Instruction Manual

Instruction Manual
Publication 350-01001-00, 8/26/05
Installation • Operation • Maintenance
Standard AC generator
Single or two-bearing
Drive-end air discharge
Kato Engineering Inc.
P.O. Box 8447
Mankato, MN USA
56002-8447
Tel: 507-625-4011
Fax: 507-345-2798
Email: [email protected]
www.kato-eng.com
Page 1
Table of Contents
Introduction......................................................... 4
Foreword............................................................................4
Safety instructions..............................................................4
Ratings/description............................................................ 4
Construction and Operating Principles............ 5
Stator................................................................................. 5
Rotor.................................................................................. 5
Bearings.............................................................................5
Connection boxes.............................................................. 6
Excitation system............................................................... 6
Optional PMG system........................................................ 7
Other options..................................................................... 7
Installation........................................................... 8
Note: Because of rapid changes in designs
and processes and the variability of Kato
Engineering’s products, information in this
manual must not be regarded as binding
and is subject to change without notice.
The image on the front cover is representative only. Several variations are available
within the range of generators covered
within this manual.
Receiving inspection.......................................................... 8
Unpacking and moving...................................................... 8
Location............................................................................. 8
Base design....................................................................... 8
Assemble to prime mover, alignment................................ 8
Two-bearing alignment............................................ 9
Two-bearing close-coupled alignment................... 11
Single-bearing alignment....................................... 17
Foot deflection................................................................. 22
Doweling.......................................................................... 22
Electrical connections...................................................... 22
Space heaters................................................................. 22
Inspection before startup................................................. 23
Operation........................................................... 24
Initial startup: generators w/auto & manual control.......... 24
Initial startup: generators w/auto control only................... 24
Restoring residual magnetism/field flashing.....................25
Continuous operation....................................................... 26
Idling................................................................................. 27
Parallel operation..............................................................27
Page 2
Maintenance.......................................................29
Schedules........................................................................ 29
Maintenance procedures................................................. 31
Visual inspection methods of windings.................. 31
Cleaning................................................................ 32
Insulation resistance tests at low voltage.............. 33
Dry out procedures............................................... 35
Bearing lubrication................................................ 35
Rectifier tests........................................................ 36
Disassembly..................................................................... 38
Overall disassembly............................................... 38
Exciter armature and PMG removal...................... 39
Bearing removal.................................................... 41
Assembly.......................................................................... 41
Bearing installation................................................ 41
Overall assembly................................................... 42
Exciter armature and PMG installation.................. 42
Storage............................................................................ 43
Troubleshooting Guide.....................................44
Appendices........................................................47
List of equipment required for installation
and maintenance............................................................. 47
Main part location............................................................. 48
Page 3
Introduction
Foreword
This manual contains instructions for installing, operating and
maintaining Kato Engineering AC brushless revolving field generators.
These generators are manufactured in many sizes and ratings and with
various options.
Lubrication information, electrical connection drawings, dimensional
drawings and parts listings for your model are contained in the manual
package as supplementary information and are the specific source of
information for making connections and ordering replacement parts.
Information about optional components of your generator may also be
contained as a supplement.
Please read this manual in its entirety before unpacking, installing, and
operating your generator.
Safety instructions
In order to prevent injury or equipment damage, everyone involved in
installation, operating and maintenance of the generator described in this
manual must be qualified and trained in the current safety standards that
govern his or her work.
While “common-sense” prevention of injury or equipment damage
cannot be completely defined by any manual (nor built into any piece
of equipment), the following paragraphs define warnings, cautions, and
notes as they are used in this manual:
Warning: Warnings identify an installation, operating or maintenance
procedure, practice, condition, or statement that, if not strictly followed,
could result in death or serious injury to personnel.
Caution: Cautions identify an installation, operating or maintenance
procedure, practice, condition, or statement that, if not strictly followed,
could result in destruction of or damage to equipment or serious
impairment of system operation.
Note: Notes highlight an installation, operating or maintenance
procedure, condition, or statement and are essential or helpful but are not
of known hazardous nature as indicated by warnings and cautions.
Ratings/description
Nameplates, which are located on the side of the generator, include
serial and model number as well as rating information and bearing and
lubrication information.
Page 4
Construction and Operating Principles
Stator
The stator consists of the supporting frame, core, and armature windings.
The stator core is made from laminations, thin sheets of electrical steel,
which are stacked and held in place by steel endrings and support
bars. The rings and bars are welded to or are part of the steel frame.
Base mounting plates are welded to the bottom of the frame. The base
mounting plates allow the assembly to be mounted on the genset base.
The windings (coils) are constructed of layered and insulated copper
wire. The coils are inserted in the core slots, connected together, and
the entire assembly is vacuum-pressure impregnated with resin. Stator
leads terminate in standard connection lug or strap terminals for ease of
connection to the load.
Rotor
The main rotor assembly is the revolving field. It consists of windings
in a core, which is in turn mounted on a steel shaft. The exciter armature
assembly and optional permanent magnet generator (PMG) rotor are also
mounted on the shaft as are the fan(s) and other optional accessories.
The core consists of laminations, thin sheets of electrical steel, which are
stacked together. The core makes the salient poles (four, six, eight or 10).
With six or more poles, the poles are typically attached to a center hub.
The rotor windings consists of insulated magnet wire wound around
each pole. V-blocks between each pole keep the rotor windings in place.
Damper windings consist of copper or aluminum rods that are inserted
through each pole surface and are brazed to copper or aluminum damper
end plates at each end of the lamination stack. The end plates are brazed
to adjacent poles to form a continuous damper winding. The ends of the
windings are supported with bars or aluminum pole shoes. The rotor
either has resin applied during the winding process or is vacuum-pressure
impregnated with resin.
