. Calls are received
10 watts to any combination of from one to four
other intercommunicating units. The feedback
is developed by the separate winding on the
combination output-line transformer, T2 (ter-
transmission line. When the amplifier is not in
over the voice transmission line and are coupled
over a separate winding to the loudspeaker,
LSI. This winding is provided with taps con-
nected to the switch-type volume control, S25,
to change the step-down voltage ratio of T2 and
thus control the volume of the incoming signal.
During the standby periods the plate current
of V2 is cut off completely and the plate current
of the output tubes, V3 and V4, is reduced to a
very low value. This reduction in plate current
is accomplished by the voltage drop across R12
connected between the center tap of the highvoltage winding of T3 and ground. This voltage
increases the bias on V3 and V4. The d-c voltage on the filter capacitors C7, C8, and C9 is
substantially the same during standby periods
(no load) and during periods of speech (load)
because R12 changes the rectifier circuit from
capacitor-input (with load) to resistor-input on
no load. The reduced voltage with capacitor
input on load is approximately the same as with
resistor input on no load. Resistor, R12, is in
series with C9 during standby periods.
This type of cutoff circuit eliminates voltage
surges on the capacitors when switching from
standby to ready conditions and also eliminates
the delay caused by charging of the capacitors.
To ready the amplifier for outgoing speech, R12
is shorted by operating the loudspeaker, LS1,
talk switch, S26, (terminals 7 and 8); by pressing
the pushbutton in the auxiliary handset or microphone (terminals C and D on J6); or by operating
an external switch connected to terminals S5 and
GND.
The upper end of resistor, R11, is connected
from the junction of R8 and R9 to ground (R12
being shorted during ready periods.) Any unbalance in the audio voltages reaching the grids
of V3 and V4 will develop a voltage across R11.
output impedance and to develop a 70-volt output
(within 3 db) when the amplifier is delivering
minals 4, 5, and 6). The voltage is fed back
symmetrically to the grids of V2 through R4
and R5.
OPERATION
To call a particular station, depress the
station selector switch of the desired station
(S2 through S11), depress the talk switch, S26,
and speak directly into the grille. Release the
talk switch, S26, to listen. When the conversation is completed, depress the release pushbutton, Si, to return the selector pushbutton
to the nonoperated position.
To accept a call from another station, listen
to the incoming call through the loudspeaker.
Do not operate any of the station selector pushbutton switches. Depress the talk switch, S26,
to reply to the incoming call. The call light is
illuminated to indicate the station is being called
by another station. If the call light remains illuminated after the conversation is
completed, remind the calling station to depress
his release pushbutton.
The audio circuit between two stations is
illustrated by the simplified schematic diagram
in figure 8-26. The talk switches at both stations
are shown in the normal (listen) position. When
the talk
switch, S26, at either station is de-
pressed, the voice coil leads of the loudspeaker
are shifted from terminals 7 and 13 of the sec-
ondary of T2 to the input transformer, T1, of
the associated amplifier. At the same time contacts 7-8 of S26 (fig. 8-25) are closed to short
resistor, R12, to ground, thereby decreasing
the bias on V3 and V4. This action increases
221
233
IC ELECTRICIAN 3 & 2
STATION 2
STAT ON I
12
T
TI
i
T2
AMPLIFIER
c,
S25
S25
0
®
0
0
0
.:
.
::
NI
TALK
TALK
o 1
%Av
0
0
1
:
RELA
Ka
---
MC2C
MC2
Figure 8 -26. Schematic diagram of audio lines between two stations.
7.27
winding of the power transformer, T3, in both
the V3 and V4 plate current through the operating
coil terminals 7-8 of relay, K1. The increase
in plate current operates relay, K1, to close
contacts 3-4 and complete the circuit from the
stations is connected through terminal XX to the
signal circuit common MCXX, which is connected in parallel with all XX terminal's through-
out the system. Terminal 8 of T3 at station 1
is connected to terminal 8 of the busy relay,
V2 cathodes through R6 to ground. This action
applies plate voltage to V2 and the amplifier at
the talking station is placed in the ready condi-
K2. When the station selector pushbutton switch
S2, is depressed to call (idle) station 2, the
tion.
The voice signals are amplified and applied
release pushbutton, Si, will be released as soon
as S2 is depressed. The latchbar switch, S23,
will operate to momentarily connect terminal 7
of the busy relay, K2, to the signal line, MC2X.
The circuit is from terminal 7 of busy relay K2,
contacts 3-2 of S23, contacts 2-1 of S2, to terminal 2X, and to line MC2X. If station 2 is idle,
line MC2X will be connected to terminal 8 of T3
at station 2. The circuit is from line MC2X to
to terminals 14 and 15 of T2 at the listening
station and appear across terminal 7 of T2 and
the moving contact of the volume control, S25,
and then to the loudspeaker.
The amplifier of the listening station is in a
standby condition. In the standby condition the
plate current of V2 (fig. 8-25) is completely cut
off, and that of V3 and V4 is reduced to a very
low value by the voltage drop across R12, which
is in the negative high-voltage center tap 2 of
terminal 1X of station 2, contacts 6-7 of 51,
through call lamp 12, and to terminal 8 of T3.
T3 to ground.
Station 1 Calling Idle Station 2
During the time that latchbar switch, S23, is
momentarily operated, terminal 7 of busy relay,
K2, at station 1 is connected to terminal 8 of T3
at station 2 through call lamp 12. Terminal 8 of
K2 at station 1 is connected to terminal 8 of T3
The signaling circuits between two stations
are illustrated by the simplified schematic diagram in figure 8-27. Terminal 9 of the 16-volt
222
"4
403
Chapter 8-ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
STATION NO 2
STATION NO
T2
T2
LATCHBAR
523
(NO( OPERATE01
Si
RELEASE
BUTTON
\\
RELEASE BUTTON
52
1
R16
R25
SI
1
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STATION
SELECTOR
BUTTON
\ (DEPRESSED)
\
T3
12
(DEPRESSED)
C.)
CALL
BUSY
RELAY
16V
0
NJ
K2
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/I
(BUSY)
0
T3
6
AUD:0
LINES
AUDIO
0)16V
13
(RELEASE)
0
LINES
6V
(:)
DIM
INSTALLATION
CABLE
MCXX
SIGNAL CIRCUIT COMMON
MC2X
SIGNAL LINE
f1
i1
MC2C
000
STATION 2
MC2
VsVOICE PAIR STATIO2
ACIX
7.28
Figure 8-27, -Schematic diagram of signaling circuits between two stations.
terminal 1X of station 1, contacts 6-5 of 51, to
at the same station. Terminal 8 of T3 at station
1 is at the same potential as terminal 8 of T3 at
station 2 and K2 does not operate.
terminal XX of station 1, and to signal line
As soon as latchbar, S23, releases terminal
7 of busy relay, K2, is open-circuited and the
connections of both the audio (heavy) lines and
the signal (light) lines between the two stations
are established. The call lamp, 12, is lighted
at station 2. The signal circuit is from terminal
8 of T3 to 12, contacts 7-6 of 51, to terminal IX,
over signal line MC2X to terminal 2X of station
1, contacts 1-2 of S2, contacts 2-1 of S23, to
terminal XX, over signal common line MCXX,
to terminal AA of station 2, and to terminal 9
of T3.
The release lamp, 13, at station 1 is lighted
(S1
released when S2 was depressed). The
circuit is from terminal 7 of T3 at station 1, to
release lamp 13, contacts 1-2 of 51, and to
terminal 6 of T3. Line MCIX is connected to
line MCXX. The circuit is over line MC1X to
common MCXX. Line MC2X is also conntected
to line MCXX. The circuit is from terminal 2X
of station 1, contacts 1-2 of S3, contacts 2-1 of
S23, to terminal XX of station 1, and to line
MCXX.
Station 1 Calling Busy Station 2
When the station selector pushbutton switch,
S2, is depressed at station 1 to call station 2,
which is busy (line MC2X connected to line
MCXX by another parallel connected station not
shown), the release pushbutton, 51, will be released as soon as S2 is depressed. The latchbar
switch, S23, will momentarily operate to ener-
gize the busy relay, K2. The circuit is from
terminal 8 of T3, terminals Y7-Y6 of station 1,
terminals 8-7 of busy relay K2, contacts 3-2 of
S23, contacts 2-1 of S2, to terminal 2X, over
223 f,'";
IC ELECTRICIAN 3 & 2
STATION 3
TALK
STATION 3A
T2
T
TALK
SWITCH
SSZ6
WITCH
S26
exa
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INSTALLATION
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7.29
Figure 8-28. Schematic diagram of two stations in parallel.
signal line MC 2X to terminal 1X of station 2,
contacts 6-5 of 51 (released), terminal XX of
station 2, over signal common MCXX, terminal
XX of station 1, and to terminal 9 of T3.
The busy relay, K2, will lock in the operated
position after latchbar switch, S23, opens. The
circuit is from terminal 8 of T3, terminals
Y7-Y6, terminal 8 and contacts 7-6 of busy
relay K2, contacts 4-3 of 51, to the busy lamp
11, and to terminal 9 of T3. The busy lamp, Il,
is now in series with the coil of busy relay, K2,
and will be lighted. The audio lines from terminals 14 and 15 of T2 to line MC2 and line
terminal 15 of T2 is through contacts 2-1 of
busy relay, K2 (released), contacts 6-5 of S2
(depressed),
to terminal 2, and to line
MC2.
Parallel Operation of Two Adjacent
Stations
The operation of two intercom stations in
parallel is illustrated by the simplified schematic diagram in figure 8-28. The incoming
speech from a remote station will be heard at
MC2C will be open at contacts 3-4 and 1-2,
respectively, of busy relay, K2, which is oper-
both stations 3 and 3A, and replies can be made
ated.
The normal connection of the audio line from
terminal 14 of T2 (station 1) is through contacts
4-3 of busy relay, K2 (released), contacts 4-3 of
S2 (depressed), to terminal 2C, and to line MC2C.
The normal connection of the audio line from
from either station. Either station can call a
third station but both stations cannot call at the
same tume. When the talk switch, S26, at station
3 is depressed to transmit a message, the talk
relay, Kl, at station 3A is operated to open the
circuit to the loudspeaker and prevent acoustic
feedback (not shown).
224
2- 6
Chapter 8- ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
and dimmer control, S27, to the extreme clock-
The incoming speech lines, 1 and 1C, of
station3 are connected to terminal 15 and 14
wise positions, and connect a microphone or
The 14-15 winding of T2 at both stations
couples the incoming speech to the tapped
Polarity Test
respectively on transformer, T2.
windings of T2 which include the volume controls, S25. Thus the incoming signals appear
across terminals 7 of T2 and the moving contact
of the volume control, S25, at both stations.
These signal sources are connected in series
addition through a closed loop containing both
loudspeakers.
The circuit is from the arm of S25 at station
3, contacts 1-2 of S26, the loudspeaker, contacts
4-5 of S26, terminals Y4 and Y3, contacts 5-6
of Kl, terminal Y2 over line MC3Y21 to terminal
handset into the microphone jack, J6 (fig. 8-25).
To test the polarity of the unit, operate the
polarity test switch, S214 (fig. 8-29), to the OK
WHEN LIT position (not shown). The indicator
lamp, 1210, should light with full intensity if the
polarity is correct. Now operate the polarity
test switch, S214, to the REVERSED position
(not shown). The indicator lamp should go out
if the polarity is not correct. The lamp may
glow faintly but it is not important. The polarity
test checks the polarity of the line and signal
Yl of station 3A, terminal 7 of T2, the arm of
S25, contacts 1-2 of S26, the loudspeaker, contaz.ts 4-5 of S26, to terminals Y4-Y3, contacts
voltage windings (terminals 10-11 and 8-9
respectively) of the power transformer, T3
minal Yl in station 3, to complete the circuit
Call Lamp Test
at terminal 7 of T2,
The volume at both stations will be the same
and can be controlled by either volume control,
S25. Both volume controls, however, should be
kept at the same setting.
To test the call lamp of the unit, operate the
call lamp test switch, S212, on the test fixture.
The call lamp, 12 (fig. 8-25) on the unit under
5-6 of K1, terminal Y2, over line MC3Y12, ter-
If the talk relay, K1, is operated at either
station, the input to the audio circuit will be
(fig. 8-25).
test should be lighted.
Amplifier and Reproducer Test
open for both stations.
MAINTENANCE
A test fixture is provided with the maintenance parts of the equipment to facilitate testing
the intercom units. The test fixture is housed
in a metal case and includes the necessary
switches, resistors, and controls to perform all
essential tests on a unit. It is provided with a
line cord and plug for connection to the ship's
115-volt 60-hertz power supply, and suitable
female connectors for attaching it to the rear
of the unit under test. The front cover contains
11 DPDT test switches, S201 through S211, a
SPST call lamp test switch, S212, a SPST talk
test switch, S213, a DPDT polarity test switch,
S214, and an indicator lamp, 1201 (fig. 8-29).
To use the test fixture, remove the intercom
unit to be tested from its case and attach the
test fixture to the rear of the unit by plugging it
into the unit and connecting the line cord and
plug to the ship's 115-volt 60-hertz power. On
the test fixture, operate the talk switch, S213,
to the OFF position and the 11 test switches,
S201 through S211, to the STANDBY position.
On the unit under test, depress the release
pushbutton, S1, turn the volume control, S25,
To test the amplifier and reproducer, depress
the (microphone) talk switch and talk into the
microphone. The talker should hear his voice
clearly through the reproducer. Rotate the
volume control knob, S25, on the unit under
test while talking into the microphone, and
observe the effect on the output volume. Now
place the microphone close to the reproducer.
A microphone feedback should be observed when
the volume control is in the full-volume position as well as at one step below full volume.
This test provides a rough indication of the
amplifier gain, power output, and the general
performance of the entire unit, except for the
signaling circuits.
Station Selector Circuit Test
On the test fixture (fig. 8-29), operate the
talk test switch, S213, to the TALK position
with the microphone reasonably close to the
reproducer to produce a microphonic howl.
Reduce the volume control to the minimum
position at which the howl can still be obtained
by moving the microphone as close to the reproducer as required. This position will preduce the minimum objectionable howl during the
subsequent station selector circuit tests.
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- .664 41 -
Chapter 8- ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
On the test fixture, operate the test switch,
S210, to the TEST position which should stop
the microphonic howl. Then restore S210 to the
STANDBY position. This test checks the circuit
from terminals 1 and 1C, through the busy relay,
K2, (not operated) to the line winding terminals
14 and 15 of the output transformer, T2 (fig.
8-25). When test switch, S201, is in the TEST
position, it places a short circuit across ter-
minals 1 and 1C to interrupt the microphonic
howl.
On the unit under test, depress the station
selector pushbutton, S2 (adjacent to release
pushbutton 51). On the test fixture opP-ate the
test switch, S202, to the TEST position which
should interrupt the microphonic howl. Then
restore S202 to the STANDBY position and
depress the release pushbutton Si, on the unit
under test. This test checks the continuity between terminals 2 and 2C (fig. 8-25) through
switch S2U and busy relay K2 to the line winding
terminals 14 and 15 of transformer T2.
Similarly, on the unit under test, depress the
remaining station selector pushbuttons S3 through
S11, using
the corresponding test switches,
S211, on the test fixture
S203
through
for each test. This test checks the continuity
of the various audio circuits. If the unit under
test is provided with facilities for originating
calls to 20 stations, repeat the foregoing tests,
using the second row of station selector push-
terminal XX (fig. 8-25). When the station selector pushbutton, S2, on the unit under test is
depressed to select station 2, it checks the busy
circuit through the lower switch assembly, 52L,
busy relay, K2, latchbar switch, S23, and
associated wiring. It also checks the operation
of the upper switch assembly, S2U, and associated wiring.
On the test fixture, operate the test switch,
S203, to the TEST position and on the unit under
test, depress the station selector pushbutton, S3.
The busy lamp Il should light. Restore the test
switch, S203, to the STANDBY position and depress the release pushbutton, 51. This test
checks the operation of the busy relay, K2, the
lower switch assembly, S3L, the latchbar switch,
S23, and associated wiring. It also checks the
operation of the upper switch section, S3U, and
associated wiring.
Test the remaining pushbuttons by operating
first the test switches, S204 through S211, to
the TEST position on the test fixture and then
depressing the corresponding station selector
pushbuttons S4 through S11, on the unit under
test. If the unit under test is a 20-station type
repeat the foregoing tests, using the second row
of station selector pushbuttons, S12 through S21.
The manufacturer's technical manual furnished with the equipment installed in your ship
contains more detailed information concerning
the operation, repair, and maintenance of inter-
buttons, S12 through S21.
communicating units.
Signal Circuit Test
INTERCOMMUNICATING UNITS
On the test fixture
LS-518/SIC AND LS-519/SIC
(fig. 8-29) operate the
talk test switch, 5213, to the OFF position and
the 11 test switches, S201 through S211, to the
STANDBY position. On the unit under test,
depress the release pushbutton, 51, for the
subsequent signal circuit tests.
On the test fixture, operate test switch, S202,
to the TEST position and on the unit under test,
depress the station selector pushbutton, S2. The
busy lamp, Il, should light. On the unit under
test, depress the release pushbutton, Sl, and
again depress the station selector switch, S2.
The busy lamp, Il, should go out and again light.
Repeat this test several times in rapid succession. On the test fixture, restore test switch,
S201, to the standby position and on the unit
under test, depress the release pushbutton, 51.
When the test switch, S202, on the test fixture
is operated to the TEST position, it makes
station 2 busy by connecting terminal 2X to
The LS-518/SIC and LS -519 /SIC intercoms (fig.
8-30) are 10-station and 20-station units, respec-
tively. Both are fully transistorized intercoms
that operate in much the same way as the older
433A and 434A types. Refer to the overall functional diagram, figure 8-31. The darkened SOLID
line in this figure shows that the audio from the
calling loudspeaker is amplified, and transmitted
via the station selector switches to the called
station. The darkened BROKEN line shows that
the audio from the calling station goes into the
speaker of the local called station, via the output
transformer T3, volume control S25, and relay
contacts of K1, K4, and K3.
The main differences between the older inter-
coms and the fully transistorized units concern
the connection of a remote loudspeaker (Model
S-223) and the addition of a so-called handsfree position to the press-to-talk switch. Connecting the loudspeaker calls for some minor
20 : 9
IC ELECTRICIAN 3 & 2
5.1L4a
:t.1
-
,2-r
CiZtrigg.W
v':17:44!
Figure 8-30.Intercommunicating units, Type LS-518/SIC & LS-519/SIC.
wiring changes, such as cutting the leads on the
switch assembly. Complete instructions for con-
necting the loudspeaker are contained in the
manufacturer'? technical manual. When the press -
to-talk switch is in the hands-free position, the
calling station controls the transmitting or receiving function; the receiving station need not
press the switch to talk.
PUBLIC ADDRESS SETS
Public address sets are used at fleet land-
140.127
under extremes of temperature and high humidity. The driver unit, microphone, amplifier
enclosure, and battery enclosure are watertight. The set consists of a loudspeaker horn,
a microphone, a transistor amplifier assembly,
a driver
unit,
eight D-size batteries, and a
pistol-grip handle with a press-to-talk switch,
battery selector switch, and external battery
connector. All components are housed in one
assembly, (fig. 8-32). A 15-foot external power
cable is provided for connecting the set to an
external 12-volt battery when desired.
ings and in amphibious operations to direct the
movement of personnel, vehicles, and small
boats; to communicate between ships and small
To operate the set, put the battery selector
boats; and to address personnel aboard ship
switch i,o the INT. position (or to the EXT.
position if operation is to be from external
practical. They are also used for entertainment,
und such functions as church services, wardroom
and ready room briefings, change-of-command
and other ceremonies, and personnel training.
hand and raise
where high noise levels are present or where
the installed announcing is inoperative or im-
battery). Grasp the pistol-grip handle with one
the unit
so that the rubber
microphone is almost touching the mouth, and
direct the horn in the direction it is desired to
communicate. Press the press-to-talk switch
and speak directly into the microphone in a
strong voice. Release the press-to-talk switch
when the message is completed. The set is
The two types of public address sets are the
electronic megaphone type, and the portable
amplifier or lectern type.
specially designed to eliminate acoustic feedback
PUBLIC ADDRESS SET AN/PIC-2
to the extent possible. Acoustic feedback may
occur however, if the horn is directed toward a
reflecting surface such as a deck or bulkhead.
The AN/PIC-2 is an electronic megaphone
type public address set designed to perform
When using the set below decks, back the volume
228
240
7.
Miaow
1
of--41-*.i
I
>El
w
5N
PIT
SIL
51U
4 Kt $ KB SNOWN ENERGIZED
5 FOR V:05Y ONERIDE REMOVE JUNIPER BETWEEN NG 4 NI
I S26 SViOil4 IN Ot.PRESSED Po.milom
2 -4> ONOTES 510NAL FLOW FOR INCCWItNG MESSAGE
(M.IFUMR IN STANDBY CONDITION)
(AMPLIFIER IN OPERATE CCNO1TIC14).
NOTES
1. -1111. DENOTES SIGNAL FLOW FOR OUT -GOING MESSAGE
1
052 CALL
1_45p
526
TS
1,04
%5
Figure 8-31.Overall functional diagram.
RFC' rIL---14.1
--r>c
14644.1 NN105ET
MK
R10
J
MONO MEM 1110 =Ism =MIN. WINN. Anala
= NOM MEM .1.<3= - - MOD 01/11 a - MOIR MINIM - - IMO= amlwa Ammo
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S25
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allle
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17410
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140.128
r_ ..... _....... .... Mow Ona.).
Ct
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z
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C)
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2nz
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CO
r.
IC ELECTRICIAN 3 & 2
LOUDSPEAKER
HORN
LUNG
tends to increase this current. To prevent this
current increase, the thermistor resistance decreases with increasing temperature, thus reducing the negative bias and keeping the nr,signal collector current small.
-DRIVER MICROPHONE
UNIT
BATTERIES
`AMPLIFIER
ASSEMBLY
D-C Power Circuits
The 12-volt d-c supply is selected from
either the internal or external batteries by the
battery selector switch S2. The press-to-talk
switch Si supplies d-c power to the amplifier
only while the switch is held closed.
The current drain is very small when S1 is
closed and no signal is applied to the micro-
VOLUME
CONTROL
phone. The current is maximum when the loudest-
PRESS TO TALK
TRIGGER
EXTERNAL BATTERY,
CONNECTOR
signal is being amplified, as the collector current of the output stage varies with the strength
BATTERY
SELECTOR
SWITCH
of the amplified signal.
Microphone and Loudspeaker
Assemblies
HANDLE
27.295
The MK1 magnetic microphone has an im-
Figure 8-32. Public address set AN,'PIC-2.
pedance of approximately 150 ohms. The microphone output is applied to transistor Q1 through
control knob off until feedback stops, then advance it gradually to a point where maximum
volume without feedback is obtained.
Amplifier Circuits
The transistor amplifier is a three-stage
transformer coupled type. It consists of a volume
control, R1, input transistor, Ql, inter, stage
transformer, T2, push-pull power transistors
the volume control R1, and capacitor Cl. A
selected portion of the sound radiated to the
rear by the loudspeaker horn acts on the back of
the microphone diaphragm. This sound is phased
so as to reduce acoustic feedback.
Loudspeaker LS1 is a moving coil permanent
magnet type. Amplifier output signals actuate
the voice coil and diaphragm, and the resulting
sound waves are amplified and directed by the
loudspeaker horn.
Q3 and Q4, and an output inductor Ll (fig. 8-33).
Maintenance
A operation, and Q3 and Q4 operate in class AB.
Preventive maintenance consists of replacing
batteries, and routine cleaning and inspections.
When the batteries are replaced, inspect the battery contact springs and clean if necessary. If
the springs are badly corroded they should be
replaced. Keep the external power cable free of
dirt and corrosion. Clean the spring clips with
sandpaper and apply a thin coat of petrolatum
to reduce corrosion. Inspect the connector and
clean if necessary.
Periodically check the microphone housing.
Keep the opening to the microphone free of dust,
oil, grease, salt crystals or other foreign
matter. Salt crystals left by the evaporation of
salt water and spray should be dissolved and
Transistors Q1 and Q2 are biased for class
The output stage bias network includes thermistor assembly RT1, to temperature stabilize
transistors Q3 and Q4 at high operating temperatures. For further stabilization, each stage includes an emitter resistor. The driver and
output stages each have reverse feedback from
collectors to bases, the feedback resistor in each
case being also part of the d-c bias network.
In addition, reverse feedback over two stages is
provided through C3 and R8, from the collector
of Q3 to the base of Q2.
The base circuits of the output stage normally have a small negative d-c bias applied
through the bias network resistors, adjusted so
that the no-signal collector current of this stage
is small. Temperature rise in the transistors
rinsed away with fresh water, then the parts
dried with a soft cloth.
230
242
1141
O
MICROPHONE
K
LO
101070
C1
<-4
NCILLIME
ft
01
1
22K
*7
011470
C3
1
47 IMO
Figure 8 -33.
R.
2111010
PI
*5
220
6-)
TI
1-7,71
2711
HOUSING ASSEMBLY
01
G.OK
RR
119
10
*71
C
270 1470
2
04
2712374
027
1110
2102374
07
-41
1111
41
r
C5
ttomro
I
L*12
CON
f
I
If
I I
juot
Inn«
sit
NC
N
CCU
st
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110
TOO
pith-
....i
INT-tx7
HANDLE ASSEMBLY
NO
LIME
CON
HORN ASSEMBLY
Public address set AN/PIC-2, schematic diagram.
2112174
10
A 151 AMPLIFIER ASSEMBLY
E
140.48
?tar
TO EXTERNAL
OAT
C)
cn
P.<
cn
z
0
0
C)
PZI
0-3
z
MI
V.
z
z0
;JD
IC ELECTRICIAN 3 & 2
and two external speakers. Power to operate
the set is provided either by the self-contained
dry battery, or an external 115-volt, a-c supply.
As an IC Electrician, you may be assigned
the responsibility for setting up and checking
out public address sets. To allow time for any
minor adjustments or repairs that may be required, always check the set or system out well
in advance of the time it is to be used.
O.
Figure 8-34.
woos..
It
:1:11.
0
27.296X
Public address set, lectern type.
Check the inside of the pistol-grip handle
001MONMI
Cl..11
0
o6)Mt
MN
occasionally. Remove the handle cover and inspect the switch contacts. Clean if necessary.
The manufacturer's technical manual contains detailed instructions for troubleshooting
and repair of the set. All components are designed for easy replacement.
PUBLIC ADDRESS SET,
LECTERN TYPE
Modern Navy ships are provided with the
lectern type puthc address set. This set (fig.
8-34) is a portable self-contained unit capable
of reproducing sound for entertainment or dissemination of information. The set consists of
an illuminated reading counter with a removable
unidirectional dynamic microphone, a transistorized amplifier and controls, an extended range
loudspeaker, a battery meter, and jacks
for microphones, record player, tape recorder,
Figure 8-35.
232
244
27.340
Control amplifier console.
Chapter 8ANNOUNCING AND INTERCOMMUNICATING SYSTEMS
CONTROL AMPLIFIER CONSOLE
rwo mono emft
amp Immo mommt mm0 ammo ammo
Sam.
mm0 a.m. amass
POWER AMPLIFIER
LOUDSPEAKER
ASSEMBLY
GROUPS
r- - - - --1
I
1
REMOTE
SWITCH.
UNIT
CONTROL
MON.
AMPLIFIER
CHANNEL .1
AMPL.
.4-L.
I
AMPLIFIER
CHANNEL al
I
I
RECORD
I
I
SWI TCHES
PLAYER
ASSY.
METERS
I
AND
I
RADIO
CONTROLS
I
I
I
RADIO
2
TAPE
RECORD
REPROO
C. ;MERSIN'.
<CPO
POWER
I
0.
CREW
I
I
I
I
I
I
I
I
I
CON TROL
AMPLIFIER
CHANNEL .2
MI C.
JACK
27.339
Figure 8-36. Basic block diagram of circuit SE.
SHIP'S ENTERTAINMENT SYSTEM
A separate shipboard announcing system,
circuit SE, is used primarily for the entertainment of ship's company. This nonvital, readiness class 4 system is capable of reproducing,
amplifying, and retransmitting, commercial radio
broadcasts, tape recordings, and voice announcements.
COMPONENTS
The system, as installed on a destroyer
class, consists of four major components and
associated speaker groups. These components;
The Control Amplifier Console, Automatic Record Player Assembly, Power Amplifier, and
Remote Switching Control Unit are usually lo-
cated in the forward IC room; however, on
occasion they may be located remotely either
together or individually. Two radio receivers
are also associated with the system, generally
they are located near the Control Amplifier
console.
The Control Amplifier Console houses a tape
recorder reproducer (3.5 dr 7.0 in. per minute),
two
two channel line amplifiers (20 watt), an amplifier for monitoring, and the necessary switches,
meters, and controls to operate the system. It
is from this console that program selection is
made and from here that any voice announcements originate. A Control Amplifier Console
Is shown in figure 8-35.
The Power Amplifier consists of two amplifiers (50 watt) and serves to boost th. Jutput of
the control amplifier for presentation to three
individual speaker groups. The loudspeakers
are divided into Officer, Chief Petty Officer,
and Crew groups.
The Automatic Record Player Assembly and
the Remote Switching Unit are used to reproduce
commercial phonograph ecordings. Operating
in conjunction with these units allows playing of
52 recording (104 selections) of the 45 rpm variety. The Record Player Assembly in addition to
the record playing function, contains components
which preamplify the signal, stop the entire unit,
supply the needed power, and reject unwanted
recordings.
233
245
IC ELECTRICIAN 3 & 2
The Remote Switching Control Unit contains
the necessary switches (pushbutton) and circuitry to select the desired recording to be
The system receives its power from
forward IC switchboard.
the
played.
Maintenance
OPERATION
The entertainment system is of primary
interest to the entire ship's company as it is
Any input may be distributed over either
channel or both channels simultaneously. Refer
to the block diagram (fig. 8-36). Two different
inputs may be distributed at the same time, one
over each channel. Either channel may be monitored. Tape recordings may be made with both
channels in operation either from the input being
distributed or from another source (not shown).
Inputs may be attained from the two external
radio receivers, the automatic record player, the
installed tape recorder-reproducer or from the
remote microphone jack. This jack can be used
in conjunction with a portable record player or
tape record-reproducer.
Two channels are initially installed at each
loudspeaker. Selection is made by a channel
selector located there. A volume selector is
also located on the speaker. The operator at
the Control Amplifier Assembly selects speaker
groups in operatio.., Officer, Chief Petty Officer,
or Crew.
often the oniy source of information and news.
Through proper planned maintenance prodedures,
casualties can be kept to a minimum.
The elai,orate switching employed in the sys-
tem makes it easy to troubleshoot. Generally,
the system can be kept at least partially in
operation during maintenance and repair evolutions.
Programming
Although this system is often located in the
IC room it is of paramount importance that the
entire ship's company be permitted to use it.
Working together with the electrical officer,
IC Electricians should draw up specific programs
that will satisfy most of ship's company.
The IC Electrician who indiscriminately shifts
programs and imposes his taste in entertainment
upon the rest of the crew soon finds himself
at odds with his messmates and his seniors.
Once a program has
planned and approved,
it should be adhered to as closely as possible.
234
246
CHAPTER 9
DIAL TELEPHONE SYSTEMS, PART I
interconnect the line stations; (3) power equipment that furnishes normal and emergency power
In addition to sound-powered telephone cir-
cuits, dial telephone systems are installed on
the Navy's combatant ships. The dial telephone
system, or circuit J, is primarily an administrative circuit that provides complete selective
telephone communication throughout the ship.
for the system, and (4) accessory equipment
used to interconnect the ship's exchange with
control, and damage control. The capacity of the
The telephone station equipment consists of
different types of telephone instruments, each
particular ship.
type designed for use in weather-protected (below
decks) or exposed (weatherdecks) locations. The
shore exchanges when the ship is in port.
TELEPHONE STATION EQUIPMENT
This system is also used to supplement other
communication facilities for ship control, fire
system varies with the size and needs of the
This chapter describes the equipment and
operating principles of the so-called Strowger
system, a typical shipboard dial telephone system manufactured by the Automatic Electric
telephone instrument is a compact unit which
transmits and receives speech, and signals the
desired station. It comprises a transmitter,
receiver, dial and ringer. The transmitter changes
sound into an undulating current that is sent over
Company.
an electrical circuit. The receiver changes the
undulating current back into sound. The c1L-1,
when operated, causes a series of interruptions
TELEPHONE EQUIPMENT
A telephone system consists of a group of
telephones with lines so arranged at a central
point that any two telephones in the system can
be interconnected. In an automatic telephone
(impulses) in the current flowing in the line
circuit. The ringer provides an audible signal
when the station is called. Remote ringing devices that contain a power-signal relay and a
system, the connections between the telephones
are completed by remotely controlled switching
mechanisms. In a manual telephone system, the
horn, bell, or siren are used in high noiselevel locations, such as machinery spaces.
connections between the telephones are com-
TYPES OF TELEPHONES
pleted by a switchboard operator.
The types of telephones furnished with the
dial telephone system are illustrated in figure
9-2. The types differ mainly in the form in
The switching mechanisms in an automatic
system are controlled at the calling telephcne
by a device, or dial on the telephone instrument.
The dial has 10 digits, any one of which can be
which the components are assembled. The components perform the same function, but the
dialed. When the dial is operated it causes a
form and mounting for each type is of special
design and depends on whether the instrument
is to be used in a protected or an exposed loca-
series of interruptions, or impulses, in a current
flowing in the line circuit. The number of impulses sent out by the dial corresponds to the
digit dialed. These impulses cause the automatic
tion.
The TYPE A desk set telephone (fig. 9-2A)
is installed in staterooms, cabins, offices, and
similar stations. The desk set consists of a
phenolic case (containing the ringer, dial and
other working parts), a handset, and connecting
cord with a terminal block for making the line
switches to operate and to select the called
telephone.
The dial telephone system (fig. 9-1) consists
of: (1) telephone station equipment, made up of
telephone instruments which may receive or
initiate calls; (2) automatic switchboard equipment that includes the switching necessary to
connections.
235
247
IC ELECTRICIAN 3 & 2
41
AutomatiP
TELEPHONE
STATION
EQUIPMENT
RINGING
MACHINES
Switchboard
Equipment
--I
M-6 SET
--I
BATTERY
POWER
AUTOMATIC
SWITCHBOARD
BOARD
Accessory
Power Equipment
Equipment
SHORE LINES
4
ATTENDANTS
CABINET
SHIPS POWER SUPPLY
Figure 9-1. Block diagram of the dial telephone system.
7.76(140B)
The TYPE F bulkhead telephone (fig. 9-2B)
can be installed in any station except those on
weather decks. The type F telephone is a non-
cups, one for the transmitter and the other for
watertight unit designed for mounting on a bulk-
the proper distance from the lips, for the average
head or on the side of a desk. It consists essentially of a metal housing on which are
mounted the handset, dial, and ringer. The line
connections are made at a terminal block inside
the housing.
The TYPE C splashproof telephone (fig.9-2C)
is installed at stations on weather decks and
other stations elpelsed to moisture. The type C
telephone is designed for bulkhead mounting and
consists essentially of a metal housing on which
are mounted the handset and dial which are
enclosed in a splashproof box. The connections
to the line are made at a terminal strip inside
the housing.
The TYPE G bulkhead telephone (fig. 9-2D),
previously installed only on submarines, is now
being installed
aboard surface ships, and is
interchangeable electrically with the type F.
The type G, which is panel mounted, is furnished also in two other enclosures. The type
G (desk) is interchangeable with the type A and
the type G (watertight) is interchangeable with
the type C.
The main assemblies that comprise a telephone
instrument are the handset and base.
liANDsET
the
receiver. The mounting cups are at an
angle with the handle to bring the transmitter
user, when the receiver is centered on the ear.
The transmitter and receiver are held in
the mounting cups by an ear cap for the receiver
and a moathpiece for the transmitter. Both retaining p eces screw on the handset handle. In
order to prevent the possibility of inserting the
transmitter into the receiver mounting cup and
vice versa, the transmitter is made to fit only
into the transmitter cup, and the receiver to fit
only into the receiver cup.
The transmitter and receiver units are both
of the capsule type. Connections from the cord
conductors are brought out to contact spring
clips in the mounting cups of the handset. The
connection between the transmitter or receiver
unit and the cord conductors is completed when
the capsule is in contact with the contact spring
clips.
Transmitter
Th.: transmitter unit consists essentially of
a metal diaphragm and an insulating cup containing loosely packed carbon granules. As soon
as the handset is removed from the cradle,
or hook switch, direct current supplied by the
common battery at the switchboard flows through
The standard handsets (fig. 9-3), consist of
a conveniently shaped handle with two mounting
the transmitter. The diaphragm is mechanically
connected to the carbon button so that sound
waves striking the diaphragm cause it to vibrate.
236
248
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
w
A-TYPE A (DESK SET) TELEPHONE
C- TYPE C'(SPLASHPROOF) TELEPHONE
D- TYPE (G) BULKHEAD 'TELEPHONE
B-TYPE F (BULKHEAD TYPE) TELEPHONE
7.83
Figure 9-2. Telephones.
2 49
237
IC ELECTRICIAN 3 & 2
,.."le,
,
Figure 9-3. Telephone handset.
The mechanical movements of the diaphragm
are transmitted to the carbon granules. When
carbon granules are compressed by an
inward movement of the diaphragm, the resistance is lowered and more current flows
through the transmitter. When the diaphragm
relaxes, the pressure on the carbon granules
is reduced, the resistance is increased, and
less current flows. Thus, as long as the diathe
phragm is vibrating from the sound waves, the
resistance of the carbon granule chamber is
constantly changing, which in turn causes the
current through the transmitter to undulate accordingly. This undulating current, called the
VOICE CURRENT, is sent out on the telephone
line after being boosted by the action of the induction coil and talking capacitor (explained
later). The receiver at the other end of the line
converts the voice current back into sound
waves.
3.198
coil-wound pole pieces and a diaphragm contained in a protective shell. The diaphragm
is mounted under a slight tension so that it is
Intlled toward the pole pieces by the permanent
magnet. The voice currents, flowing through
the coils about the two pole pieces, set up
magnetomotive forces that alternately aid and
oppose the magnetic flux of the permanent magnet. This action causes the receiver diaphragm to be attracted with alternately greater
and lesser force. As the diaphragm moves back
and forth it reproduces the vibrations of the
distant transmitter, and the sound waves thus
produced are heard at the receiver.
Base
The base includes the dial, hook switch,
ringer, two capacitors, and induction coil. The
telephones (fig. 9-2) include the same combina-
parts and assemblies, but the bases
on which the parts are mounted differ somewhat, and the mounting arrangement differs
tion of
Receiver
considerably.
Dial
The receiver unit is of the permanent magnet
polarized type. It consists essentially of apowerful
permanent magnet with two soft-iron
The dial (fig. 9-4) enables the calling party
to control the automatic switching mechanisms
238
250
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
FINGER STOP
RATCHET
PAWL
FINGER
PLATE
RATCHET
GEAR
=
IMIN.1111/11111
lllll
111711
PINION
NUMBER
PLATE
llll 111,1
1
FINGER
PLATE
WORM GEAR
ESCUTCHEON
WORM
RING
MAIN SPRING
1111.r
MLE-
1A
DIAL CARD
FINGER STOP
IMPULSE CAM
A. FRONT VIEW
IMPULSE CAM
WORM GEAR
GEAR
P NION SHAFT
GOVERNOR CUP
IMENI
MAIN
SHAFT
-I " X
GOVERNOR
IMPULSE SPRINGS
)
TO
LINE CKT
IMPULS(SPRINGS
IMPULSE CAM
IMPULSE SPRING
ASSEMBLY
7.86
WORM
Figure 9-5. Telephone dial schematic.
IMPULSE
SHORTING
ARM
SHUNT
SPRING
ASSEMBLY
GOVERNOR
ASSEMBLY
SHUNT
OPERATING
CAM
The finger plate is fitted to the main shaft,
which rotates when the dial is turned .from any
number to the finger stop (fig. 9-4). Thus, as
the main shaft rotates, the tension of the main
CAM
ASSEMBLY
MOUNTING
PLATE
1
2
3
4
SCREW TERMINALS
B. REAR VIEW
7.85
Figure 9-4. Telephone dial.
spring, which is also mounted on the main shaft,
is increased to provide the power needed to re-
turn the dial, (main gear) to normal when the
finger plate is released. When the dial is turned
from normal, the ratchet pawl (fig. 9-5) slips
over the ratchet gear which is mounted on the
main shaft with the main gear. This prevents
the main gear from rotating. When the dial restores to normal, however, the ratchet pawl
engages the ratchet gear and the main gear
by a series of interruptions, or impulses, in
the current flow. The number of impulses sent
out by the dial corresponds to the digit dialed.
The principal functions of the dial are to (1)
deliver impulses to the line, (2) short-circuit the
parts of the telephone that introduce unnecessary
resistance In the dialing circuit, and (3) prevent
the dialed impulses from clicking inthe receiver.
The principal parts and assemblies of the
dial are compactly assembled on a mounting
plate (fig. 9-4). These parts and assemblies
are (1) finger plate (with 10 holes), (2) number
plate, (3) governor assembly, (4) impulse cam
and springs, (5) impulses shorting arm, (6) shunt'
cam and springs, and (7) driving mechanism.
The dial parts and assemblies are arranged so
that when the dial is operated, the line is opened
and closed at a rate of approximately 10 interruptions per second.
r151.
rotates.
The speed of the dial mechanism as it returns
to normal under the spring tension is controlled
by the GOVERNOR ASSEMBLY. The governor
assembly consists of a worn gear shaft that is
mechanically connected to the main gear of the
dial through a gear train (fig. 9-5). Two flyball
wings are attached to the worn gear shaft. A
governor weight on the end of each flyball wing
protrudes into the governor cup. The rotary
motion of the shaft causes the flyball wings to
attempt to fly outward and due to centrifugal
force, friction is set up between the governor
weights and the governor cup. The speed of the
dial is thus regulated by adjusting the flyball
wings to increase or decrease the amount of
pressure the governor weights exert on the inside surface of the cup.
239
IC ELECTRICIAN 3 & 2
IMPULSE SPRINGS
DIAL
MAKE
CONTACTS
SHUNT SPRINGS
BREAK-MAKE
CONTACTS
L
1
1
1
1
t
1
1
--(111. +
C1
f
T
(0
TRANSMITTER
LI
C2
HOOK SWITCH
(HANDSET PEMOVED)
ANTISIDE TONE
COIL
3
RINGER
6
ligl
i
.11-111.
I
RECEIVER
HANDSET
I
o)._J_______::
CORD a
r I
L2
CORD
I
i
TERM.
BASE
1
Figure 9-6. Schematic diagram of C telephone.
The IMPULSE CAM is geared mechanically
to the main gear through a gear train (not shown)
7.87
cam by the cam shunt assembly. The last time
the cam passes, no impulse is produced, The
so that the impulse cam is caused to rotate
during the time the dial mechanism is being
returned to normal. The impulse springs are
purpose of the delay feature is to allow the
relays in the automatic switchboard to operate
properly between each series of impulses.
normally closed and are opened intermittently
by the impulse cam only when the dial is returning to normal. An impulse is produced each
time the impulse springs are opened. The travel
from any off normal position is one series of
impulses. The number of impulses in the series
depends on how far the dial is turned away from
normal. As the impulse cam rotates it opens
the impulse springs, and thus the line circuit,
the same number of times as the digits dialed.
The momentary opening of the line circuit produces the dial impulses that actuate the auto-
The SHUNT OPERATING CAM (fig. 9-4) is
mounted on the main shaft. When the dial is at
normal, the shunt cam hplds the shunt springs
in the normally open position. When the dial
is turned off normal, the shunt cam is moved
out
of engagement with the shunt spring as-
sembly and the shunt springs close to shunt the
receive and transmitter. The closure of the
shunt springs prevents the inpulses from being
heard in the receiver during dialing, and also
prevents the variable resistance of the transmitter from affecting the character of the dial
matic switching mechanism (Strowger switches)
at the telephone switchboard to extend the con-
impulses .
nection to the line associated with the dialed
Hook Switch
The dial has a time delay feature that
separates the series of dial impulses. The time
delay is the time between the last impulse of a
series and the complete restoring of the dial.
It is approximately equal to the time required
A representative telephone station circuit is
illustrated in figure 9-6. It is not desirable to
have both the talking apparatus (transmitter
number.
for one impulse and is accomplished by the
movement of the impulse springs away from the
and receiver) and the signaling apparatus (ringer
and capacitor, Cl) connected to the line while
the telephone is in use. Accordingly, the hook
switch, also called the cradle switch, monophone
240
"I:2
#6.9,1)
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
leg. The soft-iron armature is pivoted at its
PERMANENT
MAGNET
GONG
center, and lies in front of the two poles of the
electromagnet, but does not quite complete the
magnetic circuit. The permanent magnet is used
to polarize the armature ends of the electromagnet. The armature end of each coil has a
consequent north polarity produced by the permanent magnet. The two ends of the armature
have consequent south poles produced by the
permanent magnet.
ARMATURE
ELECTROMAGNET
7.88
Figure 9-7, Polarized ringer.
switch, or plunger switch (fig. 9-6) is an assem-
bly of springs arranged so that removing or
replacing the handset brings about the desired
circuit changes. When the handset is placed on
the hook switch, the ringer is connected to the
line through Cl, and the transmitter, receiver,
and dial are disconnected from the line. When
the handset is removed from the hook switch, a
pair of make contacts and a set of break-make
contacts on the switch (1) connect the transmitter, receiver, and dial to the line; (2) disconnect the ringer from the line; and (3) connect
Cl across the dial impulse springs. The hook
switch on all types of telephones has the same
function, but the mechanical arrangement differs.
Ringer
The ringer (fig. 9-7) is of the polarized,
untuned type commonly called the STRAIGHTLINE ringer (bell), It is suitable for use on
both
individual and party lines and is called
UNTUNED because it will operate over a wide
range of frequencies.
The ringer consists of a hard-steel permanent magnet, a soft-iron electromagnet, a
pivoted armature carrying a clapper rod and
clapper, and a gong or set of gongs. The elec-
tromagnet is U-shaped with a coil around each
The coils are wound on the pole pieces so
that when current flows in one direction (rig.
9-7) the mmf of coil 1 aids the permanent
magnet flux and the mmf of coil 2 opposes it.
Thus, coil 1 increases the strength of the north
pole at the armature end of coil 1 and coil 2
attempts to establish a south pole at the armature end of coil 2. Because like poles repel and
unlike poles attract, the armature moves clockwise and the clapper strikes the gong at the
right.
When the ringer current reverses, the mmf of
the coils reverses. Thus, coil 2 strengthens the
north pole at the armature end of coil 2 and coil
1 attempts to establish a south pole at the armature end of coil 1. The armature moves counterclockwise and the clapper strikes the gong at the
left. The gongs ring once for each half cycle of
ringing current. The ringing current is 17 to 25
hertz.
When no current flows through the coils,
the armature south poles attract the north poles
at the armature end of the coils and the clapper
moves either to the right or the left depending
on which air gap is the shortest. A biasing
spring (not shown) is provided to give the
armature a definite position when the gongs
are silent. This spring holds the clapper against
one gong and prevents the gong from tingling
when the other party on the line is dialing
(biasing springs on commercial telephones
prevent clapper operation when the wrong
polarity of ringing current is received in
selective ringing on four-party lines). Small
pieces of nonmagnetic material are placed
between the core end and the armature to prevent actual contact and subsequent sticking due
to residual magnetism.
Capacitors
Two capacitors are used in the telephone,
one in the ringing circuit and one in the transmission circuit (fig. 9-6). The capacitor Cl
in the ringing circuit allows a-c ringing
current to pass through the ringer and prevents
241
IC ELECTRICIAN 3 & 2
the flow of direct current. During dialing Cl
(in series with R) is shunted across the dial
impulse springs to minimize sparking and
suppress radio interference. The capacitor C2
in the transmission circuit improves the trans-
removed from the hook switch, the ringing capacitor Cl is transferred from the ringer to the
dial impulse springs, as previously mentioned,
to prevent excessive sparking at the contacts of
the impulse springs.
mission output characteristics of the telephone.
If capacitor C2 were not used, the output would
be very low because of the high impedance of
Dialing Circuit
the telephone circuit and the line circuit. The
The dialing circuit consists of line Ll, the
action of C2 is explained later.
hook switch, the dial impulse springs (shunted by
resistor R and capacitor Cl, in series), the dial
shunt springs, and line L2 (fig. 9-6). When the
dial is operated, the dial shunt springs close to
shunt the transmitter, receiver, and induction
Induction Coil
The induction coil L couples the transmitter
and receiver units to the line (fig. 9-6). It
also increases the output volume by boosting
the voice current undulations developed by the
transmitter and prevents or decreases SIDETONE. Sidetone occurs when a person hears
coil so that they will not affect the impulses sent
out by the dial.