The shaft is made from high-strength rolled or forged steel and machined
to accommodate all the rotating generator components. Keyways in
the shaft ensure precise positioning of the rotor, exciter armature, and
optional PMG rotor as well as drive couplings. On the exciter side, the
shaft has a slot or hole in its centerline for running the revolving field
leads to the rectifier.
Bearings
The generator may contain either one or two bearings. Bearings are
typically ball or roller type and are either 1) heavy duty double shielded
bearings, which are typically used on smaller generators and are greased
for life or 2) regreaseable bearings, which contain fill and drain ports
Page 5
for easy lubrication. Sleeve bearings are optional on some designs. A
supplementary instruction will be included in the manual package for
sleeve bearings if they are applicable to this generator.
Connection boxes
The main lead connection box houses the load lead terminals. In
addition, the generator may have auxiliary connection boxes for
connecting temperature detector outputs, space heater connectors, and
sensing outputs.
Excitation system
The excitation system consists of the exciter stator assembly and the
exciter armature assembly:
The exciter stator assembly consists of windings in a core. The core is
made from steel laminations that are stacked and welded together. The
main exciter stator coils are placed in slots in the core and form alternate
north and south poles. The entire assembly is either mounted to the end
bracket or mounted in a frame, which is mounted to the end bracket. The
stator is a stationary field, which is powered by the voltage regulator.
The assembly consists of two subassemblies: the exciter armature and
the rotating rectifier. The exciter armature assembly contains steel
laminations that are stacked and keyed on the shaft or on to a sleeve,
which is keyed to the generator shaft. A three-phase winding is inserted
into slots in the laminations. The coils are held in place by insulating
wedges. The coil extensions are braced with tape. Output leads from the
winding are connected to the rotating rectifier assembly.
The rotating rectifier is a three-phase full wave bridge rectifier,
converting the AC from the exciter armature to DC, which is transferred
to the revolving field windings. Two aluminum steel plates, each
containing three rotating rectifier diodes, are mounted on each side of
an insulating hub to form the negative and positive terminals. The plates
also act as heat sinks for the diodes.
Excitation system functional overview: Exciter field control is
established by the strength of the exciter field current developed by
the voltage regulator system. The DC voltage and current levels of the
exciter field signal from the voltage regulator varies depending upon the
generator output voltage and the loading of the output lines (see Figure
1).
Page 6
Power input
Voltage
regulator
Output leads
Main stator
(armature)
Exciter stator
(field)
PMG stator
(armature)
Main rotor (DC)
Prime mover
Shaft
PMG rotor
(field)
Exciter
armature (AC)
Rectifier
Figure 1: Overview of excitation system
(with an optional PMG)
Optional PMG system
The permanent magnet generator (PMG) system consists of the PMG
stator and PMG rotor:
The PMG stator is a stationary armature and is located within the stator
assembly that also contains the exciter stator or is a separate stator
mounted next to the exciter stator. The PMG stator consists of steel
laminations. The laminations are held in place by steel compression rings
and are welded to the frame bars of the exciter-PMG frame. The PMG
windings are placed in slots in the laminations. Insulating wedges are
inserted at the top of each slot to hold the coils in position.
The PMG rotor consists of rectangular permanent magnets and cast pole
tips secured to a steel hub with nonmagnetic stainless steel bolts. The
PMG rotor is keyed to the shaft and secured with a nut and lock washer.
PMG system overview: The PMG system functions as a pilot exciter,
providing power to the automatic voltage regulator power supply. The
PMG is an AC generator that uses permanent magnets in the rotor instead
of electromagnets to provide the magnetic field (see Figure 1).
Other options
Other options include, but are not limited to, space heaters, filters, and
temperature sensing devices.
Page 7
Installation
Warning: Be alert at all times when
installing, operating and maintaining the
generator. Avoid contact with the uninsulated
metal parts of the generator. Most injuries
occur from faulty ground connections on
portable electrical equipment and failure to
ground stationary equipment.
Test all portable devices frequently to
prove that a solid electrical circuit exits
from the metal frame though the grounding
conductor, in the electrical cord, to the
grounding contact in the attachment plug.
Do not use electrical equipment with frayed,
burned or damaged cords. Always take
extreme care when moving the generator.
Be careful to not strike objects or personnel.
Apply lifting force to structural points
specifically provided for lifting. Do not use
the enclosure lifting holes to lift the whole
unit. Use lifting means adequate to the
weight. Observe lifting notices attached
to the generator. Failure to observe these
instruction can result in injury and damage
to the generator.
Caution: Do not attempt to transport a
single-bearing generator without maintaining
proper rotor support and with the exciter
rotor assembly removed. Failure to observe
this warning can result in equipment
damage.
Caution: Blocking or restriction of normal air
flow into or out of the generator may cause
damage to the electrical windings.
Receiving inspection
Before accepting a shipment, examine the packaging for any sign of
damage that might have occurred during transit. Report any damage to
the transportation company and Kato Engineering.
Unpacking and moving
If the generator is received during cold weather, reduce condensation on
cold surfaces and failure due to wet windings by allowing the generator
to reach room temperature before removing the protective packing.
Unpack the generator carefully to avoid scratching painted surfaces. Do
not remove the protecting lubricant from the shaft end or drive plates.
Inspect for loosely mounted components and the presence of moisture.
Inspect to make certain foreign material, such as crating nails, loose
bolts or packing material, which may have fallen into the machine during
unpacking, is removed. If damage is noted, determine the extent of
damage and immediately notify the transportation company claims office
and Kato Engineering. Be sure to give complete and accurate details
when reporting damage.
Move the generator by attaching an overhead hoist to the eyebolts
installed on the generator frame or by lifting the generator from
underneath the skid with a forklift.
Single-bearing generators are shipped with the exciter rotor assembly
removed from the shaft and a support mounted across the drive discs to
support the rotor.
Location
Install the generator in an area so it complies with all local and industrial
regulations. Locate it in a clean, dry, well-vented area or area that is
suitable for the generator enclosure. Make sure it is easily accessible for
inspection and maintenance.
Protect generators operating intermittently in very damp locations with
space heaters. Slowly warm generators placed in operation after being
subjected to very low temperatures to prevent excessive condensation.
Check winding resistance before placing the generator in operation (see
instructions below).
Base design
The type of base to be used will depend upon the nature of the
installation site. However, the generator base must be rigid, level, and
free from vibration. Mounting holes must be larger than the fasteners to
allow for alignment.
Page 8
Assemble to prime mover, alignment
Follow either the two-bearing alignment (if your generator model has
two bearings but no adapter to bolt to an engine flywheel housing),
two-bearing close-coupled alignment (if your generator model has two
bearings and an adapter for bolting to a flywheel housing), or singlebearing alignment (if your generator has one bearing and drive plates).
Consult the factory for belt or gear drive alignment).
Two-bearing alignment
Follow the tolerances specified by the coupling manufacturer when they
are less than described in this manual.
Use shims, if necessary, between the mounting pad and the base to
properly level and align the generator to the prime mover.
Install the coupling(s) on the generator and engine drive shafts in
accordance with coupling manufacturer installation procedures. Use a
straight edge and a thickness gauge for rough alignment as shown in
Figure 2. Check for angular and parallel alignment as follows:
Straight edge
Notes: Mounting of the indicators must
allow complete rotation of the prime mover.
Thickness gauge
Figure 2: Rough alignment
Angular alignment: Fasten a dial indicator to one of the coupling halves,
and scribe the position of the dial button on the face of the opposite
coupling half as shown in Figure 3. Rotate both shafts simultaneously,
keeping the finger or button on the indicator at the reference mark on the
coupling hub. Note the reading on the indicator dial at each one quarter
revolution.
A variation of readings at different positions will indicate how the
machine needs to be adjusted to obtain a maximum misalignment of
0.001 inch for each inch of the coupling hub’s radius, total indicator
runout. Place or remove slotted shims from under the front or rear engine
or generator mounting pads and/or shift the front or back half of one
component from side to side until the components are properly aligned.
Tighten the mounting bolts, and recheck alignment.
Page 9
Use dial indicators that are rigid so indicator
sag won’t be a factor. Using the shortest
offset distance of the indicator bracket will
reduce the effects of indicator droop or sag.
During alignment, you may also need to
compensate for engine expansion due to
heating. Generator expansion is generally
not considered a factor.
If the genset is moved to a different
location, check alignment before startup.
Caution: Do not pry on the generator fan.
Caution: Generators equipped with sleeve
oil bearings must have oil added to the
bearing prior to rotation. See the bearing
manual.
Dial indicator
Figure 3: Angular alignment
Parallel alignment: Fasten a dial indicator to one of the coupling halves,
and scribe the position of the dial button on the top of the opposite
coupling half as shown in Figure 4. Rotate both shafts simultaneously,
keeping the finger or button on the indicator at the reference mark on the
coupling hub. Note the reading on the indicator dial at each one quarter
revolution. A variation of readings at different positions will indicate how
the machine needs to be adjusted to obtain a maximum misalignment of
0.002 inch. Place or remove slotted shims from under all of the engine
or generator mounting pads and/or shift one component from side to side
until the components are properly aligned. Tighten the mounting bolts,
and recheck alignment.
Dial indicator
Figure 4: Parallel alignment
Page 10
Two-bearing close-coupled alignment
Check the engine flywheel housing pilot’s radial and face runout by
mounting a dial indicator and measuring the flywheel to the flywheel
housing as shown in Figure 5. See Table 1 for maximum allowable
runout.
Flywheel
Dial indicator
pointer for radial
runout
Flywheel housing
Notes: Mounting of the indicators must
allow complete rotation of the prime mover.
Use dial indicators that are rigid so indicator
sag won’t be a factor. Using the shortest
offset distance of the indicator bracket will
reduce the effects of indicator droop or sag.
During alignment, you may also need to
compensate for engine expansion due to
heating. Generator expansion is generally
not considered a factor.
If the genset is moved to a different
location, check alignment before startup.
Shaft
Caution: Do not pry on the fan.
Caution: Generators equipped with sleeve
oil bearings must have oil added to the
bearing prior to rotation. See the bearing
manual.
Dial indicator pointer for
face runout
Figure 5: Flywheel housing check
SAE housing
number
Housing inside
dia.
Allowable
runout (TIR)
6
5
4
3
2
1
0.5
0
00
10.500
12.375
14.250
16.125
17.625
20.125
23.000
25.500
31.000
0.002
0.003
0.003
0.004
0.004
0.005
0.005
0.006
0.007
Table 1: Maximum allowable
flywheel housing runout (inches)
Page 11
Check the engine flywheel’s radial and face runout by mounting a dial
indicator and measuring the flywheel housing to the flywheel as shown
in Figure 6. See Table 2 for maximum allowable runout.
Flywheel
Flywheel housing
Dial indicator pointer
for radial runout
Shaft
Dial indicator
pointer for face
runout
Figure 6: Flywheel check
Pilot
diameter
Allowable
runout (TIR)
6.5
7.5
8
10
11.5
14
16
18
21
24
0.002
0.002
0.002
0.003
0.003
0.004
0.005
0.005
0.006
0.007
Table 2: Maximum allowable flywheel runout (inches)
Page 12
Check the generator adapter’s radial and face runout by mounting a
dial indicator on the generator shaft or coupling as shown in Figure 7.
The maximum radial and face runout on the generator adaptor must not
exceed 0.010 inch.