Transmission Circuit
his own voice in the receiver while talking int..
the transmitter.
The induction coil L consists of three
windings (1-2, 3-6, and 6-4) on a laminated iron
core. The windings are magnetically interlinked
The transmission circuit includes two distinct circuits, the main talking circuit, and the
local talking circuit. The MAIN TALKING CIRCUIT consists of line Ll, winding 1-2 of the in-
duction coil, the transmitter, and line L2 (fig.
by the common magnetic circuit provided by
the iron core. The induction coil serves as
a 3-winding autotransformer in which part of
the winding is common to both the primary
9-6). The LOCAL TALKING CIRCUIT consists of
the transmitter, capacitor C2, winding 3-6 of the
induction coil, and the antisidetone coil (fig.9-6).
This circuit is designated "local" because the
circuit is completed within the individual tele-
(input) and the secondary (output) circuits. Any
change in the current in one of the windings
phone and not through the line conductors.
causes a corresponding induced emf in all three
windings. The core is made up of high permeability laminations to provide a low reluctance
The main talking circuit is also the d-c path
through the telephone. The direct current for the
transmitters of the calling and called telephones
is furnished by the automatic switchboard
through relays associated with the connector
path for the magnetic flux. A small air gap in
the magnetic circuit prevents saturation of the
core by 'the direct current feeding the transmitter.
switch
(not
connection.
TELEPHONE CIRCUIT
A telephone circuit (fig. 9-6) comprises the
ringing, dialing, transmission, and receiving
circuits. Booster and antisidetone features are
also included in the circuit. Note that the handset
is removed from the hook switch so that the
transmitter, receiver, and dial are connected to
the line, and the ringer is disconnected from the
The ringing circuit consists of line L1, ringing capacitor Cl, make-contacts on the hook
switch, the ringer, and line L2, (fig. 9-6). This
circuit condition exists when the handset is
placed on the hook switch. When the handset is
which
establish the
When talking into the transmitter, two sets
of current undulations are set up: (1) those directly produced in the line due to the variations
in the resistance of the transmitter; and (2) those
produced in the local talking circuit by the
'
charging and discharging of capacitor C2, caused
by the varying potential drop across the transmitter.
The local talking circuit current undulations
are best understood if it is kept in mind that the
capacitor C2, is connected across the transmit-
line.
Ringing Circuit
shown)
ter, directly on one side and through winding 3-6
of the induction coil and the antisidetone coil on
the other side. Thus, the resistance variation
introduced by the action of the transmitter
causes the voltage to vary on the plates of capacitor C2. Alternating currents will then flow
in the local talking circuit as the capacitor C2
242
2S4
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
adjusts the charge on its plates to the varying
difference of potential across the transmitter.
The resulting alterating currents flowing in
winding 3-6 of the induction coil, considered as
the primary of the autotransformer, will induce
voltages in the secondary winding 1-2. The
change in current that occurs in winding 1-2 is
of greater magnitude as a result of the change
of produced current in winding 3-6 by the transmitter. The induced voltage in winding 1-2 aids
the voice currents directly delivered to the line
via the main talking circuit and thus a BOOSTER
feature is achieved.
It is important that the transmitter of the
calling telephone produces a large effect on the
receiver of the called telephone and little or no
effect on the local receiver. Accordingly, the
telephone circuit is designed so that the local
transmitter action produces a minimum of current flow through the local receiver. The means
used to lower sound in the local receiver,
windings 3-6 and 6-4 of the induction coil, the
receiver, and transmitter (fig. 9-6). As previously explained, the antisidetone feature prevents the local transmitter from affecting the
receiving circuit.
Dui ing the reception of speech, the voice cur-
rents are received via the main talking circuit
which include line Ll, winding 1-2 of the induction
coil, the transmitter, and line L2. The voice currents flowing in winding 1-2 of the induction coil,
considered as the primary of the autotrans-
former, will induce voltages in the secondary
windings 3-6 and 6-4. (Because of the antisidetone feature the local transmitter has no effect on
the receiving circuit.) The a-c voltage induced in
windings 3-6 and 6-4 causes signal currents to
flow through the receiver which (by action of the
diaphragm) reproduces the tone and words of the
person speaking into the transmitter at the other
end of the connection.
AUTOMATIC SWITCH BOARD
introduced at the local transmitter, is called
the antisidetone feature.
The antisidetone feature is obtained by
matching the impedance of the local talking circuit to the impedance of the main talking circuit
(including the line loop). Because the line con-
ditions vary with different lengths of line, the
impedance of an average line loop is used as a
standard, and the impedance of the local circuit
is arranged to balance the average line loop. If
any line loop is shorter or longer than the average loop, the sidetone will tend to increase.
When transmitting, winding 3-6 is the primary of the autotransformer and winding 1-2 is
the secondary. Winding 6-4 is inductively coupled
to the transmission circuit, and voltage is induced in wincing 6-4 that opposes the change
in transmission current. The desired inductive
balance is obtained by the impedance of the antisidetone coil so that a minimum of voltage exists
across the receiver terminals, resulting in little
or no sound in the receiver during transmission.
Receiving Circuit
The receiving circuit also includes two distinct circuits, the main receiving circuit, and the
local receiving circuit. The MAIN RECEIVING
CIRCUIT consists of line Ll, winding 1-2 of the
induction coil, the transmitter, and line L2 (fig.
9-6). This circuit is the same as the main talking circuit during transmission, except winding
1-2 now becomes the primary of the autotransformer instead of the secondary. The LOCAL
RECEIVING CIRCUIT
includes
capacitor C2,
EQUIPMENT
The automatic switchboard is the switching
center of the dial telephone system. Mounted on
this switchboard are all telephone switching
mechanisms, control circuits, line disconnect
keys, part of the testing equipment, and most
of the supervisory alarm signals.
These switch mechanisms automatically perform the following functions:
1. Locate a station desiring to make a call.
2. Respvild to dial impulses and extend the
calling station to the called station.
3. Ring the called station and, if necessary
select between the two parties on a party line.
4. Supply various tones, such as dial tone,
busy tone, and ring-back tone as required.
5. Provide "hunt-the-not-busy-line" service where required. This is a feature whereby
if the lowest numbered of a consecutively num-
bered group of line stations is called, the switchboard will automatically connect the calling line
station to the lowest numbered idle line station
of such a group. A busy signal is returned only
if all line stations of the group are 11119/.
6. Provide "executive cut-in" service to
line stations as specified. This feature enables
such line stations to complete their connection
to any line station they may call irrespective
of whether that line statioii is busy.
7. Disconnect the calling and called stations
at the completion of the conversation.
8. Perform certain other operations in con-
nection with telephone service.
243
IC ELECTRICIAN 3 & 2
VERTICAL MAGNET
ROTARY MAGNET
ROTARY
ARMATURE
SWITCH
FRAME
VERTICAL BANK
FOUND
ONLY ON
FINDER
VERTICAL WIPER
CONTROL BANK
SWITCHES
WIPER CORDS
LINE BANK
CONTROL. WIPER
LINE WIPERS
Figure 9-8.Strowger switch.
SWITCHING
Numerous methods of switching, such as "all
relay," "rotary," "panel," "crossbar," and
"step-by-step" have been devised and are used
commercially. The most
extensively used
switching equipment for shipboard installations
is the Strowger automatic type. The switch mech-
anisms used in this type of equipment operate
on a step-by-step basisthat is, the switching
functic,s are accomplished electromagnetically
in synchronism with the dial impulses.
The Strowger switch is an electromechanical
device which, switch by switch, extends the connection from the calling to the called telephone.
The assembly of electrical contacts, arranged in
ten levels, generally ten contacts to a level, is
called a bank. The electrical members which
make contact with the selected set of contacts in
the banks are called wipers. These wipers are
connected to the switch shaft.
The switch mechanism elevates the shaft
(therefore the wipers) and then rotates the shaft
!
140.129
(and wipers). Because of this up-and-around motion, the Strowger switch is often referred to as
a two-motion switch.
The Strowger switch is the basic switch of
the step-by-step system being used as a linefinder, connector, and selector, in each case
employing slightly different electrical and
mechanical variations. Figure 9-8 shows the
mechanical elements common to all Strowger
switches. As one of i*s variations, the linefinder
has an additional set of vertical wipers
connecting to a vertical bank.
LINE GROUPING AND NUMBERINC
The basic system of grouping provides for a
maximum of 100 lines, as shown in figure 9-9.
The horizontal dashes represent 100 pairs of
metallic contacts. There are 10 horizontal levels
and 10 sets of contacts in each level. Thus the
tens digit of the called number represents the
level whereas the units digit represents the individual pair of contacts in the level.
2444Itz,,,
Awka till
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
04 05 06 .1/ oil
rio
with telephone 32. Likewise, to connect the calling telephone with telephone 67, the wipers step
UP 6 steps and then rotate IN 7 steps.
00
91 92 It 14 91 le 97 11I 19 90
SI IR 13 114 SS S
BASIC 100-LINE SYSTEM
V7 tie el NO
......
I
irr2r3arireTa960
74
The system described with reference to figure
is not practical because only the calling telephone can originate calls. The basic 100 line system is shown in figure 9-10. Each
telephone is connected to the wipers of its
own connector bank. The wiper of each bank can
be stepped up and rotated in, under the control of
72 75 74 75 72. 77 7S 79 70
9-9
SI 52 53 54 55 56 57 51I 59 10
in 42 43 44 45 44 47 411 49 a
r
33 34 35 16 37 se 3.) SP
21 :2 23 24 25 76 V 29
II
IT
the dial of the associated telephone. One connector bank with its wipers and the mechanism
TO
necessary to step the wipers up and in constitute
a CONNECTOR SWITCH. A connector switch is
re7erred to as a NUMERICAL type of Strowger
Is m 13 If. 17 IS 19 10
WIPERS
67
CALLING
TELEPHONES
TELEPHONE
7.77(27C)
Figure 9-9. Connector-bank numbering.
Numbers beginning with 1 are in the first, or
bottom, level, numbei.4 beginning with 2 are in
the second level, and so on. This arrangement
switch because it operates under the control
of dial impulses.
The connector bank described with reference
to figure 9-9 has only the 100 pairs of contacts
required for the positive and negative lines. In
practice, the connector and other switches have
one or more banks, with associated wipers, contained in the same switch. However, these banks
are for control and special purposes and are not
considered now.
causes the digit "0" to be used to represent
For simplicity, only 4 of the 100 telephones
with these associated finder-connector links are
cated by the symbol for zero. Also, the 10th pair
of contacts in each level is indicated by the symbol for zero. Groups of 10 lines are referred to
as lines 11-10, 21-20, 31-30, and so forth. The
complete the circuit.
steps so that the 10th, or top, level is indi-
first 10 lines consist of 11-10, and the last 10
consist of 51-50.
Each pair of metallic contacts is connected to
a pair of wires that lead to a certain telephone.
These contacts are actually contained in aStrowger switch, arranged in the arc of a circle with
the vertical rows paralled to the axis of the
cylinder. The entire assembly of contacts is
shown in figure 9-10. Also, only 1 wire from each
telephone is indicated, and a black dash represents
1, 2, or as many contacts as are necessary to
Telephone 32 is connected to the wipers of
connector 32. Telephone 32 also has an appearance in the bank of each connector that is, it is
multipled to contact 32 in all of the connector
banks. Telep. one 67 terminates in wiper connector 67 and is likewise multipled to Us associated contact 67 in all of the connector banks.
This multiple arrangement of the connector
banks permits any telephone to be used to call
any other telephone in the system.
called a CONNECTOR BANK.
LINE FINDING
A pair of metallic wipers mounted on the shaft
of the Strowger switch is shown at the lower "afthand corner of the connector bank. These wipers
are moved under the control of the dial on the
calling telephone. For example, if the calling
telephone is used to ;al' telephone No. 32, when
digit "3" is dialed the wipe' s step UP to the third
level in the connector bank. When digit "2" is
dialed the wipers rotate IN 2 steps on the third
level. This action connects the calling telephone
The 100-line connector system described
with reference to figure 9-10 requires an individual connector switch for each line in this
system. As the connector is a relatively expensive switch, this system is not economical
because the average telephone is used for making
calls only a short time each day with the result
that the corresponding connector switch would
remain idle during the remainder of the time.
IC ELECTRICIAN 3 & 2
TERMINALS
CALLED
TELEPHONE
CALLING
TELEPHONE
LINEFINOER SWITCH
CONNECTOR SWITCH
7.78(140B)
Figure 9-10, Basic 100-line connector system,
Line finding enables a large group of lines to
be served by a smaller number of switches used
in common by all lines in the group. The linefinding principle is illustrated by means of the
diagram of two 100-point blanks shown in figure
9-10. One is called the FINDER BANK and the
other is the previously mentioned CONNECTOR
BASIC 100-LINE FINDER-CONNECTOR
SYSTEM
The system described with reference to figure 9-10 is equipped with one finder switch and
one
connector switch. Hence, only one
conversation is possible at any one time because
each conversation requires one finder and one
connector to complete and hold a connection between the calling and called telephones.
The 100-line finder-connector system is
shown in figure 9-11. Each finder switch is permanently tied "stem to stern" with a connector
switch. In other words, the finder is facing backward ready to find any line that originates a call,
whereas the connector is facing forward ready
to connect to the dialed line. Such a combination
BANK. The finder bank is similar to the connector bank. Although one telephone is shown,
actually there are 100 telephones connected to
the finder bank. One finder bank with its wipers
and the mechanism necessary to step the wipers
up and in constitute a FINDER SWITCH. A finder
switch is referred to as a NONNUMERICAL type
of Strowger switch because its operation is
automatic and not under the control of dial
impulses.
To call telephone 67 from telephone 32, remove the handset from the cradle at telephone
32. The finder switch (fig. 9-10) automatically
steps its wipers up to the third level and rotates
I
c. NDER
CONTROL
AND
DI ST RI BUTO R
in 2 steps, stopping on contact 32. Thus the c-t11-
ing telephone is extended through to the wipers
of the connector switch. When the digits "6" and
"7" are dialed, the wipers of the connector
switch step up to the sixth level and rotate in 7
steps, completing the connection between tele-
N.
3_2.1
L NE
RELAY 32
FINDER r . CONNECTOR
cm_tcn
TT
TELEPHONE
6?
LINE \--
= NORMAL
7.80(140B)
Figure 9-11.Complete finder-connector system.
phones 32 and 67.
246
e,t.:14109
Oa &PO
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
of finder and connector is called a FINDER -
The signal causes t ais equipment to start a
preselected idle finder searching for the calling
CONNECTOR LINK. One finder-connector link is
required for each of the conversations that are
to
be
held
line.
simultaneously. The links are
The finder control and distributor equipment
analagous to the "cord circuits" in a manual
at this time automatically preselect the next
idle finder to have it ready to search for the
telephone system.
next incoming call.
Each of the 100 lines is connected to each
finder bank. Hence, any idle finder is capable of
stepping up and rotating in to locate any one of
the 100 lines that originates a call. Also, each
of the 100 lines is connected to each connector
bank. Hence, under control of dial impulses from
the calling telephone the connector tied to the idle
The finder searching for line 32 finds it and
extends the connections through to the connector
switch.
At this point line 32 is made busy at the connector banks to guard against intrusion from any
incoming calls. Also, line relay 32, which is a 2-
step relay, now operates the remainder of its
finder can step up and rotate in to complete a
contact springs, which cut off its own windings
from the line. This action is called CLEARING
the line of attachments. The 2-step relays are
sometimes called LINE and CUTOFF RELAYS
connection to any one of the 100 telephones. The
leads from the connector banks to the 100 telephone lines are called LINE NORMALS.
because of this dual function.
To call telephone 89 from telephone 32, remove the handset from the cradle at telephone
The connector switch returns a dial tone to
the calling telephone and the call proceeds as
32. An idle finder, such as finder I, steps up,
rotates in, and stops on contact 32. The con-
previously explained.
Only one finder control and distributor is
figure 9-11. In practice the finder
nection is now extended through to the connector
associated with the finder, in this case connector
shown in
switches are divided into groups A and 13, with
each group equipped with its own finder control
1, and the dial tone is received by the calling
tele7hone. The DIAL TONE is a signal for the
and 'distributor equipment.
person making the call to dial the number of the
called telephone. When digits "8" and "9" are
dialed, the wipers of the connector switch step
Expanding the 100-line System
up, rotate in, and stop on contact 89.
The connection is now completed from telephone 32, through finder-connector link 1, and
back over the line normal of line 89 to telephone
89. The connector switch now tests telephone 89
and,
The 100-line finder connector system can be
expanded to service as many as 200 telephones
through the use of a party line system, made pos-
sible through the use of an additional switch
called a minor switch. This switch has rotary
motion only and is therefore referred to as a
if it is not in uce, ringing current is sent
out to operate the ringer at telephone 89. If telephone 89 is found to be in use, a busy signal is
returned to the calling telephone.
In the finder-connector system shown in
figure 9-11, the finder and connector banks are
single-motion switch. As pictured in fig re 9-12
the minor switch bank consists of ten sets of contacts over which the wipers may step under control of the dial. This switch, which may be like-
ned to a one-level Strowger switch, is a one-
each represented by 10 horizontal lines. The
function auxiliary switch used for ringing one or
the other of two pa:ties on a party line.
With the minor switch arrangement an additional digit is added tt: all phone numbers. In this
type of equipment telephones having their first
rectangles at the top of the finder and connector
banks represent the switch mechanisms. One
line relay is associated with each line whereas
one finder control and distributor equipment
digit as 1, 2, 3, 4, 5, 6, 7, 8, or 0 will receive
is common to all lines. Only one finder-connector
link is shown. However, there are many such
ring current over their positive line while those
whose first digit is a 9 will receive ring current
over their negative line.
Due to the need of certain lines beingused for
specific, predesignat...... i trposes, the dial system
using a minor switch is restricted to 196 number
assignments. These restrictions will oe covered
in the portion of this chapter dealing with types
of calls.
links provided for each 100 lines.
To call telephone 67 from telephone 32, remove the handset from the cradle at telephond
32. Line relay 32 operates and marks the position
of line 32 in the finder banks.
When the line relay operates it also sends a
START SIGNAL to the finder control and distributor equipment.
247
ti (19
IC ELECTRICIAN
&2
3
4
AOC N - SC. CCC
---
^.ALL04.
C6100.ECTOlt
G.O.
*t
01Ad
100 ,( E..10M S
1.4
AOC; SA0u
,
Aft ( At.
AGNtl
'200'
II
,_4ROo_j
t(CtAtt
ANNATAlt
SIC
100 7(1.(..0043
144 THE
I
.1C
'200' GAWP
ASSANAL,
NCANA,
I
(A
7.82(27C)
IMO CONTACT
MIN C
Figure 9-13. Basic selector system.
is similar in mechanical construction to both
the finder and connector. It has the same bank,
A IllSi AANATuAt
AOC. AtANIA
AI tINIM SC.
OttICANNG ACCA:.
wipers, and 2-motion mechanism.
Figure
140.76
9-12.
The selector faces the called line the same
Minor switch.
as does the connector. The function of the selec-
tor is to select the "hundreds" group of lines.
From then on, a connector selects both the
BASIC SELECTOR SYSTEM
"tens" groups of lines and the "units" line in that
group. Note that the lines are divided into groups
of 100. Two such groups are shown, the "200"
group with 100 lines and the "600" group with
100 lines. Each group has a corresponding group
of connectors having their banks mtutipled together.
In figure 9-14, a call through a 200-line
capacity system is traced from the calling
The system described with reference to figure 9-10 has a capacity of 100 lines. It will serve
any number less than 100, such as 50 or 25. The
number of lines to be served is wired to only the
required finder and connector banks. For systems
comprising 200 lines or more a SELECTOR
is connected between the finder and connector
switches, as shown in figure 9-13. Tne selector
telephone to the called telephone. Note that
LETS SAY YOU DIALED NUMBER 667
LIN EITTNDER
WHEN YOu PICKED UP YOUR RECEIVER
YOUR LINEFINDE PERFORMES II S JOB,
IT LOCATES YOUR TERMINALS, CONNECTS
YOU WITH A SELECTOR SWITCH, WD YOU
HEAR DIALTONE THE LINEciNDER IS
SIMILAR IN OPERATION TO A.CONNECTOR,
PUT DOES ITS WORK AUTOMATICALLY
SELECTOR
CONNECTOR
YOU DIAL THE FIRST NUMBER, 6 THE
SELECTOR STEPS TO THE SIXTH LEVEL.
THE TEN TERMINALS ON THIS LEVEL
ARE CONNECTED TO TEN CONNECTOR
SWITCHES EACH OF WHICH HAS CONNECTED
TO IT Ill TELEPHONES
THIS SELECTOR
ROTAT ES TILL IT FINDS AN IDLE TERMINAL
AND yon A-E CCNNECTED TO AN IDLE
STEPS UP SIX LEVELS YOU DIAL. 7 AND
1
THE WIPER ARM MOVES AROUND ON THE
SIXTH LEVEL TO THE SEVENTH CONTACT.
AT THIS POINT YOU'VE REACHED THE LINE
OF 667. THE CALLED PARTY'S BELL. WILL
RING UNTIL THE TELEPHONE IS ANSWERED
OR YOU HANG UP.
CONNECTOR SWITCH.
Figure 9-14.A call through a
YOU DIAL 6 AND THE CONNECTOR SWITCH
200
248
260
line systet
140.130
.
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
the finder switch is tied "stem to stern" with
a selector switch, instead of being tied to a
connector switch as in the 100-line capacity
system. However, one finder-selector link is
required for each conversation that is to be
held simultaneously. The connector switch al-
ways operates last and selects the "tens" group
of lines and the "units" line within the group.
To call telephone 673, remove the handset
from the cradle at the calling telephone. An idle
finder searches and extends the calling line to
the selector switch associated with that particular finder. The selector returns a dial tone
to the calling telephone. When the "hundreds"
digit, "6," is dialed, the selector wipers step
up to the sixth level, and automatically rotate in
on that level in search of a contact that is at-
tached to an idle connector switch. The leads to
the connectors are called TRUNKS and the
automatic selection of an idle trunk is called
TRUNK HUNTING.
A selector switch is capable of searching over
the 10 contacts, on the dialed level, more quickly
than a calling person can dial the next digit. If
all 10 contacts test busy, the selector switch re-
turns a busy signal to the calling person.
If the selector finds an idle trunk, the call is
extended through to a connector. When digits "7"
and "3" are dialed, the connector steps up 7 level
and rotates in 3 steps to complete the call. Because the dialed digits extend the call step by
step, the Strowger automatic telephone equip-
Ll and L2 on the circuit labels and telephone
wiring diagrams. On a one-party line the ringer
is across the line and the line conductors axe also
the conductors for the ringer circuit. This
arrangement is called METALLIC RING.
For a TWO-PARTY line three conductors are
required to extend the connection between the
telephone instrument and the automatic switchboard. The two line conductors are designated Ll
and L2 and the third conductor, which is connected to a ground (positive battery) common to
all ringer circuits in the shipboard dial telephone
system, is designated G.
When two telephones are connected electric-
ally to the same line circuit, their ringers cannot be connected across the line unless one
telephone is to be an extension telephone. When
two-party service with individual ringing is
desired, the two telephones must be arranged so
that ringing current will operate only the ringer
of the called telephone. Thus, to obtain separate
ringers circuits for the two telephones, the ringer
of one telephone is connected between the positive
line conductor Ll, and ground (positive ring),
whereas, the ringer of the other telephone is
connected between the negative line conductor
L2, ana ground (negative ring).
Therefore, on party lines it is necessary that
the ringers be connected to the proper side of
the line. The telephone system is arranged so
ment is , referred to as a STE P- BY-S TE P system.
that the side of the telephone line on which ringing current is applied is determined by the
telephone number.
TELEPHONE CONNECTIONS
Type A Telephone
All telephones are provided with screw type
terminals and therefore soldering is not necessary in order to connect or replace a telephone.
All conductors are color-coded and the correct
termination for each conductor is shown in
terms of the color code on the circuit lable inside
the telephone base or on the wiring diagram.
The type A telephone (fig. 9-15) is equipped
with a terminal subassembly inside the base and
a line-and-cord terminal block on the end of the
desk set cord. The lin. wires Ll and L2 from the
automatic switchboard terminate at the line-andcord terminal block and the wiring of the tele-
When changing or replacing any wiring in or to a
telephone, check the new connections against the
circuit label inside the telephone or the applicable wiring diagram.
terminal subassembly. The desk set cord extends
Line Stations
The several types of telephones can be connected for one-party service or two-party service. For a ONE-PARTY line two conductors are
required to extend the connection between the
telephone instrument and the automatic switchboard. These are the line conductors designated
phone instrument terminates at the instrument
the connection, between the telephone wiring at the
instrument subassembly and the line wiring at the
line-and-cord terminal block. The type A telephone may be connected for ONE-PARTY line
service (metallic ring) by connecting at the lineand-cord terminal block the red-coded and white-
coded wires to terminal L2, and the blackcoded wire to terminal Ll, (fig. 9-16A). Proper
operation of the ringer is determined by dialing,
from a nearby telephone, the number assigned
to the telephone just connected. The ringer should
ring.
AV.
mob.
IC ELECTRICIAN 3 & 2
HANDSET
.. --
IMPULSE SPGS
SHUNT.
SPGS
DIAL
N
RECEIVER f
UNE & CORD
TERM BLK
MONOPHONE SWITCH
IN TALKING POSITION
TRANSMITTER
ce
.1,1k,..DESK SET
CORD
RED-OR
RED-OR
-GRN
RED-BW
CI
HANDSET
CORD
OR
REDCRN
24-G
RINGER
IND COIL
Figure 9-15. Type A telephone wiring diagram.
The type A telephone (fig. 9-15) is connected
for TWO-PARTY line service (ground ring) by
connecting, at the line-and-cord terminal the
black-coded wire to terminal Ll, the whitecoded wire to terminal L2, and the red-coded
coil cores. To increase the tension in the biasing
springs bend the lower mounting lug (not shown)
downward with a pair of pliers. Repeat the test.
Type F Telephone
ground wire tc terminal 4G. One other connection
is necessary to complete the job, at the ter-
minal block in the telephone connect the redgreen-coded wire as shown in figure 9-16B for
either positive party ring or negative party ring.
From ^ ..earby telephone, dial the number assigned
to the telephone just connected. If the ringer does
not ring, reverse the line wire connections at the
line-and-cord terminal block. Repeat the test.
At the other telephone on the line, dial any
telephone number. If the ringer taps at the telephone just connected, remove the base plate and
reverse the ringer terminals 5 and G. Repeat the
test. If the ringer still taps, increase the tension
of the biasing springs. The biasing springs should
be as nearly parallel as possible to the ringer
7.89
The type F telephone (fig. 9-17) is equipped
with a terminal subassembly mounted on the
bottom rover plate inside the telephone housing.
The ship's cable consisting of line wires J95 and
JJ95, (connector terminals 95 of line 95 are used
here as an example) battery-connected wire J49,
and ground-connected wire J9, enters through a
terminal tube at the bottom of the housing.
The type F telephone is connected for ONEPARTY line service by connecting, at the term-
inal subassembly, the red-blue ringer wire to
terminal L2, the line wires J95 and JJ95 to ter-
minal Li and L2, respectively, the ground-
connected wire J9 to terminal G, and the battery-
connected wire JJ9 to terminal B. Remove th.s
1 TAiz__
250
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
CONNECTION
BOX
BLOCK
SHUNT
OIAL
DIAL
SPRINGS
IMPULSE
SPRINGS
HAND
HOUSING
BAN
RINGER
R
SET
3
L2
ANTI-SIDE
TONE COIL
G
HOOK
SWITCH
DT 0
IN
TALKING
POSITION
JJ9
0 METALLIC RING (One Party Service)
r--------,
HANDSET
-- ,
I
=
9
.
z
Ct
932
Al.
0
1 TELEPHONE
I
DIAL
kto
RINGER
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.
--
0
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i
1C2
1
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TERMINAL i
1
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....----..,
1
I
'
1
I
'I
CONNECTION
LI
etL2
JJ9
L2
1
o
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.
(511
I
f
REO
TERM BLOCK
IN OPEN POSITION
\\ HANDSE T
4
CORD
I
J95 ...IBS JJ9
I
I,
-tatE
SHIPS CABLE-
J9
1.-,..J
TO
SHIPS
(TELEPHONE
Figure 9-17. Type F telephone wiring diagram.
L. 332 .........;
0
7.90
CABLES
TWO-PARTY LINE CONNECTIONS
140.131
Figure 9-16. One-party and two-party line
connections.
At the other telephone on the line, dial any
telephone number. If the ringer taps at the
telephone just connected, reverse the red-blue
and the red-orange ringer connections at terminals 5 and G. Repeat the test. If the ringer still
taps, increase the tension of the biasing spring
handset from the hook switch. The dial lamp
should light and a dial tone should be heard. From
a nearby telephone, dial the number assigned to
the telephone just connected. The ringer should
ring.
The type F telephone (fig. 9-17) is connected
for TWO-PARTY line service by connecting at
the termi:tal subassembly, the red-blue ringer
wire to terminal G, and the ship's cable wires
J95, JJ95, and J9, and JJ9 to terminals L1, L2, G,
and B, respectively. From a nearby telephone,
dial the number assigned to the telephone just
connected. If
the ringer does not ring, re-
verse the line-wire connections at terminals Ll
and L2. Repeat the test.
(not shown) by bending the end mounting lug with
a pair of pliers. Remove Lhe handset from the
hook switch. The dial lamp should light and dial
tone should be heard. Replace the handset.
Type C Telephone
The type C telephone (fig. 9-18) is equipped
with a terminal subassembly and a terminal
block inside the housing. This ship's cable, con-
sisting of wires J95, JJ95, J9, and JJ9 are
connected to LI, L2, G, and B, respectively, on
the terminal block. The wires Ll, L2, G, and
B on the terminal block are connected to corresponding terminals on the terminal subassembly.
IC ELECTRICIAN 3 & 2
ANTI-SIDE TONE COI
L-fl
8RN
INO
COIL
BUJOR
HANDSET
OR-GRN
C2
REC I
BRN
8RN
-MAt
BLIC
RED-OR
81.0
XMTR
RED-OR
RED-6W
0
%RINGER
z
0
0
O
TERM
HOOK SWITCH
0
IN TALKING P05
CD
BLK
WH
00
00
RED
DIAL
LAMP
3
DIAL
K
0
REO -GRN
CORD
4 CONE/ CABLE
(0'
w
[email protected]
(7
D1
LAMP
HANDSET
cc
w
JO
IMPULSE
SPRINGS
RED
WH
RED
®
8
OI
SHUNT
SPRINGS
BLK
0
0
RHEOSTAT
CONNECTION
BOX
PUSH-ft
BUTTON
JJ9
J95
J9
Jl95
7.91
Figure 9 -18. Type C telephone wiring diagram.
The type C telephone is connected for ONEPARTY line service by connecting, at the terminal subassembly, the red-blue ringer wire to
terminal 4 (L2). From a nearby telephone, dial
the number assigned to the telephone just con-
nected. The ringer should ring. Remove the
handset from the hook switch. The dial lamp
should light and dial tone should be heard.
The type C telephone (fig. 9-18) is connected
for TWO-PARTY line service by connecting, at
the terminal subassembly, the red-blue ringer
wire to terminal 3 (G). From a nearby telephone,
dial the number assigned to the telephone just
connected. If the telephone ringer does not ring,
reverse the line-wire connections at terminals
L1 and L2. Repeat the test.
At the other telephone on the line, dial any
telephone number. If the ringer taps at the
telephone just connected, reverse the ringer con-
nections at terminals 3 and 5 on the terminal
subassembly. Repeat the test. If the ringer still
taps, increase the tension of the biasing spring
as previously explained. Remove the handset
from the hook switch. The dial lamp should
light and dial tone should be heard.
4
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
COIL TERMINALS
CAPACITOR TERMINALS
MICROstwiTigini
BRACKET
r
O
CORE
0
TERMINAL
SUBASSEMBLY
ARMATURE
a
LEAF SPRING
.1111MINIM.
B
A
7.92(140A)
Figure 9-19. Power signal relay.
The MICROSWITCH is provided with large
POWER SIGNAL RELAY
contact surfaces so that large currents can be
controlled with relatively small movements of
As previously stated, when a telephone is
the armature.
installed in a noisy location, an extension signal
may be connected through a power signal relay
to the telephone line. The extension signal used
with the dial telephone system is a 115-volt 60hertz motor-operated horn.
The power signal relay (fig. 9-19) includes:
(1) coil subassembly, (2) core subassembly, (3)
armature, (4) microswitch, and (5) terminal
subassembly enclosed in a steel case.
The TERMINAL SUBASSEMBLY is provided
with terminals for making the connections to the
a-c power source, the extension signal, and the
telephone line.
The telephone ringer and the power signal
relay are connected in parallel to the line of the
telephone. The power signal relay has a pair of
microswitch contacts, one of which is connected
to one side of the extension signal and the other
to the a-c power supply. The other side of the
extension signal is connected permanently to the
a-c power supply.
When the ringing current is applied to the
line of the telephone through the winding of the
connector relay F, the current energizes both the
ringer at the telephone and the coil of the power
signal relay. The coil of the power signal relay,
when energized, actuates the relay armature to
close the microswitch contacts. The microswitch
contacts, when closed, complete the a-c power
circuit to sound the extension signal. As soon a:.
the handset is removed from the hook switch, the
The COIL SUBASSEMBLY consists of a bake-
lite frame on which is wound a coil of wire.
The CORE SUBASSEMBLY consists of a number
of U-shaped laminations riveted together. Two
brass brackets are riveted to one leg of the
core for mounting the armature subassembly and
the relay terminals. The coil subassembly is
attached to the other leg of the core.
The ARMATURE completes a magnetic path
between the two poles of the coil subassembly
and actuates the nap-action microswitch. It is
provided with a brass residual pin to maintain a
small space betv.een the armature and core to
prevent sticking.
253
265
o+-
IC ELECTRICIAN 3 & 2
ringing current is removed from the line, the
power signal relay restores, and the circuit to
the extension signal is opened at the microswitch
contacts.
receiver. In the event the called station is
manned, the call should, if the phone is not in use,
be completed. In the event a busy tone is received
it is necessary that the calling phone redial the
number in order to again attempt the call.
Type F Telephone
Executive service is that additional feature
When a type F telephone is installed in a
noisy location, an extension signal is connected
through a power signal relay to the telephone
line. When the telephone is arranged for extension signal ringing, it is recommended that the
instrument be connected for ground ring irrespective of whether it is a one-party or two-party
line, in order to eliminate any possibility of the
extension signal being actuated duiring dialing.
At the terminal subassembly (fig. 9-17), connect the red-blue ringer wire to terminal G, the
ship's cable wires J95, JJ95, J9, and JJ9 to
terminals Li, L2, G, and B, respectively, and the
by which a priority telephone will cut in on a connection which has already been made to the number which he wishes to reach. An executive phone
always reaches the party called, even when the
line is busy.
Emergency service is a specifically designed
feature by which any number dialing digits 211
reaches the station at which the Officer of the
Deck has posted his watch, be it the Quarterdeck
or the Pilot House. The call is also extended
through regardless of whether the line is open or
busy. A switch controlling the recipient phone
(Quarterdeck or Pilot House) is located on the
telephone switchboard.
two line wires from the power signal relay to
terminals Li and G. From a nearby telephone,
dial the number assigned to the telephone just
connected. If the extension signal does not
connected) the caller would dial the manual
Li to the L2 terminal. Repeat the test.
extend the call through to the shore facility.
operate, move the power signal relay lead from
the
Ship to Shore Call is a call connected man-
ually through the manual switchboard. To
complete this call (possible only when in port and
switchboard and the ship's operator would then
Shore to Ship Call is also a feature conducted
through the manual switchboard. Here in again the
Type C Telephone
When a type C telephone is installed in a noisy
location, it is arranged for extension signal ringing and connected for ground ring irrespective of
whether it is a one-party or two-party line.
At the terminal block (fig. 9-18) the ship's
cable wires J95, JJ95, J9, and JJ9 are connected
to terminals Li, L2, G, and B, respectively, and
the two line wires from the power signal relay
to terminals Li and G. At the terminal subassembly, connect the red-blue ringer wire to
terminal 3 (G) and the wires from the terminal
block to the corresponding terminals, Li, L2, G,
and B. From a nearby telephone, dial the number
assigned to the telephone just connected. If the
ship's operator completes the call through the
manual facilities available to him at his station.
On most installations lines 37, 38, 39, and 30 are
reserved for the manual switchboard.
Test Call is a maintenance number, usually
line 29, used in troubleshooting the automatic
equipment.
An additional feature employed in cases
where a series of numbers serve the same space
is "hunt the not-busy feature." In this type of
arrangement, as in the case of the manual switch-
board, assuming that line 37 was in use and a
second caller dialed the manual switchboard
number 37; the call would be shifted auto-
extension signal does not operitte, move the
power signal relay lead from terminal Li to
matically through to line 38. This "hunt" feature
continues until it receives busy from the last in a
series of so connected lines.
TYPES OF CALLS
RINGING MACHINES
terminal L2. Repeat the test.
The shipboard dial telephone system is de-
Ringing equipment consists of two ringing
signed to permit a wide variety of telephone calls
to meet a variety of needs. These calls are summarized below.
machines, a ringing transformer, test and trans-
fer keys, and associated circuitry. In order to
ensure continuous service, two ringing machines
are used; one in operation, one in standby. The
operating machine provides the ring, busy, dial,
and ringback tones to the entire system.
Regular local service is the routine call
wherein the caller dials the desired number and
receives either a ring-back or a busy tone in his
254
r
I
.
Z h6
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
AO END
INTERRUPTER
SPRINGS
LOCKING
SCREWS
TERMINAL
STRIPS
-BAT. STUDS MOUNTING
STUDS
WHEEL
1
L
WORM
FILTERS'
OC ENO
140.82
Figure 9-20. Ringing machine.
The machine (fig. 9-20) is a rotary converter
used to change the d-c of the power section into
low voltage a-c and to interrupt d-c for use as
the varying tones in the system. The d-c end of
the unit is a compound motor. The a-c end of the
unit (fig. 7-21) is composed of a four-ring col-
lector consisting of three plain rings and one
segment type ring. The ring brushes ride on the
first two (plain) collector rings and extend 20-
1
LOCKING
SCREW
hertz a-c to the ringing transformer. The dial
and busy one brushes bear on the third plain
collector and the remaining segment type ring.
FUSE
ALARM BARS
Figure 9-22. Fuse panel.
140.84
SERIES
RIELO
SHUNT riELO
These latter two brushes extend an interrupted
d-c signal to the system. The dial tone is d-c
interrupted 140 times per second. The busy tone
is the same tone further interrupted 120 times
MOTOR
BRUSHES
per minute.
Mounted on the d-c end of the unit is an extenLi
sion which houses a worm, worm wheel, sad
cross shaft as well as five sets of interrupter
contacts (not shown). This unit regulates the
4 re -BR
GENERATOR
nuSpIES
a
SERIES
rIELO
duration of all extended signals.
FUSE PANEL
140.83
Figure 9-21.
The fuse panel (fig. 9-22) contains all of the
telephone fuses required fir the protection of the
R inging machine, partial
schematic.
255
267
IC ELECTRICIAN 3 & 2
The line disconnect key can be locked in the
OPEN position by inserting a cotter pin in the
hole provided in the key shaft. This locking
arrangement can be used to prevent ring-back
tone from being returned to the calling station
when the line disconnect key is associated with
4.'
an unassigned line.
ALARM SYSTEM
The dial telephone alarm system is an
arrangement of signal equipment that gives an
alarm if a nonstandard condition exists in the
telephone system. The alarm consists of both an
audible and a visual signal to indicate the nature
and general location of the trouble. The 100-line
system will be discussed.
The audible signal is a buzzer or bell that is
common to all alarms; whereas, the visual
signal is a lamp that is associated with a particular type of alarm. When the common alarm
buzzer sounds, one or more alarm lamps will
be lighted to indicate the nature of the trouble.
Nonstandard conditions cause either im-
,.$.',11110PATt,
140.85
Figure 9-23. Telephone grasshopper fuse.
switchboard equipment. These are three-ampere
alarm-type indicating fuses.
The telephone (grasshopper) fuse is illustrated in figure 9-23. This fuse consists of an
mediate or delayed alarms. For example, an
immediate alarm is given when any fuse blows;
whereas, a delayed alarm is given when a finder
insulated support provided with a terminal at
or connector fails to release after the normal
releasing time of the switch has elapsed. Predetermined delay intervals are automatically
provided by means of the timer relays for each
each end that is connected across the fuse block
on the fuse panel. Metallic strips located on the
front and back of this insulated support extend
from each fuse terminal about half the length of
type of alarm that requires a delay.
the support. The free ends of these metallic
strips are tied together by fuse wire, thereby
Lamp and Key Panel
placing these strips under slight spring tension.
When the fuse blows, the back metallic strip
The lamp and key panel (fig. 9-25) mounted on
the front of the finder board contains all the
springs backward to make contact with the alarm
bar, thereby completing an alarm circuit. The
front metallic strip springs forward to indicate
alarm lamps for the dial telephone system. The
alarm lamps are the (1) power fail, (2) power
fuse, (3) motor-generator fail, (4) attendant's
cabinet fuse, (5) switchboard fuse, (6) connector
release, (7) finder release, (8) fincter blocked, A
and B, (9) connector permanent, and (10) ringing
machine fail, 1 and 2, alarms.
In addition to the alarm lamps, various
the blown fuse.
LINE DISCONNECT KEY PANEL
The line
disconnect key panel (fig. 9-24)
mounted on the front of the finder board is
equipped with 100 keys (one for each line connected to the switchboard). Thus, any line can
be disconnected from the switchboard for testing
purposes, isolating a faulty line, or cutting out
nonessential lines when required. Each line disconnect key has the same number as its
associated line. When the key is in the normal
position, the telephone line is connected to the
associated line relay in the automatic switchboard. When the line disconnect key is operated
switches (keys) are mounted on the lamp and fuse
panel. These switches are the (1) finder reset, A
and B, (2) finder blocited, A and B (3) permanent
reset, and (4) shore-lfne control switches.
Power Fail Alarm. The power fail alarm
lamp (red) will light, and the common alarm
buzzer will sound if the switchboard BATTERY
VOLTS (maintained by the motor-generator and
storage battery in parallel) fall below a predetermined value, or if the power supply fuse
(pulled out) the connection is opened between the
telephone line and the associated line relay.
.
256
#4,768
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
27.208
Figure 9-24. Line disconnect key panel.
blows. This alarm is not provided with a delay
interval. All alarms that light the POWER FAIL
ALARM lamp should receive immediate attention
because when this lamp is lighted the switchboard is completely out of service.
Motor-Generator Fail Alarm. The motorgenerator fail alarm lamp (red) will light because of (1) failure of the ship's 120-volt power
supply, (2) operation of the controller overload
contacts (or blown controller fuse), or (3) failure
of the generator to cut in after the motor-
The power fuse alarm
generator has started. This alarm is so de-
meter fuse) should blow. This alarm is not provided with a delay interval.
PERVISORY alarm lamps provided for the power
Power Fuse Alarm.
lamp (red) will light, and the common alarm
buzzer will sound if one or more of the fuses
mounted on the power panel (except the volt-
signed that is action is delayed from 15 to 45
seconds.
The POWER FAIL, POWER FUSE, and
MOTOR-GENERATOR FAIL alarms are SU-
257
G5
IC ELECTRICIAN 3 & 2
" Switchboard Fuse Alarm. The switchboard
fuse alarm lamp (red) on the lamp and key
panel will light, and the common alarm buzzer
will sound if any fuse mounted on the fuse panel
should blow. This alarm is not provided with a
delay interval.
P7V1Ef
FAIL
ALARM
Connector and Finder. Release Alarms.
POWER
FUSE
FM. ALARM
ALARM
\
ATTENDANT
CABINET
FUSE ALARM
connector or finder switch fails to release when
SWITCH
on
The faulty finder or' connector switch is
located by plugging the hand test telephone (with
button C depressed) in the test jack of each switch
that is off-normal (if the switch is a finder, note
the number and plug the hand test telephone ..n the
correspondingly numbered connector). The hand
B
\.BLORM CKED../
test telephone is described later in this chapter
with the testing equipment. If no conversation is
heard, release button C and challenge. If no
ALA
CONNECTOR
ALARM
is delayed from 15 to 45 seconds.
FINDER
ALARM
RESET 8
the associated magnet circuit is closed. Each
of these alarms is so designed that its action
CONNECTOR
RELEASE
ALARM
BOARD
FUSE ALARM
FINDER
RELEASE
PERMANENT
answer is received, release the switch that is off normal by manually operating the release
RINGING
-
FIN DER --.
MACHINE FAIL
magnet. If this action. does not extinguish the
release alarm lamp, another switch is at fault.
If the cause of the release failure cannot be
corrected immediately, make the defective
BLOCKED 8%
'""1
0
0
0
0
KEY
A
.AO
RESET
BLOCKED
ou0
switch busy by operating the BUSY KEY on the
connector switch (fig. 9-8). This key makes busy
both the connector and the correspor'lingly numbered finder. In other words, the busy key makes
0
O
\------- FINDER
I
busy the finder-connector link. This action is
necessary to prevent seizure of the link for another call until the defective switch is repaired
0
O
SHORE
LINE 0
or replaced by a new switch.
OFF
OU0
PERMANENT
RESET
KEY
Finder Blocked Alarm.
0
O
The fipder blocked
ala.m lamp (red) will light, and the common
alarm buzzer will sound if the finder allotted
SHORE LINE
ON
140.86
Figure 9-25.
The
connector telease alarm lamp (green) or the
finder release alarm lamp (green will light,
and the common alarm buzzer will sound if a
MOTOR
GENERATOR
Lamp and key panel.
The power panel and motorgenerator are discussed with the power equipment in a separate chapter.
Attendant's Cabinet Fuse Alarm. The atequipment.
tendant's cabinet fuse alarm lamp (red) will
light, and the common alarm buzzer will sound
if a fuse associated with the attendant's cabinet
should blow. This alarm is not provided with a
delay interval.
to a call fails to function, or fails to complete its
function. Group A finders and group B finders are
each equipped with an alarm lamp. This alarm is
so designed that its action is delayed from 5 to
10 seconds.
If the blocked finder is in the A group of
finder, the call at hand, and all subsequent
calls, are transferred to the B group of finders.
However, if a blocked-call condition or an allfindere-busy condition now appears in the B
group, all calls will be transferred back to the
A group, which will have stepped on to an-
other finder. These transfers can continue back
and forth indefinitely.
Chapter 9 -- DIAL TELEPHONE SYSTEMS, PART I
For example, if the A finder blocked alarm
is lighted, the defective finder can
determined by the following procedures:,
lamp
be
When the common alarm buzzer sounds and
the connector permanent lamp is lighted, the
following procedures will be helpful in locating
the permanent.
1. Operate momentarily the FINDER RESET
key to position A.
cause the A finders to step UP and IN, and
release one after the other. This action will
1. Operate momentarily the PERMANENT
RESET key to stop the alarm buzzer and
extinguish the CONNECTOR PERMANENT ALARM lamp. However, both
alarms will operate again if the trouble is
not cleared within approximately 5 to 9
which time the B finder will start stepping.
2, Plug the hand test telephone explained
2. Operate the FINDER TEST key, mounted
on the rear of the finder board, to position A.
3. Hold the FINDER TEST key operated to
minutes.
continue until the blocked finder is reached, at
The blocked finder is the one located immediately
after the last finder that functions properly
later, (w,th button C depressed) in the test
jack of each successive connector switch.
in the A group. A finder that is properly UP
In the case of a connector that is at nor-
and IN on a call should not be considered when
determining the blocked finder. When the defective finder has been located, operate the busy
key on the correspondingly numbered connector
mal, release button C and depress it again.
This action should cause the connector to
step up one step and then release. If the
connector does not step, it is probably
permanent. If a connector is off -normal
and no dialing or talking is heard, release
button C and challenge. If no answer is
received, the connector is probably
to "busy out" the finder-connector link until
the defective
finder can be repaired or re-
placed by a new switch.
4. Operate momentarily the FINDER RESET
permanent.
key to position A to again route calls to the
A group of finders, thereby restoring normal
3. When the permanent connector has been
located, note the number of the switch and
operation.
then examine the correspondingly numbered finder.
4. Determine the number o the faulty line by
observing the position of w finder shaft
and wiper assembly, and referring to the
group A or group B finder banks designation card as the case may be. These designation cards are located inside the switchboard cabinet door.
A FINDER BLOCK key can be used to com-
pletely "busy out" either the A or B group of
finders. This provision is useful when making
repairs or replacements in the finder control
and distributor equipment of the A or B group,
and when performing routine maintenance.