Dial indicator pointer
for radial runout
Adapter
Shaft
Dial indicator
pointer for face
runout
Figure 7: Generator adapter check
Check the generator coupling’s radial and face runout by mounting
a dial indicator to the generator adapter as shown in Figure 8. The
maximum radial and face runout on the coupling must not exceed 0.003
inch.
Adapter
Shaft
Dial indicator
pointer for face
runout
Dial indicator
pointer for radial
runout
Figure 8: Generator coupling check
Page 13
Install the portion of the coupling that fits into the engine flywheel
following the manufacturer’s recommended procedures and in
accordance with engine manufacturer’s specifications. Check the
coupling’s radial and face runout by mounting a dial indicator to the
engine flywheel housing as shown in Figure 9. The maximum radial and
face runout on the coupling must not exceed 0.004 inch.
Flywheel
Flywheel housing
Dial indicator
pointer for face
runout
Shaft
Dial indicator pointer
for radial runout
Figure 9: Engine coupling check
Measure and record the engine crank shaft endplay and generator
endplay. Set the engine endplay to the manufacturer’s recommended
position for alignment. Verify the generator end-float is set at a position
of one half of the measured distance or at a position that will allow
full thermal growth of the generator shaft when operated at rated
temperatures.
Mount the generator on the skid, and move the generator to within 0.010
inch of the engine. Place two 0.010-inch shims in the horizontal
(9 o’clock and 3 o’clock) positions between the generator adapter
and the engine flywheel housing. Raising the rear, exciter end of the
generator as necessary, place two 0.010-inch shims in the vertical (6
o’clock and 12 o’clock) positions between the generator adapter and
the engine flywheel housing. This will give a good starting point for
alignment. Remove the vertical shims at this time. (If necessary, mark
holes to be drilled on the base, and remove the generator at this time.)
Page 14
Mount a dial indicator on the generator shaft or half coupling to the
flywheel radial surface for parallel alignment as shown in Figure 10.
Mount a dial indicator on the flywheel coupling to the face of the
generator half coupling for angular alignment as shown in Figure 10.
Align the engine by rotating the prime mover in 90-degree increments
and measuring total indicator runout. Tighten the generator to the base
before taking each set of readings. Raise or lower the generator by
adding or removing shims under the machined feet.
Flywheel
Dial indicator pointer
for parallel alignment
Flywheel housing
Shaft
Dial indicator pointer
for angular alignment
Figure 10: Alignment check
Following the final generator adjustment and runout check, remove
the horizontal shims from the adaptor flywheel housing, and move the
generator all the way to the adaptor. Then tighten the fasteners. Recheck
alignment. Make sure angularity (face) total indicated runout does not
exceed 0.001 inch per inch of generator shaft diameter and parallel
(radial) total indicated runout does not exceed 0.003 inch.
Torque the fasteners to the value shown in Table 3.
Page 15
Note: Clearances between the adaptor
pilot and the flywheel housing recess are
designed to meet the tolerance of 0.001 to
0.015 inches.
Grade 2
in-lbs.
Size
Grade 2
Grade 8
Grade 5
ASTM & SAE grade markings
ft-lbs
Min.
Max.
Min.
Max.
4-40
3.3
4.7
0.4
0.5
6-32
6.1
8.7
0.7
1.0
8-32
12.5
17.8
1.0
1.5
1.4
2.0
10-32
20.8
29.7
1.7
2.5
2.3
3.4
1-NM = 0.737 ft-lbs. = 8.85 in-lbs.
1/4-20
50.4
72.0
4.2
6.0
5.7
8.1
92.4
132.0
7.7
11.0
10.4
14.9
3/8-16
159.6 228.0
13.3
19.0
18.0
25.8
7/16-14 252.0 360.0
21.3
30.0
28.9
40.7
1/2-13
31.5
45.0
42.7
61.0
46.2
66.0
62.6
89.5
93.0
88.3
126.1
378.0 540.0
5/8-11
65.1
3/4-10
105.0 150.0 142.4 203.4
7/8-9
141.4 202.0 191.7 273.9
Grade 5
in-lbs.
Size
Max.
5/16-18
9/16-12
Class 10.9
Class 8.8
Metric grade markings
Min.
N-M
Grade 8
ft-lbs
N-M
in-lbs.
Size
ft-lbs
Min.
Max.
Min.
Max.
Min.
Max.
Min.
Max.
1/4-20
60
84
5
7
3.7
5.2
10-32
36
49
Min.
5/16-18
120
192
10
16
7.4
11.8
1/4-20
72
144
6
3/8-16
228
336
19
28
14
20.7
5/16-18
156
276
7/16-14
360
528
30
44
22.1
32.5
3/8-16
324
444
N-M
Max.
Min.
Max.
4.1
5.5
12
8.1
16.3
13
23
17.6
31.2
27
37
36.6
50.2
1/2-13
540
804
45
67
33.2
49.4
7/16-14
480
720
40
60
54.2
81.3
9/16-12
792
1152
66
96
48.7
70.8
1/2-13
780
1020
65
85
88.1
115.2
5/8-11
1104
1608
92
134
67.9
98.8
9/16-12
1140
1500
95
125
128.3 169.5
3/4-10
2052
2724
171
227
126.1 167.4
5/8-11
1560
2040
130
170
176.8 230.5
7/8-9
3372
4368
281
364
207.2 268.5
3/4-10
2760
3600
230
300
311.8
1-8
5160
6432
430
536
317.1 395.3
7/8-9
4320
5760
660
480
488.1 650.8
1-8
6720
8640
560
720
759.3 976.2
Class 8.8
Size
M4
in-lbs.
406.7
Class 10.9
ft-lbs
N-M
Size
Min.
Max.
Min.