Connector Permanent Alarm.
The connector
5. Operate the line disconnect key of the
faulty line. If the questionable finder releases, the trouble is not in the switchboard, but is at some point between the
operated line disconnect key and the line
station associated with that key. If the
finder does not release, the trouble is in
permanent alarm lamp (white) will light, and
the common alarm buzzer will sound if a PERMANENT occurs in the switchboard. A permanent
is any condition that causes a finder-connector
link to be held in an operated position when it
is not being used for talking or dialing purposes.
This alarm is so designed that its action is
the switchboard.
delayed from 5 to 9 minutes.
Some of the causes of permanents are:
6. Restore, when the trouble has been
cleared, the line disconnect key to normal.
1. A dislodged handset.
2. Failure of calling party to dial or to complete dialing.
3. Failure of either party to hang up at the
termination of a call.
4. A short-circuited line, eithe
inside or
outside of the switchboard.
5. A grounded line on the net,, te side,
either Inside or outside of the switchboard.
v..
boy
Ringing Machine Fail Alarm. The ringing
machine fail alarm lamp (red) will light, and
the common alarm buzzer will sound if the
ringing machine fails to start or fails to supply
ringing current to the ringing transformer. This
alarm is not provided with a delay interval.Ringing machine 1 and ringing machine 2 are each
provided with an alarm lamp. The ringing machine transfer switch (mounted on the ringing
259
1
IC ELECTRICIAN 3 at 2
machine panel' is operated in position 1 or position 2, to select the ringing machine to be placed
in service.
When the ringing machine fail alarm is
to the
chine can now.be repaired.
ment each terminate in four associated lamp and
key strips. The four lamp and key strips for the
local trunks and the four lamp and key strips for
the shore-line trunks are located on the left-hand
righ-hand sides respectively of the key panel.
The lamp and key strip for eaclocal trunk contains a ',usy lamp (red), a call lamp (white), two
interiors. The center compartment is
equipped with a hinged door for access to the
attendant's operating equipment. This door
swings forward to form a shelf or desk.
actuated, immediately operate the ringing machine transfer switch to the opposite position to
KEY PANEL. The four two-way shore-line%
start the idle ringing machine and restore serv- trunks from the top compartment and the four
ice to the switchboard. The faulty ringing ma- two-way local trunks from the bottom compartCommon Alarm Buzzer.
The common alarm
buzzer used in the alarm system provides an
audible signal in addition to the previously
described visual alarm signals. It is designed for
bulkhead mounting and is conveniently located on
the side of the automatic switchboard. The buzzer (type Z2) operates on 50-volt a-c power supplied by a transformer (mounted on the power
panel) that supplies power to the dial telephone
system. When a non-standard condition exists in
the telephone system, the alarm buzzer operates
immediately or after a predetermined delay,
depending on the class of alarm. The newer
switchboard buzzers operate from ship's power
via a relay.
ACCESSORY EQUIPMENT
The dial telephone accessory equipment includes an attendant's cabinet (fig. 9-26) that is
used to establish calls to and from shore exchanges when the ship is in port. The attendant's
cabinet is interposed between the automatic
switchboard (in the ship) and the shore exchange
by means of two-way trunks to the automatic
switchboard and two-way trunks to the shore
exchange. The cabinet is provided with a dial
telephone so that connection can be made with
an automatic or a manual shore exchange.
ATTENDANT'S CABINET
The attendant's cabinet for a 100-line system
(figure 9-27) consists of a steel enclosure designed for bulkhead mounting. The cabinet is
divided into three compartments. The top com-
partment contains the two-way shore-line trunks
and the terminal block. The center compartment
contains the key panel, the handset, and the dial.
A jack is provided for plugging in the headset.
The bottom compartment contains the two-way
local trunks and the equipment for the attendant's
telephone circuit, the fuse panel, the terminal
block, and a headset (stored in the lower left-hand
corner). The top and bottom compartments are
provided with two hinged doors each for access
260
shore trunk (cross-connecting) keys, a talk
(answering) key, and a release key. Similar
equipment is contained on the lamp and key strips
for the shore-line trunks, except for the doublethrow shore trunk keys. The final connections are
established by the shore trunk keys located only
on the local trunk strips.
The wiring of the local and shore-line trunks
and the shore trunk keys is indicated by the
single-line diagram in figure 9-28. As previously
mentioned, two double-throw shore trunk keys
are provided on each of the four lamp and key
strips of the associated two-way local trunks.
The upper shore trunk key has two positions designated TRUNK 1 and TRUNK 2, and the lower
shore trunk key has two positions designated
TRUNK 3 and TRUNK 4. All of 'the trunk 1 posi-
tions are connected in parallel with the shoreline trunk 1; all of the trunk 2 positions are connected in parallel with the shore-line trunk 2;
and so on for the remaining key positions and
shore-line trunks. The local trunk 1 is connected
in parallel with the upper and lower shore trunk
switches, so that local trunk 1 can be connected
to either the trunk 1 or trunk 2 position by the
upper shore trunk key or to either the trunk 3 or
trunk 4 position by the lower shore trunk key.
The remaining local trunks, 2, 3, and 4, each
similarly connected to an upper and lower shore
trunk key. Hence, any local trunk can be cross
connected with any shore-line trunk, and vice
versa. However, when a cross-connecting key
and any local trunk is operated to a certain number, the local trunk is associated with the correspondingly numbered shore-line trunk. Hence,
onlyione cross-connecting key should be operated
to the same number at any one time.
A push-switch type release key is provided
for each trunk. By means of the release keys, the
attendant can release either end of a connection
while holding the other end.
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
RING SHORE KEY
DIAL SHORE KEY
DIAL
ATTENDANTS
TELEPHONE
EQUIPMENT
TRUNKSTRIP PANEL
HEADSET JACK
,
140.78
Figure 9-26. Attendant's cabinet used with 100-line exchange.
261
IC ELECTRICIAN 3 & 2
SHORE TRUNKS
AND
TERMINAL
BLOCK
PAMSET
DIAL
SHORE
KEY
PANEL
RING
SHORE
HEAD SET
FiECEPTACL
LOCAL TRUNKS,
FUSE PANEL,
AND
TERMINAL
BLOCK
Figure 9-27.Attendant's cabinet.
262
r
2,74
140.79
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
provide the required signals. However, the buzz-
er will sound if the attendant attempts to dis-
TWO-WAY LOCAL TRUNKS
3
2
SNORE
v UPPER
2
connect the headset or tanh up the handset with-
ME=
W
3
V
9
out answering all new calls and releasing all
completed calls.
SP
SHORE-LINE CONTROL SWITCH
UPPER
Each local trunk is asSociated with a line
circuit (line relay) on the automatic switchboard.
These line circuits can be used for regu'ar local
(shipboard) service when they are not bei).-T used
3.
LOWER
1--.LOWER
42
.
for shore-line service. The shore-line control
LOWER
LOWER
4
4
switch, mounted on the lamp and key panel of the
automatic switchboard is provided to switch the
attendant's cabinet
140.80
Figure 9-28. Shore trunk key schematic.
in
and out of service.
LIGHTNING ARRESTOR AND
SHORE-LINE CONNECTION BOXES
A dial shore key and a ring shore key are
Each set of shore-line telephone leads from
automatic switchboard passes through a
lightning arrestor box, then --nds in a shore-line
connection box. The lightning arrestor box pro-
located on the right of the trunk strips below the
dial.
When a call is received on the local or shoreline trunks the corresponding CALL lamp lights
and the common buzzer sounds. -When the
the
tects the telephone operator and telephone equipment in case lightning should strike the incoming
telephone lines.
attendant answers by operating the TALK key, the
CALL lamp is extinguished, the buzzer is
silenced, and the BUSY lamp is lighted. When a
The lightning arrestor and shore-line con-
nection boxes may be combined in several ways.
The installations vary from ship to ship, and those
shore-line disconnects, no action occurs. However, when the local station disconnects, the local
mentioned here serve only as examples of the
variety you may find in the fleet. On a large
ship you are likely to find one arrestor box and
one connection cox on each side, port and star-
CALL lamp lights again, the BUSY lamp remains
lighted, and the buzzer sounds to signal the attendant. Thus, the two lamps provide CALL,
BUSY, and DISCONNECT indications with an
board. Some small ships have only one lightning
audible signal on the CALL and DISCONNECT in-
arrestor box in the circuit ahead of the lines
dications. A shore-line DISCONNECT signal is
that branch off to the port and starboard shoreline connection boxes. Normally, standar0 electrical connection boxes are used where the incoming shore-lines connect to the ship's lines.
A recent practice that is gaining favor calls for
the use of amphonel-type, multipin, jack-and-pin
combinations. In such a case, the plug fits the
shore-line connection box and the jack attaches
not provided because of the many and varied types
of shore exchanges that might be involved. How-
ever, the attendant is prr"rided with a means for
dialing over both thr local and shore-line trunks,
and for ringing on the shore-line trunk if the
shore exchange employs a ringing magneto and
local battery telephones.
to a portable cable which is run to the local
HEADSET. Daring busy periods the headset
can be used by the attendant instead of the hand-
shore-line connection box on the pier. Old installations also had the capability of taking on
set. When the headset is plugged into the jack
located at the bottom of the panel, the transmitter and receiver are in the attendant's 'telephone circuit at all times, and the attendant can
convene on any trunk that has the TALK key
telegraph lines through the same connection box.
The new boxes have a removable plug in the
bottom of each, box for inserting the cable.
Figure 9-29 shows the basic circuit arrangement for a typical lightning arrestor bcx. Each
lead of the incoming line has a 5-ampere fuse
and a set of carbon contacts in the line. On a
massive surge, the fuse will blow to open the
circuit to the automatic equipment, whereas the
operaied.
When the headset is plugged in (or the handset is removed) and any TALK key is operated,
the buzzer will not sound to interrupt the
attendant, but the lamps will function as usual to
263
0.4
4.3
IC ELECTRICIAN 3 & 2
to operate. The ship's IC switchboard Panel 1
supplies 450 volts a-c to a diverter pole motor
ATTENDANTS .
CAB1NE'
TERmtNAL
LINE
FUSE
*
*
I
I
I
1
F-4..
zuz)...
(fig. 9-30A).
1
I1
4-
LINE
II
ATTENDANT'S
TERMINAL
SHORE
ARRESTER ,
AT TENDANT's I
addition to providing the power for the system,
the MG set also keeps the battery fully charged.
The motor is a squirrel-cage induction type
designed to drive the generator at 1800 r.p.m.
,/, TERuNAL
a
CABINET
generator set to achieve this requirement. In
1/ SNORE
,
,
SNORE
LINE
--" TERMINAL
Figure 9-29. Shore connections.
140.81
carbon contacts will fuse together to provide a
path to ground for the incoming potential.
The generator is the diverter-pole type, and
is designed to furnish 40, 25, or 50 amps at 56
volts of d-c power. The diverter-pole type field
windings (fig. 9-30B) provide inherent voltage
regulation, and thus tend to maintain the voltage
at a constant level under conditions of load
fluctuation.
Diverter Pole Generator
FLEET ANCHORAGE COMMUNICATIONS
The diverter-pole type field windings (fig.
In order to facilitate telephone communications while at anchor many vessels have installed
in their bows permanent cabling for connection
to telephone equipped buoys. A portable telephone
cable (TPU6) is used to make the connection.
The ligi., ning arrester is used for personnel
and equipment protection, while the communica-
tions panel (see plotters transfer panel chapter
6) serves to locate the lines.
POWER EQUIPMENT
The shipboard dial telephone system power
enuipment includes a motor generator set, a battery, and panel mounted control and protective
devices. Power from the battery and generator
is cabled to the panel fuses from which it is
distributed to the various switchboard units.
The generator, battery, and switchboard are
connected in parallel, with the system drawing
power from the generator except during a generator or power failure, or when the system requirements exceed the capacity of the generator.
During these abnormal occasions the battery
supplies part or all of the required power.
The generator is capable of supplying 60 percent of peak busy hour load so that during these
peak periods the battery supplies up to 40 percent of the power required to operate the system.
This method of battery operation, except for the
slight drain during peak loads, is called the float
method of battery operation by which the battery
is kept fully charged at all times.
Motor Generator Set
The automatic switchboard and associated
apparatus require approximately 51.6 volts d-c
264
9-31A) include four main poles which are shunt
wound (connected across the generator circuit).
Associated with each pole is an interpole (the
diverter pole) which is series wound (the armature coil and the interpole are wound in series
with the load). The main pole and its associated
interpole are connected by a magnetic bridge
which includes a restricted section. The
restricted section performs two functions: it
limits the leakage from the main pole to the
diverter pole, end it acts as a magnetic choke to
regulate the magnetic flux passing the armature
from the inner face of the diverter pole.
Figure 9-31A shows also the field under anoload condition. Part of the magnetic flux resulting
from the current in the shunt winding of the main
pole is diverted through the diverter pole via the
magnetic bridge. This diverted flux is shown in
dotted lines. Since there is no load, the series
winding on the diverter pole has no magnetomotiv e force.
At 50 percent load as shown in figure 9-31B
the flow of current through the series winding of
the diverter pole increases, creating a magnetomotive force for the diverter pole. The shunt
winding of the main pole and the series winding
on the diverter pole are in opposition, therefore
as the load on the generator increases, the flux
provided by the diverter pole offers increased
opposition in the magnetic bridge to the flux
from the main pole winding. With the magnetic
bridge bloc..e.d. the greater portion of the flux
from the mat.. field is sent through the armature. It can be seen that ac the load increases,
the armature cuts an increasing number of
lines of force, and the level of generated voltage
rises accordingly, thereb!, overcoming the IR and
.
FILTERS
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
OUTPUT TERMINALS
INPUT TERMINALS
MAGNETIC
BRIDGE
4VFIELD
MAIN
POLE
MOTOR
YOKE
LEADC
BRIDGE
RESTRICTION
LDIVERTER
POLE
RESISTOR
A
I2"
SHUNT
COMPARTMENT
B
140.87
Figure 9-30. Motor-generator set.
cross-magnetization losses to hold the voltage
at a constant level.
The figure indicates increasing flux from the
diverter pole windings. Note that there are fewer
lines of force (dotted lines) from the main pole
winding through the magnetic bridge and diverter
pole, and that increasing lines of force (unbroken
of the main pole flux to the armature. This condition, shown as a decrease in the lines of force
in the armature path, will result in a drop in generator voltage. It can be seen therefore that the
diverter pole ge. rator protects itself against
the excessive current condil in of an overload.
lines) are being sent into the armature path.
Battery
During full load conditions, (fig. 9-31C) flux
from the diverter pole almost entirely blocks the
passage of flux from the main pole through the
magnetic bridge, and therefore almost all of the
flux from the main pole winding is sent into the
armature's path. In this manner the level of the
voltage is raised sufficiently to compensate for
internal losses, and the output voltage is maintained at the desired constant level.
As the generator is subjected to an overload
condition (fig. 9-31D), the ampere turns of the
The battery used with the automatic switchboard is a standard rack of 24 cells as explained
in Basic Electricity, NavPers 10086 (latest edi-
diverter pole will, at some period, equal those
in the main field. At this point,, flux from the
diverter pole will completely block the magnetic
bridge, and all main pole flux will be diverted into the armature path. With the load increasing,
but before the danger level, diverter pole flux
soon becomes strong enough to block the passage
tion).
Power Control Panel
Located on the power control panel are the
various controls associated with the power supplying units and the connections for these units.
No attempt will be made to explain these varying
controls, however figure 9-32 is a simplified diagram of the connection of the motor generator and
the battery to the switchboard.
Connection
The connection of the battery and the generator is through the nontacts of the reverse
265
A. if
IC ELECTRICIAN 3 & 2
Main Pole
with
Shunt Winding
Diverter Pole
with
TO AUTOMATIC SWITCHBOARD
Series Winding
SWBD BAT.
+SWBD BAT.
GEN
SHUNT COIL
SERIES
COIL
GENERATOR
REVERSECURRENT
RELAY
EXCHANGE BATTERY
OS II +
BATTERY CONNECTED TO GENERATOR (REVERSE
CURRENT RELAY OPERATED), PARTIAL SCHEMATIC
A
Figure 9-32. Power connection.
Diverter -pole type field winding at no
load, partial pictorial schematic
140.89
current relay. The switchboard draws power
from the battery L, hen the reverse current relay
is not operated, and draws power from the gen-
erator, or the generator and battery when the
reverse current relay is operated as shown (fig.
9-32). The reverse current relay acts as a contactor for making the connection between the gen-
erator and the battery, and also as a protective
device to prevent current from flowing from the
battery to the generator when the generator volt-
Diverter -pole type field winding at 50%
load, partial pictorial schematic
age has dropped below that of the battery.
MAINTENANCE
Dial telephone system maintenance includes
periodic tests and inspections, lubrication cleaning, and troubleshooting and repair. Test equip-
ment, special tools, and special lubricants and
charts are provided with each system, and
c Diverter-p.le type field winding at full
load, partial pictorial schematic
detailed maintenance instructions are included in
the manufacturei's technical manual.
Cleanliness is essential due to the low voltages and currents involved. Dirt and dust can
cause insulation failures, and high resistance or
partially open contacts. Use a vacuum cleaner for
removing dirt and dust from the switchboard
equipment. Relay contacts may be cleaned by
pulling a strip of bond paper between them. Use
a burnishing tool to clean pitted contacts. The ad-
Diverter-pole type field winding at over.
load, partial pictorial schematic
140,88
Figure 9-31. Motor-generator field.
justable parts of the relays and switches are
delicate and require the use of special tools to
adjust them. Do not attempt to adjust a switch or
relay until it has been definitely determined that
266
478
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
adjustment is necessary. When adjustment is
necessary, study 1.*.le manufacturer's adjustment
instructions, and follow them carefully.
Periodic ground tests should be made on all
telephone lines at least monthly, or as required
by current maintenance instructions. If a 500 volt megger is used to make the tests, test each
conductor to ground only. Do not test between
the twisted pairs as the 500 volts may damage
the capacitors in the equipment.
TELEPHONE INSPECTIONS
Periodically check the speed of all telephone
dials by dialing the digit 0. The dial should return
to its normal position in approximately 1 second.
Inspect and tighten all mouthpieces and ear-
pieces; replace if broken. Replace frayed, worn,
or noisy cords. To cheek for a noisy cord, roll
the cord back and forth between the hands while
listening for a clicking or crackling noise in the
receiver. Conduct a transmission test over each
telephone by talking with another person.
TELEPHONE LINE
STATION REPAIRS
In general, when it is necessary to work on a
telephone it should be taken out of service by
disconnecting the LI and L2 line wires. The line
wires can be disconnected in the type A telephone
at the cord terminal block located at the end of
tie desk set cord, and in the types C, F, ai ri G
telephones at the terminal strip inside the
housing. This procedure prevents the unnecessary operation of the automatic switches that
seize and hold busy a conversation link at the
switchboard. To prevent reconnecting line wires
in reverse, they should be marked when disconnected.
Removing the Dial Card
The dial card is removed by inserting the
special dial tool under the escutcheon ring (fig.
9 -4,), near the digit "5" finger hole. Press the
tool down against the. locking lever underneath
the card and move the tool counterclockwise to
the digit "6" finger hole. This action unlocks the
card assembly. Lift the escutcheon ring at the
digit "6" finger hole with the tip of the tool and
withdraw the card assembly. The escutcheon
ring, the celluloid cover, the dial card, and the
dial card clamping- plate will release as one assembly. The parts of this assembly, can be released by turning the assembly clamping plate in
a counterclockwise direction. Notice the relative
position of the parts as they are rernoved so that
they can be easily reassembled.
The components of the card assembly are
reassembled by placing the celluloid cover and
then the dial card into the escutcheon ring. Place
the dial card clamping plate over the dial card
and turn the clamping plate in a clockwise direction to engage the tongue, thereby locking the
assembly. Mount the card assembly on the dial,
with the locking lever on the finger plate pointed
midway between digits "6" and "7". Insert the
small lug on the escutcheon ring into the slot
located above the finger stop and press the assembly down into the finger plate. Hold the assembly in place and insert the dial tool under the
escutcheon ring near the digit "7" finger hole.
Press the tool down against the locking lever
underneath the card and move the tool ina clockwise direction to the digit "6" finger hole, thereby lockinr; the card in pace. Remove the tool.
Replacing the Dial
To replace the dial of any type of telephone
expose the interior, as previously described, and
disdonnect the four conductors at the rear of the
dial. Remove the three screws and lockwashers
that hold the dial in place and lift out the dial.
Mount the new dial and replace the lockwashers
and screws. Connect the four conductors to the
dial in accordance with the circuit label inside
the telephone. Dials are properly adjusted and
lubricated before shipment and should operate
for long periods of time without attention. However, if minor adjustments are required the
proper procedures are listed in the manufacturer's technical manual.
Replacing the Cords
A handset or cord on a telephone can be readily replaced because cords are carried (already
made up) in the spare parts box. When replacing
a handset or cord, refer to the circuit label inside the telephone or make awiringsketchso that
the cord can be connected properly. Allwires are
color coded, and the connections are made by
screw type terminals. Always anchor the tie cord
securely, using sufficient slack in the conductor
wires so that no strain is placed on the wires.
Replacing the Transmitter
and Receiver Units
The transmitter and receiver are both of the
capsule type and thus are completely enclosed
267
IC ELECTRICIAN 3 & 2
self-contained units.
These units cannot be
CANNOT ANSWER. If a party at a called
telephone is signaled but cannot be heard, the
fault can be caused by a shorted transmitter or a
opened without damage. In the event of trouble
the entire unit must be replaced.
The transmitter unit is held in place in the
shorted contact of the dial shunt springs. Also, if
the hook switch springs fail to operate, the ringer
will, rot be cut off when the handset is removed at
the called station.
mounting cup ',of two retaining spring clips and is
secured by the mouthpiece. Connections to the
electrodes are through springs. To remove the
transmitter unit, hold the handset in a horizontal
position (facing up) and unscrew the mouthpiece.
CANNOT HEAR WELL. If a telephone has
poor reception, the trouble may be caused by improper contact of the contact springs in the
If the hand slips, wrap a piece of friction tape
around the mouthpiece to provide the necessary
friction. Lift the transmitter urit out of the
housing, with the fingers engaging the outer edge
of the unit between the two retaining springclips.
receiver housing, a loose receiver cap, a worn
receiver cord, or loose connections inside the
telephone.
To replace the transmitter unit, hold the
handset in a horizontal position, as previously
CANNOT BE HEARD WELL. If a telephone
explained. Insert the outer edge of the unit against
the movable retaining spring clip (located in the
has defective voice transmission, the fault is
probably in the transmitter unit. To loosen the
cup) and snap into place, pressing only on the
outer edge of the transmitter. Then screw on the
carbon granules, hold the handset in a horizontal
position and shake it, using a circular motion.
If the cabon granules are not loosened by this
method, strike the transmitter end of the hand-
mouthpiece.
The receiver unit is held securely in place by
the ear cap. Connections to the electrodes are
through springs. To remove the receiver unit,
set sharply with the palm of the hand. Also, check
the contact springs in the transmitter for a tight,
clean connection to the unit.
hold the handset in a horizontal position (ear cap
facing up) and unscrew the ear cap. Place the
hand over the receiver housing and turn the handset over. The receiver unit will drop out and into
the hand.
To replace the receiver unit, hold the handset
in a horizontal position, as previously explained.
Place the receiver in the cup and screw on the
ear cap.
Some of the common dial telephone faults are
discussed briefly below.
CANNOT CALL. If a call cannot be made
from a telephone, first determine if the line relay
operates when the handset is removed at the call-
ing station. If the line relay does not operate,
short circuit the line terminals at the switch-
board. If the line relay now operates, check for an
open line between the switchboard and calling
telephone.
WRONG NUMBERS.
NOISY CONNECTIONS. Noisy connections
are caused by partial shorts or grounds on the
line, worn handset or desk set cords, noisy transmitters, and loose connections in the telephone.
CLICKS IN RECEIVER. Clicks in the
receiver while dialing are usually caused by
failure of the shunt springs to make contact
when turning the dial. If this condition is not
corrected after cleaning the contacts, look for a
broken shunt spring connection.
CALLED STATION DOES NOT P.ING.
The most frequent cause
of wrong numbers is the impulse springs in the
dial
being out of adjustment or bent. As a
consequence, the speed of the dial is reduced,
resulting in wrong numbers. Another frequent
cause of wrong numbers is jiggling the cradle
switch before starting to dial. Moving the cradle
switch up and down rapidly results in a series
of impulses similar to those sent out by the
dial. Keeping the dialing finger on the dial while
it is restoring to normal may also result in
wrong connections.
If the
bell ai 2 called station does not ring, the fault
can be caused by an open ringer coil or capacitor,
an improper adjustment of the ringer, or
reversed or loose connections at the ringer
terminals. Also, the bell will not ring properly if
the gongs have become loose or if the position of
the gongs has shifted with respect to the clapper.
TESTING EQUIPMENT
Testing equipment is provided for use in detecting and locating nonstandard conditions in the
dial telephone system. This equipment comprises (1) a line disconnect key panel (discussed
earlier in this chapter), (2) a hand test telephone,
(3) linefinder-connector test set, (4) a current
flow test set, and (5) a line routiner.
268
80
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
C/R (SLIDE) SWITCH
3.198
Figure 9-33. Hand test telephone.
A knowledge of the testing equipment is necessary to keep the telephone system operating at
a maximum efficiency. Therefore, the more
cord with a test plug is connected to the trans-
important test equipment listed above will be
discussed here.
C and R respectively are located externally on
opposite sides of the handle toward the receiver
end (a slide switch on newer designs). A
capacitor, an impedance coil, and a resistor are
Hand Test Telephone
mounted inside the case.
The hand test telephone is mounted on the
rear of the finder board by a spring clamp. The
hand test telephone can be used independently or
in conjunction with the test set, depending on the
type of tests to be conducted.
is connected in the transmitter circuit. The
mitter end of the case. Two pushswitches marked
When pushswitch C is depressed, a capacitor
capacitor cuts off the talking circuit to permit
listening only, and also prevents interference
with dial pulses when plugging in the hand test
The hand test telephone (fig. 9-33) consists
of a conveniently shaped handle with a transmit-
telephone. Pushswitch C is released when dialing
back-to-back at the other end. A 2-conductor test
phone to talk to either party.
the switch being tested, or, if the switch is
ter at one end, and a receiver and dial placed
269
already in use, when using the hand test tele-
IC ELECTRICIAN 3 & 2
DIAL IMPULSE
A fault which measures between 10,000 and
50,000 ohms will not interfere with the operation
of the telephone apparatus but it does indicate a
possible future source of trouble and should be
K2
SPRING
SLOW
corrected. A fault which measures less than
RELEASE
10,000 ohms will intJrfere with dialing.
LOOP RESISTANCE.
.....
..-
...... -
For successful opera-
tion of automatic switching equipment, lines must
be maintained within certain limitations of line
loop resistances. Line loop resistance is the
-111111-1
metallic resistance of the line conductors, and
is the resistance measured between the automatic
VERTICAL
MAGNET
switchboard and the telephone instrument (ex-
27.210
Figure 9-34. High loop resistance circuit.
clusive of the instrument).
There are two types of line loop resistance
high loop and low loop.
When pushswitch R is depressed, a 1200-ohm
resistor is connected in series with the trans-
mitter. This resistor is used to test the operation
of Strowger switches. However, this button is not
used normally because the hand test telephone is
provided with a 1000-ohm resistor (in addition
to the 1200-ohm resistor) that automaticallyprovides a high resistance in series with the line
when testing Strowger switches.
Line Routiner
The line routiner is test equipment used in
testing lines of the shipboard dial telephone sys-
tem. The rouNier consists of two unitsa test
connector and a portable line test set. The test
connector is furnished with repair parts, and is
to be jacked into a connector position when the
line routine test is made.
The effect of high fault loop resistance may
best be analyzed by ts.onsidering a line of rather
high series (line loop) resistance such as shown
in figure 9-34. When relay K1 operates, it sends
a pulse of current to slow-to-release (SR) relay
K2, and when relay K1 releases, it sends a pulse
of current to the vertical magnet. If there is too
much resistance in the line, relay K1 will be slow
to operate and will fall away quickly on dial
impulse because of the low magnetic saturation
of its core. Since relay K1 falls away quickly,
the pulse of current to relay K2 is too short, and
relay K2 will not remain operated. The vertical
magnet, on the other hand, gets too long a pulse
(sometimes called a "heavy" pulse).
The second type of line fault loop resistance
is low loop resistance. If there is negligible line
loop resistance and low insulation resistance
(fig. 9-35), a high leakage current (which con-
stitutes a low-resistance shunt) results, and line
TEST CONNECTOR. The test connector is
a Strowger witch mechanism which in appearance
is similar to a regular connector. The circuit
of the test connector, however, differs considerably from that of a regular connector in
DIAL IMPULSE
SPRING
K2
Illihi
that (1) the test connector is actuated to elevate
and rotate its wipers without pulses from a dial,
and (2) the circuit of the test connector includes
facilities for testing for the presence of line
faults.
LOW
RES
SKUNTt
LINE TEST SET.
The line test set includes
an ohmmeter, a rheostat, three keys, and a test
1
----111111-1
cord and plug. The set plugs into the test jack
VERTICAL
on the test connector and may be connected either
MAGNET
before the testing starts or when the connector
stops because of a line fault. The line test set
determines the nature and resistance of the fault.
27.211
Figure 9-35. Low loop resistance circuit.
270
t
4-
40- 0 -,
4
Chapter 9 DIAL TELEPHONE SYSTEMS, PART I
NON OPR
RESIST.
KEYS
OPR
RESIST.
KEYS
CAUTION
SW
AUX
,
FUSES
EXT
veAt't Itt.s,
BIND
POSTS
'
1
BAT.
BINDING
OUT
TEST
BIND
POSTS
POSTS
METER
SW
TEST SW
ZERO ADJ SCREW
AUX SW
BAT. CUT-OFF SW
REVERSE CURRENT SW
SOAK SW
27.212
Figure 9-36. Current-flow test set.
Thus, relay K1 operates too fast at the beginning
of a dial pulse and releases too slowly at the end
of a dial pulse. The shunt tends to maintain relay
K1 operated wher the dial impulse springs break
because of the battery cui .int through the shunt.
Since relay.K1 remains operated for a relatively
To determine that a relay operates within the
required limits, it is preferable to test the relay
with known values of current. The current-flow
test set (fig. 9-36), is a means by which known
values of current are directed to the relay under
test. The ammeter on the test set indicates the
value of the current in the test circuit, and the
key-controlled resistances are a convenient
means by which the flow of current in the test
circuit is regulated. The test set has facilities
Current-Flow Test Set
for connecting a total of 42,215 ohms into the test
circuit, 22,215 ohms be means of the resistance
keys, and 20,000 ohms by operation of the auxiliary switch.
relay K1 is held partly magnetized even after the
dial impulse springs have opened the circuit.
long time, the vertical magnet gets too short a
pulse ("light" pulse).
The
successful
operation
of
automatic
switchboard circuits requires that the relays in
such circuits perform to exact operate and nonoperate values. The operate and nonoperate requirements for each relay in a given circuit are
listed in the manufacturer's technical manual.
CURRENT-FLOW TEST CIRCUIT.
The air-
cult for the current-flow test set is always
brought through the test switch regardless of
how the set is used. Connections to the relay
under test are always made at +OUT TEST
271
IC ELECTRICIAN 3 & 2
TO RELAY
UNDER TEST
OUT TEST
161.1-1a2
SOD
11111H11101
A
8
LIN
a
RING
BUSY
Y
RELEASE
ON +
EXECUTIVE
TEST
TALK
REVERSE BATTERY
TEST
0
METER
OPR
15
0
RING
ON-
TEST SET
27.213
Figure 9-37. Current-flow test set circuit.
which means the test circuit is not closed until
the test switch is operated either to OPR or
NON OPR. A typical test circuit is shown in
figure 9-37.
Assume that a relay winding is connected
across the OUT TEST binding posts, and that a
battery is connected to the BAT binding posts.
Also assume that the BAT key (not shown) is at
TEST TELEPRON
JACK
normal, that the 50-ohm NON OPR resistance key
is operated, and that the test switch is thrown to
,...,
TEST and the winding of the relay under test.
Figure 9-38.
L
NON OPR. The test circuit is from battery
on the - BAT binding post, through - OUT
The circuit continues back through + OUT TEST,
through t! .e first pair of make springs in the
nonoperate section of the TEST switch, and
through the NON OPR 50-ohm resistance, through
the second pair of make springs in the nonsection of the TEST switch, and through make
springs on the NON OPR 50-ohm resistance
key,
to
the negative terminal on the meter,
through the meter and finally back to the positive battery on the + BAT binding post. This
is the basic test set circuit and, as may be seed,
the meter will measure the current flowing
through the winding cf the relay. The current
R
140.132
Linefinder-connector test set.
may be increased or decreased by operating additional resistance keys.
operate section of the TEST switch, through the
third pair of make springs in the nonoperate
**
The main function of the current-flow test set
is to provide the means by which, current of a
known value may be directed to the relay under
test. The test set can further provide a means
for directing a "saturate" current to this relay
and for reversing the polarity of current flow
in the test circuit without changing any leads.
Moreover this test set may serve as a resistance
box or a d-c milliammeter to measure current
less than 750 ma.
272
Chapter 9DIAL TELEPHONE SYSTEMS, PART I
test set. The tests are made by dialing the
exchange test number 29 on the hand test tele-
Linefinder-Connector Test Set
The test set (fig. 9-38) is used for testing the
operation connector switches. In the test setup,
the set is connected to a switch by a patch cord,
and the hand test telephone is plugged into the
phone, and operating the switches on the test
set to check for ring, ringback, line busy, executive-right-of-way, transmission (talk), and proper release of the connector.
273
40.
# CO
CHAPTER 10
DIAL TELEPHONE SYSTEMS, PART II
In response to the requirements for an expandable automatic dial telephone system which
Cabinets and Modules
incorporated the features of flexibility, com-
Each cabinet (system or switchboard) consists
of one rack of equipment shock mounted in a rigid
pactness, and reliability, the Marine Dialmaster
Model MDM 200/700 telephone system was Developed. The system is able to provide station-
cabinet assembly. The cabinet circuit modules,
which are accessible through front and rear doors,
plug into the framejack panel and contain all the
switching circuits necessary for system operation. Two XY-Universal switches are associated
to-station communications via automatic dial tele-
phone lines while at sea, and may be used with
commercial telephone networks by way of shipto-shore lines in port.
The main assemblies of the MDM 200/700
with each of the fifteen finder/connector circuit
modules used in each switchboard cabinet. These
switches mount in cells located on the front of
the frame and plug into tilt. associated finder/
connector circuit modules. The line connection
panels are mounted directly to the switchboard
installation are one system cabinet and from
two to seven identical switchboard cabinets. The
line capacity of the system can be increased
from 200 to 700 lines, in 100-line incremen
simply by adding switchboard cabinets and as-
frame (fig. 10-2A). These panels provide the
means for connecting the switchboard to the
ship's cables. Screw-type terminals are provided for all connections allowing line-number
sociated cabling. Thus, a 200-line system initially
installed can later be expanded to 300 lines, or
to its maximum capability of 700 lines, without
disrupting the initial installation. The number
of simultaneous calls the system can handle is
equivalent to 15% of the lines provided. As an
changes to be readily accomplished.
MAIN ASSEMBLIES OF THE
SWITCHBOARD CABINET
example, a 200-line system is capable of handling
30 calls at any one time.
The system can be used with any two-wire
There ara nine main assemblies in the MDM
200/700 system. Some perform similar functions
telephone set, manufactured in the United States,
which employs break-type dialing (a dial which
to the Automatic Electric Strowger telephone
interrupts the current flow). The compactness
of the system is due to modular construction
system. Each has both a name and number
designation.
techniques. All electromechanical and solid-state
switching circuits as well as all power equipment
are mounted on a single equipment rack.
DESCRIPTION OF EQUIPMENT
The MDM 200/7N) system is a modular,
electromechanical system using rotary stepping
switches and XY-Universal switches as the basic
switching components. The system is comprised
of one system cabinet (fig. 10-1) and from two
to seven switchboard cabinets (fig. 10-2). An
attendant's cabinet (fig. 3.f.;- 3) provides an interface between ship lines and shore installations
when the ship is in port.
Common Control Panel (100 Assembly)
The eommon control assembly consists of six
separate, though related, circuits, The main
function of the 100 assembly is to provide timing
for finder action requests and to extend finder
request ground (positive signal voltage) to the
finder allotter. This assembly also provides dial
tone and busy tone for the system.
Level Detector and Alarm Circuitry
f(200 Assembly)
The level detector panel contains ten identical
274
i
level detection circuits, one for each system level,
'86
A..
(1100 ASSEMBLY)
DISTRIBUTION
PANEL
POWER
SYSTEM
MOO ASSEMBLY)
SHORE LINE
MODULES
(1100 ASSEMBLY)
SHIP LINE
MODULES
(1500 ASSEMBLY)
PANEL
SHIP/SHORE
FRAME CONTROL.
Front View
(1100 ASSEMBLY)
BATTERY CHARGER
RING
VOLTAGE
GENERATORS
(1400 ASSEMBLY)
RING/BUSY
INTERRUPTER
MODULE
(1300 ASSEMBLY)
SHIP/SHORE
CONTROL
MODULE
11700 ASSEMBLY)
SYSTEM
CONNECTION
PANEL
Rear View
(PART OF 1100 AMINO)
SYSTEM POWER DISTRIBUTION
CONNECTION PANEL
Figure 10-1.System cabinet.
MOO ASSEMBLY)
SYSTEM MONITOR PANEL
SHIP/SHORE
FRAME
140.162
(PUT OF 1500 ASt 'MOLY)
PANEL
CONNECTION
FINDER if
(t00 ASSEMBLY)
DETECTOR
MODULE
LEVEL
MODULE
(300 A3SEMILY)
FINDER II
ALLOT7ER
(400 ASSEMBLY)
CONNECTOR
MODULES
Front View
Figure 10-2.Switchboard cabinet.
COMMON CONTROL
MODULE (100 ASSEMBLY)
(300 ASSEMBLY)
SUPPLY
POWER
(300 ASSEMBLY)
DISTRIBUTION
MODULE
SWITCHBOARD
POWER
(300 ASSEMBLY)
SWITCHBOARD
MONITOR
PANEL MODULE
SWITCHES
XT
(300 MEW(S)
LINE CONNECTIOL PANELS
Rear View
-\
140.163
(MO ASSEMBLY)
SELECTION
MODULES
Chapter 10 DIAL TELEPHONE SYSTEMS, PART II
alarm conditions. The panel also contains a jack
for the systems test number plus switches and
indicator lights used to control audible and
visual alarms.
Line Panel (600 Assembly)
There are ten line panels in each switch-
board cabinet. Each panel provides connections
and switching facilities for one level of ten
telephones. The line disconnect switches are
located in this panel, which is also where a
station can be wired for executive-right-of-way
or become part of a line hunt group.
Selector Panel (700 Assembly)
There are five selector panels, each containing
three identical selector circuits. The selector
circuit provides the means by which a telephone
station can call any other station in the system.
This assembly performs the same function as
the selectors in the AE system.
Power Supply (800 Assembly)
Figure 10-3.
140.164
Attendants console.
The power supply unit uses a single phase,
full-wave rectifier with choke input for regulation
and diode surge current protection. A choke
and major and minor alarm circuits. The func-
together with filter capacitors provide low ripple
tion level of the detector is similar to that of
the start level marks system in the Automatic
d-c power. Each switchboard contains its own
power supply unit.
Electric system.
Power Distribution Panel (900 Assembly)
Finder Allotter Panel (300 Assembly)
This assembly distributes d-c power toequipment in the switchboard cabinet.
The finder allotter panel, also referred to as
the link allotter, contains fifteen identical cir-
cuits, one for each finder circuit. The circuit
is very much the same as the finder-distributor
relays in the Automatic Electric system, as it
is used to select the next idle finder in the system.
Finder/Connector Panel (400 Assembly)
The finder/connector panel, also referred to
as a "link", is made up of two main sections:
the finder circuit where linefinding is accomplished and the connector circuit where connection to the calling line is accomplished. The
transmission path is established in this assembly
between the calling and the called telephones.
Switchboard Monitor Panel (500 Assembly)
The switchboard monitor panel contains three
alarm signaling circuits which react to different
MAIN ASSEMBLIES OF THE SYSTEM
CABINET
The system cabinet consists of nine main
assemblies: 1100, 1200, 1300 through 1900. Four
of these (1100, 1200, 1300, and 1500) are associated with the operation of the attendant's
console.
Ship Line Modules (1100 Assembly)
There are eight identical ship line modules,
one for each ship line connected to the attendant's
console.
Shore Line Modules (1200 Assembly)
This assembly consists of eight identical
shore line modules, one for each shore line
associated with the attendant's console.
277
289.
IC ELECTRICIAN 3 & 2
Ship/Shore Control Module (1300 Assembly?
Attendant's Console
This module contains all the necessary circuitry used to control the operation and interconnection of the ship and shore lines through
the attendant's console.
Ring/Busy Interrupter Panel
panels (one for each ship line), 8 shore line
(1400 Assembly)
This panel consists of tone interrupter circuits
and a ring timing circuit. It generates ground
pulses which control ring voltage and busy tone
interruptions used in the selector circuitry.
Ship/Shore Frame Panel (1500 Assembly)
This panel is capable of connecting the eight
ship lines to the shore lines, monitoring the
ring and busy interrupter circuits, visually indicating that the attendant's console is energized,
and providing a direct audio path to the at-
tendant's console for test purposes.
panels (one for each shore line), and one control
pinel. The attendant's switching circuit is controlled from a remotely located attendant's console (fig. 10-3).
Since all of the attendant's switching equip-
ment is mounted in the system cabinet, each
console (a maximum of 3 per system) is used
only to perform the functions of a standard
telephone with pushbutton control of switching
modules to seize and interconnect ship lines
and shore lines. The consoles are not much
larger then standard type-G telephone sets and
can be mounted on a desk or bulkhead, or flush.
mounted in a suitable panel.
The attendant's console will not be discussed
detail. From the operator's viewpoint, its
basic operation is similar to the operation of
in
System Power Distribution Panel
(1600 Assembly)
the Automatic Electric system attendant's cabinet.
This assembly contains two solid-state ring
generators, switches for controlling ring voltages,
and four major power distribution buses and their
associated terminal connectors.
SYSTEM OPERATION
This section explains the fundamentals of
XY-switching as used in the MDM 200/700
system and describes the operation of the rotary
switch that is used as a selector and the opera-
System Connection Panel
(1700 Assembly)
tion of the switchboard and control cabinets.
Eight terminal blocks are mounted on this
panel. They are used as connection points for
various system functions.
Switching Components and Linefinding
The XY-Universal switch (fig. 10-4) is the
heart of the MDM system in that it provides
the means for establishing connections through-
Battery Charger (1800 Assembly)
The battery charger is a standard, alternating to direct current, solid-state unit of
suitable voltage to maintain a 23-, 24-, or 25-
cell battery in a fully charged condition.
System Monitor Panel (1900 Assembly)
The system monitor panel is integrated in
the MDM system, and can monitor and test all
finder/selectors and connectors in the system.
The panel contains call count indicators and alltrunks-busy indicators; also, voltage monitoring
and alarm locating circuits that give the maintenance man a quick indication to the condition
of any switchboard cabinet in the system.
The MDM 200/700 installations are equipped
with attendant's switching circuitry to provide
for attendant-assisted ship-to-shore communications. This circuitry is mounted in the system
cabinet, (fig. 10-1) and consists of 8 ship line
.
.
out the system The XY-Universal switch is a
100-point, two - motion, remote-control device
which may be operated under the control of a
dial or automatically pulsed from associated
control circuitry. A 100-point, two-motion switch
is one that can make electrical contact with any
of 100 sets of contacts, taking two motions to
accomplish the connection. With the switch
mounted in a horizontal plane, the switch car-
riage moves first in the X-direction, (left to
right parallel to the wirebank) and then in the
Y-direction (into the wirebank). When mounted
in the switchboard, the XY-switch is located
adjacent to a 42- by 10-wire matrix, called a
wire bank. This wire bank runs the length of
the switchboard and serves as the contacts for
the wipers of all the XY- switches in the system.
290
Chapter 10DIAL TELEPHONE SYSTEMS, PART H
-die-
RELEASE MAGNET
X MAGNET
xt-x ma
T,R,S,NS
WIPERS
00°
N.-
Y MAGNET
X CARRIAGE
Y CARRIAGE
MECHANISM PLATE
Figure 10-4. XY switch.
The XY Switch
The main components of the XY-switch (fig.
10-4) are an X-stepping magnet, a Y-stepping
magnet, a release magnet, spring pileups, and
associated mechanical drive hardware. A simpli-
fied schematic of the XY-switch is shown in
figure 10-5. The switch steps first in the X-
direction controlled by a series of ground (positive) pulses (periods of current flow) extended
to the X-stepping magnet. Each time the magnet
operates, the wipers are advanced one step in
the X-direction. The Y-stepping magnet functions
in a similar manner to drive the wipers in the
Y-direction, which is into the wire bank.
140.165
The overflow, X-off normal, and Y-off normal
spring pileups depend only on the position of
the wipers for their operation. The spring position shown in figure 10-5 is the normal position.
These springs are used by the associated cir-
cuitry to perform various supervisory and control
functions. When the wipers are stepped in the
the X-off normal springs are
operated; when stepped in the Y-direction the
Y-off normal springs are operated. Only 10
steps are allowed in either direction; if these
X-direction,
are exceeded, the overflow springs are operated.
When the X-off normal or Y-off normal springs
are operated, an opereing path is completed to
the release magnet. A ground (signal) can then
IC ELECTRICIAN 3 & 2
KUM
.10
OVERFLOW
O? MORN
-
OFF NOW
4
-4
NR
STE
W AS
RWIE
rn
aa
140.166
Figure 10-5.XY universal switch, schematic diagram.
be extended to pin 29 of the XY-switch plug to
operate the release magnet, causing the wipers
10-6A).The X-motion of the switch locates the
wiper at a position (or Jank) opposite the proper
section of the wire bank. The Y-motion of the
switch positions the wiper into the bank to
to return to the normal position. The release
springs are operated to release the external
control circuitry. The release magnet restores
establish the connection at the proper point.
when both the X-- and Y-off normal springs return to normal.
a0 0 0/0 0090
0 0 0 0 0 000
n0 0 0 0 0 0 0 0 0 011
The Wire Bank
The 42- by 10-wire bank associated with
IS 0
the XY-switch is actually made up of six smaller
wire banks: four 10- by 10-wire banks and two
1- by 10-wire banks. The 10- by 10-wire banks
20
SO
TO
SO
00 00
0
0
00
000
0
IT
10
001
0 0000
40 0 0 0 0 0 0 0 0 000
ISO 0 0
0 0 0 0 0 000
140 0 0 0 0 0 0 0 0 001
are used with the four wires associated with
each telephone line. These four wires are the
tip (T) and ring (R) for transmission, and sleeve
(S) and helping sleeve (HS) for supervisory and
switching. The 1- and 10-wire banks (XX and X)
are used to electrically indicate the X-position
0 1 0 0 0 0 0 0 003
0 0 1 0 0 0 0 0 0 002
0
13 0
NINON MINN
S
Mal 4
1
12 0
11 a0001
00000003
3 41
a a
II
1
of the wipers when the wipers are stepped in
the X-direction. Each of these banks is associated with its own particular wiper on the XYswitch; hence, the switch wipers are referred
51
I
i
to as the T, R, S, HS, and XX-X wipers or beaks.
IN
110110TEN Is SET Of 111r1LKS°Pram TO FOS01
T
4
1411 IN 011131141. 1110111141.110141011
Figure 10-6 is a simplified diagram of one of
the 10- by 10-wire banks (as seen from above)
NOTE: Marro OF 10211 WNW MATEO WI
and the associated wiper.
This wire bank runs the length of the switch-
140.167
board and is associated with the same wiper in
all the other XY-switches in the system (fig.
Figure 10-6.Wire bank and associated XY
switch wiper, simplified schematic diagram.
280
A:
92
Chapter 10DIAL TELEPHONE SYSTEMS, PART II
Figure 10-6A. XY switch cell and wire banks.
The switch will then remain in position indefinitely
140.168
Automatic Electric Strowger system. Both use a
certain amount of "shared" equipment since all
stations will not be in use all the time. Sharing
makes it possible to reduce the number of pieces
until it is released. A terminal block at the end
of the wire bank provides the necessary connections to the system circuitry. A simplified
schematic diagram of the four 10- by 10-wire
banks and the XX-X wire banks is shown in
figure 10-7. Figure 10-7A shows the wipers in
of switching equipment needed to operate the
system. The main pieces of equipment used in
linefinding are the line circuit, the linefinder,
the normal position. When one wiper of the XY-
and the allotter.
switch is in a given position in its 10- by 10wire bank, the other three wipers are in the
Line Circuit
same position in their respective 10- by 10-wire
banks. As the switch steps a certain number of
steps in the X-direction (fig. 10-7B), the XX-X
wipers advance the same number of steps into
Since the shared equipment must be available
on an equal basis to all stations and is not normal-
ly connected to any one station, there must be
a method of indicating that a particular station
requires switching equipment. The line circuit
does the indicating by sending a signal to the
shared equipment when a station wishes to originate a call. There is one line circuit associated
with each station in the system, arranged so that
on an incoming call to the station, the shared
equipment is not connected with the station.
the XX-X wire banks. As the switch steps in
the Y-direction, the T-, R-, S-, and HS-wipers
advance into the wire banks to the desired posi-
tion (fig. 7-10C).
PRINCIPLES OF LINE FINDING
The basic principles of linefinding in the MDM
200/700 system are similar to those used in the
281
X93
"93
IC ELECTRICIAN 3 & 2
a
tt
XX
OA
H Ille
X
0
0
0
0
0
0
0
0
0
0
J .1 4.d
7. W
M.
00
0
0
0
0
0
0
0
0
0
0
S0 0 0
BO 0 a
700 0
A0 0 0
50 0 0
40 0 0
30 0 0
STUN, 20 0 0
I0 0 0
W
a
THIS SPACE FILLED WITH
ADDITIONAL BANK WIRES
(TSAI LEVELS 3-10
:
a w po
.1
Ea 4:. JI
H
00
g/
0
0
0
0
0
0
30
60
TO
60
50
40
30
O
O
au's._ 2 0
O
"14 0
12
VI
00
00
00
00
00
00
00
00
00
00
4,
.5 THIS SPACE FILLED WITH
L...
ADDITIONAL SANK WIRES
(56061 LEVELS 310
0
0
0
0
0
0
0
0
0
0
WIPERS IN
NORMAL
911171011
WM IN
NNW POSIT01
Figure 10-7A.
Four wire banks and associated wipers shown in the normal position.
The Linefinder
Figure 10-8 illustrates the basic principles
of linefinding. For the sake of simplicity, the
allotter is not shown. When the calling party
operates his hookswitch by removing the handset
from the cradle, the line circuit sends a linefinder start signal to the linefinder. This signal
causes the XY-switch to step automatically in
the X-direction, searching for the level in the
bank where the calling line is located. The XXX bank and wipers serve to indicate the tens
level (level 6 would be the tens level for line
62) of the calling line. When the XY-switch
reaches this level, it stops and starts moving
into the wire bank in the Y-direction. When
....
..,
>
a
XX - X
00
O O
0
0
0
0
O 0
0 0
0
0
0
0
00
30
70
50
so
40
30
STEP......_ 20
-.. I 0
I
;
a
;
O
LTGR LEVELS 3-0
..,,,
,-,,,
>
,,,,
ta
>
to
'21
-a
L.
..,,
:,L. THIS SPACE FILLED WITH
to>
a
00 0 0 0
O
O
B0 0 0 0
RIT-B WIPERS
IN STEP 2
XX
THIS SPACE FILLED WITH
W ACOITIONAL BANK WIRES
L.--:
0 0 0
0 0 0
0 0 0
O0 0
O0 0
O0 0
O0
140.169.
STEP,
O
AOOITIONAL BANK WIRES
/ (SA
LEVELS 3.0
90 0 0 0
SO O 0 0
TO 0 0 0
60 0 0 0
SO O 0 0
40 0 0 0
30 0 0 0
20 0 0 0
I0 0 0 0
X
WIPERS IN
s2 POSITION
I
I
iS
NS
WIPERS IN
In POSITION
Figure 10-7R.
140.169.1
Four wire banks and associated wipers shown in the "X2II position.
282
r
1
,424
Chapter 10DIAL TELEPHONE SYSTEMS, PART II
,.,
e
W
-..
00
00
00
00
00
00
00
00
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00
90
IT& FO LEALS 3.0
00
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IS& HSI LEVELS 3-0
12
0
0
0
0
0
SO 0
70 0
60 0
S0 0
WIPERS IN
40 0
POSITION:6
OfT 0 0
30 OfS0
OTIS
siErz,: 01 0 0
10 01 0 0
Ex
'/
90 0
STEP......._ 2 0 01 0 0
XXX WIPERS
IN STEP 2
.
..
5
-6
la,
la,
....
0
0
0
70
60 0
S0 0
40 0
....
X00v.
0
e0
30
THIS SPACE FILLED WITH
ADDITIONAL 80411 WIRES
01 0 0
1
1
1
1
140.169.2
Four wire banks and associated wipers shown in position 26.
Figure 10-7C.
and is released when the calling party hangs
the proper line is located, it stops again and
establishes the necessary connections so that
the calling station may control the connector
with the dial and complete the call. A dial
tone then informs the calling party that his
line has been found. The linefinder remains
connected to the line during the entire call,
up his handset.
The Allotter
Only one linefinder is shown in figure 10-8.
from
When other calls are made simultaneously
CALLING
Non: LINEFINDER SHOWN CONNECTED
TO LINE 110 29
ALL OTHER LINE CIRCUITS
WIRED To LINETINDER RANKS
IN PROPER NUMEITICAL POSITION
STATION
LINE CCT
"V ORM LEAD MT I
23
MS
T
S
0
ro
x
O
0 O
TENS
POSID0
oNEFINO(9
STINT
0
/
LEvELSS,HS
O
O
O
020
OO
OO
OO
OO
OO
O
O
X
0
-\
j3-----90°0
0 0
CC
0 0CI 0
XX
--,
,3
00
00
00
0O
0
0
0
0
LEVELS-T,4
o 0
0 0
0 0
00
00
00
00
00
00
00
00
S
T
O
114.
o
T
IT
LINEEINOER
CET UNIVERSAL SWITCH)
CONNECTOR
(0 UNIVERSAL
S
SWITCH)
)SEE NOTEI
HS
(SHANE° NONNumERICAL ETPAPTIENTI
(SNARED NUNERKAL EOuIPENTI
140.170
Figure 10-8. Block diagram of linefinder operation.
ar
. ki
ANe
j
283
IC ELECTRICIAN 3 & 2
patios
STA=
00
OATK11
55
L IE CCT
ILINt ACCT
5
CONTROL
CONTROL
CONTROL
14321
(AST)
(UT)
-START
ALLOTTER
LOOMS
TENS
CONTROL
POSITION
0
0
S
7
6
4
1
LENS
2
TAS,05
7.1.3.16
CONNECTOR
I
2
3
4
00
5
6
7
CONNECTOR
0
/112
7,1.1,10
LOT
CONNECTOR
I
4444
140.171
Figure 10-9.-100 line XY system using shared equipment.
284
L.86
Chapter 10DIAL TELEPHONE SYSTEMS, PART II
41=IMEMn
WIPERS
INTERRUPTER
CONTACT
OFF NORMAL
CONTACTS
FRAME
ASSEMBLY
BANK
CONTACTS
BANK
ASSEMBLY
NGFEOCBA
140.172
Figure 10- 10. Rotary stepping switch, selector.
other stations, additional linefinders must be
available. The function of the allotter (fig. 10-9)
is to assign linefinders to any of the line circuits
as required. When any line requests service,
the allotter assigns a linefinder to the call,
then pre-selects the next idle linefinder to be
assigned to the next call. As busy linefinders
become idle, they are made available for allottment to any subsequent calls. When one XY-
switch is connected to a given position in the
wire bank, no other XY-switch in the system
may connect to that position. The S-lead of the
telephone and the S-wire bank are used to
indicate the busy condition. For example, if
station 55 calls station 21, a busy indicator,
The Selector
The selector in the MDM 200/700 system
performs the same basic function as the selector
in the Automatic Electric system. Connected
back to back with a finder, the selector locates
an idle connector in the group of lines (switch-
board) to which a call is being made.
The MDM 200/700 system uses a 20-point,
8-level, rotary switch as a selector (fig. 10-10).
This switch may be stepped by pulses from
the dial or be operated in an automatic hunt
sequence by use of interrupter spring contacts.
The rotary switrh wiper moves after it has
wire bank (under the control of dial pulses from
station 55), a busy mark is applied to that posi-
been released electronically; that is, when the
step magnet is operated the wipers do not go
into the next position until the step magnet
is released. In a typical commercial XY-installation the rotary switch is used with the allotter
circuits. However, in the Marine Dialmaster,
the rotary switch is used in the selector circuits.
If any other station, say station 78, now tries
A typical MDM system having 300 telerhone
stations,' in three groups (switchboards) of 100
called mark, is immediately extenried to position
55 of the S-wire bank from the station 55-line
circuit. After the associated connector XYswitch has been stepped to position 21 of the
tion in the S-wire bank from the connector.
to call station 55 or 21, the associated connector
XY-switch will encounter the busy mark and send
a busy signal to the calling party (station 78).
each, is represented by the block diagram of
figure 10-11. One finder/selector, one allotter,
and one connector represents each switchboard.
285
"97
IC ELECTRICIAN 3 & 2
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Figure 10-11. The rotary switch in the selector, simplified block diapam.
Each selector terminates into a connector circuit.
The selector (using a rotary switch) is the link
between the linefinder and the connector. Although the rotary switch has 20 positions, only
10 are shown.
140.173
A. Each telephone station has audio (tip and
ring) leads which terminate in the wire bank of
a switchboard cabinet.
B. A calling station initiates finder action by
removing the handset from the cradle, causing
shared witching equipment to be placed under
the control of the calling line by way of a con-
SAMPLE CALL
nection in the wire bank.
Figure 10-12 is a simplified block diagram
tracing a sample call from one station to another.
As an aid toward understanding the actions involved in completing this call, keep in mind the
following facts concerning the MDM system:
C. Dialing from the calling station extends
the switching link to a wire bank position which
terminates the audio leads of the called station.
The sample call diagrammed in figure 10-12 is
between station 262 (the calling party) and station
286
238
--v.
TO
HOOK
PARTY
CALLING
262
STATION
OFF
WIREBANK
B
SEIZURE
TR
-4POCZ
A
262
STATION
LINE CIRCUIT 26?
AUDIO
PATH
EXTENDS
FINDER ALLOT TER
XY
s
STEPS X SI IT
SWITCH
LINE
2
SELECTOR SEIZURE
PINDER
START
TORE
LEVEL 4
XX
TR
I
I
-----r
I
I
I
I
I
I
D GIT 4
CALLING
PART*/ DIALS
SELECTOR NO.15
MI
MARK
I
1
I 4 TD LINE ER
RINGOACK
CALLING PARTY
DIALS 7 8 4
IDLE CONN.
STITCHROARD 2
CONNECTOR 13
STEPS TO LINE 474
KY SWITCH
CALLED
PARTY
CABINET 2
WIREBANK
POSITION 74
ogrontiat
1
i
1
TO POSITION I
ROTARY
SWITCH
SIIITCH STEPS
OF SWITCHBOARD 2
SEIZED
CONNECTOR 13
NO.13
CONNECTOR
SWITCHBOARD CABINET 2
Figure 10-12.Sample call audio path and switch control path.
LEVEL MARK
FINDER
RESPONSE
IDLE FINDER
FINDER N0.15
Ntquer'SEQUEN-0TIALLY
IPINDER
e
LINE MARK
IDLE MARK
SELECTOR
NO.15
____.,
FINDER
NO.15
62
LINE C17,2.111T
LEVEL DETECTOR
H
ol
CABINET 1
WIREBANK
POSITION 62
CABINET 1
NITCHBOARD CABINET 1
CABINET 2
RINGINS
474
STATION
i
1
74
LINE CIRCUIT
140.174
7
LEVEL
4
LINE
IC ELECTRICIAN 3 & 3
474 (the called party). Assume that station
474 is not busy at the time of the call and that
the idle connector is connector No. 13 in the
switchboard of the called station.
The T- and Rleads for line 262 terminate in
switchboard cabinet No. 1 and extend to wire
bank position 62 by way of the line circuit
serving level 6, line 2. When the calling party
operates the hook switch, line circuit 262fAtends
two sources of battery (negative signal voltage),
one to the S.-wire bank position for line 62 for
Y-direction hunt stop, and the other to scize the
6-section of the level detector. The level detector responds to level 6 seizure by extending
level mark ground to mark position six of the
XX-wire bank for X-direction hunt stop, and
request ground to the finder allotter.
The finder allotter, which serves to allot idle
finders, routes the request ground to the next
available finder in the allotter sequence. Assume
that finder No. 15 is the next one available.
This finder responds to automatically hunt for
the calling line in the wire bank by stepping
its associated XY-switch in the X-direction
until the XX-wiper encounters the level mark
ground in the XX-wire bank. The X-direction
hunting then stops and Y-direction hunting auto-
matically begins. After two steps, the S-wiper
encounters the line mark battery which halts
the Y-direction hunting. The finder XY-switch
wipers now rest in the wire bank position of the
calling line 262.
As soon as line 262 is found, finder No. 15
seizes its associated selector (No. 15). and dial
tone is returned to the calling station by way
of the wire bank connection. The calling party
now dials the initial digit 4 of the called station
(474) and the rotary switch associated with
selector No. 15 steps to seize the next id...,
connector in switchboard No. 2. The next idle
connector in this case was connector No. 13.
Selector No. 15 extends a seizure ground which
prepares the connector circuitry for the second
and third digits to be dialed. When the calling
party dials digit 7, the wipers of the XY-switch
associated with connector No. 13 step seven times
in the X-direction, following the dial pulse.
When the digit 4 is dialed, the wipers step four
times in the Y-direction. The XY-switch wipers
now rest on the wire bank position corresponding
to called line 474. The connector extends ring
voltage from the selector to the called line.
When the called party answers, the switchthrough is completed. The audio path for the
call is shown In part B of figure 10-12.
288
300
CHAPTER 11
SOUND RECORDING AND REPRODUCING SYSTEMS
Sound recording and reproducing systems are (5) a recording medium, usually a vinyl disk. The
used on board ship and at shore stations to mon- microphone converts the sound waves produced
itor radio and soundpowered telephone cir- by the voice into corresponding electrical signals
cuits for short-memory and permanent-record that are applied to the amplifier. The output of
applications and to record signals for future the amplifier is fed to the recording head, which
analysis for instrumentation applications. They converts the electrical signals into mechanical
are used also to train, entertain, and provide energy causing a lateral movement of the stylus.
religious services for personnel and for office The stylus either engraves or embosses the refunctions, such as dictation, conference, and cording medium as it moves from side to side.
The components necessary to play back a disk
telephone recording.
This chapter describes techniques of recording are: (1) a playback head, (2) a stylus,
recording and reproducing sound, characteristics (3) an audio amplifier, and (4) a biudspeaker.
and operating principles of a typical record When a disk recording is played back, the disk
player, the AN/UNQ-7E sound tape. recorder- is rotated at the same speed as that at which the
reproducer set, and a representative commercial recording is made. The playing stylus, or needle,
tape deck. Also included are general instructions rests in the groove and follows the pattern of the
on how to operate and maintain a tape recorder. sound groove. The playback head into which the
stylus is mounted converts the mechanical movements into corresponding electrical signals,
which are applied to the audio amplifier. The
output of the audio amplifier is fed to a loudThe basic techniques of recording and re- speaker, which converts the electrical signals
producing sound are (1) mechanical, (2) photo- into corresponding audio signals.
SOUND RECORDING AND
REPRODUCING TECHNIQUES
graphic, and (3) magnetic. The recording medium
is a disk, film, tape, or wire; it is usually PHOTOGRAPHIC TECHNIQUE
determined by the recording technique.
In the photographic recording technique, the
Disk, film and wire mediums are becoming
obsolete due to the superiority of tape mediums. sound is recorded by exposing a moving photosensitive film to a beam of light, which is modulated by the sound pattern being recorded. When
MECHANICAL TECHNIQUE
the film is developed, it can be reproduced by
In the mechanical recording technique, the passing the sound track, which contains the light
material is mechanically cut (engraved) or de- and dark areas, through a beam of light focused
formed (embossed) as it is driven past a stylus, on a photoelectric cell. The output of the cell
or cutting needle, to form a spiral groove in is fed to an audio amplifier, and then to a loudthe recording material and thus preserve the speaker, which reproduces the electrical signals
pattern of the sound. The sound pattern can be into sound waves. The methods of recording
engraved on disks and embossed on disks or sound photographically are (1) variable area and
films. Embossed disks are rarely used in the (2) variable density recording.
Navy today, except for some dictation equipVariable Area Recording
ments.
The components necessary to mechanically
In variable area recording, the sound pattern
record sound are (1) a microphone, (2) an audio
amplifle (3) a recording head, (4) a stylus, and is recorded by a small mirror mounted on a
289
301.
IC ELECTRICIAN 3 & 2
GALVANOMETER
LOOP
MIRROR
WINDOW
LIGHT STOP
SPHERICAL LENS
LIGHT SOURCE
.00."
MAGNETIC LINES
OF FORCE CONTROLLED
BY AMPLIFIER
SCALE
FILM
CYLINDRICAL
LENS
SPHERICAL
LENS
APERTURE
DISC
SCREEN
LENS
0
0
0
n
Figure 11-1. Variable area recording.
sensitive galvanometer. The modulated current
produced by the sound vibraLiusus sa the micro-
phone is amplified and fed to a sensitive galvanometer consisting of a fine loop of wire. A
7.50
small mirror is attached to this loop and the
loop is suspendeu in a magnetic field (fig. 11-1).
A beam of light from a high intensity lamp passes
through a condenser lens and is focused on the
290
V U12
Chapter 11SOUND RECORDING AND REPRODUCING SYSTEMS
galvanometer mirror from which it is reflected
through another condenser lens to a slit or aperture. The resulting slit of light passes through a
projector lens onto the film. when current flows
through the galvanometer, tie wire loop is set
in vibration, carrying the mi ror with it to trace
a line of light not to exceed the width of the slit
across the sound track of the film. This type of
sound track has a constant density and a vary-
Tape Recording
In magnetic tape recording, a flat, polyester
coated, plastic tape is used as the recording
medium (fig. 11-3A). The magnetic fields that
comprise the sound pattern are established on the
tape, which is coated with very fine steel particles (fig. 11-3A). The recording head and its air
gap (fig. 11-3B comprise a series magnetic
circuit. The principle involved is the same as
that for wire recording, but tape recording has
ing width along one edge of the film.
the advantage of being easier to handle and less
Variable Density Recording
expensive.
In variable density recording, the sound pattern is recorded by varying the densities of the
A-C Biasing
image, which is produced by light passing through
a special type of light valve, as shown in figure
In most magnetic re cording, an a-c bias
is used on which the audio signal is superimposed and applied to the recording head. This
bias is a relatively high-frequency, a-c signal,
11-2A. The light val ie consists of a Duraluminum
ribbon loop, suspended between the two pole
pieces of a powerful electromagnet. The t- 3
halves of the ribbon loop are connected to a recording amplifier. The loop opens and closes
that is above the audio range, and therefore can-
not be heard during playback. A-c biasing is
used to obtain a substantially linear relationship
between the flux density in the recording medium
in response to the input signals to allow varying
amounts of light to expose the film as shown in
and the magnetizing force. Thus, the induced
signal voltages are related linearly to the re-
figure 11-2 B and C. This type of sound track
has a varying density and a constant width along
one edge of the film.
cording fields.
The magnetization curve (heavy line) of the
iron oxide used as the recording medium is
MAGNETIC TECHNIQUE
similar to that shown in figure 11-3C. At points
near the origin the curve is nonlinear, and without some corrective factor, the signal recorded
on the tape would not be directly proportional
to the signal applied to the recording head. This
condition would cause distortion when the tape
In the magnetic recording technique, a permanent magnetic material is magnetized in
accordance with the pattern of the sound, as the
recording medium is driven past a recording
head. Similar to mechanical recording, the sound
waves are picked up by a microphone, converted
was played back.
The distortion is greatly reduced by mixing
a high-frequency, constant-amplitude signal with
the audio signal. The a-c bias is placed in series
with the audio signal. This connection causes the
average bias to be shifted in a positive direction
to corresponding electrical signals, and amplified. Unlike mechanical recording, the amplified electrical signals are applied to the recording head, which orients the magnetic particles
in the tape or wire.
on the positive alternations of the audio signal
and in a negative direction on the negative alternations of audio signal. If the audio signal
being recorded is of sine waveform, the flux
pattern will be of sine waveform. The waveform
is developed from the vertical to horizontal
projections obtained from the magnetization
The recording head consists of coils wound
on an iron core similar to an electromagnet.
During one-half cycle, the signal current flows
through the coils in one direction. The iron core
becomes magnetized, and establishes a north
and a south pole at the ends of the U-shaped elec-
(transfer) curve shown in figure 11-3C.
tromagnet. A magnet field exists in the air gap
between the poles. When the direction of the cur-
While the tape is in the recording gap the
a-c bias causes the magnetization of the iron
oxide to follow the dashed line loops (minor
hysteresis loops). As the tape leaves the gap
rent through the coils is reversed, the direction
of the lines of force across the air gap is re-
versed. If a magnetic wire is placed across the
gap of the magnet, most of the lines of force
would be confined within the wire, and it would
the influence of the mmf is reduced to zero and
the degree of magnetization existing at that time
become magnetized.
291
303
IC ELECTRICIAN 3 & 2
VARIABLE DENSITY RECORDING LIGHT VALVE
r m,
CONDENSER
LIGHT
LENS
SOURCE
OBJECTIVE
LENS
11111=:4111
Ul
FILM
DURALUMINUM
RIBBON
.001"
Al=.1
w
ELECTRO-MAGNET
CONTROLLED BY
RECORDING AMPLIFIER
A. LIGHT AND OPTICAL SYSTEM FOR SOUND
FILM RECORDINGS
RIBBON
LIGHT
SEPARATION
.002 INCHES
CLOSED
POSITION OF THE TWO
SIDES OF THE DURALUMINUM
RIBBON WHEN SLIT IS
CLOSED AND NO LIGHT
GETS THROUGH
OPEN
e POSITION OF THE RIBBON WHEN
THE SLIT IS OPEN AND
MAXIMUM LIGHT GETS THROUGH
Figure 11-2. Variable density recording.
292
304
7.51
Chapter 11 SOUND RECORDING AND REPRODUCING SYSTEMS
tape is then moved past a reproduce head that
is like the record head, the flux on the tape will
induce a voltage in the coil of the reproduce
-,APE DIRECTION
TAPE
head. This voltage comprises the audio signal.
Notice that the a-c bias keeps the remnant
N
5
4 ::
flux sufficiently removed from the origin (zero
:,-..; FLUX
:111=.2): ',,,--:00imiwfrz=1:
N
5
N
S
N
s
magnetization with zero magnetizing force) to
prevent distortion of the audio signal. The flux
pattern established by the a-c bias 100,000 Hz
is of sufficiently high frequency not to be heard.
SIGNAL
Erasing
E
A
The recording sound track on a magnetic
recording medium can be erased (by a special
erase head) and the medium used again for further recording. The erase head is located so that
the wire or tape must pass through it before
reaching the recording head. A high-frequency
TAPE MAGNETIZATION
a-c signal is fed to the erase head and thus
cancels the magnetic fields from a previous
recording by completely disorienting the magnetic particles in the wire or tape.
RECORD PLAYERS
The main elements of a record player are
the cartridge, turntable, and tone arm. An ampli-
B
fier and speaker may also be included, but in
most instances will be separate. The turntable
RECORDING HEAD
a
may come equipped with a record changer which
MAGNETIZATION
will permit the loading of as many as a dozen
records at one time. Every Navy record player
SATURATION
LEVEL
MINOR
HYSTERESIS
LOOP
does not have a record changer, which is usually
a feature of civilian equipment acquired through
open purchase. Today's record players offer
a choice of four speeds: 16 2/3, 33 1/3, 45,
and 78 rpm.
H
(MAGNETIZING FORCE)'
MAGNETIZATION
1-1
WAVEFORM
1
I
1
1
1
ON TAPE
CARTRIDGES
144AVERAGE
CURVE
1
1
I
COMPOSITE SIGNAL
AT RECORD HEAD
SIGNAL
AC BIAS
C- A-C BIASING
7.53
Figure 11-3. Tape recording.
The phonograph cartridge, or pickup, is used
to convert variations in the grooves of a phonograph record into corresponding electrical signals. Phonograph cartridges can be divided into
two types: (1) ceramic or crystal cartridges and
(2) magnetic cartridges. Each type of cartridge
is either monophonic for monaural records or
stereophonic for stereo records.
The crystal cartridge was used extensively
on early record players but is rarely found in
modern record players. The ceramic cartridge,
maining when the magnetizing force is removed.
having replaced the crystal, is the most common
of those used in Navy record players. However,
on the tape is proportional in magnitude and
direction to the signal being recorded. If the
have magnetic cartridges which are capable of
better reproduction than the ceramic cartridges.
depends on the remnant magnetism or that reAfter the recording process, the flux pattern
those purchased on the open market usually
293
3Q5
IC ELECTRICIAN 3 & 2
MOVABLE STYLUS
PRESSURE WEIGHT
THUMBSCREW
MOUNTING
BOARD
CARTRIDGE
ADJUSTABLE
BALANCE WEIGHT
Figure 11-5. Tone arm.
140.134
the way of the record as it drops into place,
then moves to the start position over the record,
and drops slowly until the pickup touches the
record. In the single-record player, the tone
arm is lifted by hand to the start position over
the record and then lowered into place. Care
must be taken so as not to damage either the
cartridge or the record.
140.133
Figure 11-4. Turntable drive system.
TURNTABLES
The tone arm used in a high fidelity or
The turntable of a record player is simply
a rotating platform, on which one or more records are placed for playback. This platform is
stereo system has -several balances or adjustments which are critical to the sound reproduction of the system. These adjustments Loncern
the lateral and vertical movements of the tone
arm and also static and dynamic balancing of
the arm. Do not try any of these adjustments
unless you have a complete list of the manufacturer's specifications for your system. Figure
driven by a motor or some form of drive system.
There are two types of turntables: the single
record player that requires manual record changing and the automatic record changer.
Most turntables are driven by a constant
speed motor through a drive system consisting
of a drive wheel and an idler wheel. The drive
wheel is either uniform or stepped. The stepped
drive wheel (fig. 11-4) is used in multispeed
turntables with each step corresponding to a
different speed. The idler wheel is used to reduce rumble or uneven motion of the turntable.
When the largest step of the drive wheel is
in contact with the idler wheel, the turntable
will turn at its maximum speed; when the smallest step is in contact with the idler wheel, the
turntable will turn at its lowest speed. In this
11-5 shows a typical tone arra that has
movable weights for balancing the arm.
two
SOUND RECORDER-REPRODUCER
SET AN/UNQ-7E
The AN/UNQ-7E is designed as a dual tape
transport to record and reproduce audio frequencies on standard 1/4-inch magnetic record-
ing tape. It consists of two major assemblies:
the equipment cabinet which houses two recorder-
reproducers (tape transports No. 1 and 2) and
way, a 4-step wheel can drive the turntable
at its different speeds: 16 2/3, 33 1/3, 45, and
the remote control unit (RCU). See figures 11-6
and 11-7. The numbers, 1 and 2, associated with
the tape transports refer to the upper and lower
transports, respectively.
78 rpm. Various n-lthods of shifting from one
speed to another exist, but most manufacturers
use a spring-loaded cam or similar device.
Electrical signals falling within the normal
audio frequency spectrum can be recorded at
TONE ARMS
The tone arm of a record player is used to
hold the cartridge and carry it into position
over the record. When used with an automatic
record changer, the tone arm is moved out of
tape speeds of 3.75, 7.5, or 15 inches per second
(ips). Only one tape transport at a time can
record. Information that was previously recorded
on one transport can be played back at the same
time other information is being recorded on
294
r 306
Chapter 11 SOUND RECORDING AND REPRODUCING SYSTEMS
7.40(140B)
Figure 11-7. Remote control unit.
and B record preamplifier, a channel A and B
reproduce amplifier, a bias and erase oscillator,
7.54(140B)A and an a-c power supply. With the exception of
parts of the power supply and the power ampliFigure 11-6. Recorder-reproducer.
fiers, these assemblies are self-contained modular components which plug into rack-mounted
receptacles within the cabinet.
the second transport. TI-e).re are two channels
The record preamplifier in' orporates a manone for voice recordin ; Achannel A) and the
ually
operated automatic gain control (AGC)
data
information
(channel
B).
Figure
other c .
11-8 is a functional block diagram of this re- defeat switch for disabling the channel B AGC
circuit during certain recording applications.
corder-reproducer.
All functions of the recorder-reproducer set,
first
contacted
by
the
erase
The tape is
head which removes any previously recorded with the exception of the channel B bias defeat
signal. It is then contacted by the record head and AGC defeat, can be controlled from the front
which magnetizes the tape in proportion to the of the equipment cabinet. A two-position toggle
audio signal. When operating in the reproduce switch is used to turn the power off and on. All
mode the tape contacts a reproduce head which other function control switches on the front of
senses the fluctuations in magnetic field strength the cabinet are three-position, center off, moand converts them into electrical signals. These mentary contact toggle switches. One tape trans-
port can record while the other reproduces
signals are then amplified by the reproduce
pre-recorded data, and one can record or reproduce while the other is in either the fast forward
amplifier. The control section selects the transport, controls movement of the tape, and selects
the amplifier section. The remote control unit
on rewind mode of operation. The controls
also facilitate any combination of simultaneous
functions are limited to record and stop. The
power supplies provide the proper level and
fast forward and rewind operation of the two
tape transports. A three-position, rotary speed
amount of regulation required by each group of
circuits.
selection switch, a momentary, push-action stop
button, and a fast-forward-rewind toggle switch
are located just below the supply reel on each
EQUIPMENT CABINET
transport. Also located on the front of the cabinet
are the channel A and B record level VU meters
and record level controls, channel A and B out-
The electrical equipment cabinet (fig. 11-9)
contains the two tape transports (fig. 11-10) and
the following electronic assemblies: a channel A
put jacks and output level controls, reccrd and
295
307
IC ELECTRICIAN 3 & 2
.1101.11.111,
SIGNAL
INPUT
SIGNAL
OUTPUT
RECORD
AMPS
REPRODUCE
AMPS
BIAS & ERASE
CONTROL
SUPPLY
ERASE
RECORD
REPRO
TAKE Al P
REEL
HEAD
HEAD
HEAD
REEL
i
SUPPLY
REEL
ERASE '
HEAD
RECORD
REMHO
TAKEUP
HEAD
HEAD
REEL
POWER
SUPPLIES
117 VAC
60
INPUT
140.135
Figure 11-8.Recorder-reproducer overall functional block diagram.
296
V 308
Chapter 11SOUND RECORDING AND REPRODUCING SYSTEMS
7.54(1408)B
Figure 11-9.
Operating controls, recorder-reproducer.
A9079
IC ELECTRICIAN 3 & 2
Figure 11-10.
Recorder-reproducer, magnetic (tape transports).
reproduce indicator lights for tape transports
1 and 2, and a power on indicator light. All
indicator lights have mechanical dimmer mechanisms.
The meter is used to monitor the record
TAPE TRANSPORTS
The remote control unit (fig. 11-7) permits
operation of the record function of either tape
transport at locations away from the equipment
Two identical tape transports, one of which
is shown in figure 11-10, are mounted on slides,
one above the other in the electrical equipment
cabinet. This unit contains the following controls
and indicators: one three-position, center off,
transport selector switch; one two-position,
cabinet, and are used to transport magnetic
standby lamps; a meter; and a two-position
channel selector switch
The standby lamps illuminate continuously
when the tape ie threaded and transports are in
the stop position. The lamps also act as end-of
tape indicators by flashing when a transport
is within five minutes of end of tape. The five
minute warning is based on a tape speed of
7.5 ips. The time to end of tape will vary
proportionately for the _other tape speeds of
3.75 and 15 ips. When lit, the standby lamps
do not indicate that proper tape speed is selected
or that record levels have been adjusted.
level of channel A or B, depending on the position
of the channel selector switch.
REMOTE CONTROL UNIT
record-standby switch; two record lamps; two
7.54(140B)C
recording tape past the head assemblies which
are mounted on the font of each transport between the supply and take-up reels. Operating
speeds are 3.75, 7.5, and 15 ips for record and
reproduce. For fast forward and rewind the
speed is 300 ips averaged over 1200 feet of
tape. Each tape transport has a control assembly
made up of electronic parts, relays, etc., that
control the operation of the individual tape
transports. A bias defeat switch, located on the
chassis of the control assembly, permits removal
of the bias from channel i3. A three-digit counter
with reset knob is located on the front of each
tape transport and provides an indication of
tape usage.
298
310
Chapter 11 SOUND RECORDING AND REPRODUCING SYSTEMS
supply reel (on the rewind turntable) to the takeup reel (on the takeup turntable), overcoming the
Tape Drive Components
The tape drive components include a synchronous drive motor, a capstan and capstan idler,
a reel idler, and a tape guide. The drive motor
is a hysteresis synchronous motor with three
windings to provide the three tape speeds. The
motor shaft is attached to a flywheel pulley
which drives the capstan by means of a nylon
belt. The drive motor will start and the capstan
will rotate as soon as power is applied.
The drive belt tension is maintained by a springloaded pivot arm on which is mounted the CAP
STAND IDLER. The capstan idler consists of
a rubber-tired idler wheel mounted on an arm
which is attached to the shaft of a rotary solenoid.
When the capstan idler solenoid is energized, it
moves the idler arm against the capstan, provid-
ing a bearing surface for the capstan, which
drives the magnetic tape at a constant speed.
A TAPE GUIDE positions the tape vertically
with respect to the head assembly. A REEL
IDLER smooths out any transient variations in
tape speed originating in the tape supply reel.
Rewind and Takeup Components
The rewind and takeup components are identical in construction. Each consists of an induction motor, brake drum, and turntable.
The rewind motor and takeup motor are
so connected that when power is applied, one
motor operates at cull torque and the other at
reduced torque. In the record or reproduce
mode, a series resistor is placed in each rewind
and takeup motor circuit to reduce the normal
torque of the motors while optimum tape tension
is obtained at each reel.
The reels of tape are isolated from each other
by the capstan and capstan idler. The capstan
pulls the tape from the supply reel, overcoming
the difference in torque of the rewind motor,
which provides hold -pack tension. A tape loop
reduced torque of the rewind motor. The tape
tension is proportional to the difference in the
forces exerted at the periphery of the two reels.
In the REWIND MODE of operation, the fore-
going procedure is reversed. The resistor is re-
moved from the rewind motor circuit, and a
resistor is placed in the takeup motor circuit.
The rewind motor will operate at full torque, the
takeup motor at reduced torque, and the tape will
be pulled from the takeup reel to the supply reel
being held under tension by the reduced torque of
the takeup motor.
When the equipment is being operated in any
mode of tape travel, the correct tape tension is
determined by the power applied to the rewind and
takeup motors. However, when power is removed
from these motors the forces exerted on the tape
are removed, and the tape tension must be maintained by the operation of the brakes.
The brakes consist of brake drums attached
to the shafts of the takeup and rewind motors and
brake bands equipped with high-tension and lowtension springs, which determine the brakii.g
force applied for each direction of rotation. The
biake bands are held from contact with the brake
drums by the brake solenoid when the equipment
is operated under any mode. When power is removed front the equipment the solenoid is deenergized and allows the brake bands to move into
contact with the brake drums. To avoid throwing
tape loops as the tape comes to a stop, it is nec-
essary that the braking force on the trailing
turntable (turntable from which tape is being
pulled) always be greater than that which is
applied to the leading turntable (turntable which
is taking up the tape). However, the braking differential must not be so great that the tape is in
danger of being deformed or broken.
Head Assembly
The head assembly consists of erase, record,
and reproduce heads. In the record or reproduce
modes of operation, a point on the tape will pass
over the erase, record, and reproduce heads in
will be thrown when any malfunction of the equip-
ment allows the feed rate to exceed the takeup
rate. If the loop is sufficiently large, or if tape
breakage occurs, the safety switch arm will be
released tc, actuate the safety switch, and stop
the equipment.
In the FAST FORWARD MODE of operation,
that order. The outer tracks of the record and
reproduce heads are for channel A, and the
inner tracks are for channel B. The erase head
is full track, and thus erases the full width of
the tape on both channels.
the series resistor is removed from the takeup
motor circuit, and a resistor is placed in the rewind motor circuit. The takeup and rewind
motors operate at full and reduced torques, re-
OPERATION
As an IC Electrician you will normally operate
the AN/UNQ-7E set only when necessarj to
spectively, and the capstan pulls the tape from the
299
311
ANIMMEIle.
IC ELECTRICIAN 3 & 2
_.1
Figure 11-11. Tape threading path.
troubleshoot it. All functions of the set can be
operated at the front of the equipment cabinet.
Only the record and stop functions can be operated
at the RCU. Operating the set is similar to
operating a basic tape recorder. You should
be able to do so by carrying out the instructions
that follow.
7.54(140B)
1 or 2, depending on the tape transport selected.
Make sure that the tape beginc, to move forward
at the correct speed, and that the red record lamp
for this tape transport comes on. To stop the
tape transport, simply press its stopbutton. Ob-
serve that the tape stops moving and the red
record lamp goes out.
Pre-operation Procedure
Reproducing
Before operating the equipment, take the following steps. Rotate all dimmer mechanisms on
indicator lights counterclockwise to their full
open positions. Turn the power switch (on central
control panel) to ON. Observe that the white
power lamp is lit. Place a full reel of tape on
After taking the last pre-operation step, you
can reproduce by turning the reproduce switch
to position 1 or 2, depending on the tape transport
selected. Make sure that the tape moves forward
at the correct speed and that the green reproduce
up turntable. Next, thread the tape from the
lamp comes on. As in recording, you stop the
tape transport by pressing its stopbutton. Notice
that the tape stops and the green reproduce
supply reel through the tape head and onto the
take-up reel as shown in figure 11-11. Then set
light goes out.
the tape counter to the 000 position, and the speed
Recording from Remote Control Unit
speed. Finally, adjust the input level. The channel
In operating a tape transport from the RCU,
be sure that both standby amber lamps are lit
the supply turntable of the selected tape transport,
No. 1 or No. 2, and an empty reel on the take-
selector on the tape transport to the desired
A and channel B record levels, as monitored
by the meters, are set by the record level
controls on the recorder reproducer control
panel. It is not necessary to be in the record
mode of operation to obtain record level indications.
(an indication that power is applied and that the
tape is threaded properly). To record from the
RCU, move the TRANSPORT selector switch to
position 1 or 2, depending on the transport
selected. Then position the RECORD-STANDBY
switch to record. Check to see that the standby
lamp for the selected tape transport goes out
and that the red record lamp comes on. To stop
recording from the RCU, return the RECORD-
Recording
After taking the last pre-operation step, you
record by turning both record switches to posit;on
STANDBY switch to the standby position, and the
300
312
Chapter 11SOUND RECORDING AND REPRODUCING SYSTEMS
TRANSPORT switch to its OFF position. Observe that the standby lamp comes on and the
record lamp goes out.
MAKE
SUS tOLVT
Rewinding
If
the tape is threaded on the recorder-
LT
reproducer and is not in motion, you can move
it rapidly in either the forward (fast forward)
A
Tun osTAOLC
or reverse (rewind) direction by placing the
Daivt
tiCTOn
rewind-fast forward switch S1 in the appropriate
11CLT
position. You can stop the moving tape by re-
MAKE
turning this switch to its OFF position. The
OLEN
TAO(
11..11.HCAO
tape-motion components will be automatically
deactivated at the end of a reel.
GUIDE
MCC NCAO
(RASE
*VIVI
HEAD
NOLL(11
7
111.
COMMERCIAL TAPE
RECORDER/REPRODUCERS
CAPSTAN
USSUR1
1110i
This section is concerned only with the
operating principles of a typical single-motor
tape transport as used in commercial tape
140.136
Figure 11-12.
recorder-reproducers (tape decks).
MODES OF OPERATION
Tape transport mechanism in
stop position.
at a rate slightly faster than necessary to take
up the tape. The turntable will, however, turn
at a constant rate even as the circle of tape on
the takeup reel increases in diameter because
the drive belt is designed to slip on the takeup
reel spindle. The takeup reel and the pinch
The operating modes for a tape deck are STOP,
RECORD/PLAYBACK, and REWIND/FAST FORWARD. A pushbutton or switch is operated to se-
lect the desired mode. Depending on the mode
selected, the tape transport mechanism enables
the tape to move, or' keeps it from moving, from
the supply turntable (reel) to the takeup turntable.
Stop Mode
The mechanism shown in figure 11-12 is in
the STOP mode. Notice that the brakes are engaged and the drive idler is disengaged from
the capstan flywheel. The motor is running,
and the idler drive and idler wheels rotate in
the directions indicated by the arrows.
Record/Playback Mode
When the mode selector switch is moved to
the record or playback setting, the brakes re-
lease and a cam engages the drive train between
the drive motor and the capstan flywheel. The
pressure pads move the tape into contact with
the heads, and the rubber pinch roller moves
to hold the tape firmly between it and the rotating
140.137
capstan. The tape is now driven as shown in
figure 11-13. The belt connecting the drive motor
idler to the takeup turntable drives the turntable
Figure 11-13. Tape transport mechanism in
record or playback position.
301
313
IC ELECTRICIAN 3 & 2
CLEANING
The largest single reason for tape deck
operators complaining about poor quality of
reproduction is dirty tape heads. As the tape
deck is used, an oxide from the tape surface
rubs off and builds up on the face of the heads.
The deposit prevents the tape from making good
contact with the tape head, causing a reduced
output and sometimes magnetically short circuiting the gap between the heads. Clean the heads
with the tip of a cotton swab dipped in alcohol
or in a rommercial tape head cleaner.
Binding or worn drive wheels and pulley
belts of the tape transport result in almost as
many trouble calls as the heads. A dirty or worn
belt can cause the output to flutter or the tape
past the heads at a constant speed.
speed to vary. Remove all traces of oil or dirt
from belts and rubber-tired drive wheels with
alcohol. You should take the pulleys and drive
wheels off their shafts and clean them at regular
intervals. After reassembly, apply a light coat
of machine oil to all bearing surfaces. When a
machine is being repaired in the shop, have it
cleaned and vacuumed. If cleaning the belts or
wheels does not correct the fault, then replace
Rewind/Fast Forward Mode
MECHANICAL ADJUSTMENTS
With the wide selector switch in REWIND
or FAST FORWARD, the tape transport mechanism is positioned as shown by figure 11-14.
The brakes disengage, the pressure pads move
away from the heads, and the pinch roller moves
The alignment of the tape heads is important
for proper operation cf the recorder/reproducer.
Usually the tape heads must be aligned in azimuth
and height only while playing a test tape. Test
140.138
Figure 11-14. Tape transport mechanism in
rewind or fast forward position.
roller capstan drive combine to move the tape
the parts with new ones.
tapes are available through electronic supply
stores, and contain complete directions or their
away from the capstan. Also, the drive train
disengages from the capstan flywheel. Now the
use.
tape can pass freely from reel to reel. In the
FAST FORWARD mode, the high speed idler
drive wheel is shifted into contact with the takeup
Most tape recorders use springs to maintain
tension on the pinch roller and the brake shoe.
Usually you can adjust the tension by turning
a nut (fig. 11-15A) or attaching the spring to
turntable so that the tape will move quickly onto
the takeup reel. In the REWIND mode, the idler
drive wheel is shifte'd in tlx opposite direction
and pushes the sub idler so as to drive the supply
wheel at high speeds, thereby rewinding the tape
a different hole (fig. 11-15B). If there is no
way to adjust the spring tension, replace the
spring with a new one. Adjusting the tension
on the pinch roller spring requires the use of
onto the supply turntable.
a spring scale, such as the one shown in figure
11-16A. Spring scales are available from commercial electronics supply stores. In using a
spring scale, follow the instructions furnished
by the manufacturer of the tape deck. A handy
tool for hooking the springs from hole to hole
TAPE RECORDER MAINTENANCE
Tape recorder maintenance includes cleaning,
adjusting, demagnetizing tape heads, tape erasing,
and tape splicing. Just as in other well-designed
electromechanical devices, most troubles in tape
recorder/reproducers are usually cleared up by
routine cleaning or minor mechanical adjustment.
can be made from a firm piece of wire. See
figure 11-16B. This tool reduces the chance of
the spring flying off when you are unhooking it.
302
314
Chapter 11 SOUND RECORDING AND REPRODUCING SYSTEMS
the model, they are normally hand held and about
the size of a pen light: It is best to demagnetize
the heads after they are cleLled. First remove
all head covers and shields, then plug the demagnetizer into a 115-volt a-c power source.
Bring the tips. of the demagnetizer close to the
head, straddling the head gap with the tips of
the demagnetizer. Never allow the tips of the
demagnetizer to touch the surface of the tape
A
a.ror
SD4
head. Slowly move the demagnetizer up and down,
°F.%S.C%1::uST,NS NUT
three or four times, along the entire length of the
head and at the same time pull the demagnetizer
away from the head in a slow, steady motion,
allowing the influence of the alternating current
to gradually die away. Repeat this process with
the capstan and the tape guides. Then remove
LE YEA
P AV*
POI.LER
the demagnetizer and disconnect its power source.
ERASING MAGNETIC TAPE
0 CAPSTAN
I
AO.RAT.P.:..OLCS
N
140.139
Figure 11-15A. Spring tension adjusted by a
lock nut. B. Spring tension using holes to
adjust tension.
Magnetic tape recording is economical because the tape can be erased and reused over
and over again with little or no loss in the
quality of recording. Erasing is done by means
of a bulk eraser or the erase head of the tape
recorder/reproducer.
Bulk erasing will completely and quickly
DEMAGNETIZING TAPE HEADS
erase an entire reel of tape, usually in less
than a minute. In erasing, you place the reel
In normal use, the tape heads become magnetized and lose their fidelity or ability to reproduce sound accurately. A demagnetizer safely
removes the magnetism from the heads to restore
the loss in fidelity. Though the shapes of demagnetizers may differ slightly according to
reverts to a neutral condition with all previously
recorded information removed. Since each bulk
of tape on a bulk eraser, then subject the tape
to a strong alternating magnetic field. Start
with a maximum amount and slowly taper off
to zero. This magnetic field leaves the tape in
a demagnetized or "degaussed" state. The tape
eraser differs slightly in operation, be sure to
follow the manufacturer's instructions.
When using the erase head of the recorder/
reproducer, thread the tape in the normal manner,
then turn the record level to the lowest position.
Make sure that all microphones are unplugged.
Select the fastest tape speed and turn the mode
selector switch to the record position.
SPRYa
SPLICING MAGNETIC TAPE
You can repair breaks in magnetic tape by
cutting the broken ends and splicing the cut
ends together.
Also, you can cut out a piece of tape or add
another piece to the existing tape. To make a
strong and otherwise superior splice or joint,
JAPPROX.
3/16 to 1/4 INCH
B
A
140.140
be sure to use only the kind of tape that is
Figure 11-16. Spring scale and spring removal
designed for splicing magnetic tape and a machine,
such as the one shown in figure 11-12.
tool.
303
31 5
IC ELECTRICIAN 3 & 2
OVERLAP TAPE ENDS
MAKE DIAGONAL CUT
SECURE WITH SPLICING
TAPE ON THE SHINY
SIDE
B
TRIM TAPE
Figure 11-18.
140.91(140B)B
Magnetic tape splicing.
Pull splicing tape forward and apply to
cut tape (fig. 11-17B).
Position control knob forward to TRIM
position and press down (fig. 11-17C).
Lift operating lever and fingers. Remove
140.91(140B)A
Figure 11-17. Magnetic tape splicing.
spliced tape.
Remove any excess tape that adheres to
cutter.
Splicing is a relatively simple technique.
For best results, follow the procedure below
You may also splice tape by hand, using a
step by step.
sharp pair of scissors or a knife. First hold
the cut or broken ends of the magnetic tape so
they overlap as shown in figure 11-18A. With the
Insert the overlap cut or broken ends of
magnetic tape in tape guides (1). Lower
magnetic tape properly aligned, cut diagonally
through both pieces of tape. Clear away the loose
ends and place the tape on a clean and dry surface,
the tape holding fingers (2).
With operating lever (3) up, slide position
making sure the shiny side is up. Next, place a
control knob (4) to CUT position. Press
operating lever down with just enough
pressure to cut tape. Lift lever and blow
piece of splicing tape across the cut (fig.11-18B).