Max.
Min.
Max.
20
32
1.7
2.7
2.3
3.6
M4
in-lbs.
ft-lbs
N-M
Min.
Max.
Min.
Max.
Min.
Max.
22
36
1.8
3
2.5
4.1
M6
65
113
5.4
9.4
7.3
12.8
M6
77
122
6.4
10.2
8.7
13.8
M8
168
264
14
22
20
30
M8
192
288
16
24
22
32
M10
324
516
27
43
38
58
M10
384
576
32
48
43
66
M12
612
900
51
75
69
101
M12
672
996
56
83
77
112
M14
960
1428
80
119
109
161
M14
1080
1554
90
132
122
179
M16
126
184
170
250
M16
140
206
190
279
M18
183
243
248
330
M18
205
271
277
368
M20
263
341
357
463
M20
294
381
398
517
M22
367
457
497
619
M22
409
510
554
691
M24
465
580
631
787
M24
531
662
720
898
Table 3: Recommended lubricated torque values. (If no lubricant is used, increase values by 25%.)
Page 16
Single-bearing alignment
Before assembling the generator to the prime mover, remove the exciter
cover and adapter cover. Remove the blocking holding the drive discs to
the adapter. Also make sure the generator bearing end clearance is not
less than the total engine crankshaft axial movement plus 1/16 inch. The
generator is shipped from the factory with 1/8-inch minimum bearing
end clearance. (This dimension is recorded on the Factory Recorded
Dimensions sheet, packaged with the generator.)
Measure the distance from the end of the exciter shaft extension to the
bearing housing on the endbracket (dimension A in Figure 11). This
dimension is recorded on the Factory Recorded Dimensions sheet,
packaged with the generator. If the dimensions do not match, move the
rotor axially relative to the stator until the dimensions are equal.
Notes: Mounting of the indicators must
allow complete rotation of the prime mover.
Use dial indicators that are rigid so indicator
sag won’t be a factor. Using the shortest
offset distance of the indicator bracket will
reduce the effects of indicator droop or sag.
During alignment, you may also need to
compensate for engine expansion due to
heating. Generator expansion is generally
not considered a factor.
If the genset is moved to a different
location, check alignment before startup.
Caution: Do not pry on the generator fan.
Endbracket
Exciter field
Bearing
A
Shaft extension
Figure 11: Generator coupling check
Page 17
Caution: Generators equipped with sleeve
oil bearings must have oil added to the
bearing prior to rotation. See the bearing
manual.
Check the engine flywheel housing pilots’s radial and face runout by
mounting a dial indicator and measuring the flywheel to the flywheel
housing as shown in Figure 5. See Table 1 for maximum allowable
runout.
Check the engine flywheel’s radial and face runout by mounting a dial
indicator and measuring the flywheel housing to the flywheel as shown
in Figure 6. See Table 2 for maximum allowable runout.
Caution: Never grind the OD of drive
discs or attempt to drill out the holes. If the
dive discs do not fit properly, use different
discs or a different flywheel.
Measure the generator drive plate diameter (dimension S of Figure 12)
and flywheel bore diameter (dimension B of Figure 13). Drive plate
diameter must not be greater than the flywheel bore diameter. Also check
to make sure the hole centers match (dimension W of Figure 12 and
dimension C of Figure 13).
Measure the axial distance from the surface on the generator adapter
to the outside surface on the drive disc coupling plates (dimension Y
in Figure 12). This dimension is recorded on the Factory Recorded
Dimensions sheet, which was packaged with the generator. If the
dimensions do not match, move the rotor axially relative to the stator
until the dimensions are equal.
Y
Drive
plates
Adaptor
Fan
Shaft
S
W
A
Bolt holes
Figure 12: Single bearing generator drive plate
and adaptor
Page 18
Measure the axial distance from the machined surface on the engine
flywheel housing the bottom of the flywheel drive disc recess
(dimension G in Figure 13). Make sure the difference between
dimensions Y (of Figure 12) and G are less than 1/32 inch. If G is
more than Y, install additional spacers between the drive discs and the
generator hub. If Y is more than G, remove spacers between the drive
discs and generator hub.
Tapped
bolt holes
C
Flywheel
B
G
Figure 13: SAE flywheel and adapter
Install the generator to the engine. Make sure the drive discs seat in
the recess of the flywheel housing. Secure the generator to the engine
(drive discs to flywheel, adapter to flywheel housing), and the base. Use
lock washers on all bolts. Torque the adapter and drive discs in a crisscross pattern to the values in Table 3.
Ensure that the bolts in the flywheel do not bottom out. If they are too
long or cannot be tightened with a socket or box wrench, use 1/4 to 3/8inch long spacers inserted in the bolts as shown in Figure 14 to increase
the clearance between the bolt head and the flywheel.
Lock washer
Bolt
Spacer
Drive hub
Drive plates
Flywheel
Figure 14: Disc-to-flywheel installation
Page 19
Caution: The number and thickness
of drive discs are specified for torque
requirements. Do not remove drive discs
to compensate for spacing.
Occasionally, there is insufficient clearance to install the bolts that
fasten the drive discs to the engine flywheel, and the fan will have to be
temporarily moved to accommodate this. This situation will typically
occur with several types of generators:
• With the three-frame units that have an aluminum fan, loosen the fan
hub bolts to move the fan. After installing the drive disc-to-flywheel
bolts, move the fan back so the rotor-side edge is flush with the air
opening and the minimum distance between the windings and the
fan is 3/8 inch. Torque the fan hub bolts to 75 ft-lbs.
Note: The generator with sheet metal fans
and cast fan hubs is shipped from the
factory with the fan 1/2 to 3/4 inch from the
fan baffle and clear of the inside adaptor
for optimum air flow through the exhaust
screen.