After the splicing tape adheres to the magnetic
excess tape away (fig. 11-17A).
figure 11-18C.
tape, trim the excess splicing tape as shown in
304
I
316
CHAPTER 1.2
GYROCOMPASSES, PART I
The ship's gyrocompass system is an important responsibility of the Interior Communi-
free to rotate on its bearings about the hori-
(gunfire support, for example). Other missions,
such as ASW and underway replenishment, could
be carried out only with difficulty and increased
V-V', giving the third degree of freedom.
zontal axis, H-H', giving the second degree of
cations Group. In case this system fails, the
ship could not perform some missions at all
freedom. The outer gimbal ring is free to
rotate on its bearings about the vertical axis,
GYROSCOPIC PROPERTIES
risk.
This chapter describes the principles and
applications of basic north-seeking and northindicating gyroscopes, including how they are
designed for use as shipboard gyrocompasses.
When the gyroscope rotor is spinning it
develops two characteristics, or properties, that
THE FREE GYROSCOPE
The gyroscope is a heavy wheel, or rotor,
suspended so that its axle is free to turn in any
direction. As you can see in figure 12-1, the
rotor axle is supported by two bearings in a
ring. This ring is supported by means of studs
and bearings in a slightly larger outer ring.
The two rings are called gimbals. The outer
gimbal is mounted in a supporting frame by
two bearings.
The rotor and the two gimbals are pivoted
.Ind balanced about their axes. The axes are
perpendicular to each other, and intersect at
the center of gravity of the rotor. The bearings
of the rotor and gimbals are virtually frictionless,
and have almost no effect on the operation of the
gyro.
THREE DEGREES OF FREEDOM
The gimbal mounting permits the rotor lo
turn in three planes, giving it three so-called
degrees of freedom: (1) freedom to spin, (2)
freedom to turn, and (3) freedom to tilt. The
three degrees of freedom permit the rotor to
assume any position within the supporting frame
12-1). The rotor is free to spin about its
own axle, spinning axis S-S', giving the first
degree of freedom. The inner gimbal ring is
(fig.
77.194
Figure 12-1. The gyroscope.
305
35 _7
IC ELECTRICIAN 3 & 2
it does not have when at rest. These properties
make it possible to convert the gyroscope into
a gyrocompass. They are rigidity of plane and
precession.
Rigidity of Plane
When the rotor of a gyroscope is set spinning with its axle pointed in one direction (fig.
12-2A) the rotor continues to spin with its axle
pointing in the same direction, no matter how
the frame of the gyroscope is tilted or turned
(fig. 12-2B). As long as the bearings are frictionless and the rotor spins, no turning of the supporting frame can change the plane of the rotor
with respect to space. This property of the gyro-
scope is called rigidity of plane. Other names
for the same property are gyroscopic inertia
and stability.
Newton's 'first law of motion states that a
body in motion continues to move in a straight
line at a constant- speed unless acted on by an
outside force. Any point in a spinning wheel
tries to move in a straight line, but being a
part of the' wheel, must travel in an orbit a-
round the axle. Although each part of the wheel
is forced to travel in a circle, it still resists
any other change. Any attempt to change the
alignment or angle of the wheel is resisted by
both the mass of the wheel and the velocity
of that mass. The combination of mass and
velocity is the kinetic energy of the wheel, and
this kinetic energy is applied to give the rotor
rigidity of plane.
A gyroscope can be made more rigid by
making the rotor heavier, causing the rotor
to spin faster, and concentrating most of the
rotor weight near the circumference. If two
rotors with cross sections like those shown in
figure 12-3 are of equal weight and rotate at the
same speed, the rotor in figure 12-3B is more
rigid than the rotor in figure 12-3A. This condition exists because the weight of the rotor in
figure 12-3B is concentrated near the circumference. Both gyroscope and gyrocompass rotors
are shaped like the rotors shown in figure 12-3B.
(A)
Figure 12-2. Rigidity of plane of spinning
gyroscope.
77.196
27.128(27B)
Figure 12-3. Weight distribution in rotors.
306
318
Chapter 12GYROCOMPASSES, PART I
Precession
Precession describes how a gyro reacts to
any force that attempts to tilt or turn it. Though
vector diagrams can help explain why precession
occurs, it is more important to know how precession affects gyro performance.
The rotor of a gyro has one plane of rotation
as long as its axle is aligned with, or pointed at,
one point in space. When the axle tilts, turns,
or wobbles, then the plane of rotation of the rotor
changes. Plane of rotation means the direction
that the axle is aligned or pointed.
Torque is a force that tends to produce
rotation. Force acts in a straight line, at or
on a point. Torque occurs within a plane and
about an axle or axis of rotation. For a given
amount of force, the torque is greater as it is
applied to a point farther from the axis. If the
force acts directly on a point on the axis, no
torque is produced.
Because of precession a gyro will react to
the application of torque by moving at right
angles to the direction of the torque. If the
torque is applied downward against the end of
the axle of a gyro which is horizontal, the gyro
will swing to the right or left in response.
The direction in which it will swing depends
on the direction the rotor is turning.
A simple way to predict the direction of
precession is illustrated in figure 12-4. The
force that tends to change the plane of rotation
of the rotor is applied to point A at the top of
the wheel. This point does not move in the
direction of the applied force, but a point displaced 90° in the direction of rotation moves
in the direction of the applied force. This is the
direction of precession.
Any force that tends to change the plane of
rotation causes a gyroscope to precess. Pre-
cession continues as long as there is a component of force acting to change the plane of rotation and precession ceases immediately when
the force is removed. If the plane through which
the force is acting remains unchanged, the gyroscope precesses until the plane of the rotor is
in the plane of the force. When the position is
reached, the force is about the spinning axis and
can cause no further precession.
If the plane in which the force acts moves
at
the same rate and the same direction as
the precession which it causes, the precession
will be continuous. This is illustrated by figure
12-5 in which the force attempting to change
the plane of rotation is provided by a weight W
suspended from the end of the horizontal axle.
Although the weight is exerting a downward force,
it must be remembered that the force it pro-
duces against the particles in the spinning wheel
is .horizontal. This force is imparted to the
particles in the wheel as exemplified by arrows
F and F'. If the wheel rotates clockwise as seen
from the weighted end, precession will occur
in the direction of arrow P. As the gyroscope
precesses it carries the weight around with it
so that forces F and F' continuously act at right
angles to the plane of rotation and precession
continues indefinitely.
FORCE OF TRANSLATION
Any force operating through the center of
gravity of the gyroscope does not change the
angle of the plane of rotation but moves the gyro-
scope as a unit without changing its position in
space. Such a force operating through the center
of gravity is known as a force of translation.
Thus, the spinning gyroscope may be moved
freely in space by means of its supportingframe,
without disturbing the plane of rotation of the
rotor. This condition exists because the force
that is applied through the supporting frame acts
through the center of gravity of the rotor and
is a force of translation. It produces no torque
on the gyro rotor.
EFFECT OF EARTH'S ROTATION
As just explained, a free-spinning gyroscope
can be moved in any direction without altering
27.131
Figure 12-4.
Direction of precession.
307
319
IC ELECTRICIAN 3 & 2
Figure 12-6.
12.144(77A)A
Free gyroscope at the Equator
viewed from space.
to the earth's surface. At 0600, 6 hours after
the gyroscope was started, the earth has rotated
90° and the axle of the gyroscope is aligned
with the original starting position. At 1200 the
earth has rotated 180° while the gyroscope
retains its original position. The figure shows
how the gyro completes a full cycle in a 24hour period.
APPARENT ROTATION OF
THE GYROSCOPE
Figure 12 -5. Continuous precession.
An observer on the earth's surface does not
see the operation of the gyro in the same way
77.197
as an observer in space does. On the earth
the gyro appears to rotate, while the earth stands
the angle of its plane of rotation. If this free-
still. As the earth rotates the observer moves
spinning gyroscope is placed on the earth's
with it, so the gyroscope seems to rotate around
its horizontal axis. The effect the observer sees
on the earth is called apparent rotation, and also
surface at the equator, with it6 spinning axis
horizontal and aligned east and west, an observer in space below the south pole would
note that the earth rotates clockwise from west
to east and carries the gyroscope along. As the
earth rotates, rigidity of plane keeps the gyroscope wheel fixed in space and rotating in the
same plane at all times. Figure 12-6 shows how
this gyroscope would appear. Assume that the
gyroscope is set spinning at 0000 hours with its
spinning axis aligned east and west and parallel
is referred to as horizontal earth rate effect.
If the gyro were started with its axle vertical
at one of the earth's poles it would remain
in that position, and produce no apparent rotation
around its horizontal axis. Figure 12-7 illustrates the effect of apparent rotation at the
equator, as seen over a 24-hour period.
Now assume that the spinning gyroscope,
with its spinning axis horizontal, is moved to the
308
320
a
Chapter 12 GYROCOMPASSES, PART I
EAlk,s
77.198
Figure 12-8. Apparent rotation of a gyroscope
at the North Pole.
12.144(77A)B
Figure 12-7. Free gyroscope at the Equator
viewed from the earth's surface.
North Pole (fig. 12-8). To an observer on the
earth's surface the gyroscope appears to rotate
about its vertical axis. To an observer in space
the gyroscope axle appears to remain fixed and
earth's surface at 45° north latitude and 0°
longitude, as shown in figure 12-9.
A gyroscope, if set on any part of the earth's
surface with the spinning axle riot parallel to
the earth's polar axis, appears to rotate, over
the earth appears to rotate under it. This apparent rotatiun about the vertical axis is referred
to as vertical earth rate effect. It is maximum
at the poles and zero at the Equator.
When the gyroscope axle is placed parallel
to the earth's axis at any location on the earth's
surface, the apparent rotation is about the axle
of the gyroscope and cannot be observed. At any
I
point between the Equator and either pole, agyro-
scope whose spinning axis is not parallel to the
earth's spinning axis has an apparent rotation
that is a combination of horizontal earth rate
and vertical earth rate.
The combined earth rate effects at this
/
Eaurni's
point make the gyro appear to rotate partly
about the horizontal axis and partly about the
vertical axis. The horizontal earth rate causes
the gyro to tilt, whereas the vertical earth rate
nauses it to move in azimuth with respect to the
earth. The magnitude of rotation depends on the
latitude of the gyro.
Apparent rotation is illustrated by placing
77.199(140B)
Figure 12-9. Apparent rotation of a gyroscope
a spinning gyroscope with its axle on the meridian (aligned north-south) and parallel to the
at 45°N latitude.
309
321.
IC ELECTRICIAN 3 & 2
Figure 12-10.
77.200
Path of the spinning axle of a free gyroscope.
a 24-hour period, about a line passing through
the center of the gyroscope and parallel to the
the means by which the gyroscope can be made
into a north-seeking instrument.
counterclockwise direction when viewed from
south to north. The path that the north axle describes in space is indicated by the line EAWB
MAKING THE GYROSCOPE A
GYROCOMPASS
earth's axis. This apparent rotation is in a
back to E (fig. 12-10).
Before a simple gyroscope can be made into
a gyrocompass, its mounting must be changed
The effect of the earth's rotation causes the
north end of the gyrreci.ipe axle to rise when east
of the meridian and to fall when west of the meridian in any latitude. This tilting effect provides
VERTICAL
RING
as shown in figure 12-11A. Here, the basic
gyro is modified by replacing the inner gimbal
with a sphere or case, a feature of all compass
gyro which serves to protect the rotor. Avacuum
VERTICAL
GYRO
GYRO
RING
SPHERE
SPHERE
A
B
27.135; .136
Figure 12-11.A. Simple gyroscope, B. Modified gyroscope.
310
i
322
Chapter 12GYROCOMPASSES, PART I
'VERTICAL
RING
GYRO
SPHERE
WEIGHT
w
PHANTOM
0
(A)
EARTH'S ROTATION
ktip.
(e)
tvEST TO EAST
ASSUME EXTERNAL MEANS
ARE PROVIDED TO TURN
PHANTOM SO AS TO FOLLOW
THE GYRO IN AZIMUTH.
I CURVE IS EXAGGERATED)
lf
Figure 12-12. Effect of weight and earth's rotation on the gyroscope.
in the sphere cuts down air friction on the spinning rotor. In another modification, the base is
replaced with a phantom ring, or phantom. The
phantom differs from the base of a simple gyro
in that it is turned by aservomechanism to follow
To become a gyrocompass the gyro must be
modified so it can:
1. aiign its axis on the meridian plane
2. align its axis nearly horizontal
3. maintain its alignment horizontally and
on the meridian once attained.
the horizontal angle of the gyro axle. The phantom
provides the vertical ring with freedom to tilt
and treedom to turn. With this modified mounting
the gyro maintains its Mule of rotation as long
as it spins and nothing touches it.
There must also be a means for making the
gyro seek out and point to true north. For the
purposes of this explanation, true north is the
direction along the meridian plane from the point
of observation to the north pole, and is the horizontal direction relative to the point of 1)1)servation. In, other words, it is the direction a
magnetic compass would point if the North
Pole and magnetic north pole were at the same
place.
27.137
In figure 12-11B, a weight has been added to
the vertical ring, making it bottom heavy, or
pendulous. Because of the additional freedom
given by the phantom this weight will exert a
force on the gyro whenever the rotor is not level
with the earth.
To understand how this pendulous weight
affects the gyro, remember that the rotor is
spinning in the same direction aq the earth
when the gyro points north and thal. the weight
will not move the rotor to a level position, but
will precess it horizontally. Figure 12-12 shows
311
3Z3
IC ELECTRICIAN 3 & 2
how the modified gyro acts. It does not steady
on north, but oscillates equally from one side to
the other of the desired direction. The period
of oscillation is much less than the 24 hours
required for an unmodified gyro; the actual time
is determined by the weight and speed of the
rotor, and the amount of the pendulous weight.
VERTICAL
GYRO
RING
WEIGHT W,
The greater this weight, the faster the precession, therefore there is less time for horizontal earth rate to cause tilt. The gyro now
seeks north, and the next step is to modify it
so it will come to rest on the north-south
SPHERE
meridian, indicating the direction of true north.
To make a gyro a north seeking compass it
PHA TOM
is necessary to suppress the movement of the
gyro about the meridian. Therefore, a smaller
weight is added on the "east" side of the rotor
case or gyro sphere. This weight, W1, is shown
in figure 12-13. With the gyro axle level, the
WEIGHT
W
27.138
Figure 12-13.Gyroscope with weights on the
vertical ring and sphere.
torque produced by gravity acting on weight W1
is restrained by the vertical axis bearings. When
the gyro tilts because of earth rate, the weight
and gravity causes a torque to act around the
vertical axis. Because the rotor is spinning the
torque produced by weight W1 causes precession
which tends to level the gyro.
Both weights, W and Wl, influence the gyro
when it is not aligned with the meridian. When
the gyro is started while pointed away from the
meridian it is caused to tilt by the effect of earth
rate. As a result of the leveling action of Wl, it
tilts less when the action of weight W brings it
to the meridian than it did with only weight W.
Having less tilt applied as it traverses the
meridian means that it cannot overshoot as much
to the other side. If started to the east of the
meridian this gyro does not precess as far to
the west as it was to the east at the beginning
of the oscillation.
The oscillation continues, l' Jwever, and after
reaching its westerly limit the north end of the
gyro tilts downward. The gyro now precesses
across the meridian to the east, but again the
precession is less due to the reduced tilt
..--- _
... ....
?
1
..,
UST
GYRO COMPASS SETTLING
WEIGHT W
27.139
Figure 12-14.
Effect of weights on the gyroscope.
312
....h3,nt
Chapter 12GYROCOMPASSES, PART I
.1110.1=May
caused by Vi. Since each successive oscillation
is reduced, the path is spiral-shaped instead of
elliptical. See figure 12-14.
Considering the action of the weights, you can
ee that in the only position of rest possible for
the low, or south, end. Because of the small
he gyro, its axle is horizontal and on the meridian.
lous weight on the high end of the axle. The
longer the tilt is maintained, the grsater is the
amount of oil in the south tank and the smaller
The free gyroscope has become a gyrocompass,
able to settle only on the meridian and level.
The addition of W1 changed it from a north-
opening in the tube, the flow of oil is not effective for some time. If the tilt is maintained long
enough, however, sufficient oil accumulates in
the south tank to reduce the effect of the pendu-
is the net force exerted by the pendulous weight
on the north axle.
seeking to a north-indicating gyro. The period,
or amount of time to complete each oscillation,
If the tilt is reversed and the south axle is
can be decreased by increasing weight W.
elevated the excess oil in the south tank acts on
the high end of the axle. The small opening in
the tube prevents the oil from flowing immedi-
This basic north-indicating gyro operates
satisfactorily only at the Equator and when
mounted on a stable platform. More design
improvements must be made so it can contend
with the acceleration and motion of a ship, and
ately into the north tank. Hence, for a short
time after the tilt is reversed the weight of the
oil in the south tank adds to the force exerted by
the weight on the high south axle.
with the effects of changes in latitude.
In figure 12-16A, the axle has just been
tilted with the north end up, and the nil has not
had sufficient time to run into the south tank in
STABILIZING THE GYROCOMPASS
To allow the gyro to function as a compass any great amount. In figure 12-16B, the tilt
on a ship, and over a wide range of latitudes, has been maintained long enough for a large
there must be a waylo stabilize it when it is amount of oil to flow into the south tank, and the
level with the earth's surface instead of the resultant force is greatly reduced. In figure
earth's axis. Also, the effects of ship's ac- 12-16C, the tilt has just been reversed and there
celeration and deceleration must be damped, .is still excess oil in the south tank. This excess
otherwise they would soon put the compass out oil adds to the pendulous weight and results in
of line if it were fitted with only the two weights In increased force. In figure 12-16D, the south
of the basic gyrocompass. All of the several axle has been tilted up for some time and the
methods of stabilizing a K,rocompass involve
some form of damping. Two simple methods,
used in older gyrocompasses, are described in
this chaptei. Both methods use the effects of
V
weight and hydraulic action to damp movements
and stabilize the gyrocompass.
Pt
PENDULOUS METH OD
Gyrocompasses made by ARMA use pendulous
weight W; however, weight W1 is replaced by an
oil ballistic as shown in figure 12-15.
Two tanks, partly filled with a light oil, are
secured to the rotor case in line with the northsouth rotor axle on opposite sides of the rotor.
The tube that connects the tanks has a small
Vr-
opening so that the oil flows slowly from one tank
to the other.
The action of the damping is delayed because
5, N WINNING AXIS
weight.
A, A OIL TANKS WITH PIPE CONNECTION
R
RESTRICTED OPENING IN OIL LINE
W WEIGHT OR PENDULOUS CHARACTERISTIC
GRAVITATIONAL FORCE
F
of the small opening in the tube. The effect of
this damping lags behind that of the pendulous
If the north end of the gyroscope axle is elevated, the pendulous weight exerts a downward
force on the high, or north, axle. At the same
time oil begins to (1) flow from the north tank
to the south tank and (2) exert a small force on
313
725
V, V' VERTICAL AXIS
H, H' HORIZONTAL AXIS
77.208
Figure 12-15. Damping arrangements of the
pendulous compass.
IC ELECTRICIAN 3 & 2
--WM'
-. H - H.
rHORIZONTAL
itV
S
"
N
PLANE
w
IV
77.210
B
....
r
.. ..
Figure 12-17.--Path followed by the north axle of
a damped pendulous compass.
W M'
accumulating in the south tank produces a tor-
,- H-H'
que about the horizontal axis opposing the torque
produced by the pendulous weight making the
net torque less than that produced by the pendulous weight above. The rate of precession will
be less because there is now less torque causing
precession. The north axle of the compass will
Ift
FN
continue to rise as long as it remains east of
Cf
FSFORSt [SUMO ST
ON. IN SOUTH TANK
rieronct SURTO S
D
the meridian so that the per.dulous weight will
always exert enough torque to cause it to reach
FIT
the meridian (point B, fig. 12-17). It cannot
remain on the meridian however, because at
/W./OROS UtRTIO WI
PINOULOWS WIISTIT
this time it has maximum tilt, therefore maximum rate of precession. As the north axle of
the compass crosses the meridian to the west,
77.209 the earth's rotation will now cause the north
Figure 12-16. -- Action of damping tanks.
axle to fall. This action further .reduces the
effect of the pendulous weight. As oil has been
transferring to the south tank all this time beoil has built up in the north tank so that the ef- cause of the elevation of the north axle, a point
fect of the weight has been reduced. The length is soon reached at which the torque produced by
of the arrows indicates the magnitude of the the oil ballistic is exactly equal and opposite
force that is being exerted.
to the torque produced by the pendulous weight.
At this time the net torque about the horizontal
Starting with the compass displaced 30° to axis is zero (point C, fig. 12-17). Therefore
the east of the meridian and level (point A, fig. precession to the west ceases; however, the
12-17) the earth's rotations will cause the north north axle of the compass (being west of the
axle to rise. This causes the pendulous weight meridian) continues to fall due to the earth's roto become elevated, the north axle up. This will tation further reducing the torque produced by
produce a torque about the horizontal axis caus- the pendulous weight. The torque produced by
ing precession about the vertical axis to the the oil ballistic is now greater than that prowest; however, due to the elevation of the north duced by the pendulous weight and causes preaxle, it will cause the north tank to be elevated. cession to the east even though the axle has not
This will cause a transfer of oil, to the south yet become level. As the north axle becomes level
tank. This transfer of oil to the south tank will (point D, fig. 12-17) there is still an excess of
be very slow because of the restriction in the oil in the south tank due to the restriction in the
connecting line and will not have much effect at oil line. This excess of oil in the south tank
the beginning. As time goes on however the oil causes it to continue to precess to the east, and
OR. IN NORTH TANK
F.MLIKILTANT /ORM
314
326
Chapter 12GYROCOMPASSES, PART I
the north axle continues to fall due to the rotation of the earth, elevating the south axle. The
pendulous weight now produces a torque about the
horizontal axis that also causes precession to the
east. At this time the oil ballistic and pendulous
weight are exerting torques that are aiding each
other. As the south axle is now elevated, however,
oil will be transferring to the north tank until a
point is reached where there is equal oil in both
tanks (point E, fig. 12-17). Precession continues
to the east because of the torque produced by
the pendulous weight. The south axle beingelevated causes oil to continue to transfer to the north
tank. This action produces an excess of oil in the
north tank, causing a torque about the horizontal
axis oppi)qing that torque produced by the pendulous weight, As long as the north axle remains
west of the meridian however, it will continue to
fall, producing enough torque to cause it to reach
the meridian (point F. fig. 12-17). At this time
there is maximum tilt and maximum rate of precession, therefore, it cannot remain on the meridian. The north axle of the compass is now east
of the meridian and will rise due to the earth's
rotation further reducing the effect of the pendulous weight. As oil has been accumulating in the
north tank during this time, a point is soon
reached at which the torque produced by the oil
ballistic is exactly equal and opposite to that
produced by the pendulous weight. The net torque
about the horizontal axis is now zero and precession to the east ceases (point G, fig. 12-17).
The north axle continues to rise due to the
earth's rotation further reducing the effect of
the pendulous weight. The oil ballistic is now
producing a greater torque than the pendulous
weight and causes precession to the west even
though the north axle is not yet level. When the
north axle becomes level (point H, fig. 12-17),
there is still an excess of ail in the north tank
because of the restrictor in the connecting line
which causes the compass to continue to precess
to the west. As the north axle becomes elevated
dtie to the earth's rotation, it raises the pendulous weight to the north which produces a torque
about the horizontal axis that also causes precession to the west. The torques produced by
the pendulous weight and the oil ballistic now aid
each other. As the N-axle is now elevated, oil will
transfer to the S-tank. A point is soon reached
at which there is equal oil in both tanks (point
I, fig. 12-17). Precession continues to the west
due to the pendulous weight, and nil continues
to transfer to the south tank which now produces
a torque about the horizontal axis opposing the
torque produced by the pendulous weight. The
north axle will continue to rise as long as it
remains east of the meridian. As it reaches
the meridian it has maximum tilt and therefore
maximum rate of precession and therefore cannot remain on the meridian (point J fig. 12-17).
This action continues for about 2 1/2 oscillations
at which time the compass has settled P.nd is an
the meridian.
Because of the restriction a the flow of oil,
the oil flow of the damping tanks alwt.:1 lags behind
the tilt of the rotor. This lag
the oil
ballistic useful as a damping device because
the ballistic peliuits the weight of the oil to
act at just the right time to oppose the oscillations away from the meridian.
NONPENDULOUS METHOD
The method of controlling the gyro axle attitude in Sperry gyrocompasses is by a mercury
ballistic that is balanced about its mounting
axis so as to be nonpendulous until the mercury
flows when the gyro tilts.
Mercury Ballistic
In its simplest form, the mercury ballistic
A
B
77.201
Figure 12-18. Action of a mercury ballistic.
oulusists of two mercury-containing reservoirs,
one mounted at each end of the rotor axle. The
two reservoirs are connected by a pipe so that
the 'mercury is free to flow from one reservoir
to the other, as shown in figure 12-18.
315
IC ELECTRICIAN 3 & 2
When the axle is level (fig. 12-18A), each
reservoir contains the ir.,)ne amount of mercury,
each weighs the same, and each exerts the same
downward force on its end of the axle. Therefore, no torque is produced about any axis.
When the axle is tilted, even slightly (fig. 12-18B),
mercury runs through the connecting tube from
the higher container to the lower container.
The amount of mercury in the two tanks is no
longer equal. The lower tank is heavier because
it contains more mercury. Therefore, the lower
tank exerts more force against its axle than
does the upper tank, and produces a torque
WM'S ROTATION. WEST TO EAST
about axis H-H'. This torque which seemingly
tends to increase the tilt, instead, causes precession about the vertical axis, V-V'.
The rotor in this gyrocompass spins counterclockwise when viewed from the south end of
the ax.t. When the north end is low, the excess
mercury in the north tank exerts a downward
pressure on the north end of the axle and causes
precession to the east, or clockwise. When the
north end is high the excess mercury in the south
tank exerts a downward pressure on the south
end of the axle and causes precession to the
west, or counterclockwise.
As you have learned, when the north end of
the rotor axle is east of the meridian, the earth's
rotation causes it to rise. When a mercury ballistic is added to the gyroscope, the elevation of
the north axle produces a torque about the horizontal axis that causes counterclockwise, or
westerly; precession. When the north end of the
axle is west of the meridian, the earth's rotation
causes it to drop. A low north axle causes the
mercury ballistic to exert a torque about the
horizontal axis that gives clockwise, or easterly
precession.
If this gyroscope with its mercury ballistic
is set on the Equator with the axle pointing to the
east of the meridian and with the rotor spinning
counterclockwise (fig. 12-19A) the north end of
the axle tilts upward because the earth rotates
under it. When this tilt occurs mercury flows
from the north to the south tank, and the south
tank becomes the heavier. The south tank applies a torque about the horizontal axis (fig.
12-19B). This torque results in a precessional
motion about the vertical axis toward the meridian and the west. Because the earth is constantly turning, the gyroscope continues to tilt
upward, more mercury flows to the south tank,
77.202
Figure 12-19. Elementary Sperry gyrocompass
at the Equator.
gyroscope axle is on the meridian (fig. 12-19E).
The south tank contains .nore mercury than the
north tank, and the gyroscope is tilted upward
its greatest amount. At this point the rate of
precession is at its peak.
After the gyroscope axle crosses the meridian
it begins tilting downward so that mercury flows
from the south tank to the north tank. This
transfer of mercury gradually red:Ices the tor-
que about the south end of the axle with a corresponding gradual reduction in the rate of precession of the gyroscope about the vertical axis.
When the gyroscope axle is once more level, it
points to the west of the meridian, the mercury
is distributel equally in both tanks, no torque
is applied to either the north axle or the ecuth
axle, and precession ceases.
As the earth continues moving, the north end
of the gyroscope axle tilts downward, and mercury flows into the north tank, which applies a
torque to the north end of the spin axis. Hence,
the direction of precession is reversed and is
now toward the east. The downward tilt of the
spinning axis continues, and the torque and rate
of precession increase. By the time the gyroscope axle reaches the meridian, it has attained
is maximum rate of precession again, but it
now has a downward tilt. After the gyroscope
passes the meridian, the rotation of the earth
starts the nortl id of the gyroscope axle tilting upward. As this action occurs the torque
about the north axle gradually diminishes to zero
and the precessional motion about the vertical
axis slows down until the gyroscope axle is once
and the torque about the horizontal suds g.adually
more horizontal and precession ceases. When
increases with a corresponding increase in the
precession about the vertical axis (fig. 12-19
C&D). This upward tilting continues until the
the gyroscope axle becomes horizontal, the axle
points in its original starting position. Figure
316
I
Ct
Chapter 12GYROCOMPASSES, PART I
12-20 shows that the path followed by the north
axle of the gyroscope has the shape of an ellipse.
The gyroscope continues these oscillations in-
definitely as long as the wheel is spinning.
Oscillations are damped in this nonpendulous
gyrocompass utilizing the mercury ballistic by
employing a portion of the torque produced by the
action of gravity upon the mercury ballistic
to remove some of the tile given the rotor
axle by the rotation of the earth.
In the previously described mercury ballistics, the tanks are attached directly to the bearings at the ends of the shaft. In the actual com-
3
pass the ballistic is pivoted on studs and bearings
on an outside ring, called the phantom ring, in
such a way that its only point of contact with the
I . ROTOR CASE
gyroscopic element is through a connecting arm,
or link, which bears against the bottom of the
case in 'which the rotor spins (fig. 12-21). The
rotor case corresponds to the inner ring of a
gyroscope and holds the bearings on which the
axle turns.
If the point of connection between the mercury ballistic and the rotor case is in the line
2. VERTICAL RING
3. CENTER LINE 4. PHANTOM ELEMENT
5. MERCURY
BALLISTIC
6. OFFSET ARM
CONNECTION
77.206
Figure 12- 21. Elements of a nonpendulous
compass.
of the vertical axis the only torque that can be ex-
erted by the mercury ballistic is about the horizontal axis, and the resulting precession is only
about the vertical axis. Thus, the compass would
oscillate only back and forth across the meridian.
However, if this point of connection between the
ballistic and the rotor case is bet a fraction of an
inch to the east of the vertical axis (fig. 12-21),
the force exerted by the mercury ballistic is applied about both the horizontal and the vertical
axes, and torque is exerted about both the axes.
Precession then results about both the vertical
and the horizontal axes. Precession about the
horizontal axis is much slower than precession
about the vertical axis because the point of connection is offset from the vertical axis only a
small amount.
With the compass displaced 30°E of the me-
ridian and level (point A, fig. 12-22) the earth's
rotation will cause the north axle to rise. When
the north end rises it causes a transfer of mercury to the south tank. Gravity action on this excess of mercury in the south tank causes torques
to be exerted about both the horizontal and
vertical axes. The torque about the horizontal
axis causes precession of the north end of the
gyrocompass axle tv the west about the vertical
axis. The torque about the vertical axis causes
precession of the north end of the gyrocompass axle downward about the horizontal axis. At
this time the precession about the horizontal axis
opposes apparent rotation about the horizontal
axis. The precession about the vertical axis will
cause the compass to precess to the meridian.
However, the compass cannot remain on the
meridian (point B, fig. 12-22), because at this
time it has its maximum tilt and therefore maximum rate of precession about the vertical axis.
77.203
Figure 12-20. Undamped period of the Sperry
compass at the Equator.
As the gyro precesses past the meridian, the
317
3g9
IC ELECTRICIAN 3 & 2
2 1/2 oscillations, and the compass would then
settle on the meridian.
COMPARISON CURVE
For comparison, the oscillation curve of an
undamped compass and the oscillation curves of
a damped nonpendulous and pendulous compass
are shown in figure 12-23. Note that the damped
period for both compasses is somewhat longer
than the undamped period and that the damped
period of the pendulous compass is longer than
that of the nonpendulous.
The amount by which each successive swing
past the meridian is reduced by the damping device is not the same for all swings. In the pendu-
77.207
Figure 12-22. Path followed by the north axle
lous compass it is less on the first swing than
of a damped nonpendulous compass.
on the following swings. In the nonpendulous com-
direction of apparent rotation about the hori-
pass it is greater on the first swing than on succeeding swings. The average amount by which
successive oscillations are reduced is called the
percentage of damping or the damping factor. It
is about 70 percent for both pendulous and xi-
zontal axis and the direction of precession about
the horizontal axis are now both downward. This
action causes the gyro to become level (point C,
fig. 12-22). When the axle becomes level, precession ceases as there are no torques being ap-
plied by the mercury ballistic. If the proper
(correct) torques have been applied, the compass
would be only 10°W of the meridian, reducing the
oscillation by 66 2/3 percent. As the earth con-
tinues to rotate, however, the compass will not
remain level. Apparent rotation about the horizontal axis causes the north axle to tilt downward. This action causes a transfer of mercury
to the north tank. Gravity action on this excess
of mercury in the north tank will produce torques
about both the horizontal and vertical axes. The
torque about the horizontal axis will cause pre-
cession about the vertical axis, the north end
moving toward the east. The torque about the
vertical axis will cause precession abruk the
horizontal axis, the north end moving upward,
again opposing apparent rotation about the hori-
zontal axis. The precession about the vertical
axis will cause the gyro to precess to the meridian (point D, iig. 12-22). It cannot remain in
the meridian however because at this time it has
maximum tilt, therefore maximum, rate of precession, causing the gyro to precess past the meridian. Now that the north axle is again east of
the meridian, the apparent rotation about the
horizontal axis and the direction of precession
about the horizontal axis both cause the north axle
to become level (point E, fig. 12-22) more
quickly. At this time the compass would be ap-
proximately 3 1/3° east of the meridian. This
damping action would continue for approximately
318
330
pendulous type compasses.
SPERRY MK 11 MOD 6 GYROCOMPASS
The Sperry Mk 11 Mod 6 gyrocompass is used
principally on destroyers. The complete system
consists of the master compass, the control sys-
tem, alarm system, followup system, and the
transmission system. The master compass in-
cludes five major components: (1) sensitive element, (2) mercury ballistic, (3) phantom element,
(4) spider, and (5) binnacle and gimbal rings. The
binnacle and gimbal rings enclose and support
the other four major components (fig. 12-24).
SENSITIVE ELEMENT
The sensitive element (fig. 12-25) is the
north-seeking element of the master compass.
It consists of the gyro unit, vertical ring, compensator weights, followup indicator, and suspension.
Gyro Unit
The gyro unit provides the directive force
for the sensitive element that makes the compass north-seeking. The unit consists of the
rotor and case (fig. 12-26). The gyro rotor
is 10 inches in diameter, 4 1/2 inches wide,
and weighs approximately 72 pounds. It is machined and balanced to rotate on special ball
bearings at a normal speed of 11,000 rpm.
Chapter 12GYROCOMPASSES, PART I
30
20
10
'0
10
20
30
UNDAMPED CURVE
DAMPED CURVE NON PENDULOUS
DAMPED CURVE PENDULOUS
77.211
Figure 12- 23. Oscillation curves of damped and undamped compasses.
The gyro case includes a 3-phase, doublestator winding, one stator being mounted in
each half of the case.
An upper and a lower guide bearing prevent
the vertical ring from moving laterally within the
phantom ring.
erates in a vacuum (26 to 30 inches of mercury)
to reduce the friction caused by air resistance.
A vacuum gage (not shown) is mounted near the
top of the north half of the case to indicate the
degree of vacuum.
A spirit level (gyro case level in fig. 12-25)
from the bottom of the phantom ring.
The case is made airtight and the rotor op-
is mounted on the lower part of the north side
of
the case to indicate the tilt of the rotor.
A small window (not shown) is provided in
the south half of the case through which the spin-
ning rotor can be observed during starting.
Vertical Ring
The vertical ring (fig. 12-25) is attached to a
The upper guide bearing has its outer race
secured in the phantom ring. The inner race is
formed by the lower stud of the suspension. The
lower guide bearing has its outer race secured
in the bottom of the vertical ring. The inner race
is formed by a vertical stud that projects upward
The gyro case lock at the bottom of the case
prevents the gyro case from tilting about its hori-
zontal axis when the compass is not operating.
This latch should be disengaged only when the
rotor is running at normal speed. It is located on
the lower part of the south side of the vertical
ring. The vertical ring loc& keeps the vertical
wire suspension from the head of the phantom
ring in line with the phanTam ring when the
compass is not operating. This lock prevents
vertical ring and surrounds the entire sensitive
element. It is kept in alignment with the vertical
ring, while the compass is in operation, by the
action of the followup system, discussed later.
supported by two frames that are attached to the
element. The phantom ring is concentric with the
the wire suspension from acquiring a permanent
set which would affect the settling point of the
compass.
The compensator weights (fig. 12-25) are
319
IC ELECTRICIAN 3 & 2
Figure 12-24. Sperry Mk 11 Mod 6 gyrocompass.
vertical ring. These frames project out beyond
each end of the rotor axle. The weights can be
moved in or out along their studs. The function
of the weights is to provide an even distribution
The armature of the signal pickoff or followup
transformer is attached to an arm that protrudes
horizontally from the upper part of the south
compensator-weight from (fig. 12-25).
The followup indicator (not shown) indicates
the position of the phantom element with relation
of the weight of the gyrocompass about the
vertical axis.
320
1
40.35
33Z
Chapter 12GYROCOMPASSES, PART I
I SUSPENSION
ARMATURE FOR SIGNAL
FICKUP TRANSFORMER
LERO CASE LEVEL
IVERTICAL RING LOCK
I OIL SIGHT GLASS 1
GYRO CASE LOCK'
VERTICAL RING1
Figure 12-25.Sperry Mk 11 Mod 6 sensitive element.
40.30
Figure 12-26.Sperry Mk 11 Mod 6 gyro unit. B, rotor; A and C, case.
40.31
321
333
IC ELECTRICIAN 3 & 2
2 MERCURY BALLISTIC FRAME
46
48
49
50
LATITUDE SCALE
DAMPING ELIMINATOR MAGNET
NON-PENDULOUS BALANCING WEIGHTS
HORIZONTAL BALANCING WEIGHTS
148 NO-DAMPING ADJUSTMENT SCREW
149 DAMPING ADJUSTMENT
183 MAGNET LINK SPRING
OFFSET CONNECTION BEARING STUD
40 MERCURY RESERVOIRS
41 MERCURY TUBE
42 CONNECTION ARM
16
43 MERCURY BALLISTIC SUPPORT STUD
44 MERCURY RESERVOIR SUPPORT STEM
45 LATITUDE SETTING THUMB WHEEL
186 LEVELING SCREW HOLES
Figure 12-27. Sperry Mk 11 Mod 6 mercury ballistic.
to the sensitive element. This indicator consists
of a scale and a pointer. The scale is attached to
the phantom element below the spider table and
the pointer is attached to the north compensator
weight frame. The scale is calibrated in degrees
with the center marked "0". Thus, a misalignment between the phantom element and sensitive
element is indicated in degrees.
The suspension (fig. 12-25) suspends the entire sensitive element from the phantom element.
It consists of a bundle of small steel wires secured at the upper end to a support stud and at
the lower end to a guide stud. A nut and check nut
secures the support stud to the phantom element,
and provides a means to adjust the sensitive
element vertically. The guide stud passes through
a hole in the upper part of the vertical ring
and is clamped to the ring by a nut. This stud
also serves as the inner race of the upper
guide bearing of the ring.
322
3 ,14
40.32
MERCURY BALLISTIC
The mercury ballistic (fig. 12-27) is that
group of parts which applies the gravity control-
ling force to the gyro unit and makes it northseeking. It consists of a rigid frame supported
on bearings in the phantom ring. These bearings
are in line with the horizontal case bearings in
the vertical ring so that the mercury ballistic
is free to tilt about the east-7.cst !kids of the sensitive element.
The frame supports a mercury reservoir in
each of its four corners. The N and S reservoirs
on the east side of the compass are connected by
a U-shaped tube and the N and S reservoirs on
the west side are similarly connected. The
gravity controlling force of the mercury ballistic
is applied to the bottom of the gyro case through
an adjustable offset bearing stud mounted on the
ballistic connection arm.
Chapter 12GYROCOMPASSES, PART I
The connection bearing is offset to the east
from the vertical axis by a short distance to provide the damping adjustment. When it is desired
to eliminate damping, a solenoid (damping eliminator magnet) is energized by an automatic
damping eliminator switch (discussed later) that
attracts a plunger which moves the pivoted connection arm until the connection bearing is in line
with the vertical axis of the gyro. In addition,
each mercury reservoir is offset from its supporting stem so that each can be rotated around
its stem through an arc of about 110° in order to
vary the lever arm of each tank. Thus the period
of an undamped oscillation of the gyrocipass
is maintained constant in all latitudes by adjust-
ment of the mercury reservoirs. This adjustment is referred to as the ballistic latitude
adjustment.
POLLOWUP
TRANSFORMER
RESISTORS
PHANTOM ELEMENT
I
The phantom element (fig. 12-28) is a group
of parts that acts to support the sensitive element. It consists essentially of a hollow cylin-
drical stem that projects radially from the phan-
tom ring. The stem is mounted in the spider
and extends down from the central hub of the
spider table.
The phantom element supports the sensitive
element by means of the suspension (w:re bundle).
The phantom element has no.north- seeking prop-
erties of its own, however it does continuously
indicate north, because it is made to follow
all movements of the sensitive element by the
40.33
Figure 12-28. Sperry Mk 11 Mod 6 phantom
element.
action of the followup system.
A thrust bearing on the top of the stem (fig.
12-28) rests in the hub of the spider table and
supports the weight of the phantom and sensitive
elements. The upper and lower stem bearings
SPIDER
keep the stem in alignment with the vertical axis
of the spider but permit the phantom element to
rotate about its own vertical axis.
The phantom ring also carries bearings that
support the mercury ballistic. The axis of these
bearings coincides with the axis of the horizontal
cast aluminum alloy that supports the entire
inner, or moving, member of the compass by
The spider (fig. 12-29) is a circular table of
means of the hub on which the thrust bearing that
supports the phantom element rests. The spider
is supported in the inner, or cardan, ring of the
two rings that comprise the gimbal system. A
bearings of the gyro case. Collector rings are
mounted on the phantom stem below the upper
stem bearing to connect the various electrical
circuits from the fixed to the moving parts of the
compass. The large and small azimuth gears are,
included in the azimuth followup mechanism (to
be discussed later).
An eccentric groove called the cosine cam is
cut into the upper surface of the large azimuth
in the center of the table supports the
thrust bearing and the upper and lower stem
boss
bearings.
The azimuth followup motor and the auto-
matic damping eliminator switch are mounted on
the forward side of the spider table. The speed
and latitude correction mechanism and the auxiliary latitude corrector are mounted on the after
side of the spider table. The 36-speed synchro
gear. The cosine cam is associated with the
speed and latitude corrector mechanism.
323
3;35
1
IC ELECTRICIAN 3 & 2
344PEED
COLLECTOR -RING
GRUDGES
TRANSMITTER
LEADS
I4PERD
TRANSMITTER
LEADS
1p
t
t
TRUNNION
SEARING
TERMINAL
STRIP
114
11110111111111011300
VMS
GUARALRING
REARM
CHIRAL RING
Figure 12 -29. Sperry Mk 11 Mod 6 spider.
transmitter is located on the port side and the
single-speed synchro transmitter is located on
The primary power source is the ship's 3-phase,
120-volt, 60-hertz supply and the emergency
the starboard side of the spider.
power source is the 24-volt battery.
CONTROL AND ALARM SYSTEM
The Sperry Mk 11 Mod 6 gyrocompass control and alarm system consists of a motor-
generator, speed regulator, control panel, bat-
tery throwover panel, and bridge alarm indicator,
with the necessary apparatus for the operation
and control of the master compass. The principal components of the system are illustrated
in figure 12-30.
The gyrocompass drive system consists of
the primary and emergency sources of power.
40.34
Motor-Generator Sets
Two separate motor-generator sets are provided with each complete Sperry gyrocompass.
Each set consists of an induction motor, a d-c
emergency motor, an a-c generator, and a d-c
generator (fig. 12-30). The induction motor and
the d-c emergency motor are mounted on a
common shaft in a single frame. The a-c genera-
tor and the d-c generator are also mounted on
a common shaft in a single frame. The shafts
324
Chapter 12GYROCOMPASSES, PART I
r
1
1
I
3 # _120 V. 60 ti BUS
I# .120 V, 60N BUS
BRIDGE 1
ALARM r
1 INDICATOR I
1
1_110 V D C CIRCUITS
I
SPEED
-IFIEGULATOR
1
(
CONTROL
PANEL
1
r
DC
MOTOR
BATTERY
THROW-OVER
PANEL
E
AC
AC
MOTOR
DC
1
r--24V
GEN. GEN
1
1'M-"-
G2
-,
L___I
;BATTERY;
%I -G
Imim
4.... ............m... mow. ammo...
40.36
Figure 12 -30. Sperry Mk 11 Mod 6 gyrccompass control and alarm system.
of these two units are directly coupled together.
the induction motor, the d-c motor operates
complete unit and mounted on a single bedplate.
The induction motor is a 3-phase, 120-volt,
d-c generators. As a d-c motor, it has an
intermittent-duty rating of 22.5 volts at 70
Each motor-generator set is assembled as a
60-hertz, wound-rotor motor with slip rings.
Under normal operating conditions, the induction
motor drives the d-c motor, the a-c generator,
and the d-c generator. It operates at a constant
speed of 1460 rpm (necessary for the a-c generator to deliver a constant 3-phase output of
60 volts at 195 hertz), which is maintained
from the battery supply to drive the ,a-c and
amperes.
The a-c generator is a 3-phase, 60-volt, 195 hertz, inductor type generator having 16 polar
projections. Both the field and the armature are
stationary. The 16 polar projections (inductors)
are rotated continuously at approximately 1,460
rpm thereby varying the magnetic field flux
constant by means of a speed regulator that
through the armature windings and generating
a-c voltages at a frequency of 195 Hz. The arm-
in the ship's primary power supply frequency.
ature consists of a wye-connected, 3-phase winding, and the field consists of a singled-c winding.
Slip rings are not required with this type of generator. The machine supplies power to drive the
gyro rotor and to energize the amplifier and the
followup system.
compensates for a maximum of +10% variaticns
The d-c motor is a shunt-wound machine. Under normal conditions of induction motor drive,
the d-c motor operates as a self-excited d-c
generator for charging the battery with a contin-
uous-duty rating of 27 volts at 7 amperes.
The d-c generator is a 120-volt, compound
wound, interpole, self-excited generator. This
Under emergency operating conditions because of failure in the ship's 3-phase supply to
325
3;:p7
IC ELECTRICIAN 3 & 2
PRESSURE
SPRING
INTERNAL STOP
HOLDING
COIL CONTACTS
@
I
MOVABLE
i 11
©1
ECCENTRIC
OPERATING STUD
LINK
111
H NGED
NUTS
PLATE
BRACKET...,
r
B
KNURLED
NUT
COUNTERWEIGHT
ON ARMATURE
LEVER ARM
DASHPOT DAMPER
BRACKET
STUD D
PIVOT POINT
OF ARMATURE
LEVER ARM
OUTSIDE
ARMATURE
STOP
ARMATURE
INSIDE
ARMATURE
STOP
CARBON
PILES
VOLTAGE
COIL
°
Figure 12-31. Speed regulator schematic.
machine supplies excitation for its own fields,
the a-c generator field, and the azimuth-motor
field. It also supplies d-c power for the damping eliminator, the azimuth-motor cutout relay
the dead-reckoning equipment, and the voltage
coil of the speed regulator.
40.38
The speed regulator consists of a wye-connected, carbon -pile voltage regulator connected
in the form-wound rotor circuit of the 3-phase
induction motor by means of slip rings.
The actuating coil of the speed regulator is
connected in a shunt circuit across the output
terminals of the d -o generator , therefore,
responds to changes in d-c a
voltage occasioned by any changes in spee4 of the motor
generator. The voltage coil attracts a springloaded pressure arm that varies the pressure on
the carbon piles in accordance with any change
Speed Regulator
The speed regulator (fig. 12-31) is a separate
unit located near the motor-generator sets. It
compensates for variations in the ship's supply
voltage or frequency to maintain the speed of
in voltage across the coil.
If ihe ship's supply voltage or frequency in-
the induction motor constant and thereby causes
creases, the induction motor-rotor current increases. This action causes a slight increase in
the a-c generator to deliver a constant output
to drive the gyro motor. The same speed regulator
is used for each of the two motor-generator sets
the speed of the motor-generator. The consequent slight increase in d-c generator volt-
because they are not operated simultaneously.
age causes the voltage coil of the speed regulator
326
3;ei
Chapter 12 GYROCOMPASSES, PART I
40 mg
VCLT.AMM[TER
SINCHEI
REPEATER srsint
I SELECTOR SWITCH1
AZIMUTH MOTOR
SWITCH
SUPPLY AMMETER
[SUPPLY LOW VOLTAGE RELAY AtO
REPEATER LOW VOLTAGE RELAY
MOTOR GENERATOR
TRANSFER SWITCH
AZIWAN MOTOR
SUPPLY SWITCH
ALARM SELECTOR SWITCH
FOLLOW-UP
SUPPLY SWITCH
111'
,110.1
.0411110
-4- 4.-
DC SERVICE SWITCH
4`
FUSE PANEL
t
*NM
DC VOLTMETER
24 -VOLT ALARM
t
1.4";,
swath
DC
1
BATTLRY SWITCH
'STARTING PUS' WITCH (I)
',USE PANEL
FIR
D.R.A.
CONTROL
SWITCH
'VOLTAGE ADJUSTMENT RHEOSTATS
SWITCH
'RELAY TRANSMITTER1
IBATTERY GENERATOR
TRANSFER SWITCH
'REPEATER PANEL
REPEATER PANEL j
40.39
Figure 12-32.Sperry Mk 11 Mod 6 gyrocompass switchboard.
to attract the spring-loaded arm. This action de-
Compass Control Panel
output voltage.
The compass control panel is located at the
upper left-hand section of the gyrocompass
switchboard (fig. 12-32). The control panel is
used to control and indicate the operating conditions of the master compass. The ship's 3phase, 120-volt, 60-hertz power supply and the
ship's single-phase, 120-volt, 60-hertz power
creases the pressure on the carbon piles. The
accompanying increase in rotor resistance restores the rotor currents to their normal value
and checks the rise in speed and d-c generator
A dashpot damper is connected in the pressure arm to prevent hunting when rapid changes
occur in the voltage or frequency.
327
0
IC ELECTRICIAN 3 & 2
supply are connected directly to terminals on the
back of the compass control panel. The 3-phase,
120-volt, 60-hertz power supply is fed from these
terminals on the control panel through the battery
throwover relay on the battery throwover panel
to the motor-generator transfer switch on the
compass control panel. The switches and fuses
necessary for these power supplies are included
on the IC switchboards, but are not provided on
the gyrocompass switchboard.
The a-c ammeters and an a-c voltmeters are
mounted at the top of the control panel to indicate
the operating conditions of the master compass.
One ammeter indicates the 60-hertz alternating
current supplied to the synchro repeater system
by the master compass transmitter. The other
by turning the selector switch to the position
indicating the trouble.
The followup supply switch is an on-off
switch. In the ON position it energizes the
followup panel from one phase of the 3-phase
gyro supply, and heats the filaments of the
amplifiers and rectifier tubes in the followup
system.
If the followup switch is in the OFF position,
the compass supply ammeter and voltmeter indicate the current and voltage to the gyro rotor
only; whereas, if this switch is in the ON position,
the meters will indicate the 195-hertz current
voltage to both the gyro rotor and the followup
panel.
The d-c service switch is the master switch
ammeter and the voltmeter indicate the 195-
for the 120-volt, d-c circuit. It supplies the
1. ::tz current and voltage supplied by the 3-phase
damping eliminator circuits, azimuth-motor field,
and azimuth-motor cutout relay coil.
a-c generator to the gyrocompass rotor.
The azimuth-motor cutout detent release, the
single and 36-speed overload signal lamps; and
the volt-ammeter selector switch are mounted
just below the two ammeters and the voltmeter.
The azimuth motor cutout detent release is
provided to reset the cutout after a fault has been
cleared on the followup system.
The volt - ammeter selector switch is a 3position rotary switch. The three switch positions provide for shifting the ammeter and voltmeter to any one of the three phases of the a-c
gyro rotor supply to obtain current and voltage
readings of the ;elected phase.
The fuses for the compass control panel are
within an enclosure located at the bottom of this
panel.
Battery Throwover Panel
The battery throwover panel is located di-
rectly below the compass control panel (fig. 1232). It is used to transfer automatically the gyrocompass circuits from the ship's 3-phase supply
to the battery supply in the event of failure of
the ship's supply. The 24-volt storage battery
is normally connected to the battery-charging
generator of the motor-generator set and floats
The motor-generator transfer switch and
the compass rotor switch are mounted on the
on the line.
third row from the top.
If the ship's 3-phase supply voltage or frequency drops below the predetermined value
The motor-generator transfer switch is a
double-throw rotary switch provided for selecting either of the two motor-generators.
The compass rotor switch connects the 3phase, 55-volt, 195-hertz power from the a-c
generator to the gyrocompass rotor.
The azimuth-motor switch, the alarm selector switch, the followup supply switch and the
d.c. service switch are located at the bottom of
(+10% of the normal value), the movement of the
pressure arm on the carbon piles of the speed
regulator will open the battery throwever relay
holding coil contacts, thereby deenergizing this
relay. When this relay is deenergized, the (1)
ship's 3-phase supply is disconnected from the
motor-generator set, (2) battery is connected to
the d-c motor (charging generator) as a primary power source so that the d-c motor be-
the control panel.
The azimuth-motor switch controls the rectified a-c supply circuit to the azimuth motor
armature and the d-c supply to the azimuthmotor field.
The alarm selector switch is a rotary switch
with four positions marked normal low frequency,
repeater supply, and ship's supply. In the NOR-
MAL position, the alarm bell sounds if the
ship's supply or the repeater supply fail or if
the supply voltage or frequency fall below a
predetermined value. The alarm bell is silenced
comes the prime mover for the motor-generator
set, and (3) alarm bell rings.
When the ship's 3-phase power supply is
restored, retransfer of the drive to the induction
motor must be accomplished manually.
A 24-volt alarm supply switch and a battery
voltmeter and ammeter are mounted at the top
of the battery throwover panel.
The 24-volt alarm supply switch is &separate
switch provided for cutting out the supply to the
entire alarm system.
328
340
Chapter 12GYROCOMPASSES. PART I
rtAtipmG_goatiiiipltfUl*TT074.1
.
77.212
Figure 12-33. Bridge alarm indicator.
The d-c ammeter and the d-c voltmeter connected between the battery switch and the battery-
generator transfer switch, indicate the current
and voltage respectively in the battery line.
The fuses for the battery throwover panel
are within an enclosure located in the center of
the panel.
The battery switch and the battery-generator
transfer switch are located on the left-hand and
the right-hand sides of the fuse enclosure, respectively.
The battery switch is a DPST lever-switch
that connects the 24-volt battery supply to the
battery throwover panel.
The battery generator transfer switch is a
DPDT lever-switch that connects the battery
to one or the other of the two battery generators.
The starting pushswitch is mounted below the
battery switch. It is used to start the motorgenerator 9111 also to restore the circuit to the
holding coil of the battery throwover relay after
the system has been interrupted because of a
failure of the ship's supply or low voltage and/
or frequency.
An additional pushswitch in parallel with
the starting pushswitch on the battery throwover panel is located on the bridge alarm indicator so that, if desired, the ship's power supply
can be restored to the compass equipment from
this station.
Two voltage adjustment rheostats, one for
each of the battery generators, are mounted at
the bottom of the panel. These rheostats are used
to adjust the generator-field resistance to con-
trol the charging rate of the battery when the machine operates as a generator. The rheostats are
cut out when the machine operates as a motor,
and the resistance that is cut into the field by the
battery throwover relay automatically incresqes
the speed to the proper value.
Bridge Alarm Indicator
The bridge alarm indicator (fig. 12-33) is
located in the pilot house. The indicator includes
329
341
IC ELECTRICIAN S & 2
eummlw..0.0
a red, a blue, and a green indicator lamp,
a damping-eliminator pushswitch and a starting
pushswitch. These components are enclosed within
a metal case provided for bulkhead mounting.
An external alarm bell is adjacent to this in-
of output rectifiers is conducting when the plates
of the voltage amplifiers are positive.
Followup Panel
dicator.
The red indicator lamp in the battery supply
indicates operation of the compass equipment
from the 24-volt battery supply.
The blue indicator lamp is in the damping-
to the compass control panel. It includes a
damping-eliminator coil is energized.
that amplify the weak signal voltage from the
eliminator circuit as a warning whenever the
The green indicator lamp in the ship's a-c
supply is lighted as long as the ship's supply
is connected to the compass equipment.
Each indicator lamp is provided with a series
The followup panel (fig. 12-32) is adjacent
voltage amplifier and a power amplifier.
The voltage amplifier contains two twin triodes
followup transformer. The power amplifier con-
tains two pair of thyratron rectifiers that supply the azimuth motor armature current.
variable resistor to control the intensity of
Followup Transformer
The starting pushswitch is in parallel with
the pushswitch on the battery throwover panel
The followup transformer comprises three
coils wound on an E-shaped laminated core
(fig. 12-35). The primary coil (P) mounted on
illumination.
as mentioned previously.
The damping-eliminator pushswitch is in
parallel with the automatic damping-eliminator
switch on the master compass and may be manually operated to energize the damping- eliminator
coil and thus remove damping.
FOLLOWUP SYSTE .vi
The followup system includes the followup
mechanism, the followup transformer. the P.Zimuth motor, and the followup panel. The system
functions to detect any misalignment between the
phantom and sensitive elements and to drive the
phantom element in the proper direction to
restore alignment. Any misalignment between
the phantom and sensitive elements results in a
signal voltage output from the followup transformer. The amount of misalignment determines
the magnitude of this signal voltage and the di-
rection of misalignment determines its phase.
The signal output from the followup transformer
is amplified by a voltage amplifier and used to
control the output t3f ft power amplifier which
operates the azimuth motor. The azimuth motor
in driving the phantom element back into alignment with the sensitive element also drives the
single and 36- sped synchro transmitters, and
a lost motion device through the azimuth followup
gearing mechanism (fig. 12-34).
The azimuth motor is a d-c motor having
its field excited by the 120-volt d-c output from
the motor generator. Its armature is connected
the center leg, is connected to the 3-phase 195 hertz compass rotor supply. One primary lead
is connected to one phase through resistor R1
which limits the primary current to a few ma.
The other primary lead ties to the common connection of phasing resistors R2 and R3 across
the other two phases. This provides the proper
phase relation between the followup signal voltage and the followup amplifier bias and plate
voltages.
An armature carried on the sensitive element
serves as a closing link in the double magnetic
circuit of the followup transformer. The armature is positioned so that a small air gap is
maintained between the armature and the transformer.
Secondary coils A and B on the outside legs of
the transformer are connected in such a manner
that the induced voltage in one leg is 180° out of
phase with the induced voltage in the other leg.
Small capacitors C connected across the secondary coils, are in parallel resonance with the coils
at 195 hertz in order to obtain the maximum voltage across the coils at that frequency. To
balance the voltage output of the secondary coils
when the armature is centrally located, two fixed
resistors (not shown) are connected across the
capacitors.
The E-shape followup transformer is mounted
on the phantom element and will move with a
change in the ship's heading. The armature,
hoiever, is mounted on the sensitive element
c r the north-seeking part cf the compass and
does not move once the compass has settled
either cle or the other of the two output
rectifier circuits of the power amplifier. The
in
direction of rotation depends upon which pair
on the meridian.
330
342
Chapter 12GYROCOMPASSES, PART I
SPEED AND LATITUDE
CORRECTOR SETTING KNOB
AUXILIARY LATITUDE
CORRECTOR SETTING KNOB
36-SPEED
TRANSMITTER
SPEED 3 LATITUDE
SINGLE-SPEED
TRANSMITTER
CORRECTOR
MECHANISM
CORRECTOR
SEMICIRCULAR
GEAR
ROTCR
ROTOR
FIXE
BEARING
STATOR
STATOR
STATOR GEAR
STATOR
GEAR
Unt11014111111111 iiiiiiiii
TRANSMITTER
DRIVE
4041
iiiii
SMALL
AZIMUTH GEAR
ROTOR GEAR
COURSE ARM
111 lllll 111111111111ili
"H"'""""""'" 441aitatnutssitutimumillio
ROTOR GEAR
AZIMUTH GEARS
ON PHANTOM
ELEMENT
11111111.1.11
COSINE CAM
11Uu111111+1M111111111111111111111111111111111111
LARGE
AZIMUTH GEAR
LOST-MOTION DEVICE
(FOR DAMPING
ELIMINATOR SWITCH)
7 9Ia
ii- Until iiiii SIMI lllllllll
44";;F; IIIU llllllll WIN
lllllllll
AUTOMATIC
DAMPING
ELIMINATOR
('~"SWITCH
Ar'
AZIMUTH
4."'"'MOTOR
40.40
Figure 12-34. Azimuth followup mechanism gearing.
With the compass settled on the meridian the
phantom element is in alignment with the sensitive element, and the compass card will indicate
the ship's heading. In this neutral position the
voltages induced in the two secondaries of the
followup transformer will be equal in amplitude,
but differ in phase by 180 degrees. The outptiih
voltage, therefore; is zero and consequently no
input signal is fed to the voltage amplifier.
However, when the followup transformer is
moved either to the left or right, due to a change
in the ship's heading, unequal fluxes pass through
the transformer secondaries. As a result the
secondary voltages become unbalanced. The resultant output voltage will be the vector sum of
the two voltages and the phase of the output voltage will be the same as the phase of the secondary voltage having the greatest amplitude.
The phase of the output voltage is determined
by the direction of the followup transformer
movement and the voltage amplitude is determined by the amount of the movement.
331
343
IC ELECTRICIAN 3 & 2
coil is connected in series with a transmitter
stator lead. An increase in the current through
R2
any or all of the coils above a critical value attracts the relay armature, causing it to move.
3 PHASE
195 Ma
COMPASS
R3
ROTOR
This action closes a contact that lights a red
1. SUPPLY
signal lamp on the panel front, indicating trouble
in the transmitter circuit. A stepdown transformer (115 volts to 7 volts) on the panel supplies the indicator lamp circuits.
Repeater Panel
The repeater panel (fig. 12-32) is below
the followup panel. It comprises an assembly
of rotary switches, and auxiliary equipment.
Each switch with its associated fuses and over-
FOLLOVIUP SIGNAL TO
VOLTAGE AMPLIFIER
GAIN CONTROL
load indicating devices is assembled as a unit and
can be withdrawn from the front of the panel for
inspection and repair.
Each compass repeater switch is arranged to
connect the circuits of two repeater compasses
so that either one, or both, may be driven by the
master compass transmitters.
77.213
Figure 12-35. Simplified schematic diagram of
followup transformer, Sperry Mk 11 Mod 6
gyrocompass.
Thus, the output signal from the followup
transformer to the voltage amplifier is proportional in magnitude and phase to the amount and
direction of the armature displacement or ship's
movement.
TRANSMISSION SYSTEM
The Sperry Mk 11 Mod 6 gyrocompass transmission system provides a means of transmitting
the readings of the master gyrocompass to a
number of repeater compasses located at various
stations in the ship. The single and 36-speed
synchro transmitters (driven by the azimuth
followup motor) control the may
of the
repeater compasses that indicate the readings
of the master compass at the remote stations.
The transmission system also includes the
overload relays, repeater panel, relay transmitter repeater panel, relay transmitter, relay
transmitter amplifier panel, differential alarm
relay, and repeater compasses.
Transmitter Overload Relays
Two similar transmitter overload relays,
mounted on the back of the compass control
panel, provide a visual alarm when an overload
occurs in the transmitter circuits. One relay is
connected in the single-speed transmitter circuit, and the other relay is connected in the
36-speed transmitter circuits. The relay consists of three legs with a coil on each leg. Each
Each repeater circuit is provided with an
overload indicator, comprising a transformer
and a neon lamp. The transformer has two primaries, which are connected in series respectively with two of the three secondary leads to
the repeater The transformer secondary is connected across the neon lamp. When the repeater
is approximately alined with the transmitter, the
very small current in the transformer primaries
does not generate sufficient voltage across the
secondary to illuminate the lamp. However, ex-
cessive current in the transformer primaries
causes the lamp to glow and thus indicate trouble
in this repeater circuit.
Associated with each of the repeater circuit
switches are four fuses, access to which is
through the hinged door just above the switch
handle. Two of the fuses are in the primary circuit to the 1-speed repeater, and the remaining
two are in the primary circuit to the 36-speed
repeater.
The rotary type switch designated on the panel
as the fire control switch is not provided with an
overload alarm because connections are made
from this Siiitch to the fire control switchboard,
which has an alarm for each circuit leaving the
board, However, at the fire control switch on the
repeater panel the two indicators are (1) a pilot
lamp, connected across the a-c supply to this
switch and therefore illuminated as long as this
supply is available, and (2) a transformer and
neon lamp arranged to indicate when one or both
of the a-c supply fuses blow.
332
344
Chapter .12GYROCOMPASSES, PART I
drives a commutator type transmitter, the output of which energizes the repeaters, causing
The rotary type switch designated on the panel
as the dead reckoning analyzer switch is provided
to operate the DRA from the underwater log
transmitter and the 1-speed transmitter on the
master compass. This switch also supplies
them to follow the master compass. The followup
motor also drives the secondaries of the control
transformers to the zero-voltage position, thereby
single-phase, 120-volt, a-c power and 120-volt,
synchronizing the relay transmitter with the
two fuses. A neon lamp across each fuse in the
d-c circuit is lighted when the fuse blows.
Relay Transmitter Amplifier Panel
Relay Transmitter Repeater Panel
12-32) is adjacent to the followup panel. It
The relay transmitter repeater panel (fig.
12-32) is adjacent to the repeater panel. This
panel and the repeater panel are arranged so
that the repeater compasses can be connected
to either the master-compass transmitter or to
amplifier. The voltage amplifier receives the
signal from the oontrol transformers, and the
d-c power necessary for the operation of the
DRA. Each of these circuits is provided with
master compass.
The relay transmitter amplifier panel (fig.
consists of a voltage amplifier and a power
output is fed to the power amplifier. The power
amplifier provides the controlled power necessary to operate the followup motor in response
to the signals from the voltage amplifier.
the relay transmitter.
The relay transmitter repeater panel includes eight rotary switches: a checking repeater switch, a fire control switch, a relay
Differential Alarm Relay
transmitter supply switch, an emergency navigation transfer switch, two compass repeater
switches, and two radar mast (special) switches.
The checking repeater switch connects the
gyrocompass-room checking repeater to either
the master compass or to the relay transmitter.
Two fuses are connected in series with the primary leads on the load side of the switch. Two
transformer and neon-lamp overload indicators
(one for each circuit) are connected in the transmitter secondary circuits to indicate an overload
in these circuits.
The differential alarm relay (fig. 12-37) is a
device for sounding Pn alarm whenever the relay
Relay Transmitter
of the relay transmitter to keep in synchronism
causes the rotor to move from the neutral position to that amount corresponding to the diver -
In order to actuate a number of repeater
compasses without imposing this load directly
on the compass transmitters, an intermediate
instrument known as a relay transmitter is used.
The relay transmitter (fig. 12-36) consists of
a single-speed and a 36-speed synchro control
transformer (CT), a commutator transmitter,
a followup motor, and a reactor. These components are enclosed within a metal case provided
for bulkhead mounting (fig. 12-36A).
The relay transmitter is synchronized with
the master compass by means of the synchro
control transformer followup motor, and relay-
transmitter loses synchronism with the master
compass. The amount by which the transmitter is
allowed to diverge, before the alarm is sounded,
is adjustable from 0° to 2.5°.
The device comprises a synchro differential
receiver. The stator receives its signal from the
36-speed output of the relay transmitter; the
rotor circuit receives its signal from the 36speed transmitter at the master compass. As
long as the two outputs are in agreement, the
rotor remains at the neutral position. Failure
gencc fruin synchronism.
A bakelite disk that has a metallic segment is
mounted on the shaft of the differential receiver
(fig. 12-37A). Two trolleys bear on the periphery
of the disk. These trolleys are arranged so that
rotation of the disk causes one trolley to contact
the metallic segment. This action closes the 120 volt, a-c circuit to a relay (fig. 12-37B), which
in turn, closes the 120-volt, a-c supply to the
alarm bells located in the pilot house.
transmitter amplifier (fig. 12-36B). The control-
ling signal voltage from the master compass
energizes the primaries of the control trans-
formers. The output of the control transformers
is fed to the amplifier, the output of which controls the followup motor. The followup motor
An 8-pole switch on the relay transmitter
repeater panel is provided for disconnecting the
differential synchro receiver and the alarm circuit (fig. 12-37B). The toggle switch disconnects
only the alarm circuit.
333
34S
IC ELECTRICIAN 3 & 2
1 -SPEED
SLIP RINGS
AND BRUSHES
) RESISTOR R31
36-SPEED
1 -SPEED
COMMUTATOR
BRUSHES
1 -SPEED
CONTROL
TRANSFORMER
I REACTOR 1
1 FUSE PANEL I
A. INTERNAL VIEW
COMMUTATOR
TRANSMITTER
LC I
LCCO
120 V 60 HERTZ SUPPLY
FROM RELAY TRANSMITTER
REPEATER PANEL
GREEN ALARM LAMP AT
RELAY TRANSM.7TER
SUPPLY SWITCH ON RELAY
TRANSMITTER REPEATER
PANEL
TO
REPEATER
PANEL
\
.-
1
4
FOLLOW -UP
MOTOR
SIGNALS FROM MASTER
COMPASS
36..1 AND I - I
SYNCHRO
CONTROL
TRANSFORMERS
RELAY TRANSMITTER
SUPPLY SWITCH ON
RELAY TRANSMITTEn
REPtATER PANEL
.as .- +
6 -POLE
T1
RELAY
TRANSMITTER
AMPLIFIER
T2
1t
S
SWITCH
B. SCHEMATIC DIAGRAM
Figure 12-36.Sperry Mk 11 Mod 6 relay transmitter.
334
346
40.45
Chapter 12GYROCOMPASSES, PART I
RECEIVER -DISK
DIAL POINTER
TROLLEY
RECEIVER-DISK
DIAL. POINTER
TROLLEY SETTING SCALE
LOCK SCREW FOR
TROLLEYS
RECEIVER-DISK DIAL
LEAD TO
CENTER CONTACT
CONNECTION
TO TROLLEYS
ZERO SETTING KNOB
=LW f:e
SYNCHRO
RECEIVER
UNIT
DISK
CONTACT MECHANISM
A
TO ALARM BELL
4LC
l?
e-POLE
4LCC"
10
TO RELAY TRANSMITTER
LC
1004
TO MASTER TRANSMITTER
LC
100e
1006
I
I
LC
104
SEE NOTE
LC
105
4
10
SWITCH
CONTACT
SEGMENT
ROTATED BY
SYNCHRO UNIT
RELAY
TOGGLE
SWITCH
TROLLEYS
NOTE: SUPPLY LEADS 4LCIO AND 4LCCIO FED TO
RELAY TRANSMITTER REPEATER PANEL.
SCHEMATIC DIAGRAM
B
40.47
Figure 12-37.Sperry Mk 11 Mod 6 gyrocompass differential alarm relay.
335
IC ELECTRICIAN 3 & 2
ERROR CORRECTION
by an auxiliary latitude corrector (fig. 12-38)
that enables the lubber's line to be moved
Unless located on a steady platform at the
Equator, a gyrocompass will not point to true
north, but will be slightly deflected toward the
east or west, depending on conditions. It is
possible to predict the amount or angle of defleetion,--when the latitude, ship's speed, and
direction of the ship's motion are known. This
manually the exact amount of the error and in
the proper direction. The corrector is cali-
brated in degrees of north and south latitude.
Setting the latitude dial to the local latitude
moves the lubber's ring and the transmitter
stator so that the compass card and the repeaters indicate the true angle between the
angle is called the VIRTUAL MERIDIAN. The
difference between the virtual meridian and the
ship's heading and geographical north.
true meridian is the sum of two errors: the
tangent-latitude error, and the speed-courselatitude error. Other errors caused by roll and
pitch of the ship and acceleration are also
preseilt, But because these errors are small,
SPEED-COURSE-LATITUDE ERROR
The magnitude of the speed-course-latitude
error depends upon the speed, course, and latituck, of the ship. The gyrocompass tends to be
north- seeking because north is at right angles
to the west-to-east direction in which the earth's
rotation carries the compass. The gyrocompass
thus tends to settle with its axle at right angles
to its plane to travel through space at all times.
A compass on the earth's surface is carried
from west to east only when it is stationary with
and come and go, they are not corrected when the
virtual meridian is being determined.
TANGENT LATITUDE ERROR
The tangent latitude error is the direct consequence of the method used in the Sperry compass to damp the horizontal oscillations of the
gyro axle. At the equator the compass settles in
respect to the -earth's surface, or when it is
moving true east or true west. If any component
of the course is north or south, the plane of motion is no longer west to east.
the meridian with its axle horizontal and with
equal amounts of mercury in each tank. In any
other latitude a torque must be applied to the
gyro to keep it continually precessing or the gyro
will leave the meridian because of its rigidity of
plane and the earth's rotation. For the compass
to reach a settling point, the north axle must be
tilted upward in northern latitudes and downward in
southern latitudes.
The upward tilt of the axle in northern latitudes causes an excess amount of mercury to
collect in the south tanks. As previously explained, the point of connection between the
mercury ballistic and the rotor case is offset
a short distance east of the vertical axis to provide damping. Therefore, the excess mercury
in the south tanks exerts a force through the
offset connection that applies a torque simultaneously about both the horizontal and vertical
axes. The downward precession tending to tilt
If the
ship travels on any other than a
true east or true west course the ship's motion
carries the compass in some direction other
than west to east. In this case the compass
seeks a new resting position away from the true
meridian. This position is at right angles to
the plane containing the path of the compass.
The speed-course-latitude error is westerly
if any component of the ship's course is north.
Conversely, the speed-course-lattitude error is
easterly if any component of the ship's course is
south. The magnitude of this error is proportional to the latitude, the speed, and the course
of the ship. The direction of this error is determined by the ship's course.
Compensation for Errors
the north axle below the horizontal is offset
by the earth's rotation tending to tilt the axle
upward. This action prevents the torque produced 'uy the mercury ballistic from bringing
the axle horizontal and in the meridian. The
north axle leads or lags the meridian just
enough to keep the gyro precessing at a constant rate. The angle between the meridian and
the settling position is called the TANGENT
and
The Sperry compass is provided with a speed
latitude corrector to compensate for the
speed, course, latitude error and an auxiliary lati-
tude corrector that compensates for the tangent
latitude error. The speed and latitude corrector
consists of a stationary plate (fig. 12-38) on
which are engraved several speed curves, and
a movable plate on which are engraved various
latitudes. The movable plate is controlled by
means of an adjusting knob. The corrector is
LATITUDE ERROR. This error is compensated
for in the Sperry Mk 11 Mod 6 gyrocompass
set by turning the adjusting knob until the mark
336
t
348
Chapter 12
GYROCOMPASSES, PART I
ut/mSE Anti
[conHer 171
GEAR
AuxIL 'AMY
LATITUDE
SCALE
ISTEP-OYSTEP1
MOTOR
SPEED AND LATITUDE
[AUXILIARY LATITUDE
CORRECTOR SETTING KMOU
CORRECTOR SETTING KNOB
40.49
Figure
12-38. Speed-course-latitude
correction mechanism.
indicating the local latitude intersects the speed
curve corresponding to the ship's speed. When
set to the proper speed and latitude, the corrector
automatically shifts the lubber's line in the right
direction and the proper amount to compensate
course arm (fig. 12-34) forward or aft. The
movement of the arm operates a system of
levers that automatically shifts the lubber's
line the proper amount and in the right direc-
latitude.
On a northerly course, the cam is in its most
forward position and the maximum correction
for speed and latitude is applied to the lubber's
for ship's speed and earth rate at the local
Changes in ship speed may be automatically
introduced into the corrector mechanism by an
automatic speed corrector unit associated with
the Sperry Mk 11 Mod 6 gyrocompass. A speed
input from the ship's underwater log positions
a step-by-step transmitter in the automatic
speed corrector (fig. 12-39). The step-by-step
tion to compensate for ship's course.
line.
When the speed and latitude corrector is set
to the proper speed and latitude, and is combined with this automatic course compensating
transmitter drives the step-by-step motor (fig.
12-38) to position the corrector mechanism.
The effect of the ship's course on the speed,
feature, the total resultant correction for the
speed, course, latitude error is transmitted to
pensated for by an eccentric groove, or COSINE
amount of the resultant correction. The movement of the lubber's line ring shifts the stators of
the synchro transmitters so that the repeaters
and the compass cards indicate the true heading
on all courses.
course, latitude error is automatically comCAM cut into the upper surface of the large
azimuth gear which is located below the small
azimuth gear. As the ship turns around the compass, the cosine cam moves a follower, or
the lubber's line. The lubber's line then moves
automatically to port or starboard the exact
337
349
IC ELECTRICIAN 3 & 2
a_ more gradual change of the same amount
results in a smaller force being exerted for a
longer time. The total precession in either case
is the same. The precession resulting from such
a force is called BALLISTIC DEFLECTION.
When the ballistic deflection is exactly equal to
the change in the speed, course, latitude error
for a change in speed or course, the compass
settles quickly in the virtual meridian and there
is no error iri its indication. When the ballistic
deflection is not equal to the change in the speed,
course, latitude error, the resulting error is
called the BALLISTIC DEFLECTION ERROR.
This error consists of a series of decreasing
oscillations across the normal settling point of
the compass. Therefore, it cannot be corrected
by shifting the lubber's line or the compass
card.
LATITUDE
ADJUSTING KNOB
40.48
Figure 12-39.Sperry automatic speed corrector.
Sperry compasses that are used for navigation are constructed with a fixed undamped
period of about 85 minutes at 40.7° latitude.
Hence, there is no ballistic deflection error at
40.7° latitude with this period. In fact, the error
at any latitude is small and does not affect the
accuracy of navigation to any great extent.
Compasses that are used for fire control
BALLISTIC DEFLECTION ERROR
The ballistic deflection error is dependent
upon the rate of change of the ship's speed or
course. It is a transient error that is introduced
into the compass only during changes of speed
or course. The gyrocompass is subjected to the
action of the forces of inertia when a ship changes
speed or course.
When a ship steaming north increases its
speed, the mercury in the mercury ballistic is
forced aft, or to Uie south, by the effect of its
inertia. A portion of the mercury in the north
container flows to the south; the south container
becomes heavier and a downward force of gravity
is exerted on the south end of the rotor axle. A
similar force acts on the pendulous weight compass and pushes south at the bottom of the rotor.
This is equivalent to a downward force on the
north end of the axle.
In either case, fortunately, the direction of
the force is such as to cause the compass to
precess toward a settling position which compensates for the new speed-course-latitude error.
The force is exerted during the time in which the
change is being made and its strength is pro-
portional to the rate of the change. Thus, a rapid
change in speed results in a comparatively large
must maintain a constant and accurate indication of the ship's heading. This condition is
accomplished by maintaining a period of about
85 minutes in all latitudes. On these compasses
the mercury ballistic is constructed so that the
tanks can be set closer to, or farther from,
the horizontal axis about which they operate.
At the equator, the tanks are set in their innermost position. For north aad south latitudes
where the period would normally be longer, the
tanks are set farther out. This adjustment pro-
vides the additional torque necessary to cause
a faster rate of precession and thereby shorten
the period. To set the ballistic for any latitude,
a knob (thumb wheel) mounted on the ballistic
frame (fig. 12-27) is turned until an attached
scale indicates the correct latitude.
AUTOMATIC CORRECTION DEVICES
The Sperry Mk 11 Mod 6 gyrocompass is provided with two automatic devices associated with
error correction. They are (1) an automatic
speed corrector associated with speed course,
latitude error correction, and (2) an automatic
damping eliminator which prevents the introduc-
tion of ballistic damping errors during rapid
force being exerted for a short time, whereas
changes in ship's speed or course.
338
250
Chapter 12GYROCOMPASSES, PART I
be set into the compass. This correction is transmitted to the step-by-step motor on the compass
by a step-by-step transmitter driven by the followup motor that rotates the cam. The followup
AUTOMATIC SPEED CORRECTOR
The Sperry automatic speed corrector (fig.
12-39) automatically transmits corrections for
the ship's speed to the speed correction mech-
motor elso drives a centrifugal type dampingeliminator switch to eliminate damping during
anism on the master compass. The step-bystep motor geared to the corrector spindle on
rapid changes in speed.
the speed correction mechanism (fig. 12-38) is
The instrument (fig. 12-39) is provided with
a dial to indicate the ship's speed, graduated in
remotely controlled by a step-by-step trans-
mitter in the automatic speed corrector. A switch
is mounted on the compass for opening the motor
knots, and visible through a window in the cover.
The latitude adjustment, which determines the
lengthwise position of the three-dimensioned
cam, is shown on another dial, also visible
circuit when setting the correction device by
hand.
The automatic speed corrector is mounted
on the bulkhead in the vicinity of the master
through a window in the cover.
compass.
The ship's speed is introduced into the auto-
AUTOMATIC DAMPING ELIMINATOR
matic speed corrector by a synchro motor controlled by the underwater log. In operation, the
rotor of the synchro motor takes a position representing the ship's speed and correspondingly
locates a pair of trolleys bearings on a follow-up
ring assembly (fig. 12-40).
When the position of the trolleys is not on
the gap in the followup contact rings, the followup
The Sperry compass uses a mercury ballistic
connected slightly east of the true vertical axis
of the gyro to damp the oscillations across the
meridian, or about the vertical axis, as stated
previously. The slight error introduced by this
damping arrangement during changes in speed or
course is called the BALLISTIC DAMPING ER-
motor is energized. The motor drives a three-
ROR. This error, like the ballistic deflection
error, oscillates and is a temporary error.
The ballistic damping error is eliminated in
synchronism with the trolleys. The cam is designed so that when it is correctly positioned
lengthwise for the local latitude, the amount it
must turn to synchronize the trolleys and rings
is proportional to the speed correction that must
the Sperry Mk 11 Mod 6 gyrocompass by means
of an automatic damping eliminator. This device
automatically moves the mercury ballistic connection arm from the offset position to the true
vertical axis of the gyro whenever a change in the
ship's course is greater than 15° and faster than
dimensioned cam, which, by means of a follower
and gears, drives the followup contact rings into
40° per minute, or whenever the ship's speed
changes faster than 2 knots per minute. Moving
this offset connection to the true vertical axis
II5V AC
TROLLETDRIveN
eliminates the torque about this axis caused by the
centrifugal force and prevents the compass from
By SyNGNRO,
going through a damped oscillation. A pushbutton is located on the bridge alarm indicator
FOLLOW UP
MOTOR
STEP-BY-STEP_
TRANSMITTER
FOLLOWER
II
Y._
(fig. 12-33) for manual elimination of damping.
The automatic damping eliminator (fig.12-41)
consists of two centrifugal governor-operated
switches, one geared to the azimuth motor, and
one to the followup motor of the automatic speed
corrector; and an electromagnet that moves the
mercury ballistic connecting arm from its offset
position to a true vertical position.
The governor switch geared to the azimuth
-,vTO STEP
MOTOR ON
MASTER
COMPASS
DAMPING
ELIMINATOR
SWITCH
GEAR BOX
LATITUDE ADJ
-.1-11113-DIMENSIONEDCAM
40.50
Figure 12-40.Schematic diagram of Sperry
automatic speed corrector.
motor takes care of changes in course where
no change in speed is involved. The governor
is driven through a gear train which speeds
the governor shaft to about 4300 revolutions
to one revolution of the phantom. To eliminate
constant starting and stopping of the governor
339
351
IC ELECTRICIAN 3 & 2
to eliminate damping during rapid changes in
ship's speed.
AZIMUTH MOTOR
I
11
OPERATION
LOST MOTION
MECHANISM
Operating the compass consists of starting,
stopping, adjusting correction devices, and making checks for any indications of abnormal operating conditions.
FLYBALL GOVERNOR
STARTING THE COMPASS
CONTACT
IISV RC
r
DAMPING ELIMINATOR MAGNET
TO CENTRIFUGAL SWITCH ON
AUTOMATIC SPEED CORRECTOR
40.51
Figure 12-41. Schematic diagram of Sperry
automatic damping eliminator.
when the ship is yawing, a lost-motion me-
chanism and a helical driving spring are inserted between the switch driving gear in the
azimuth motor train and the first gear in the
train to the governor shaft. As the ship yaws,
the lost-motion mechanism comes into play.
This mechanism prevents transmission of motion
to the governor shaft.
If the ship turns more than 15 degrees, the
helical spring is wound in one direction or the
other until there is sufficient tension in the spring
to set the governor in motion. As the governor
spins, the balls fly up, raising a sliding collar on
the governor shaft which engages an arm operating the riagnet circuit contact, thus closing
the 115-volt d-c supply circuit to the damping
eliminator magnet.
A friction brake on the governor, and a spring
disk friction clutch in the gear train, prevent the
governor from spinning too fast. The contacts are
adjusted so that the circuit is closed when the
ship turns at a rate of more than 40 degrees
per minute.
The gearing arrangement from the azimuth
motor through the lost motion device to the fly-
ball governor is also shown in figure 12-34.
The damping-eliminator switch (fig. 12-40)
driven by the followup motor in the automatic
speed corrector operates in a similar manner
352
If possible the compass should be started at
least four hours before it is needed. Before
checking the compass make sure that all switches
on the compass and repeater switchboards are off.
Ensure that the gyro case lock and vertical ring
lock (fig. 12-25) are in the locked position, and
that the vacuum gage (not shown) indicates approximately 28 inches. Take hold of both sides of
the phantom and vertical rings and turn slowly
until the compass card indicates the approximate
heading of the ship. Never turn the compass by
exerting pressure on the compensating weights
or mercury ballistic. Check the oil sight glass to
ensure that the rotor bearings will be tupplied
with oil. Set the auxiliary latitude corrector, the
speed and latitude corrector, and the ballistic
latitude adjustment to the proper settings (discussed later). After completing the above checks,
preceed to start the compass as follows:
1. After closing the necessary supply switches
on the IC switchboard, turn the motor-generator
transfer switch on the control panel (fig. 12-32)
to the motor-generator set desired.
2. Press the starting pushbutton, turn the
compass rotor switch to the motor-generator
set in use, then close '.he d-c service switch.
3. When the gyro rotor has been running for
about 30 minutes, close the followup supply
switch, then wait approximately 15 minutes for
the gyro rotor to come up to normal speed.
Normal speed will be indicated by a reading of
approximately 60 volts of the compass rotor
supply voltmeter (fig. 12-32), and from 2 to 3
amperes on the compass rotor supply ammeter
when the voltammeter selector switch is in the
number 1 phase position.
4. Release the vertical ring lock, then release the gyro case lock. Be sure to release
the vertical ring lock first.
5. Turn the azimuth motor supply switch on
the control panel to ON, and note whether the
340
Chapter 12GYROCOMPASSES, PART I
azimuth motor starts operating. It may be neces-
sary to press the azimuth motor cutout detent
release (fig. 12-32) to complete the circuit
to the azimuth motor.
6. Turn the battery generator transfer switch
on the battery throwover panel to the motorgenerator set in use, close the battery switch,
and adjust the battery charging rate with the
voltage adjusting rheostat.
7. Level the rotor case, then precess the
compass to the approximate heading of the ship.
To level the rotor case, apply a slight pressure
on one side of a rotor case bearing housing as if
to turn the compass in azimuth. If the rotor case
starts to tilt in the wrong direction, apply the
pressure to the other side of the housing. To precess the compass in azimuth, apply a slightdown-
ward pressure from the top of the rotor case
bearing housing. If the compass starts to precess
in the wrong direction, apply the pressure upward
from the bottom of the housing.
8. Close the repeater supply switch on the
IC switchboard (not shown), the 24-volt alarm
switch on the battery throwover panel, (fig. 1232), and the rotary switches for the relay trans-
mitter supply and differential alarm relay on
the relay transmitter repeater panel, (not shown).
9. Close the switch on the relay transmitter
(fig. 12-36A).
10. Close the followup switch on the relay
transmitter amplifier panel (fig. 12-32), wait
about one minute for the tube filaments to heat
up, then close the azimuth motor switch. The relay transmitter should synchronize immediately
to the same heading as the master compass.
11. Close the toggle switch on the differentia:
alarm relay (fig. 12-37B), and turn on all repeaters.
SETTING CORRECTION DEVICES
The gyrocompass operator must ensure that
all error correction devices are properly set
before starting the compass. While the ship is
underway; he is further concerned with adjusting
these devices. For the Sperry Mk 11 Mod 6 gyrocompass system, these devices include the speed
and latitude corrector, the automatic speed cor-
rector, the auxiliary latitude corrector, and t".e
ballistic latitude adjustment.
Speed and Latitude Corrector
To set the speed and latitude . corrector
(fig. 12-38), without utilizing the automatic speed
corrector, turn the knurled knob at the upper
center of the corrector until the point on the
latitude scale corresponding to the local latitude intersects the speed curve corresponding
to the ship's speed. For maximum accuracy
the corrector should be kept within 2 degrees
of the local latitude and within 2 knots of the
ship's speed. It is impractical, however, to
attempt to keep the speed settings within these
limits witout utilizing the automatic speed corrector.
'ro put the automatic speed corrector in
operation, set the speed and latitude corrector
at zero, and turn the corrector step-by-step
motor switch to ON. After the ship is under-
way and the underwater log is in operation, turn
the switch on the upper right side of the automatic speed corrector to ON. Set the corrector
to the local latitude with the latitude adjusting
knob. Adjust the latitude setting when the ship's
latitude changes as much as two degrees or as
ordered by the ship's navigator.
Auxiliary Latitude Corrector
To set the auxiliary latitude corrector, turn
the smaller knurled knob on the right side of the
corrector (fig. 12-38) until the line engraved
on the large gear segment coincides with the
point on the latitude scale corresponding to
the local latitude. Change this adjustment for
changes in ship's latitude of 2 degrees, or as
ordered by the ship's navigator.
Ballistic Latitude Adjustment
To make the ballistic latitude adjustment,
turn the knurled latitude setting thumbwheel
(fig. 12-27) until the pointer on the ballistic
frame points to the local latitude on the latitude scale located on top of the mercury reservoir. Make the same adjustment on the opposite side of the ballistic. Make these
adjustments for changes in latitude of 10degrees,
or as ordered '.)3, the ship's navigator.
STOPPING THE COMPASS
To stop the Sperry Mk 11 Mod 6 girocompass, proceed as follows:
1. Turn the switch on the automatic speed
corrector, and the step-by-step speed corrector
motor switch on the master compass to OFF.
2, On the battery throwover panel (fig. 1232) open the 24-volt alarm switch, the battery
switch, and the battery generator transfer switch.
341
353
IC ELECTRICIAN 3 & 2
3. Open the toggel switch on the differential
alarm unit, then open the azimuth motor switch
and the followup switch on the relay transmitter
amplifier panel.
4. Open all repeater switches, and the rotary
switch for the differential alarm unit.
5. Open the azimuth motor supply switch on
the control panel, then lock the gyro case, and
vertical ring locks (fig. 12-25). Be sure to lock
the gyro case lock first.
6. On the control panel (fig. 12-32), open the
followup supply switch, the d-c service switch,
the compass rotor switch, and the motor generator transfer switch.
7. Open the repeater supply, and control
panel supply switches on the IC switchboard,
(not shown).
INDICATIONS OF NORMAL OPERATIONS
more accurate operation above 60 degrees lati-
tude. Parts of the compass which have been
changed are the mercury ballistic, the auxiliary
latitude corrector, the speed and latitude correction, and the automatic speed corrector.
The modified mercury ballistic has larger
pots and an enlarged frame. The mounting of
the pots permits them to be swung through an
arc of 136 degrees instead of 110 degrees of the
former unit. A valve between one pair of pots
permits these to be disabled when the ship is
operating below 60° latitude. There are two
latitude scales for each set of pots; a green
scale for latitudes 0 to 60 degrees, and a red
scale for 60 to 80 degrees. The south-west
and the north-east pots have green scales; the
north-west and south-east pots have the highlatitude red scales.
A knurled nut moves the pots through a
Normal operating conditions for the compass
worm and sector gear. When the ship is at
the Equator, the pots are turned in close to
meters and overload indicators on the gyrocompass switchboard. Normal readings for the elec-
the nut to move the pots out, until they are fully
extended at a latitude of 60°. If the ship continues
system are indicated by the various electrical
trical meters are listed in the manufacturer's
technical manual.
As these readings may vary slightly for
different installations, the average meter readings during actual normal operation should be
recorded and used as the normal readings.
Normal operating conditions are also indicated by the gyro case level and vacuum gauge
On the sensitive element, and the presence of
the blue flame in the compass followup and relay transmitter power amplifier thyratrons.
Study the gyrocompass installation on your
ship and become familiar with all indications
of normal operation. This will enable you to
recognize and abnormal condition immediately.
HIGH LATITUDE MODIFICATION
The Sperry Mk 11 Mod 6 compass described
in
this chapter has been modified to permit
the case. As latitude increases, you must turn
to higher latitudes the second pair of pots is
activated, all pots are swung in, and adjusted
outward again as latitude increases to 80°.
The new scale on the auxiliary latitude corrector is calibrated from 0 to 60 degrees in green,
and from 60 to 80 degrees in red. The new scale
makes it easy to adjust the lubber's line at the
higher latitudes. The speed and latitude corrector also has a modified scale to facilitate its
adjustment. A red engraving on this scale is for
use above 70 degrees of latitude.
You must take care in adjusting this compass
when you move to and from the higher latitudes.
The correction devices must be properly set,
and operators must note which scale is in use.
Before closing the valve to disable the auxiliary
pots when returning to lower latitude operation,
be sure the compass is level, so the pots will
contain an equal amount of mercury.
CHAPTER 13
GYROCOMPASSES, PART II
The Navy's need for a compact, rugged,
An electronic followup system is provided
low-voltage gyrocompass led to the development which furnishes accurate transmission of lof the Mk 23 gyrocompass by the Naval Ship and 36-speed heading data.
Systems Command in conjunction with the Sperry
The system consists of tiie master unit,
Piedmont Company. This "latest development" control cabinet, speed unite, alarm control, and
gyrocompass applies the gyroscopic principles the alarm bell, and compass failure ai...anciator
discussed in the preceding chapter, and incor- as shown in figure 13-1.
porates some major changes in gyrocompass
design, such as the electronic control system MASTER UNIT
and a sensitive element suspended in oil. This
The master unit (fig. 13-1) consists of a
serves as a representative gyrocompass, and shock mounted oil filled binnacle and the gyro-
chapter concerns the Sperry Mk 23 Mod 0, which
explains how its many components and systems
function and how it can be operated.
compass element. The unit is designed for deck
mounting and the compass element is gimbaled
in the binnacle so as to have a freedom of ±45
degrees about the roll and pitch axes. The
SPERRY MK 23 MOD 0 GYROCOMPASS
By design, the Sperry Mk 23 Mod 0 gyrocompass is small and capable of withstanding
the severe operating conditions encountered in
amphibious craft and submarines without sacrificing its primary function cs.f furnishing accurate heading data. It is also used as an auxiliary gyrocompass aboard larger combatant
ships. The force of gravity, instead of acting
directly to control the compass, merely acts
sensitive element has a freedom of +70 degrees
about its horizontal axis. Heaters in the binnacle
keep the oil 'bath at a temperature of 100° F,
and drain plugs are provided in the lower bowl
for draining the oil. The complete master unit
weighs approximately 100 pounds.
Gyrocompass Element
The gyrocompass element is the principle
of the compass system and consists of
on a special type of electrolytic bubble level (grav- three basic elements: the sensitive element,
ity reference) which generates a signal propor- phantom element, ard the spider element.
tional to the tilt of the gyro axle. This signal,
unit
THE SENSITIVE ELEMENT. The sensitive
after amplification, is used to apply torque
electromagnetically about the vertical and/or element (fig. 13-2) consists of the vertical ring,
horizontal axes to give the compass the de- adapter ring, and gyrosphere.
sired period and damping. The gyro unit is enclosed in a sphere called a gyrosphere, and is
The gyrosphere is pivoted about the vertical
axis within the vertical ring. The vertical ring,
in turn, is pivcted about the horizontal axis in
The compass is compensated for speed er- the adapter ring. At riru' angles to the vertical
ror, latitude error, unbalance, and Lupply volt- ring is a horizontal ring, carrying the pivots
age fluctuations. In addition to the normal op- about which the vertical ring and gyrosphere
erating range of latitudes, the compass incor- rotate. The horizontal ring also provides surporates controls which make it suitable for ac- faces for mounting the electrolytic level (gravcurate operation in high latitudes, and as a ity reference), followup pickoff, and leveling
torquer.
dirntional gyro near the poles.
suspended in oil.
3
n
IC ELECTRICIAN 3 & 2
ALARM BELL
ALARM
SPEED UNIT
CONTR74WL
ANNUNCIATOR
CONTROL CABINET
MASTER UNIT
7.167
Figure 13-1.
Mark 23 Mod 0 gyrocompass equipment.
35d44
Chapter 13GYROCOMPASSES, PART II
GYROSPHERE
VERTICAL
RING
ELECTROLYTIC
LEVEL
FOLLOW-UP PICKOFF
AZIMUTH
CONTROL
TORQUER
EXCITATION
TRANSFORMER
.af
41.
elm
ADAPTER
RING
HORIZONTAL
AXIS BEARINGS
Figure 13-2. Sensitive element.