• With sheet metal fans with cast hubs that are in turn mounted on the
drive hub, mark the drive hub as closes as possible to the fan hub.
Loosen the two set screws, the fan clamping bolt, and the fan bolts.
Wedge the fan open, and move it out of the way (See Figure 15).
After attaching the drive discs-to-fly wheel bolts, align the fan hub
to the mark to move the fan back to its original position. Ensure
the key is fully in place under the fan hub and positioned so the set
screw will press on the key. Tighten the fan hub clamping bolt and
the set screws. Install the fan bolts and torque them according to
Table 3.
Fan
Drive discs
Fan bolts
Set screw
Keyway
Key
Bolt holes
Alignment mark on
drive hub
Fan hub bolt
Fan hub
Figure 15: Moving sheet metal fans
Page 20
After installing the drive disc-to-flywheel bolts, check the runout of the
generator shaft by placing the base of a dial indicator on the generator
frame and positioning of the probe on the shaft as shown in Figure 16.
If the total indicated runout exceeds 0.003 inch, remove the drive discs
bolts, and rotate the generator relative to the engine flywheel. Reinstall
the bolts, and check the runout again.
Recheck the shaft-end-to-bearing-housing distance (dimension A in
Figure 11).
Mount the brushless exciter armature assembly to the generator shaft
(as described in the assembly procedures below).
Adapter
Fan
Dial indicator pointer
Shaft
Drive plates
Drive hub
Figure 16 Runout check
Page 21
Foot deflection
After alignment, check for foot deflection or “soft foot” condition on
each shim location to eliminate distortion of the generator frame. Do
this by loosing one mounting bolt at a time and checking deflection
after retightening. Deflection at the shim location from shims under
compression to a loosened condition must not exceed 0.003 inch.
Doweling
In case the mounting bolts loosen during operation, doweling will
prevent movement of the generator. Dowel as follows:
Check the alignment after the generator has been in operation for at least
48 hours. If alignment is not satisfactory, realign.
Drill holes through the footpads and into the base in two mounting pads
opposite each other. Drill the holes slightly smaller than the dowel pin.
Ream the holes to the proper diameter for the pin. Clean out chips, and
install the pins.
Electrical connections
If the generator was subjected to a rapid change in temperature, freezing
or wet conditions during shipment or storage, measure the insulation
resistance of each winding and dry the generator, if necessary, as
described in the maintenance section below.
Make all electrical connections (main load, temperature monitoring
device, space heater, AVR) in accordance with local regulations and
national/international electrical code requirements. Check the electrical
diagrams provided with the generator or manual. The main terminals
need to be properly spaced for the load connections. Refer to Table 3 for
the proper torque values for the connections.
On larger generators grounding points are provided for properly
grounding the system to the generator frame. The grounding wire must
be sized to national/international code requirements.
Space heaters
Warning: The space heaters are designed
to be energized when the generator is
shut down. They are hot enough to cause
skin burns. Terminals for power at the
space heaters are live during operation.
Disconnect power to the space heaters
before removing the generator covers.
When the generator has optional space heaters to prevent water
condensation during long periods of downtime, connect the space heaters
so they start when the generator is turned off and stop when the generator
is switched on. Refer to the electrical diagrams for the space heater
characteristics.
Page 22
Inspection before startup
After electrical connections have been made, perform the following
checks:
•
Check all the connections to the electrical diagrams provided.
•
Secure all covers and guards.
•
Turn the rotor slowly with the appropriate starting mechanism (bar
the engine or flywheel) through one revolution to see if the rotor
turns freely.
•
Check the bearings to see they are properly lubricated.
•
Determine the direction of the engine rotation, and make sure that it
matches the rotation of the generator.
•
Make sure the power requirements comply with the data on the
generator nameplate.
•
Make sure that the engine-generator set is protected with an adequate
engine governor and against excessive overspeed.
•
Make sure the output of the generator is protected with an overload
protection device, such as circuit breakers or fuses, sized in
accordance with national/international electrical code and local
electrical code standards. Fuses need to be sized using the lowest
possible current rating above the full-load current rating (115% of
rated current is commonly recommended).
•
Remove tools and other items from the vicinity of the generator.
Page 23
Caution: Do not pry on the fan.
Operation
Initial startup: generators with both automatic and
manual voltage control
1. Disconnect the generator output from the load by opening the main
circuit breaker.
2. Turn the manual voltage adjust rheostat fully counterclockwise.
3. Put the auto-manual switch in the manual position.
4. Start the prime mover, and bring the set to rated speed. Turn the
manual voltage adjust rheostat to reach rated voltage. Close the
output circuit breaker, and apply load in steps until the rated load is
reached. Adjust the manual adjust rheostat as necessary to obtain the
desired output voltage.
5. Gradually reduce load, and adjust the rheostat accordingly until no
load is reached. Open the circuit breaker, and stop the prime mover.
6. Actuate the auto voltage rheostat. Then start the genset, and bring it
to rated speed. Adjust the voltage to the desired value.
Caution: Do not actuate the auto-manual
switch with the full load applied to the
generator. Whenever possible, stop the
generator before switching.
7. Close the output circuit breaker. Then check the generator voltage
and voltage regulation. Apply load in steps until the rated load is
reached.
8. Check for vibration levels at no load and rated load. A slight increase
is normal. As the load is maintained for 2-3 hours, the vibration
levels will gradually increase and reach a final level.
Initial startup: Generators with automatic voltage control
only (generator has an automatic voltage regulator (AVR)
with no auto-manual switch)
1. Disconnect the generator output from the load by opening the main
circuit breaker.
2. Turn the voltage adjust rheostat fully counterclockwise. Start the
prime mover, and bring the set to rated speed. Turn the voltage adjust
rheostat to obtain the desired voltage.