The adapter ring provides mounting surfaces
for the azimuth control torquers, the horizontal
axis bearings, and the excitation transformer.
In addition, the adapter ring provides a method
of mounting the sensitive element to the phantom
bowl, which provides for ready replacement of the
sensitive element if the need should arise.
The gyroshpere is the heart of the whole
system, as it encloses the gyro and is the
north-seeking part of the compass. It is composed of a center ring called the equator and
two hemispherical shells (fig. 13-3). The gyro
unit is driven by a 2-pole, 115-volt, 400-cycle,
3-phase squirrel cage induction motor. The
rotor speed is approximately 23,600 rpm and
the direction is clockwise when viewed from
7.175
the south end. The gyro is hermetically sealed
within
the sphere and the complete unit is
suspended in oil. The gyrosphere is evacuated
and partially filled with helium gas, which serves
to transfer the heat generated by the gyro motor
windings to the surface of the sphere.
When the weight and buoyancy of the gyro
are properly adjusted in the oil, no load is
placed on the vertical pivots, the vertical bear-
ings serving only as guides for the sphere.
This liquid suspension eliminates the effect of
shifts of the center of mass of the sensitive
element with respect to the suspension axis.
Liquid suspension also serves to protect the
gyro from destructive shocks which are absorbed by the oil-filled compass enclosure,
345
357
IC ELECTRICIAN 3 & 2
Figure 13-3. Exploded view of gyrosphere.
and the acceleration effects on the sensitive
element are minimized because the center of
gravity and center of buoyancy coincide. In
addition to eliminating the load on the vertical
pivots, oil flotation greatly reduces the load on
the horizontal axis pivots. Only the weight of
the vertical ring and its components, which are
also reduced in weight due to partial flotation,
loads the horizontal bearings.
PHANTOM ELEMENT. The phantom element (fig. 13-4), is a bowl-shaped casting sup-
7.173
carries the bearings supporting the phantom
and caging mechanism. The eager is solenoid
operated, and fits up into the hollow shaft of
the phantom. Mounted on the spLler are the
1- and 36-speed synchro heading data transmitters, the followup motor, and the speed
resolver. The spider supports the phantom,
gyrosphere, and vertical ring assembly. The
spider, in turn, is supported by the gimbal
ring and the complete gyrocompass element
(fig. 13-6) is gimbaled in the binnacle by a
gimbaling system.
ported on ball bearings, located within the spider,
and rotates about the vertical axis of the gyro-
sphere. A the ship turns with respect to the
gyrosphere, the phantom is servomotor driven
by the followup system so as to always maintain
the horizontal axis of the vertical ring at right
angles to the gyro axle (fig. 13-5). The phantom
element mounts the azimuth gear and slip rings.
SPIDER ELEMENT. The spider element
(figs. 13-4 and 13-5) is a cast member having
two ribbed arms carrying pivots which fit in
bearings on the gimbal ring. The lower section
346
358
CONTROL CA BINE T
The control cabinet (fig. 13-1) contains all
the equipment required for operating and indicating the condition of the master compass
except the compass failure annunicator and
alarm bell. It houses the control panel, control amplifier, followup amplifier, and power
supply.
SPEED UNIT
The speed unit (fig. 13-1) contains the nec-
essary components to produce an electrical
Chapter 13GYROCOMPASSES, PART II
a
\
0000
z.31.1.
---
PHANTOM
AZIMUTH
UPPER PHANTOM BEARINGS
SLIP RINGS"",-1 SPEED SYNCHRO
HEADING DATA
z
36-SPEED SYNCHRO
HEADING DATA
TRANSMITTER
TRANSMITTER
SPEED
RESOLVER
FOLLOW-UP
,i0TOR
RECTIFIER
40//F-
:71:164` LOWER PHANTOM BEARING
PHANTOM RETANING NUT
GAGER
27.159
Figure 13-4. Exploded view of phantom, spider, and cager.
347
359
IC ELECTRICIAN 3 & 2
GRAVITY REFERENCE SYSTEM
GYRO
VERTICAL
RING
COLLOWJP PCKC),%,
The gravity reference system consists of
the electrolytic bubble level, excitation transformer, and tilt signal amplifier.
,...,,,
PHAN7011
1
\\
SPHERE --..\<\
A)(12
The electrolytic bubble level (fig. 13-2) is
mounted on the horizontal pivots, so that it is
parallel to the gyro axle. It is a cylindrical
glass vial containing three platinum electrodes,
the vial being nearly filled with an electrolyte
so that a bubble is formed at the top of the vial
(fig. 13-8). When the vial is horizontal, the
bubble is centered, and the resistance between
the t. etectrode and either lower electrode is
equal. If the vial tilts so that the bubble moves
to the
I, there is less electrolyte between
the top electrode and the lower left electrode
and consequently the resistance between the
two is increased. The resistance between the
"'-.'-
\,,
3V.uP ,>
Con ploy
-11J(,,xED
SPIDER
,
_=-0Licmup
yDroR
S..P BY GRIBaLsy
HEADING
SYNCHRO
'RANS11,'-ER
F 0,L3A UP
GEAP
4,EADV4G DATA
7.174
Figure 13-5.
Followup controls.
top and lower right electrode is correspondingly
decreased, the difference in resistance beingproportional to the movement of the bubble.
signal proportional to the ship's speed, as will
be discussed later. Speed data is received from
the ship's underwater log equipment, or set in
The two lower electrodes are excited from
the opposite ends of the output winding of the
excitation transformer T102 mounted on the
adapter ring. One phase of the 400-cycle, 115 volt, 3-phase power supply excites the excitation transformer primary winding. The tilt
signal output from the electrolytic bubble level
is obtained between an accurately determined
center-tap (signal common) of the excitation
transformer secondary and the top electrode.
When the level is horizontal, the voltage between the top electrode and either lower electrode are equal and opposite and the tilt signal
manually. Speed range of the unit is 0 to 40 knots.
ALARM CONTROL
The alarm control (fig. 13-1) contains the
necessary relays and components to actuate a
flashing light or bell alarm when certain portions of the system become inoperative.
ALARM BELL AND ANNUNCIATOR
output is zero. When the level is tilted from
the horizontal, an output signal voltage will be
produced which is proportional in magnitude to
The alarm bell (fig. 13-1) is a standard
Navy B-10 bell. A Navy type B-51 or B-52
alarm panel may be used in place of the an-
amount of tilt and with the phase or instantaneous polarity of the voltage dependent
the
nunciator. The alarms are actuated by the alarm
upon the direction of tilt.
The tilt signal amplifier is included in the
control panel portion of the control cabinet,
and is used to amplify the tilt signal before it
is supplied to the leveling and azimuth control
systems. The amplifier consists of a pentode
stage (V301 fig. 13-8) and two cathode fol-
control and either the bell or annunciator, or
both, may be used to indicate system failure.
MK 23 GYROCOMPASS CONTROLS
All controls for the Mk 23 gyrocompass
(fig. 13-7) may be divide I into two
systems, the compass control system and the
followup system. The compass control system
may be further divided into three separate
systems: the gravity reference system, the
azimuth control system, and the leveling control system.
lowers (V302A & B) one for the damping signal
and the other for the meridian control signal.
In addition to its normal 90-minute compass
period with 65 percent damping, the compass
includes a 30-minute settling period with 90
percent damping, which greatly reduces the
time required for the compass to settle on the
meridian after starting. The operation switch
system
348
f
360
Chapter 13 GYROCOMPASSES, PART II
ELECTROLYTIC
LEVEL
VERTICAL
RING
GYROSPHERE
LEVELING
TORQUER
ADAPTER
RING
( PHANTOM)
AZIMUTH
CONTROL
TORQUER
GIMBAL
RING
.gec;44 "Pf
SPEED
RESOLVER
1 SPEED HEADING
DATA TRANSMITTER
`SPIDER
Figure 13-6. Gyrocompass element.
S302, in conjunction with the
tilt signal am-
plifier, alters the amplification of the tilt signal
to obtain these two operating conditions.
The tilt signal is fed to the grid of V301
through the series grid resistor R301, and blocking capacitor C301. Cathode bias for V301 is ob-
tained from a voltage divider, R303 and R304
connected across the plate supply. The output of
27.160
V302B is fed back from the cathode through blocking capacitor C302 to the common connection be-
tween the plate load resistors R305 and R306 of
V301. This feedback is of the same phase as the
plate signal of V301 and therefore changes the po-
tential at the common connection of R305 and
R306 at the same time and in the same direction
as the tilt signal input changes the potential at
the plate end of R306. Thus, the voltage drop
across R306 is maintained constant. This feature
V301 is fed to the grid of the meridian control signal cathode follower V302B. Potentiometer R310
in the cathode circuit of V302B provides a method
of adjusting the magnitude of the meridian control
ensures that the V302B grid will remain negative
with respect to the cathode and will not draw cur-
signal. This adjustment is set at the factory and
should not be changed. A portion of the output of
R306 is also reduced by negative feedback to the
rent. The change in voltage at the plate end of
screen grid through voltage divider R307 and
361 349
IC ELECTRICIAN 3 & 2
MERIDIAN
CONTROL
DAMPING
SIGNAL
BALANCE
COMPENSATION
S HIGH
X
S3071-7.3
SIGNAL
10
0
T302
N HIGH
ELECTROLYTIC
LEVELING
BUBBLE LEVEL
CONTRMPL O
VERTICAL
RING
LEVELING
TILT
SIGNAL
GYM',
TORQUER
400^.
(GRAVITY
REFERENCE)
FOLLOWUP PICKOFF
RI
Z
FROM
T 302
R2
SPIDER
VERTICAL
EARTH
RATE
COMPENSATION
(FIXED TO SHIP
BY GIMBALS)
SPHERE
B301
LATITUDE CONTROL KNOB
FOLLOWUP
AZIMUTH CONTROL
TORQUER
COMPL
NTRO
FOLLOWUP
MOTOR
SPEED RESOLVER
NORTHERLY SPEED
X
RESOLVER
Z
`n
HEADING SYNCHRO
TRANSMITTER
o sn
HEADING DATA
SPEED
UNIT
7.170
Figure 13-7. Simplified diagram of Mk 23 gyrocompass with all controls.
R308 to ground. The gain of the tilt signal amplifier without negative feedback is about 2000. The
gain required for the 30-minute setting period is
90 and a gain of 10 is needed for the normal 90-
minute period. To obtain the required gain for
both periods, another feedback loop is provided
from the V302B cathode through C304, R309,
R302, and C301 to the V301 grid. For the 30minute period (operation switch S302 (A) in the
SETTLE position) both resistors R309 and R302
are in the feedback loop and the amplifier gain is
90. For the 90-minute period (operation switch
8302(A) in the NORMAL position) resistor R309
is shorted out and the amplifier gain is 10.
The meridian control signal is obtained from
the cathode of V302B and is fed through R310,
C305 and operation switch S302(B), which connects the meridian control signal to the azimuth
control amplifier during the normal and settle
modes of operation.
The meridian control signal obtained from the
V302B cathode is applied to the V302A grid. Potentiometer R311 in the cathode circuit, provides
a factory adjustment of the damping signal. The
damping signal is coupled through C306 to the
voltage divider R317 and R318. The operation
switch S302(C) connects the proper damping signal network for the mode of operation selected.
During the settle mode of operation the signal is
taken from the voltage divider giving the compass
90 percent damping. During level, normal, and
directional gyro modes of operation the signal is
taken via C306 from potentiometer R311. As the
gain of the amplifier is increased during level,
settle, and directional gyro, the signal voltage
at R311 will be greater during these modes of
operation. The meridian control signal, however,
is disconnected by operation switch 5302 (B) during certain modes of operation as discussed later.
AZIMUTH CONTROL SYSTEM
The azimuth control system (fig. 13-9) consists of the latitude switch S308, balance sense
switch S307, latitude resolver B301, azimuth
control amplifier, and azimuth control torquers.
350
nC2
Chapter 13GYROCOMPASSES, PART II
ELECTROLYTIC
BUBBLE LEVEL
TILT SIGNAL AMPt IFIER
TILT SIGNAL
OPERATION SWITCH
KEY
+260V DC
FINE FILTERED
C - CAGE
UC - UNCAGE
+260 V DC
R305
FINE FILTERED
T102
v302A
I2AT7
L - LEVEL
S- SETTLE
N- NORMAL
OG - DIRECTIONAL
GYRO
C306 R317
R318
AA
vv.
R302
DO
UC
uc
TO FIG.13 -IO
OPERATION
SWITCH
DAMPING
SIGNAL
TO F10.13-9
S302
MERIDIAN
WNTROL
bIGNAL
27.162
Figure 13-8. Simplified schematic diagram of gravity reference system.
The system functions to produce a torque about
gyro horizontal axis, causing precession
the
about the vertical axis toward the meridian,
thus making the compass north seeking.
To give the compass the same period both at
high and low latitudes, a latitude switch (S308), is
provided whi t alters the connection of the meridian control signal mixing resistors R601 and R602.
Above 75 degrees latitude the period of the Mk 23
compass lengthens considerably and the accuracy
is thereby impaired. Th Irectional gyro mode of
operation is for use when . these latitudes,In this
mode of operation the meridian control signal is
disconnected from the azimuth control amplifier
(by operation switch S302B fig. 13-8) andthegyro
operates as a free gyroscope corrected for vertical earth rate and speed.
The balance adjustment (fig. 13-9) is pro-
vided as a convenience for shipboard operation.
This adjustment permits the effects of mechanical unbalance in the master compass to
be corrected without actually making the me=
chanical adjustments. The balance adjustment
provides an electrical signal to the azimuth
control amplifier to compensate for any mechanical unbalance. Power is supplied for the
adjustment from the center tapped secondary
of T302 in the voltage compensator. Balance
sense switch S307 enables the operator to compensate for a north end high or south end high
of the gyro axle. Potentiometer R314 is used to
adjust the magnitude of the balance correction.
The effect of vertical earth rate causes the
gyro to move in azimuth with respect to the
earth as explained in the preceding chapter.
To compensate for this effect, a vertical earth
rate compensation circuit is provided consisting of a latitude resolver B301, potentiometer
R312, resistor R332, and capacitor C310 (fig.
13-9). Vertical earth rate effect is the product
of earth rate and the sine of the latitude. It
is maximum at the poles (equal to earth rate
itself) and zero at the equator. The input to
the system is latitude which is set in manually
by the latitude control knob on the control
panel. The rotor of the resolver B301, is excited from the secondary of T302. This voltage is used as the earth rate reference voltage.
The output voltage of the resolver (between S1
and S3) is the product of the excitation voltage
(earth rate voltage) and the sine of the angle of
the latitude control shaft displacement. This
voltage is proportional to the local vertical
351
c._ 3
ECONTROL
LATITUDE
4
C3I0
V E.R
R612
R2
RESOLVER
S3
8301
LATITUDE
SIGNAL
6.3
COMPENSATION
SIGNAL
BALANCE
R602
COMPENSATION
R314
R601
NhAr----
R604
V602A
12AT7
I
C603
R609
i
AZIMUTH CONTROL AMPLIFIER
VOLTAGE COMPENSATOR
R605
+ 260 V DC
FINE FILTEREO
V603
6A05
T601
SUPPLY
II5V, 4001.,
-C208
C207
TOROUERS
B104
AZIMUTH CONTROL
Figure 13-9.Simplified schematic diagram of azimuth control system and voltage compensator.
RI
SI
7ITCH
SENSE
BALANCE
S308
S387
N.HI H
CI
S HIGH
45
65
FI0.13-8
SIGNAL FROM TILT
SIGNAL AMPLIFIER
MERiOIAN CONTROL
27.164
).-c. GYRO
Chapter 13GYROCOMPASSES, PART II
earth rate. Potentiometer R312 across the resolver output is used to adjust and calibrate
the vertical earth rate signal. Resistor R332
and capacitor C310 compensate for the phase
light the lamp. In addition the compensator has
The voltage compensator shown in figure
operation. Failure of the ballast tube or power
shift in the resolver.
considered a part of the
azimuth control system, is essential to the
proper functioning of the system. If the voltage on the torquer fields should vary due to
13-9, although not
power line variations the torque produced would
consequently vary, and if not compensated for
would unsettle the compass. The method used
to compensate for power line variations is to
compensate the excitation voltages of the signal
sources. This compensation is such that the excitation voltages are changed by the same percentage as any power line change but in the opposite sense. If the power line voltage drops,
the excitation voltage rises. The net result is
that the torque produced by the torquers is constant.
The 115-volt 400-cycle power line voltage is
impressed across the series circuit inthe voltage
compensator consisting of resistors R319 and
R333, ancipallast current regulating tube V306 (fig.
13-9). Because of the constant current design of
the tube, the voltage across the series resistors
remains constant. The voltage change across V506
is the same as the voltage change of the power line.
The voltage across V306 is impressed onthe primary of the stepdown transformer T301. The volt-
age across the secondary of transformer T301 is
subtracted from the constant voltage drop across
the series resistors and the differ 'nce is impressed on the primary of excitation trans-
former T302. The output from the secondary of
T302 is fed to the various correction circuits. If
the power line voltage drops, the voltage across
V306 and, therefore, the voltages across the pri-
an alarm output voltage to an alarm iclay in
the compass alarm system. The relay is operated
by the voltage developed across resistors R319
and R333 which is about 70 volts during normal
line supply causes the relay to drop out and sound
the alarm. The voltage compensator supplies ex-
citation voltage for all compass control signals
except the tilt signal from the electrolytic bubble
level. The tilt signal is normally zero while the
other signals have a definite value other than
zero.
The azimuth control amplifier mixes three
input signals, amplifies the combined signal,
and supplies the control fields of the azimuth
control torquers. The amplifier (fig. 13-9) con-
sists of a triode input stage driving a pushpull output stage. Three signal voltages are
fed through mixing resistors so that the re-
sultant input signal to the V602A grid is the
meridian control signal compensated for compass mechanical unbalance, vertical earth rate,
and latitude. Capacitor C607 connected from
the plate of V602A to ground limits the high
frequency response of the amplifier and provides increased stability.
The output stage consists of two pentodes
V603 and V604 connected in push-pull. Output
transformer T601 is used to match the im-
pedance of the output stage to the tuned impedance of the series connected control fields
of the azimuth control torquers.
Capacitor C605 in series with L601 across
the secondary of T601 corrects the power factor
of the torquer load, and the inductor L601
alters the frequency characteristic of the amplifier and ensures stability. A negative feedback
voltage is taken from a tap on the secondary
of the output transformer and is fed back to the
V602A cathode. This feedback keeps the overall
voltage gain of the ampEfier to 2 and the maxi-
mary and secondary of T301 must drop. The voltage across resistors R319 and R333 however, remains constant. This means the sum of the voltage
drops across the secondary of T301 and the primary of T302 must equal the voltage drop across
mum power output to 5.5 watts.
The azimuth control torquers are the output
elements of the azimuth control system which
R319 and R333. For this condition to exist the
actually
decreases. Resistor R319 is adjustable to provide a method of calibrating or adjusting the
circuit. The indicator lamp 1302, connected across
V306 is a neon corrector failure indicator. When
the circuit is operating properly, the voltage
across the lamp will not be sufficient to cause
the lamp to glow; however, if the ballast tube
fails, the voltage across the lamp will rise and
353
;.:65
apply torques about the gyro hori-
zontal axis causing precession about the vertical axis or causing the gyro to turn in azimuth toward the meridian. The torquers are
located diametrically opposite each other on
the adapter ring, and are electrically connected to act together to produce the torque.
Each torquer consists of an open-E rack
structure of soft iron laminations, upon which
are wound a control field (on the 2 outer legs)
and a fixed or reference field (on the center
voltage across the primary of T302 must increase
when the voltage across the secondary of T301
IC ELECTRICIAN 3 & 2
r
1
SPEED CORRECTOR
A
SPEED UNIT 8701
OM
+260V DC
S2
1
1
1
A
1
FINE FILTERED
1
1
LEVELING AMPLIFIER
R615
I
FROM'
C604 R 619
1
1
SHIPS'
PIT
LOG I
1
V602
LEVELING TORQUER
53
0701
R6I4
C60
I
R701
oM 1
R2
ow. 0
Z
X
1A
200 V
1
D
CLOC SE
R6I6
1
FROM T302
FIG 13.9
1
R62I
1
,FILTERED
R618
1
1
MAN
C204
R2
1
RI
1 HEADING FROM
COMPASS PHANTOM
' GEARING
SPEED
RESOLVER
8108
1
S3
St
TILT
R313
115v 400.,
M301
SUPPLY
0
R331
152
0308
-at
TILT
NAL
AMPUFIER
FIG 13-8
.--UC
-0
UC
o-
5302 0205c20
T303
DAMPING SIGNAL
RSIGM
FO
INDICATOR
S306
115V 400.4 SUPPLY
3
R323
R320 ZERO CHECK
C307
1.0
C
0S30
C
3 AN
De
UC
A
SIMPLIFIED TILT INDICATOR CIRCUITS
27.164
Figure 13-10. Simplified schematic diagram of leveling control system and tilt indicator.
354
;36
Chapter 13GYROCOMPASSES, PART II
leg) displaced 90 degrees to form an arrangement similar to a 2-phase induction motor.
The control fields are excited from the azi-
muth control amplfier output and the fixed or
reference fields are excited from the 115-volt
400-cycle supply. When the torquer windings
are energized, a moving field is set up in the
air gap. This field induces currents in the vertical ring and a torque is developed that tends
to drag the vertical ring along with the moving
field. The magnitude of the torque is proportional to the strength of the signal fed to the
control windings, and the direction of the torque
depends upon the phasing of the control field
voltage which may lead or lag the fixed field
voltage by 90 electrical degrees. To obtain
the correct phase relationship between the control
and fixed fields, capacitors C207 and C208
shift the phase of the fixed field.
rotor of the resolver, B108. For manual op-
eration the input from the pitometer log is disconnected and the ship's speed is cranked in
manually by the manual control knob.
The rotor of the speed resolver is posi-
tioned by the azimuth gear on the phantom, and
thus represents the ship's heading. The re-
solver then functions to resolve the magnitude
of the voltage on its rotor representing ship's
it's northerly or southerly component. Thus the resolver output (between 51
and S3) is a voltage proportional to northerly
speed into
or ,southerly speed.
Potentiometer R313 provides a method of
adjusting the resolver output and is a factory
adjustment. Capacitor C701 serves to correct
the power factor of the speed signal.
The leveling amplifier (fig. 13-10) is similar to the azimuth control amplifier. It func-
LEVELING CONTROL SYSTEM
tions to amplify the damping signal and supply
the control field of the leveling torquer.
The leveling control system (fig. 13-10) consists of the speed corrector, the leveling amplifier, and leveling torquer. The system functions
The amplifier input is the damping signal from
the tilt signal amplifier, compensated for northerly or southerly speed, and is fed through resistor
R614 to the grid of V602B.
to apply a torque about the gyro vertical axis
causing the gyro to assume a level position.
If a ship is traveling on a north-south
course, as it follows the curvature of the earth,
the north end of the gyro would appear to tilt.
For a northerly course, the resultant tilt sig-
nal .will cause the gyro to precess to the west,
while a southerly course will cause precession
in the opposite direction. If the ship's course
is east-west, however, the ship's motion would
have no tendency to tilt the gyro as the ship's
direction of travel would be parallel to the
plane of the gyro. The rate of gyro tilt depends
upon the speed of the ship in a northerly or
southerly direction, and is equal to the ship's
speed times the cosine of the ship's course.
This tilt is compensated for in the Mk23 gyrocompass. by the speed corrector, which consists of a speed unit B701, and speed resolver
B108, (fig. 13-10).
The speed unit consists of a synchro geared
to potentiometer R701. Potentiometer R701 is
a precision linear potentiometer excited with a
fixed excitation voltage from the output of transformer T302 in the voltage cr. )ensator,
(fig. 13-9). For automatic operatio% the Onchro receives the ship's speed inpt -om the
pitometer log system, and position:. tentio-
meter R701 which results in a voltage drop,
proportional to ship's speed, across R701. A
portion of this voltage is impressed on the
Z67
The output stage consists of the dual triode
V601A and B. Output section V601A is excited from
the output of V602B and V601B is excited from the
secondary of output transformer T602.
The use. of part of the output from the transformer to excite V601B produces the proper phase
inversion for push-pull operation. Output transformer T602 also serves to match the impedance
of the output stage to the tuned impedance of the
leveling torquer control field.
Power factor correction and frequency characteristic alteration are accomplished by capacitor C606 and inductor L602 across the secondary
of output transformer T602. A portion of the output
is fed back as negative feedback to the input stage
V602B. The magnitude of the feedback limits the
amplifier voltage gain to 1, with an output power
of 1.5 watts.
The leveling torquer is the outputelement that
actually produces the torque about the gyro ver-
tical axis, causing the gyro to assume a level
position. It is mounted on the horizontal part
of the vertical ring. It is a duplicate of the azimuth
control torquers, and operates in the same
manner.
To reduce the time required to level the
gyro during the starting period, operation switch
5302D, in conjunction with capacitors C204, 205,
and 206, increase the leveling torquer fixed field
voltage. In all positions, except the levelposition,
3 55
IC ELECTRICIAN 3 & 2
the operation switch connects capacitors C204
and C205 in parallel across the torquer fixed
field. This arrangement produces about 6 volts
across the field with a 90-degree phase shift.
With the operation switch in the level position,
capacitor C205 is connected in parallel with
capacitor C206 and both are in series with the
fixed field. This connection produces about 60
volts across the fixed field, with the same 90degree phase shift.
During starting and operating, a visual in-
ring is continuously aligned with the plane of
the gyro. The system is a closed-loop servosystem in which a followup pickoff device between the vertical ring and gyrosphere
vides a misalignment signal to a followup amplifier. The followup amplifier amplifies the
signal and operates the followup or azimuth
motor which drives the phantom, Etna therefore the vertical ring, into alignment with the
gyrosphere. The followup motor driving through
compass level cannot be seen when the com-
the azimuth gearing also positions the synchro
heading data transmitter and the steed resolver
as indicated in figure 13-7.
provided on the front of the control panel.
To detect the direction of tilt, a full-wave
diode phase sensitive demodulator circuit is
The system consists of the followup pickoff,
followup motor, followup amplifier, manual azimuth controls and followup alarm.
dication of the gyro tilt is desirable. As the
pass is assembled, a tilt indicator meter is
used as shown in figure 13-10. The circuit may
be considered to be composed of two half-wave
sections, using the reference transformer T303
with resistor network R321, R322, R323 and R324
and balance potentiometer R315 for both halfwave sections. The input is the damping signal
from the tilt signal amplifier and is applied
effectively between the center tap of the diode
load resistors and the center tap of the reference
voltage transformer through balance potentiometer R315. The signal is either in phuse or
180° out of phase with the reference voltage.
If the input signal is zero (gyro level) the
output voltage of the demodulator section (to
the tilt indicator) will also be zero. If an input
signal is in phase or adding to the a-c ref-
erence voltage applied to V304A, it will sub-
tract from the a-c reference voltage applied
to V304B. Tube section V304A therefore will
conduct more current. The voltage drop across
the meter on one half cycle will be greater
that on the next half cycle, and the net
d-c output voltage will be proportional to the
a-c signal voltage. If the phase of the signal
than
voltage is reversed, the polarity of the d-c
output voltage will reverse.
As the voltage gain of the tilt signal am-
plifier is altered during certain operating modes,
operations switch S302E shorts resistor R320
during the low gain periods, thus keeping the tilt
meter calibration the same for both high and low
amplifier gain.
Zero switch 5306 is used to short the input
signal to the tilt indicator circuit for calibrating and zeroing the tilt meter.
The followup pickoff consists of an E core
followup transformer mounted on a horizontal
portion of the vertical ring under the electrolytic bubble level, and a ferramic armature
cemented to the gyrosphere, that bridges the E
core gap. The followup pickoff is constructed
in the
same manner and its operation is
identical to the followup transformer described
in the preceding chapter. The followup trans-
former primary, on the E core center leg, is
excited from the output of excitation transformer T102 the same transformer used to
excite the electrolytic bubble level.
The followup motor is mounted on the spider
and geared to the azimuth gear on the phantom.
It is a 2-phase 4-pole induction motor having
a fixed field connected to one phase of the
115-volt 400-cycle supply through a capacitance network which gives a 90-degree phase
relationship between the fixed and control field.
The direction of rotation depends upon the instantaneous polarity of the signal from the
followup amplifier with respect to that of the
control field, and the speed of rotation de-
pends upon the magnitude of the signal, or the
amount of displacement between the vertical
ring and gyrosphere.
The followup amplifier provides the required
voltage and power amplification to the followup
pickoff signal to operate the followup motor as
previously indicated. In addition it provides the
required stabilization for the followup system.
The amplifier (fig. 13-11) consists of a
half-wave phase sensitive demodulator input
stage, V501A and B, employing a feedback
rate and displacement networks for
FOLLOWUP SYSTEM
loop to
The followup system functions to drive the
phantom bowl in azimuth, so that the vertical
second stage, V502A and B, and a push-pull
356
368
system
stabilization,
a half-wave modulator
output stage, V503 and V504.
CID
Cr)
CA:
en
7101
PICKOFF
FOLLOW-UP
R514
115V 400.v
AC
8504
C503
7502
Figure 13-11. Simplified schematic diagram of followup amplifier
7501
R507
7.186
MOTOR
FIELD OF
FOLLOW-UP
TO CONTROL
.10
IC ELECTRICIAN 3 & 2
The followup pickoff signal is fed to the
of input transformer T501 and is
stepped up by a ratio of 10 to 1. The secondaries feed the stepped up signal to the grids of
the twin-triode demodulator tube sections.
Each tube receives the same magnitude signal
but opposite in phase. Series grid resistors
The d-c output voltage of the demodulator
stage is applied to the grids of the half-wave
modulator tube sections V502A and B. The
rlates of each half of the tube are connected to
opposite ends of the center-tapped primary
winding of modulator transformer T503. The
center tap of this winding is connected to the
400-cycle reference voltage obtained from one
primary
R501 and R502 prevent loading the input transformer and provides tube protection on pos:tive
grid excursions. The plates of the demodulator
winding of the plate reference transformer T502.
As the plates are excited through the center tap
tube are excited with a 400-cycle voltage obtained from the plate reference transformer
T502, phased so that the plates of both tubes
are positive or negative at the same time. (Note
upper and lower plate windings of T502). This
voltage is phase-lock- ' with the excitation volt-
of transformer T503, the two sections conduct
at the same time during their posit:vs vuitage
excursions.
If the input voltage is zero, V502A and B
conduct the same amount of current. The current from V502A through tLe primary of T503
is opposite to that from V502B, therefore the
age of the followup pickoff. Thus, the followup
signal voltage is either in phase or 180 degrees
secondary output of T503 is zero.
out of phase, with the voltage applied to the
The output voltage of the modulator is applied to the grids of the push-pull power output
tubes, V503 and V504. Transformer T504 is the
output transformer and matches the plate impedance of V503 and V504 to the tuned im-
plates of V501A and B, depending upon the direction of the displacement between the vertical ring
and gyrosphere. As current flows through the
tube only during the positive plate excursion,
the output of each tube section is a half-wave
pedance of the followup motor.
rectified current. A d-c voltage is developed
All plate voltages, the bias voltage for the
output stage, and the filament voltages are oh
tained from the d-c power supply in the control
across R504 and R505 proportional to the magnitude of the followup pickoff signal, with its
polarity dependent upon the phase of the pickoff
signal. Capacitors C502 and C503 serve to sup-
press the harmonics and smooth the rectified
half-wave d-c signal. A negative feedback sighal
across R519 and R506 in the modulator stage
V502A and B, required for the stabilization of
the control loop, is generated from this d-c
FROM 115 V, 400'14 30 SUPPLY
(DI
C312
voltage.
A network in the positive
/02
.111 3
1C313
feedback loop'
of V501A and B serves to produce a signal,
proportional to the rate of change of the followup pickoff signal, for momentarily increasing the demodulator gain. This network, called
a rate circuit, enables a servo to overcome
effect of inertia in the moving parts of
the
the
followup system. The effect of the rate
signal is
to prevent a large momentary
displacement between the pickoff and the
gyrosphere.
For most effective servo control it is necessary to combine displacement and rate signals. Two circuits combining these signals are
used in the demodulator stage. The feedback
loop for V501A consists of part of potentiometer R503 resistors R517, R515, and R511,
FROM
FOLLOW-UP
AMPLIFIER
I
TO FOLLOW -UP
MOTOR CONTROL
FIELD
and capacitor C504. The feedback loop for V5018
consists of part of potentiometer R503 resistors
R518, R516, and R512 and capacitor C505.
27.166
Figure 13-12. Simplified schematic diagram of
manual azimuth control circuit.
358
370
Chapter 13GYROCOMPASSES, PART II
cabinet. Capacitors C309, C311, an C508 serve
as phase shift correction for the pickoff signal.
Potentiometer R316 at the T501 input is the
servo gain adjustment.
A manual azimuth control circuit (fig.
13-12) is provided for slewing the sensitive
element in azimuth to the meridian when starting. This allows the compass to settle on the
meridian in a minimum time. The manual
azimuth switches 3303 and 5304 are connected
to the followup motor control field when operation switch 5302 is in the cage position. The
voltage applied to the control field is obtained
from the 115-volt 400-cycle 3-phase supply.
Capacitors C312 and C313 provide the correct
voltage and also the necessary phase shift, with
respect to the fixed field, to drive the motor.
Switch 5303 applies voltage to the control field,
phased properly to slew the compass in a counter-
clockwise direction and switch 5304 applies
voltage 180 degrees out of phase, to slew in a
clockwise direction.
The movement in azimuth of the sensitive
element with respect to the phantom is re-
stricted to about ±8 degrees by mechanical
limit stops. To indicate when the phantom reaches
this limit, a followup failure alarm circuit (fig.
13-13) is provided. The circuit consists of a
followup failure switch 5101, a thyratron tube,
V305, and a neon followup failure indicator light,
1301.
The followup failure switch is mounted on the
vertical ring and consists of two fine V- shaped
wires insulated from each other. An actuator
on the equatorial band of the gyrosphere (fig.
13-3) shorts the two wires when the limits of
travel are reached.
Thyratron V305 has its grid connected to
the negative bias supply through resistor R337.
The plate is connected to a positive 260-volt
-:oarse-filtered direct current through the indicator lamp series resistor R334 and normally closed alarm reset contacts. Ore of the
V-shaped wires of 5101 is connected to the
V305 grid and the other to the d-c common
(ground).
Under normal conditions the thyratron is
biased so no plate current will flow. When
switch 5101 is actuated, the grid will be connected to the d-c common, removing the bias,
causing the thyratron to fi .. The indicator
lamp 1301 will glow, and the voltage output to
the alarm control energizes an alarm relay to
actuate the alarm. The thyratron will tontinue
to conduct until the alarm reset button is pushed,
removing the plate voltage.
Resistor R335 across the neon failure lamp
is used to endure that the lamp will glow when
the thyratron fires.
OPERATION
_14335
ALARM
CONTROL
R 334
+260V DC
1301
V ?C5
0 0
S305
COARSE
FILTERED
ALARM
RESET
The operating procedure for the Sperry Mk
23 gyrocompass is summarized on the starting
instructioa plate (fig. 13-14) located on the front
of the control cabinet (fig. 13-1). Normally the
compass should be started at least two hours
before it is needed for service.
If it becomes necessary to stop the compass in a heavy sea for any reason, other than
failure of the followup system, the following
procedure should l followed:
C31.1,
1
R337
1. Place the power switch in the AMPL's
position.
-22V OC
2. Wait 30 minutes then place the operation
switch in the CAGE position.
27.167
Figure 13-13. Simplified schematic diagram of
followup alarm circuit.
3. Place the power switch in the OFF position. In case of followup system failure, place
the operation switch in the CAGE position immediately, and the power switch in the OFF
position.
IC ELECTRICIAN 3 & 2
OPERATING PROCEDURE
TO
SE'
A- PRELIMINARY
!OPERATION SWITCH
'CAGE'
mom* SWITCH
'OW
ILATITUOE OIAL
4LATITUOE SWITCH -
PROPER LATITUDE
RANGE CLOSER TO LOCAL LATITUDE
ION REAR OF
CONTROL PANEL)
&SPEED UNIT
SYNCHRONIZE WITH WIT-LOG
FOR AUTOMATIC INPUT
Net WITHOUT AUTOMAT, C REED INPUT SET DIAL MANUALLY
TO SNIP'S 511110
B-STARTING
urowart SWITCH
!POWER SWITCH
"MOOS'
&COMPASS CARO
SHIP'S HEADING SY MANUAL
POWIR SWITCH
-GYRO -WAIT 0 SECONDS
&OPERATION SWITCH
&OPERATION SWITCH
"uNCAOr-vstIT 10 SECONDS
' LEVEL - ALLOW GYRO TO LEVEL.MLT
INGICATGR READING AVERADES ZERO)
"Frer-ALLOW S MiNuTGG wARMuP
=;I KNOTS 7.1
14114 Iwo.?
111:$40.11
AZ.MUTH INCH SUTTONS
0
9Valr
101..11,
4=,
Itit
I
111.1ISI II? :I12
Azle IvI ri
fp
I
1 II4
nit ram f*:
a
C-COMPASS
LoPtmenoN SWITCH
"SETTLI.-WAIT 30-40 MINUTES
!OPERATION SWITCH
"NORMAL'
0-0.G. OPERATION
I.START GYRO HENVIEICADvANCE OPERATION SWITCH TO OA.
EJI, OPERATING AS COMPASS.ADVANCE OPERATION SWITCH TO OM
E -SHUT DOWN
0
(.OPERATION SWITCH I 'CAGE' WAIT 10 SECONOS
(AVER PATCH
"orP
STARTING INSTRUCTION PLATE
SPEED UNIT SHOWING LON I ROLS
Ile
hit
.46
C
I
to -
CONTROL PANEL
77.225
Figure 13-14. Operating procedure and controls, Sperry Mk 23 Mod 0 Gyrocompass.
360
372
years
years
Cause
RIIMAIIISI IT NAVIGATOR
Relieved from compass duty (date)
Assigned compass duty (date)
Mark on scale of 4
Experience
Rate
RIMARRII IT NAVIGATOR
months.
months.
DATA TO BE ENTERED BY NAVIGATOR
Name of gyro electrician
Cause
Relieved from compass duty (date)
Assigned compass duty (date)
Mark on scale of 4
Experience
Rate
Name of gyro electrician
DATA TO BE ENTERED BY NAVIGATOR
Figure 13-15.Gyrocompass service record book page.
111-1M11-11
Whenever inspections, overhauls, or repairs are made, the following information shall be entered below:
1. Date.
2. Results of the inspection.
3. Reason for the overhaul or repair.
4. Description of the work done.
5. Data and recommendations for future reference.
6. Repair activity.
7. Signature.
INSPECTION, OVERHAUL, AND REPAIR
$11-1$11011
140.141
IC ELECTRICIAN 3 & 2
If
power to the compass fails, place the
power switch in the FIL's position and the
operation switch in the CAGE position. When
the power is restored, restart the compass in
the usual manner.
a gyro logbook. A service record book is furnished with each gyrocompass installed aboard-
ship. As the gyro electrician you enter in this
book information concerning inspections, over-
hauls, and repairs to the gyrocompass. Each
page of the book shows seven items of information
Setting Correction Devices
Correction device settings for the Mk 23
gyrocompass include the manual speed setting
on the speed unit, the latitude control knob setting on the control panel, and the latitude
switch setting on the rear of the control panel.
When operating the speed unit varuaklY,
adjust the speed settings to correspond-to the
average ship's speed. Change the latitude con-
trol knob setting on the control panel when
the ship's latitude changes as much as two
degrees or as ordered by the ship's navigator.
Throw the latitude switch on the rear of the
that you must record for each inspection, overhaul, or repair. See figure 3-15. This figure also
shows the. kinds of data that the ship's navigator
can enter in the gyro record book. His signature
proof that he has read the entries in the
is
record book.
In addition to the service record book, most
ships have a daily gyro log sheet that is filled
out on the hour by the watchstander. His entries
show the conditions of the gyrocompass and
the power sources available. These entries are
checked the next day for accuracy and neatness
by the leading petty officer.
control panel to the 65 degree position for normal
operation when the ship's latitude is above
60 degrees. The position of the latitude switch
is ii.imaterial for directional gyro open.,..N.1.
SYNCHRO SIGNAL AMPLIFIERS
Synchro signal amplifiers are used to reduce
the size of synchro .ransmitters in gyrocom-
pass are indicated by the following.
passes, wind indicators and other sensingdevices
that are more accurate if there is only a small
load on their outputs. Synchro signal amplifiers
must meet some or all of the following operational requirements.
1. The followup failure and corrector failure !amps on the control panel (fig. 13-14),
amplify the signal, and use the amplified signal
Indications of Normal Operation
Normal operating conditions for the com-
Accept a low current synchro signal,
should be dark.
to drive large capacity synchro transmitters.
3. The speed dial should indicate the ship's
speed for normal operation or zero for direc-
Isolate oscillations in a synchro load
which may be reflected from the input signal
2. The master unit should be lukewarm.
tional gyro operation.
4. The tilt indicator pointer should be os-
cillating evenly about the zero position.
bus.
Permit operation of a synchro load in-
dependent of the input synchro excitation.
MAINTENANCE
Routing maintenance instructions for an installed gyrocompass are part of both the Planned
Maintenance Subsystem and the manufacturer's
technical manual. This manual also contains cor-
rective maintenance procedures and troubleshooting hints. The key to troubleshooting and
repairing the gyrocompass is to follow the stepby-step methods as outlined.
GYRO RECORDS AND LOG ENTRIES
Provide multiple channel output trans-
mission of a single channel input signal.
Permit operation of a synchro load in-
dependent of the input synchro excitation.
Figure 13-16 is a block diagram of a basic
synchro signal amplifier. The input signals may
be derived from any number of sources, but the
most common application is in gyrocompass
transmission. From the compass, information
As an IC Electrician you will be keeping
records on the gyrocompass and other major
pieces of IC equipment, also making entries in
362
374.
is sent out through a dual-speed synchro system.
This system uses two .transmitters and two
receivers. One transmitter receives the input
to the system, and passes the input signal to
Chapter 13GYROCOMPASSES, PART II
ALARM
RELAY
SIGNALING
CIRCUIT
36X CONTROL
TRANSFORMER
36x
4
0
cc
0
2
0
SYNCHRO
INPUT
I
(FINE)
SERVO
MOTOR
FINE OR
SERVO GAME
COARSE
CUTOVER
CIRCUIT
(2
DATA
APLIPFLIEIFRIER
A CATHOOE FOLLOWER.
ANO A
PUSH-PULL AMPUFIER)
IXOR2X
(COARSE)
Ix OR
SMOOTHING
CIRCUIT
IX OR 2X
CONTROL
TRANSFORMER
2X1---- 76);1
11,76727--
36x
(15v
400 HZ OUTPUT
60 HZ OUTPUT
140.131
Figure 13-16. Block diagram of synchro signal amplifier.
the second transmitter through a gear train. The
ratio of the gear train will determine the t1.3.43
specific "speeds" which the system will use to
transmit data. In this case the ratio is 1:36,
so both single and X 36-speed information is
sent to the control transformers in the ampli-
circuit is the error signal. It is amplified by
vacuum tube amplifiers, magnetic amplifiers, or
transistor amplifiers. The amplified signal that
goes to one stator coil of the servo motor. The
motor turns, driving the retransmitting synchros
until their output matches the input, and there
fier. The control transformers compare the input
and output signals and produce error signals.
The fine error signal will have 36 times the
angular displacement of the coarse signal. In
tracing the signal in figure 13-16 the next
component the signal goes to is the cutover
circuit. This cutover circuit will normally select
the 36-speed input. But when the output signal
is more than 2.5 degrees out of correspondence
with the input signal, the cutover circuit will
switch to the coarse, or single speed, informa-
tion. Whichever signal is selected by the cutover
is
provide signals to 400-Hz and 60-Hz equipment
by using two sets of synchro transmitters and
the necessary two power supplies.
ELECTRONIC COMPONENT
The electronic component contains the cutover
circuit, relay signaling circuit, servo amplifier
with negative feedback, and transformer coupling
to the servo motor in the electromechanical unit.
363
375
no signal from the control transformers.
The synchro amplifier in figure 13-15 can
IC ELECTRICIAN 3 & 2
Figure 13-17A.
Mechanical unit (top view).
The input signal to be amplified is selected by
the cutover circuit. The cutover is basically a
relay that will switch from the fine, or 36 speed
40.132.1
ELECTROMECHANICAL UNIT
Figure 13-17 shows the top and bottom of
the electromechanical unit of a synchro amplifier. Notice the two input control transformers
(1X and 36X) the rotors of which are positioned
mechanically by the gear train on the bottom of
the unit. The difference between the rotor angles
of the control transformers and the electrical
angles of the input signals cause error voltages
to be generated in the control transformer rotor
windings. These signals go to the electronic unit
just discussed, here one of them is amplified to
become the control current in the servo motor.
signal to the coarse signal when the coarse signal
reaches a certain strength. Figure 13-16 shows
the basic concept of the cutover circuit. The
signal theft undergoes two stages of amplification.
These stages incorporate a cathode follower
phase splitting network or some other means of
damping out_ electrical oscillations. After the
first two stages of amplification the signal drives
a push-pull output amplifier, which produces the
control current for the servo motor in the electromechanical unit.
364
1..gy
f't)
Chapter 13GYROCOMPASSES, PART II
40.132.2
Figure 13-17B. Mechanical unit (bottom view).
The control current causes the servo motor to
operate to drive the gear train until the rotor
angles and electrical angles of the input control
transformers are the same, and there is noerror
signal.
The servo motor is a two-phase, low inertia,
induction motor. One of its two stator coils is
connected to the a-c line. The other stator coil
receives the control current from the amplifier.
Inductors and capacitors, alone or in combination
are used to displace the electrical angle of the
control current 90° from the reference current.
The control current from the amplifier has the
direction of the initial error signal, so this current
will cause the servo motor to rotate in the proper
direction to correct the error, and vary the speed
of the motor in pr. ()portion to the amount of
error.
365
".1
Because of the gear train that connects the
input and output synchro units, as the servo
motor drives the input control transformers
to their null or zero error signal position, it
also positions the output synchros to retransmit
or repeat the original signal. The output synchros
may be either synchro transmitters or differential
generators. As you can see from figures 13-17A
and 13-17B coarse and fine outputs for both
60-Hz and 400-Hz systems are available from
the one synchro signal amplifier. If differential
generators are used for the output, they will
transmit the sum or difference of the original
signal, and a synchro signal from another source.
STICKOFF CURRENT
A control transformer wi. produce zero
error signal kipth at the angle of correspondence
IC ELECTRICIAN 3 & 2
between synchro signal and rotor position, and
also at 180° out of correspondence. This is
ALARM SWITCH
not a great problem in a two-speed synchro
system such as the one described, since the
single- or 2-speed unit will register an error
even when the 36-speed unit is "hung up"
An alarm switch is provided on the front
panel of the synchro signal amplifier. This switch
is the only control that needs to be touched during
normal operation of the amplifier. The effect
approximately 180° out of phase. However, if
the coarse unit is exactly 180° out of phase,
the fine unit will also be 180° out of phase. To
prevent the system from locking onto a 180°
error, a stickoff current is applied to the coarse
control transformer.
of the alarm switch and associated relay circuits
is to energize an external alarm when any one
The effect of adding a small current to the
rotor of the control transformer is to offset the
point at which it will not generate an error
signal. If this offset amounts to 2.5° in one
direction, the rotor zero position is offset 2.5°
in the opposite direction. When this is done,
the single speed control transformer will produce a zero error when its position corresponds
to the input signal, but will show an error when
180° out of correspondence. There will be a
null position at 175° or 185°, but at these points
the fine, or 36-speed CT is indicating an error
The alarm switch is on and one or more
of the input or output synchros are not
of the following three conditions is present:
Input and output synchros and excited and
the alarm switch is off.
excited.
The servo unit fails to follow, within 2.5°,
the input signal.
MAINTENANCE
Alarm circuits should be checked monthly.
and will drive the system.
As a general rule in checking them, you energize
the equipment that supplies voltage to the compass
and turn on the alarm system. Then you displace
the test knob, where provided, noting whether the
FREQUENCY OF INPUT SIGNAL
deenergaed relay causes its alarm to function.
Next, deenergize each output supply circuit one
at a time; the alarm should sound each time.
The synchro signal amplifier just discussed
can be used on 400-Hz or 60-Hz input power
source, signals, and reference voltages by
changing some of the resistors and capacitors
All gearing is inspected annually. Turn the
gears by hand with the equipment deenergized.
If dirt is found, clean the gears; if they show too
much wear, replace them. Fut a light coating of
instrument grease on the gears.
A yearly accuracy check is required which
concerns the performance of individual amplifiers. In this check, you compare the readings
the circuits of the amplifier and synchro
capacitors on the inputs to the control transformers. Any unit which has been installed
in
will be set up as necessary for its service,
but you may note that there will be almost no
recognizable difference between 60- and 400-Hz
units.
at the input with those at the output repeater..
The readings should not vary by more than 0.1 9-.
Check the alignment o..:findividual units, following
Because of different manufacturers and the
requirements of different applications you will
instructions in the manuft.oture, s manual. Remember that these instructions always supersede
general instructions found elsewhere.
find a variety of synchro sipal amplifiers in
the fleet. These may be more simple or more
complex than the unit just discussed. Several
different ways of damping oscillations through
the amplifier will be used, and some units may
incorporate cooling fans. All of them will
incorporate the basic concept of applying the
input synchro signal through a control trans-
former, amplifying it, and using a servo :motor
to drive a gear train that simultaneously drives
the control transformer to null the error signal,
and positions the output synchro units.
ELECTRICAL ZERO
Each type of synchro has a combination of
rotor position and stator voltages which is
called its electrical zero. The electrical zero
condition is the reference point for the alignment of the synchro.
Electrical zero is the condition in which the
axis of the rotor is lined up with the axis of
the S2 winding (fig. 13-18A).
366
378
Chapter 13GYROCOMPASSES, PART II
and the voltage from S2 to S3 is in phase with
S2
the voltage from R1 to R2.
A synchro transmitter (CX or TX) is properly
zeroed if electrical zero voltages exist when
the unit whose position the CX or TX transmits
RI
is set to its mechanical reference position. A
synchro receiver (TR) is properly zeroed if,
when electrical zero voltages exist, the device
THREE
SECONDARIES
PRIMARY
actuated by the receiver assumes its mechanical
R2
reference position. In a receiver or other unit
having a rotatable stator, the zero position is
the same, with the added provision that the unit
to which the stator is geared is set to its refer-
SI
S3
175.6
Figure 13-18A. Conventional synchro unit.
ence position. The terminal-to-terminal voltages
for 115- and 26-volt synchros at electrical zero
are as follows:
In both the 0° position and the 180° position,
the terminal voltage between S1 and S3 is zero.
However, in the 0° position the voltages from
S2 to S3 or from S2 to S1 are IN PHASE with
,115-VOLT SYNCHROS
26-VOLT SYNCHROS
rotor position the voltage from 52 to S3 (or S1)
R1 to R2 115 volts
S2 to 51 78 volts
S2 to S3 78 volts
S1 to S3 zero volts
R1 to R2 26 volts
S2 to 51 10.2 volts
S2 to S3 10.2 volts
S1 to S3 zero volts
the voltage Loin R1 to R2, while in the 180°
is 180°
out of phase with the rotor voltage.
The electrical zero position is therefore
completely defined as the position of the rotor
in which the voltage between S1 and S3 is zero,
A differential synchro unit is zeroed if the
unit can be inserted into a system without introducing a change in the system. In the electrical
zero position the axes of coils R2 and S2 are
at zero displacement. Terminal voltages for
differential units are as follows:
ARROW STAMPED ON
FRAME
MARK 1N SHAFT
EXTENSION
,.,
115-VOLT SYNCHROS
26-VOLT SYNCHROS
R1 to R3 zero volts
S1 to S3 zero volts
R3 to R2 78 volts
S3 to S2
78 volts
R2 to R1 78 volts
S2 to 51
78 volts
R1 to R3 zero volts
S1 to S3 zero volts
R3 to R2 10.2 volts
S3 to S2 10.2 volts
R2 to R1 10.2 volts
S2 to S1 10.2 volts
A synchro control transformer (CT) is properly zeroed if its rotor voltage is minimum when
electrical zero voltages are applied to its stator,
and turning the CT's slightly counterclockwise
produces a voltage between R1 and R2 which is
in phase with the voltage bet. ireen R1 and R2 of
the CX or TX supplying excitation to the CT
stator. Electrical zero voltages for the stator
only are thv same as for transmitters and
receivers.
ZEROING METHODS
175.18
Figure
13-18B. Coarse
markings.
electrical
zero
There are various methods for zeroing synchros. Thy procedure used depends upon the
IC ELECTRICIAN 3 & 2
facilities and tools available and how the synchros
are connected in the system. Also, the procedure
Standard synchros have an arrow stamped
on the stator frame and a reference line scribed
for zeroing a unit whose rotor or stator is not
free to turn may differ from the procedure for
zeroing a similar unit whose rotor or stator is
free to turn.
on the rotor shaft, as shown in figure 13-18B. With
Voltmeter Method
check.
the synchro input on zero or the reference value,
the alignment of the arrow and the line or the
rotor will set the synchro on approximate zero.
Thus, with standard synchros, this is the coarse
ZEROING
The most accurate method of zeroing a synchro is the a-c voltmeter method. The procedure
and the test-circuit configuration for this method
vary somewhat, depending upon which type of
synchro is to be zeroed. Transmitters and receivers, differentials, and control transformers
each require different test-circuit configurations.
TRANSMITTERS
AND
RE-
CEIVERS. Control transmitters, torque trans-
mitters, and receivers are functionally and physically similar. Therefore, they are zeroed in
the same manner. The zeroing procedure is
broken down into steps as follows.
1. Carefully set the quantity whose position
the synchro transmits to its zero or mechanical
reference position.
2. Deenergize the synchro circuit and disconnect the stator leads. Set the voltmeter to
its 0- to 250-volt scale and connect it into
the synchro circuit as shown in figure 13-19A.
Many synchro systems are energized by in-
An electronic or precision voltmeter having a
0- to 250-volt and a 0- to 5-volt range should
be used. On the low scale the meter should be
able to measure voltages as low as 0.1 volt.
There are two major steps in the zeroing
procedure of a synchro. First, the coarse or
approximate setting is determined, and, second,
the fine setting is made. The coarse adjustment
dividual switches, therefore be sure that the
synchro power is off before working on the
is a check between the correct setting and a
connections.
setting 180° out. Recall from the discussion of
electrical zero that the difference between the
two positions determines the phase relation
between the voltages on S2 to 51 (or S3) and on
R1 and R2. The voltages are in phase when the
rotor is at its electrical zero position, and 180°
3. Energize the synchro circuit and turn the
stator or rotor until the meter reads about 37
volts (15 volts for 26-volt synchros). This is
the coarse setting and places the synchro approximately on electrical zero.
4. Deenergize the synchro circuit and connect the meter as shown in figure 13-19B, using
the 0- to 5-volt scale.
5. Reenergize the synchro circuit and adjust
the rotor or stator for a null (minimum voltage)
out of phase when the rotor position is 180°
away from electrical zero. Hence the coarse
check provides a means to determine the phase
relation between the supply voltage and the induced voltages in the S2 and S1 stator windings.
reading. This is the electrical zero position.
0-250 VOLT RANGE
0-5 VOLT
SI RANGE
RI
115 V (OR 26 V) R2
(B) FINE SETTING
(A) COARSE SETTING
,, a
Figure 13-19. Zeroing transmitter or receiver by voltmeter method.
368
53.26
Chapter 13GYROCOMPASSES, PART II
(B) FINE SETTING
(A) COARSE SETTING
1.121(53)A
Figure 13-20. Zeroing differential synchros by voltmeter method.
/
The common electrical zero position of a
TX-TR synchro system can be checked with a
jumper. Put the transmitter and receiver on zero
and intermittently jumper S1 and S3 at the receiver. The receiver should not move. If it does,
the transmitter is not on zero and should be
rechecked.
stator for a null reading, clamp the CT in posi-
tion, and reconnect all leads to their original
position.
Electrical Lock Method
The electrical lock method (although not as
accurate as the voltmeter method) is perhaps
...
ZEROING DIFFERENTIAL SYNCH:10S. To
zero differential sync hros by the voltmeter method
proceed as follows:
1. Set the unit concerned accurately to its
zero or mechanical reference position.
2. Remove all other connections from the
differential leads, set the voltmeter on its 0to 250-volt scale, and connect as shown in
figure 13-20A. If a 78-volt supply is not available, 115 volts may be used. If 115 volts are
used instead of 78 volts, do not leave the unit
connected for more than two minutes or it may
overheat.
3. Unclamp the differential and turn it until
the meter reads minimum. The differential is
now on appropriate, electrical zero. Deenergize
and reconnect as 'shown in figure 13-20B.
4. Set the voltmeter on the 0- to 5-volt scale,
and turn the differential transmitter until a null
(minimum voltage) reading is obtained. Clamp
the differential in this position, deenergize, and
reconnect all leads for normal operation.
le To zero a CT by the voltmeter method, remove the connections from the
ZEROING A CT.
CT and reconnect as shown in figure 13-21A.
Turn the rotor or stator to obtain a minimum
voltage reading, then reconnect the meter as
shown
II
FINE SETTING
53.36
Figure 13-21.
in figure 13-21B. Adjust the rotor or
369
Zeroing control transformer by
voltmeter method.
IC ELECTRICIAN 3 & 2
be zeroed together. As pointed out earlier, the
coarse synchro will define the position of a
quantity to within the range of the fine synchro's
capability to define the position more precisely.
From this you can reason that the coarse synchro provides the first significant figure in the
numerical description of the quantity's position.
Obviously then the coarse synchro is zeroed
first. When zeroing the synchros in a system
you can consider each synchro as an individual
unit. Thus one of the methods already described
can be used to zero the coarse synchro.
The next step after the coarse synchro is
zeroed is to zero the fine synchro. A sine synchro provides the next significant figure in the
numerical description of the quantity's position.
The fine synchro is zeroed as an individual unit.
But the quantity's zero or reference position has
already been established with respect to the
coarse synchro's electrical zero position. Hence
when you zero a fine synchro the setting of the
coarse synchro and the quantity must be set
53.30
Figure 13-22. Zeroing a synchro by the electrical lock method.
the fastest method of zeroing synchros. This
method can only be used however, provided the
rotors of the units are free to turn and the
lead connections are accessible.
To zero a synchro by the electrical lock together.
method, deenergize the unit, connect the leads,
There are a few three-speed synchro sysand apply power as shown in figure 13-22. The tems. These systems are zeroed in the same
synchro rotor
will then quickly snap to the manner as the dual-speed systems. First, eselectrical zero position and lock. As stated tablish the zero position for the synchro which
previously, 115 volts may be used as the power provides the most significant figure, and work
supply instead of 78 volts provided that the down to the least significant figure. Remember
unit does not remain connected for more than that all the synchros in a system must have a
two minutes.
common electrical zero position.
ZEROING MULTISPEED
ZEROING A RESOLVER
SYNC HRO SYSTEMS
If a fine and a coarse synchro are used to
There are many methods used to zero re*refine a quantity's position, the synchros must solvers. Each manufacturer has his own method.
JUMPER
S
0-
A
JUMER
S2
F-115-
111
S4
.
Figure 13-23. Zeroing a resolver, (A) coarse setting, (B) fine setting.
370
LD ")
LL) La
,\
Chapter 13GYROCOMPASSES, PART II
To make the coarse zero adjustment, loosen
principles underlying all the different resolver the flange mounting screws of the stator. Look-
The method described below uses the basic
ing at the rear (brush end), turn the stator
Before a resolver can solve a problem it counterclockwise. Stop turning when the volt-
zeroing methods.
must have a reference position from which the meter reads the input voltage, E. At this point
input values are measured. This is the zero you know the R2 - R4 coil has no induced voltposition of the resolver. The zero position of age because the voltmeter reads the input volta resolver is determined by the angular rela- age alone, meaning that the R2 - R4 is aptionship between the rotor and stator windings. proximately at right angles to 51 - S3 and the
Each stator winding must be perpendicular to rotor is at coarse zero.
a corresponding rotor winding. When this relaWith the voltmeter reading the E voltage,
tionship is established, there will be no magnetic coupling between corresponding windings. turn the stator a little beyond coarse zero. The
The absence of a magnetic coupling between voltage at the voltmeter should INCREASE ABOVE
corresponding rotor and stator windings is pos- E, because the voltage induced in the R2 - R4
sible at two positions 180° apart. To ensure coils add to E. Be sure the voltage at the voltthe correct position, so that the phase relation- meter increases to prevent zeroing at 180° out
ship between the rotor and stator is correct, of phase.
the coarse zero test is made first. Figtle
The next step is to set the resolver on fine
13-23A shows the connections for the coarse
zero test. The voltage applied to the stator zero. Figure 13-23B shows you how to reconnect
winding S1 - S3 is a reference voltage specified the jumper and voltmeter. Turn the stator so that
fur the resolver. The two windings are con- the voltage on the voltmeter decreases, and
nected in parallel by the voltmeter and the keep shifting the meter to the lower scales untii
jumper. The voltmeter will read the applied the minimum voltage reading is obtained. The
voltage, plus or minus any voltage induced in minimum voltage reading means thi t R2 - R4
the rotor winding. The jumper across the winding is exactly at right angles to 51 - :13, and the
S2 - S4 is to eliminate any stray voltage that rotor is at fine zero. Recheck this voltage after
might originate from the winding.
you secure the mounting screws.
t..t.-4J
CHAPTER 14
SHIPS CONTROL ORDER AND INDICATING SYSTEMS
Current design of naval ships requires the
mounting of control order and indicating units
On combatant ships, this system usually
consists of two separate circuits: 1MB starboard and 2MB port. Each circuit has a synchronous transmitter to actuate receivers and
in consoles for ease of operation. Two units
the steering control console. On ships with
currently in use are the ship control console and
an audible signal to indicate a change in orders.
automatic propulsion systems the steeringcontrol
and ship control consoles are combined into one
unit which contains all the necessary equipment
needed for control of the ship's engineering
plant. Since the circuitry in these combined units
is placed in a direction, ahead or astern, contrary to the received order.
of this chapter:
shows the various units and their locations. Two
transmitter-indicators are mounted in the upper
The newest systems include circuit DW (Wrong
Direction Warning) which automatically signals
an alarm at the throttle concerned if the throttle
is similar to that in older shipboard consoles,
you can develop an understanding of all types
of units through studying the following circuits
(1)
(2)
A Klock diagram of the system (fig. 14-2)
section of the ship control console located in
the pilothouse. Each engineroom has one indicator-transmitter (fig. 14-3A) for its asso:iated
the engine crder system, circuit MB;
propeller revolution order system, cir-
shaft. Engine room No. 1 also has one indicator
(fig. 14-3B) for the orders to the No. 2 engine.
CIC, fireroom No. 1, and fireroom No. 2 each
cuit M;
(3)
(4)
rudder angle order indicator, circuit N;
rudder angle order transmitter, circuit
have one engine order double indicator (fig. 14-3C)
which keeps CIC advised of speed changes and the
L;
(5)
(6)
(7)
steering emergency signal, circuit LB;
valve position indicator, circuit VS: and
burner order indicator, circuit BC. '.i.
THE SHIP'S CONTROL CONSOLE
Incorporating in a single unit the equipment
required to transmit orders relative to the speed
of the ship, the ship control console (fig. 14-1)
is the control center for the following:
firerooms alerted to changing steam requirements.
The desired speed and direction is inserted
at the console by the operator and immediate
indication is transmitted to both enginerooms
over circuits 1MB and 2MB. Each engineroom individually acknowledges receipt of the
orders. The order or order and answer is
transmitted simultaneously toi.yarious stations
dependent upon their equipment capabilities.
All the engine order information transits
the ACO section of the main IC switchboari
for damage control protection as described in
1MB engine order starboard circuit.
2MB engine order port circuit.
Propeller revolution order system.
Speed lights.
chapter 4.
PROPELLER REVOLUTION ORDER
ENGINE ORDER SYSTEM
SYSTEM
In addition to providing a means of transmitting desired engine direction and speed orders,
the engine order system can transmit acknowledgement of these orders and relay the information to remote stations.
each propulsion gage board the ordered number
of propeller revolutions per minute, and acknowledges the order ':rom the main propulsion
Circuit M transmits frcm the pilothouse to
gage board to the transmitting station. The control
372
!
384
Chapter 14 SHIPS CONTROL ORDER AND INDICATING SYSTEMS
ENGINE ORDER TRANSMITTER
OPERATING HANDLES
PORT & ST'B'D
ENGINE ORDER - CRDER & ANSWER
ENGINE ORbER
ORDER & ANSWER-PORT
ST'B'D
ENGINE ORDER IND.
TRANSMITTER-PUSH-
ENGINE ORDER IND. TRANSMITTER
PUSH BUTTON & PILOT LIGHT ( ST'B'D)
INDICATOR LIGHT - WHITE
BUTTON & PILOT LIGHT
(SPEEDLIGHT)
(PORT)
INDICATOR LIGHT-RED
(SPEEDLIGHT)
SPEEDLIGHT SIGNAL SELECTOR
SWITCH
SPEEDLIGHT CIRCUIT
HAND PULSE PUSHBUTTON
(SPEEDLIGHT)
CONTROL SWITCH
PROPELLER REVOLUTION
TRANSMITTER-INDICATOR
CIRCUIT CONTROL SWITCH
OPERATING
$4,4___. PROPELLER REVOLUTION
TRANSMITTER
KNOBS
PUSHBUTTON - PROPELLER
REVOLUTION
.-
MASTER DIMMER
PROPELLER REVOLUTION
ANSWER ALARM
lirNe.:,..e
(BUZZER)
ENGINE ANSWER ALARM
BELL (ST'B'D)
ENGINE ANSWER ALARM
BELL (PORT)
-.......- FRONT ACCESS PANEL TO
TERMINAL BOARDS FOR
SHIPS WIRING
Figure 14-1. Ship control console.
7.132
which is coupled to a dial. The transmitters
unit for this system is currently installed in the
ship control console.
are further coupled to control knobs.
On the gage board of the No. 2 engineroom
is a propeller order indicator (fig. 14-4B).
Ordered propeller revolutions are inserted
at the pilothouse unit and indicate on both gage
boards. The throttleman at the No. 1 engine-
A propeller order indicator-transmitter (fig.
14-4A) is on the main gage board in engineroom
No. 1. Like the pilothouse unit, it is self-
synchronous, containing three synchro transmitters and three synchro receivers, each of
room board acknowledges the received order.
373
285
IC ELECTRICIAN 3 & 2
T
PILOT HOUSt
NAVIGATION BRIDGE
{
NO 2
NO 1
C I.C.
ENGINE OROER
ENGINE OROER
XlATR a INDICATOR WIATR aitipscATOR
NO 1
NO.2
ENGINE OROER
INDICATOR
ENGINE ORDER
INOICATOR
(IN SHIP CONTROL CONSOLE)
-7-4--
4
NO 1 a NO 2
ENGINE ORDER
INOICATOR
1
ACO
SWITCH
7-1
1
(DOUBLE)
1
a
1
t
1
e
1
I
1
1.C. GYRO a MISSILE PLOTTING RM NO.1
1
FWO MAIN I.C. SWITCHEWARO
I
I
1
f
NO 2
ENGINE ORDER
IN OICATOR
i
N1.1
ENGINE OROER
INOICATOR
TRANSMITTER
NO.1 a NO.2
NO.2
ENGINE OROER
1NOICATOR
140.14. NO.2
LNGINE OROER
ENGINE OROER
INOICATOR
(DOUBLE)
TRANSMITTER
I NO ICATOR
(DOUBLE)
1
1
1----
ENGINE ROOM NO. 2
NO.1 FIRE ROOM
ENGINE ROOM NO I
sreo SHAFT
ORDERS
NO.1
ANSWERS -
NO.2 PORT SHAFT
NOTE
NO. 2 FIRE ROOM
Figure 14-2. Engine order system (circuit MB).
.I
140.108
In the event of an engineering casualty or speci-
Course to steer indicator, circuit LC.
minute.
Combination rudder angle order indicator
(circuit N) and rudder angle order trans-
fic test, the engineroom can reverse the procedure by requesting specific revolutions per
mitter (circuit L).
SPEED LIGHTS
Ship steering wheel (helm).
A circuit for the regulation of the speed lights
is part of the navigation lights, and is main-
Steering emergency signal switch, cir-
THE STEERING CONTROL CONSOLE
It may or may not have a magnesyn
cuit LB.
Helm angle indicator.
tained by the Electrician's Mates.
compass repeater.
The steering control console incorporates
the indicators and controls required to navigate
the ship from the pilothouse, and to transmit
steering orders to the steering gear room, when
the ship is being steered from there. This console (fig. 14-5) consists of the following:
Ships course indicator, circuit LC.
SHIP'S COURSE INDICATOR
The ship's course indicator is a standard
synchro-driven, dual-dial gyrocompass repeater.
It differs from the normal gyrocompass repeater
in that it is mounted in a console and not in its
own housing for bulkhead mounting.
386374
Chapter 14SHIPS CONTROL ORDER AND INDICATING SYSTEMS
Figure 14-3A. Indicator-transmitter
7.126.2
(circuit
7.126.3
Figure 14-3B. Indicator (circuit MB).
MB).
COURSE TO STEER INDICATOR
This indicator is a normal dual-dial repeater.
It differs mainly from the ship's course indicator in that its dials are positioned from a
synchro transmitter located in sonar, CIC, or
other weapons control station. This repeater
enables sonar, CIC, or other station to transmit
a course for the helmsman to steer without
having to use a means of voice transmission.
The helmsman has only to match his course
with the course indicated on this repeater.
RUDDER ANGLE ORDER INDICATOR
Circuit N provides a means of electri3ally
transmitting the angular position of the ship's
rudder at the rudder head to designated stations throughout the ship.
The transmitter (fig. 14-6) is located at
the rudder head and consists of a synchronous
375
C87
transmitter mechanically linked to the rudder
stock in such a manner that its shaft follows
the movement of the rudder. It transmits rudder angle data to the ACO section of the steering
gear room IC switchboard and from there to
various ship's indicators.
The indicators consist of a fixed dial and
pointer, which is mounted on the shaft of a
synchro receiver. The receiver rotates the
pointer to the transmitted angular displacement
on the dial face.
Figure 14-7 is a block diagram of the rudder
angle order system, showing the various units
and their locations.
The
rudder
angle indicator-
order transmitter is mounted in the
rudder order
steering control console. A combination rudder
angle indicator - rudder order indicator (fig.
14-8A) is located in the steering gear room.
IC ELECTRICIAN 3 & 2
PUSH SWITCH
7.122.1
Figure 14-4A.
Propeller order indicator-transmitter (circuit M).
7.126.4
Figure 14 -3C. Double indicator (circuit M3).
Single rudder angle indicators (fig. 14-8B) are
found in the enginerooms, bridge wings, CIC,
and pilothouse as well as on top of the pilothouse.
RUDDER ANGLE ORDER TRANSMITTER
Circuit L provides a means of electrically
transmitting rudder angle orders from the
steering control console to the steering gear
room when the ship is being steered from there.
The transmitter for this circuit is located
in the steering control console.
The indicator combined with a circuit N
indicator (fig. 14-8A) is located in front of
the steering gear room trick wheel.
The rudder angle order transmitter is a
synchronous transmitter, the shaft of which
7.122.2
Figure 14-O.Propeller order indicator (cir-
376
cuit M).
Chapter 14 SHIPS CONTROL ORDER AND INDICATING SYSTEMS
RUDDER ANGLE ORDER
INDICATOR TRANSMITTER
EMERGENCY STEERING SWITCH
RUDDER ORDER TRANSMITTER
OPERATING KNOB
REMOTE IND. MAG. COMPASS
REPEATER
RUDDER ORDER ATTENTION
PUSH SWITCH
MASTER DIMMER CONTROL
RUDDER ORDER TRANSMITTER
"POWER ON" PILOT LIGHT
COURSE TO STEER
INDICATOR
SHIPS COURSE
INDICATOR
STEERING WHEEL
GRAB BARS
HELM ANGLE
INDICATOR
STEERING CONTROL
"POWER ON"
INDICATOR LIGHTS
DOOR FOR ACCESS
TO TERMINAL BOARDS
FOR SHIPS WIRING, ON
THIS END
Figure 14-5. Steering contvol console.
377
X89
7.133
IC ELECTRIMN 3 & 2
A pushbutton is provided on the console to
ring a bell in the steering gear room in order
that the emergency helmsman can anticipate
an angle order change.
STEERING EMERGENCY SIGNAL CIRCUIT
Circuit LB provides a means by which the
pilothouse can warn the after steering station
that a steering emergency has occurred and that
steering must be controlled from there. This
circuit consists of a spring return lever switch
(chapter 3) located on the steering control console,
and a siren (chapter 7) located in the steering
gear room.
HELM ANGLE INDICATOR
7.129
Figure 14-6. Rudder angle transmitter.
The Helm Angle Indicator is a synchro receiver which is connected to a synchro transmitter attached to the steering gear. It therefore indicates the position of the steering gear
or "helm angle" at all times.
is geared to a pointer and a control knob.
When operated, the transmitter sends the desired rudder angle in degrees left or right to
the receiver in the steering gear room.
VALVE POSITION INDICATOR AND
BURNER ORDER INDICATOR SYSTEMS
At the indicator in the steering gear room
the operater receives the ordered helm ang1,1,
then positions the trick wheel to cause the
The valve position indicator (circuit VS) and
burner order indicator (circuit BC) inform per-
rudder angle indicator (circuit N) to match the
order.
COMBINED RUOOER
ANGLE INO:CATOR
RUODER OROER X MTR
PILOT
sonnel at remote stations of the positions of
TOP OF PILOT HOUSE
HOUSE
1
C.I.C.
SECONDARY CONNING
f*URFACEOPER. AREAUASW C ONTROL AREA)
IRUOOER ANGLE
INDICATOR
A.C.O.
SWITCH
RUOOER ANGLE
INDICATOR
A.C.O.
SWITCH
RUOOER ANGLE
INDICATOR
RUOOER ANGLE
INOICATOR
STATION
RUODER ANGLE
INDICATOR
I
I. C.SWITCHBOARD
STEERING GEAR ROOM
RUDDER ANGLE-ORD:R
INDICATOR
RUDOER ANGLE
TRANSMITTER
STEERING GEAR RAM RM.
Figure 14-7. Rudder angle order system.
378
Z90
RUDOER AN3LE
INDICATOR
ENGINE RM. NO.1
RUDDER ANGLE
INDICATOR
I
ENGINE RM. N0.2
140.109
Chapter 14SHIPS CONTROL ORDER AND INDICATING SYSTEMS
7.126.5
7.126.6
Figure 14-8A. Rudder angle order indicator
Figure 14-8B. Rudder angle indicator (circuit
(circuit L & N).
N).
certain valves. Sensitive switches, mounted on
the valve housing and actuated by the valve,
energize the indicators. On most installations
you will find two switches, one indicates that
the valve is open and the other that the valve
is closed. They normally have a "make" contact
arrangement. Figure 14-9 shows a typical VS
(40)
O OPEN
LIGHT
circuit arrangement. There are usually two
lamps in each indicator; one lamp for the open
position of a valve and the other for the closed
position. The remote indicators may be found
singly but are normally grouped into VS boards
of from 5 to 15 indicators to indicate the positions of valves located in the same engineering
CLOSED
t
I
POWER
SOURCE
OPEN
SWITCH
MIR
CLOSED
S WITCH
space.
MAINTENANCE
1111111
If the
ship control order and indicating
equipment does not function properly and the
cause is not immediately apparent, check for
failure of the power supply, blown fuses,
burned-out
dial illumination,
and defective
379
Figure 14-9.
140.157
Valve position indicator.
IC ELECTRICIAN 3 & 2
115-V
60'v
S2
R1
R2
S1
S3
S1
TRANSMITTER
Figure 14-10. Simple synchro transmission system.
7.134
S2
0
I15-V
SYNCHRO
TRANSMITTER
060ry
Si
ci(
. , .,.
/c 02
\\\
Si u
SWITCH SI
.--0.4-1,1;2
POSITION
CONNECTIONS
t
BOTH
2
I
3
OFF
4
2
SWITCH SHOWN
IN POSITION I
I
y
---r-
.%-
\s/(v g
,\,e,
2
c \ / Sld s_, S
0..-S3 o3 o-otrS2
03
I
b\,
>f
g
SI
SI
o3 0-4--0RI 03
1
I
1
y
o4
04
03
1
V
p4
Z4
4
S2
RI
R2
RI
I
R2
SYNCHRO
S3 RECEIVER
SI
.-- ,,SYNCHRO
b.:
SI.
RECEIVER
7.135
Figure 14-11. Connections of syrchro transmitter and two independent synchro receivers through a
rotary switch.
1
te
Chapter 14SHIPS CONTROL ORDER AND*INDICATING SYSTEMS
wiring, before starting a detailed examination
of the circuit units and parts of the equipment.
Some faults such as burned-out lamps, rheostats, shorted transformers, or wiring can often
be located by sight or smell. Check for smoke
of the line. The stator leads of both the transmitter and receiver are connected lead for
leadthat is, Si is connected to Sl, S2 to S2,
and S3 to S3. Thus, when an increasing reading
is sent over the transmission system, the rotor
of the synchro receiver will turn in a counter-
or odor of burned or overheated parts.
Troubleshooting of electrical circuits and
components is readily accomplished by follow-
clockwise direction.
When it is desired that the shaft of the
synchro receiver turn clockwise for an increasing reading, the R1 and R2 transmitter and
receiver leads are connected as before, and the
Si transmitter lead is connected to the S3
ing standard procedures for circuit tracing to
isolate the fault. Do not attempt to disassemble
the unit until all signal and power sources have
been checked and the trouble has been definitely
located on the unit. The ship control order and
indicating systems operate on a standard syn-
receiver lead, the S2 transmitter lead to the
S2 receiver lead, and the S3 transmitter lead
chro transmission system. Detailed information concerning the operation and maintenance
of synchros is contained in the manufacturer's
to the Si receiver lead.
The standard connections of a synchro
transmitter to two independent synchro receivers
technical manual furnished with the equipment,
through a rotary switch is illustrated by the
Basic Electricity, NAVPERS 10086-B, or Synchro
Servo and Gyro Fundamentals, NAVPERS 10105.
wiring diagram in figure 14-11.
STANDARD SYNCRHO CONNECTIONS
SETTING SYNCHROS
Standard connections for synchros have been
established to avoid confusion when many syn-
If a synchro system is to operate with any
degree of accuracy, its synchros must be in a
tional connection is for ctAlnterclockwise rotation for an increasing reading.
The standard connections of a simple synchro transmission system consisting of a synchro transmitter and receiver are illustrated in
figure 14-10. The R1 transmitter and receiver
leads are connected to one side of the 115-volt
zeroing synchros involve the use of a voltmeter,
position of electrical zero. The methods of
chros are installed in a system. The conven-
neon lamps, two lamps and a headset, and
other synchros in the system. However, the
most accurate method of setting both synchro
transmitters and receivers involves the use
of a voltmeter as illustrated in figure 14-12.
At electrical zero, the voltage between the
Si and S3 leads must be zero and the rotor
and stator voltages are subtractive between
a-c supply line, and the R2 transmitter and
receiver leads are connected to the other side
S2
S2
52V
115-26-52=37V
115V
60ry
S3
S3
SI
26-26::0V
A
B
Figure 14-12. Zeroing synchros.
381
X33
7.136
IC ELECTRICIAN 3 & 2
R1 and S2 when R2 and S1 are connected together. Connect a voltmeter across the S1 and
S3 leads (fig. 14-12A) and rotatk. the energized
rotor until a zero reading is obtained. However,
there are two rotor positions 180° apart where
a zero reading will be obtained on the voltmeter.
To locate the proper zero position, it is neces-
sary to determine that the rotor and stator
voltages are subtractive. To do so, connect a
jumper from SI to the R2 leads and a voltmeter
across the S2 and R1 leads (fig. 14-12B). When
the polarity relationship is correct, the voltmeter will read 37v (115v - 78v = 37v). If the
voltmeter reading is GREATER (115v + 78v =
193v) than the line voltage, then the rotor must
be rotated 180 degrees. When the proper polarity
relationship has been ascertained, connect the
circuit again as in figure 14-12A, and readjust
the
rotor for a zero voltage reading across
leads S1 and S3.
If for any reason, you must apply an external
voltage tO the stator windings for any length of
time, use a means of obtaining a maximum of
78 volts, such as a transformer, autotransformer, variac, or dropping resistor.
382
2.94
.
CHAPTER 15
SHIP'S METERING AND INDICATING SYSTEMS
In order to properly operate a modern naval
vessel, a vast amount of information must be
available throughout the ship in spaces far remote from the area in which the information
is originated. This information must be made
the position of the roller on the disk is varied,
the speed of the roller is varied in direct proportion to the distance the roller is positioned
degree of accuracy.
The complexity of modern warfare requires
known speed with a known speed through a differential and using the output of the differential
to make these quantities approach equality. Elec-
available on a continuing basis with a high
that many different weapons systems control
stations have available ship's speed and wind
direction. Good piloting demands that the officer
of the deck have shaft speed available at all
times. The circuits which measure and transmit much of this information are designated
IC circuits.
In measuring speeds of rotation, it is often,
necessary to use an indirect method, such as
the one that enables a tachometer to measure
the speed in rpm of an automobile engine by
measuring the angle displaced by a pointer or
indicator. The following IC systems apply a
similar method of indirect measurement, using
a friction disk and roller assembly: propeller
revolution indicator system, wind direction and
speed indicating system, and underwater log
system.
FRICTION DISK AND ROLLER
ASSEMBLY
If a disk is driven by a synchronous motor
supplied with a controlled frequency, the disk
W.' run at a constant speed irrespective of
fluctuations of the ship's supply frequency. A
roller placed in the center of the rotating disk
does not turn.
If the roller is moved out from the center
of the disk, the roller turns at a speed.that is
proportional to the distance from the center of
the disk. If the roller is moved out one-half
inch from the center of the disk, the roller runs
at twice the speed at which it ran when moved
one-fourth inch from the center of the disk. If
from the center of the constant-speed disk.
As illustrat-'d in figure 15-1, this device
operates on the principle of comparing an un-
trical contacts operate in response to the differential output and control a followup motor
that matches the two speeds (fig. 15-1A).
The rotation that is to be sonvorted to an
angular displacement is the unknown speed input. This input is received by the synchro re-
ceiver, which is geared to the right face gear
of the differential and is free to turn about the
differenpal (response) shaft. An extension of
the synchro rotor shaft drives the six-place
odometer (fig. 15-1B).
The synchronous motor is energised from the
60-hertz bus. This motor drives the friction
disk at a constant speed and is the known speed
input. The friction roller drives the pinion and
the left face gear of the differential through a
spur gear. This assembly is also free to turn
about the differential (response) shaft. Hence,
the left face gear rotates at a speed proportional to the distance between the position of
the roller on the disk and the center of the
disk. The right and left face gears of the dif-
ferential rotate in opposite directions.
The slipring and contact assembly is se-
cured to the differential (response) shaft. This
assembly carries two outside contacts, CW and
CCW, each connected to a slipring. These contacts
do not normally make contact with the center
contact C, which is mounted on the followup
shaft. Thus, the contact assembly can be turned
-In either direction so that one or the other of
the outside contacts can make contact with the
censer contact. This action energizes the followup motor and determines its direction of
rotation.
383
IC ELECTRICIAN 3 St 2
FRICTION DISK
AN D ROLLER
A sSEMSLY
KNN
SPEED
DIFFERENTIAL
INPUT
UNKNOWN
EED
INPUT
\\xt
SYNCHRONOUS
MOTOR
RECEIVER
SPEED
INDICATOR
12=1:117
R ECVOOULNUira
CONTACTS
SYNCHRO
TRANSMITTEF
OUTPUT
A
SCHEMATIC
SPEED INDICATOR
REVOLUTIONS
COUNTER
FOLLOW-UP
MOTOR
YOKE
LEAD
SCREW
OUTPUT SHAFT
FRICTION
DISK
.51RAL
SPRING
SYNCHRONOUS
MOTOR
KNOWN
SPEED
I U.
SHAFT
SYNCHRO
RECEIVER
UNKNOWN SPEED
INPUT
SYNCHRO
TRANSMITTER
OUTPUT
INPUT
1
OUTPUT
B PICTORIAL
Figure 15-1. Friction disk and roller assembly.
384
236
140.59
Chapter 15SHIP'S METERING AND INDICATING SYSTEMS
The followup motor drives the lead screw,
which moves the yoke in or out (depending on
the direction of rotation), thereby varying the
revolutions per minute of the friction roller and
the left-face gear of the differential. This action continues until the number of revolutions
are the same as the right-face gear of the dif-
shaft stops rotating to prevent hunting or overtravel of the lead screw.
PROPELLER REVOLUTION
INDICATOR SYSTEM
ferential. When this equality is reached, the
differential (response) shaft ceases to rotate
and the contact assembly opens the circuit to
The propeller revolution indicator system,
circuit K, is used to indicate instantaneously
and continuously the (1) revolutions per minute,
(2) direction of rotation, and (3) total revolutions
the followup motor.
of the individual propeller shafts. The information is intlicated in the enginerooms, pilot
A pinion is cut on the end of the output shaft
and engages a gear train that drives the fol-
lowup shaft very slowly in the same direction as
the. differential (response) shaft whenever the
followup motor is operating. This action restores the contacts to their normal (open) position slightly before the differential (response)
0 INDICATOR
IK
house, and other required locations.
The system comprises the (1) synchro type
equipment and (2) magneto-voltmeter type equip-
ment. The synchro type equipment is installed
in large combatant ships and in many newly
01
INDICATOR
PILOT HOUSE
2K
14,,,
ANGULAR
ANGULAR DISPLACEMENT
DISPLACEMENT
Ix
ACO
I
2K
ACO
ANGULAR
DISPLACEMENT
INDICATOR
INDICATOR
TRANSMITTER
ANGULAR
DISPLACEMENT
=
2K
1K
1.' IDICATOR
IK
TRANSMITTER
MED
2K
(TRANSMITTER
.C1:0:1I
K
=
TRANSMITTER
ROTARY MOTION
ROTARY MOTION
2K
NO.2 ENGINE ROOM
NO.1 ENGINE ROOM
27.331
Figure 15-2.
Propeller revolution indicator system.
385
Zi37
IC ELECTRICIAN 3 & 2
constructed small ships. r..3 magneto-voltmeter
associated indicator-transmitters which convert
the received rotary motions into stationary
angular synchro displacements. The angular displacements, which are proportional to the speeds
type equipment is less complicated and is installed in small ships.
SYNCHRO TYPE EQUIPMENT
of the propeller shafts, are transmitted to indicators located at various stations. The in-
A representative synchro type propeller revolution indicator system installed in a DLG
is illustrated by the block diagram in figure
15-2. The system consists of various transmitters, indicator-transmitters, and indicators.
dicators repeat the rpm readings received froLi
the associated indicator-transmitters.
Transmitter
The transmitters for shafts 1 and 2 are installed
on the actual propeller shaft usually near the
reduction gear. The transmitters are electrically
connected to indicator-transmitters in their re-
spective throttle stations. Indicators are also
installed on the gage boards in the opposite
enginerooms and in the pilot houses as required by the types of ships. Each indicator
is provided with a backing signal lamp which,
when lighted, denotes astern rotation of the
propeller shaft.
The rotary motions of the propeller shafts
are transmitted by the shaft transmitters to the
The transmitter, one for each propeller shaft,
is used to indicate the revolutions of the propeller shaft and to transmit the speed and
direction of rotation of the propeller shaft to
the associated indicator-transmitter.
The unit consists of a running synchro transmitter, revolution counter, and contact assembly
(fig. 15 -d). These components, which are actuated by suitable gearing, are mounted
a
watertight housing to form a complete transmitter subassembly. The transmitter is either gear
driven from the propeller shaft, or is directly
30
PROPELLER
SHAFT
RUNNING
SYNCHRO
TRANSMITTER
Figure 15-3. Gearing diagram of transmitter.
386
298
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Chapter 15SHIP'S METERING AND INDICATING SYSTEMS
coupled to the end of a stub shaft of the pro-
pulsion machinery as required by the particular
installation. The synchro transmitter is always
driven at twice the propeller spcad in a constant
clockwise direction.
A drive worm, cut integral with the shaft
56, meshes with worm gear 12, which is secured
to shaft 14. The ratio is such that shaft 14 is
1111
and one of the stationary contacts energize the
signal lights in the remote indicator when the
propeller shaft rotates in the astern direction.
Indicator-Transmitter
The indicator-transmitter installed in each
throttle station is used to convert the running
20 are free to swing on the shaft. The lower
speeds (received from the associated shaft transmitters) into angular synchro displacements which
are transmitted to the various indicators.
of gear 25. This action engages gear 26 with
a watertight housing.
driven at exactly one-tenth the propeller speed.
The gear 25 is attached to shaft 14 and the links
ends of links 20 support the swinging shaft 31.
The gear 26 is attached to shaft 31. The friction
blocks 23 are held in contact with the hubs of
gears 25 and 26 by the spring 24. The friction
blocks restrain the rotation of the gears 25 and
26 and swing the links assembly, including
shaft 31 and gear 26 in the direction of rotation
The unit (fig. 15-4) consists of a running
synchro receiver, a speed-mer Turing mechanism, a positioning synchro transmitter, revolution counter, two pointers, a dial, and a backing
signal. These components and associated gears
are mounted on a baseplate to form a complete
indicator-transmitter subassembly enclosed in
one of the two gears 27, the selection depending
on the direction of rotation of gear 25. The
screws 80 limit the angular swing of the links
The two concentric revolving pointers indicate on a dual-marked fixed-dial the output in
rpm of the speed-measuring mechanism. The
inner scale, marked for each 100 rpm only, is
indexed by the short pointer 88. The outer
scale, calibrated from zero to 100 rpm with
numerals for each 5 rpm is indexed by the long
pointer 89. The positioning synchro transmitter
7. and pointer 88 and 89 are geared to the friction roller 60, and followup motor 9. The long
assembly.
The gears 27 and secured to the respective
side shafts 35, which also carry gears 29 and
69. These gears are meshed and drive each
other alternately, depending on which one of the
two gears 27 is engaged with the swinging idler
gear 26. Gears 29 and 69 do not reverse when
the propeller shaft reverses because idler gear
26 reverses rotation each time it swings from
side to side. The same is true for gears 28 and
57, because they are mounted on the hubs of
gears 29 and 69, respectively. Gear 57 engages
gear 58 which is mounted directly on the shaft
of the synchro transmitter 37. The overall gear
ratio between the transmitter shaft 56, and the
shaft of the synchro transmitter is such that the
synchro shaft is always driven at twice the propeller speed in a constant clockwise direction.
The revolution counter 38 which is driven
at one-tenth the propeller speed, is driven
through helical gears 28, 48, 47, and 30. The
reading is directly in terms of propeller revolutions because each revolution of the counter
shaft registers a count of ten. The brake shoes
50 prevent the synchro transmitter 37 from
driving the counter 38, backward during brief
periods of rapid speed reduction.
The contact assembly is actuated by a small
insulating block 22, attached to one of the swinging links 20. The block moves up and down as
the link swings with reversals of driving rotation. -This action moves the center spring contact 44 from the bottom to the top stationary
contact 42, and vice versa. The center contact
pointer 89 makes one complete revolution every
100 rpm and the short pointer 88 makes one
complete revolution for full scale indicatiora.
The relative direction of the speed is indicated
by the backing signal indicator which is lighted
only when the propeller shaft rotates in the
astern direction.
The running synchro receiver 8 is driven
electrically by the associated shaft transmitter
at a speed exactly one-tenth that of the propeller shaft. The running synchro drives the
input shaft of the speed-measuring mechanism
through gear 118. The speed-measuring mechanism converts the rotary motions into proportional angular displacements. The running sync hro
8 also drives the revolution counter 141 through
gears at a speed exactly one-tcnth that of the
propeller speed. The revolution counter registers
the total propeller revolutions directly, irrespective of the direction of rotation.
The positioning synchro transmitter 7 re-
ceives the angular displacement from the speedmeasuring mechanism and transmits these displacements to the remotely located indicators.
The speed measuring mechanism operates
on the friction disk and roller assembly principle.
387
Z99
;
IC ELECTRICIAN 3 & 2
141
89
88
-16
28
5
32
CW
85
CCW
39
40
54
42
118
TO
INDICATORS
FROM SHAFT
TRANSMITTER
LEGEND
4 - SYNCHRONOUS MOTOR
32- HELICAL GEAR
GEAR
7 - POSITIONING SYNCHRO TRANSMITTER 39- SLIP RING AND CONTACT ASSEMBLY
8 - RUNNING SYNCHRO RECEIVER
40- HUB ASSEMBLY
9 - FOLLOWUP MOTOR
42- INPUT SHAFT
15 - TRAVELING YOKE
54- SPRING WASHER
16 - LEAD SCREW
so - FRICTION ROLLER
25 - SWITCH OPERATING SCREW
70 - LIMIT SWITCH
28 - HELICAL GEAR
85- POINTER SHAFT
30 - FRICTION DISK
88- INNER POINTER
89 -OUTER POINTER
114 -DRIVEN DISK
115 -DRIVE DISK
118 -INPUT GEAR
141 - MECHANICAL COUNTER
200- SPEED SIGNAL SWITCH
204- ACTUATOR SCREW
205 -BRACKET
Figure 15- 4. Gearing diagram of indicator-transmitter.
388
r
:
400
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Chapter 15 SHIP'S METERING AND INDICATING SYSTEMS
The unknown speed is the input of the running
synchro receiver 8, which is geared to the input
shaft 42 of the speed-measuring mechanism
through gear 118.
The known speed is provided by the synchro-
nous motor 4, which drives the friction disk
through gears at a constant speed. The gearing
30
is such that the disk speed is 16 2/3 rpm for
200 range units and 33 1/3 rpm for 400 range
units. The friction disk is held in continuous
contact with the friction roller 60, which is
integral with the helical gear 28. The friction
roller and helical gear are mounted on the
traveling yoke 15, which has a total longitudinal
motion of approximately 1.10 inches along the
radius of the friction disk 30. The yoke is posi-
tioned along the disk radius by the lead screw
16, which is driven by the followup motor 9.
The friction roller 60, integral with helical
gear 28, drives the helical gear 32, which is
mounted on, but free to turn through a limited
range about, the input shaft 42. Thus, the helical
gear rotates at a speed proportional to the distance between the position of the roller on the
disk and the center of the disk. The radius of
contact at any given point will determine the
drive ratio and speed at which the roller 60,
and gears 28 and 32 will rotate.
The speed of helical gear 32 is automatically
adjusted to match the speed of the running synchro driven gear 118, by the slipring and contact
assembly 39, the upper two sliprings of which
are mounted on the hub of gear 32 and are free
to turn through a limited range about the input
shaft 42. The assembly carries two outside
brush contacts CW and CCW, each of which
slides on a slipring. The center brush contact
C slides on a slipring Witch is attached to the
hub 40 and is secured to the input shaft 42 by
the friction thrust washer 54. The contact assembly can be turned in either direction so that
one or the other of the outside contacts can
mate with the center contact. This action energizes the followup motor 9 and determines its
direction of rotation.
When the input gear 118 and the helical gear
32 are running at exactly the same speed, the
contacts are open, the followup motor 9 is deenergized, and the indicator pointers 88 and 89
are stationary. However, if the speed of gear
contacts close. The contacts will remain closed
to energize the followup motor. in a correcting
direction until the radius of disk contact with
roller 60 reaches a new value where the speed
of gear 32 is again equal to that of gear 118.
At this point the contacts open to deenergize the
followup motor.
At zero (rpm) input from the running synchro receiver 8, gear 118, is stationary and the
contacts of the slipring assembly will cause the
followup motor 9 to move the lead screw 16,
forging the friction roller 60, toward the center
of the friction disk 30. At the exact center, the
indicator pointers 88 and 89 should read zero
rpm, and the positioning synchro transmitter 7
should be on electrical zero. However, the
pointers will not reach the exact scale zero because a limiting switch (not shown in fig. 15-4)
deenergizes the synchronous motor 4 at a pointer
indicator of approximately 1 rpm.
The full scale indication should occur when
the point of roller contact is exactly 1 inch from
the center of the disk 30. The indicators provide for an overspeed indication of about 10
percent above full scale (1.10 inches disk radius)
before the limit switch 70 is actuated.
The indicator-transmitter can be provided
with speed signal switch 200 to continuously
energize a remote light or other signal at propeller speeds below a specified value. The signal setting is adjustable from about one-quarter
of full speed down to about 5 rpm. As the speed
of the propeller shaft decreases from higher
values above the switch operating point, the
yoke 15, bracket 205, and actuator screw 204,
are advanced along the lead screw 16, until the
roller and arm of the stationary SPDT switch
200, are lifted by the actuator screw 204. The
speed value at which the switch is operated is
determined by the height of the actuator screw
204, above the bracket 205. The speed signal
switch is adjusted by turning the actuator screw
until the desired operating point is obtained.
After the switch has been actuated in decreasing
speed direction, it will remain actuated at lower
speeds down to zero. Also, when the propeller
speed increases, the OFF or release point of the
switch will occur tl`