3. Close the output circuit breaker, and apply load in gradual steps until
the rated load is reach. Note the voltage regulation with the changes
in load steps.
4. Check for vibration levels at no load and rated load. A slight increase
is normal. As the load is maintained for 2-3 hours, the vibration
levels will gradually increase and reach a final level.
Page 24
Restoring residual magnetism/field flashing
The direct current necessary to magnetize the revolving field is obtained
from the exciter. Upon starting the generator, current and voltage is
induced into the exciter by the magnetic lines of force set up by residual
magnetism of the exciter field poles. Residual magnetism of the exciter
field poles may be lost or weakened by a momentary reversal of the field
connection, a strong neutralizing magnetic field from any source, or nonoperation for a long time. If the generator fails to generate voltage after
it has come up to rated speed, it may be necessary to restore residual
magnetism.
To restore the small amount of residual magnetism necessary to begin the
voltage build up, connect a 12 or 24-volt battery to the exciter field coil
circuit and flash as follows:
1. Open the output circuit breaker, and stop the engine.
2. Disconnect the exciter field coil wires EF1 at the terminal EF1 and
EF2 at the terminal EF2, and connect the battery positive lead to the
field coil lead EF1.
3. Flash the field by touching the battery lead to the field coil circuit
terminal EF2.
4. Disconnect the battery leads.
5. Reconnect the field coil lead EF1 to terminal EF1, and reconnect the
field coil lead EF2 to terminal EF2.
6. Start the generator, and check for voltage build up. Reflash if
the generator output voltage does not build up, or flash with the
generator running, the field coil wires connected to the regulator, and
a 3-amp or larger diode off the positive terminal of the battery per
Figure 17.
- 12 or 24 V
battery
+
3 amp or
larger diode
EF2
FF+
Voltage
regulator
EF1
Figure 17: Field flashing setup with the field wires
connected to the regulator
Page 25
Note: If the polarity of the exciter is reversed
by flashing the field, it may be corrected by
interchanging the battery leads.
Continuous operation
Operate the generator within the nameplate values . If the generator is
operated below the rated power factor and voltage, decrease the kVA to
prevent overheating of the field and stator windings. Consult the factory
for derating factors if the application requires the unit to be operated
beyond nameplate values.
Rotor overheating may occur when the generator is carrying excessive
unbalanced loads. Negative sequence currents flowing in the field pole
face cause the rotor heating. For a general guide to the allowable phase
unbalance, see Figure 18, Guide to allowable phase unbalance (which is
based on a 10% equivalent negative sequence current).
100
Min. current in any phase (% of rated)
Caution: Operating the unit beyond nameplate values may cause equipment damage
or failure.
80
Allowable
unbalance
60
Excessive
unbalance
40
20
0
20
40
60
80
100
Max. current in any phase (% of rated)
Figure 18: Guide to allowable phase unbalance
The guide is used in the following manner: Find the point where the
vertical line (determined by the minimum current in any of the phases
and expressed in percent of rated current) crosses the horizontal line
(determined by the maximum current in any of the phases and expressed
in percent of rated current). Ensure the point where these two lines
intersect is within the permissible allowable unbalance region for safe
operation of the generator.
Loss of field excitation can result in the unit operating out of
synchronization with the system when operating is parallel. This has the
effect of producing high currents in the rotor, which will cause damage
very quickly. Protective relays should be considered to open the circuit
breaker.
Page 26
Idling
Unless the voltage regulator has V/Hz protection built in, having the
generator set in operating mode while idling the engine can cause
permanent equipment damage. If engine adjustments require that
the engine be run at idle speed and the regulator does not have V/Hz
protection, make the generator regulating system inoperative during
idling by one of the following methods:
Caution: Refer to the voltage regulator
manual for complete details and possible
additional instructions. Damage to the rotating diodes, generator, and voltage regulator
can be caused if the regulator is operated
improperly.
When the generator is provided with a voltage shutdown switch, be sure
the switch is set to the idle position while the engine is running at idle
speed.
Where the generator set is provided with field circuit breakers, set the
circuit breaker to the off position while the generator is running at idle
speed.
Where the generator set is provided with an automatic/manual control
switch that has an off position, switch it to off while the engine is
running at idle speed.
Where the generator set does not have any of the above options, remove
the wires from the voltage regulator input power terminals when the
engine is running at less than rated speed.
Parallel operation
For the generator to operate in parallel with a system in operation, the
phase sequence of the generator must be the same as that of the system.
Use transformers to reduce the voltage to an acceptable level, and then
use a phase rotation meter or incandescent lamp method, described in
electrical machinery handbooks, for a phase sequence check.
The output voltage at the paralleling point must be the same as each
instant, which requires that the two voltages be of the same frequency,
same magnitude, same rotation, and in coincidence with each other.
Voltmeters indicate whether the voltage magnitude is the same, and
frequency meters indicate whether the frequencies are the same. Whether
the voltages are in phase and exactly at the same frequency is indicated
by a synchroscope or by synchronizing lamps.
A synchroscope can be used to indicate the difference in phase angle
between the incoming machine and the system. The generator can be
paralleled by using incandescent lamps connected as shown in Figure 19.
The voltage rating of the series lamps must equal the voltage rating of the
transformer-low voltage winding.
Each prime mover in the system must have the same speed regulating
characteristics, and the governors must be adjusted to give the same
speed regulation as determined by applying load that is proportional to
the full load rating of the generator.
Page 27
Caution: Do not make connections or otherwise make contact with the generator leads
or other devices connected to them unless
the genset is stopped and the phase leads
are grounded.
System bus
Load
switch
Synchronizing
lamps
Load lines from the incoming generator
Figure 19: Synchronizing paralleled generators with test lamps
The voltage regulator must include paralleling circuitry. In addition, the
voltage, droop settings and the V/Hz regulation characteristics must be
the same for all the voltage regulators. This will allow the generators to
properly share reactive loads.
If cross-current compensation is used, paralleling current transformers
must give the same secondary current.
Current transformer secondary windings provide reactive kVA droop
signal to the voltage regulator. Accidental reversal of this electrical
wiring will cause the voltage to attempt to rise with load rather than
droop. If this occurs during paralleling, stop the unit and reverse the
wires at the voltage regulator terminals.
If the set is provided with a unit/parallel switch, set the switch to the
parallel position on the unit being synchronized.
Synchronize the generator by adjusting the speed (frequency) slightly
higher than the system. Observe the synchroscope or the lamps. The
lamps should fluctuate from bright to dark at the rate of one cycle every
2 to 3 seconds. When the generator is in phase (the lights will be dark),
close the circuit breaker. Immediately after closing the breaker, measure
the line current kVAR of the generator. The readings must be within
the rating of the unit. A high ammeter reading accompanied by a large
kW reading indicates faulty governor control. A high ammeter reading
accompanied by a large kVAR unbalance indicates problems with the
voltage regulator. Adjusting the cross current or voltage droop rheostat
should improve the sharing of kVAR.
To shut down the generator operating in parallel, gradually reduce the
kW load by using the governor to reduce speed. When kW load and
line current approach 0, open the generator circuit breaker. Operate
the generator unloaded for several minutes to dissipate the heat in the
windings. Refer to the prime mover manual for shutdown and cool-down
procedures.
Page 28
Maintenance
Schedules
A regular preventive maintenance schedule will ensure peak
performance, minimize breakdowns and maximize generator life. The
schedule listed below is a guide for operating under standard conditions.
Specific operating conditions may require reduced or increased
maintenance intervals. Also, if there is a different or more specific
schedule for your generator than the schedule provided below, it will be
included as a supplement to the manual package.
Every day
Visually check generator bearing housings for any sign of oil seepage.
Check the operating temperatures of the generator stator windings.
Check the control panel voltmeter for proper stability and voltage output.
Monitor the power factor and generator loading during operation.
With generators that have sleeve oil bearings, check the operating
temperatures and sight glass levels (if applicable).
Every week
Visually inspect the bearing exterior for dirt, and clean if necessary.
Inspect any generator air filters for build up of contaminants, and clean or
replace as required
Every 2000 Hours or 6 months of operation
Remove generator outlet box cover. Visually inspect the stator output
leads and insulation for cracking or damage. Check all exposed electrical
connections for tightness. Check transformers, fuses, capacitors, and
lightning arrestors for loose mounting or physical damage. Check all lead
wires and electrical connections for proper clearance and spacing.
Clean the inside of the outlet box, air screens, bearing housings, and air
baffles with compressed air and electrical solvent if needed.
With generators that have ball or roller bearings, check machine
vibrations and bearing condition with a spectrum analyzer or shock
pulse.
Regrease the regreaseable-type bearings. With generators that have
sleeve oil bearings, inspect bearing oil for proper levels and clarity.
Page 29
Warning: Do not service the generator
or other electrical machinery without deenergizing and tagging the circuits as out of
service. Dangerous voltages are present,
which could cause serious or fatal shock.
Every 8000 hours or 1 year of operation
Check insulation resistance to ground on all generator windings,
including the main rotating assembly, the main stator assembly, the
exciter field and armature assemblies, and the optional PMG assembly.
Check the space heaters for proper operation.
Check the rotating rectifier connection tightness.
With generators that have sleeve oil bearings, replace the bearing oil.
Every 20,000 hours or 3 years of operation
With generators that have sleeve oil bearings, perform a sleeve bearing
inspection to include the removal of the upper bearing housing and
bearing liner to inspect the liner, shaft journal, and seal surfaces for wear
or scoring.
Remove the endbrackets, and visually inspect the generator end windings
for oil or dirt contamination. Excessive contamination may necessitate
surface cleaning with compressed air and electrical solvent.
Inspect the fan and fan hub for damage.
Every 30,000 hours or 5 years of operation
(Contact Kato Engineering for assistance)
Disassemble the generator (this includes rotor removal).
Clean the generator windings using either (depending upon the severity
of contamination) 1) compressed air and electrical solvent or 2) degreaser and high pressure hot water wash. Dry the windings to acceptable
resistance levels (see the dry out procedure).
Inspect the rotor shaft bearing journals for wear or scoring.
With generators that have ball or roller bearings, replace the bearings.
With generators that have sleeve bearings, replace the bearing liners and
oil seals.
Page 30
Maintenance procedures
Visual inspection methods of windings
Electric machines and their insulation systems are subjected to
mechanical, electrical, thermal and environmental stresses that give rise
to many deteriorating influences. The most significant of these are the
following:
Thermal aging: This is the normal service temperature deteriorating
influence on insulation.
Over temperature: This is the unusually high temperature of operation
caused by conditions such as overload, high ambient temperature,
restricted ventilation, foreign materials deposited on windings, and
winding faults.
Overvoltage: This is an abnormal voltage higher than the normal service
voltage, such as caused by switching or lightning surges or non-linear
loads. Operating above rated nameplate voltage will reduce insulation
life.
Contamination: This deteriorates electrical insulation by 1) conducting
current over insulated surfaces 2) by attacking the material to reduce
electrical insulation quality or physical strength, or by 3) thermally
insulating the material so the generator operates at higher than normal
temperatures. Such contaminants include water or extreme humidity, oil
or grease including unstable anti-wear and extreme pressure lubricants,
conducting and non-conducting dusts and particles, industrial chemicals
such as acids, solvents, and cleaning solutions.
Physical damage: This contributes to electrical insulation failure by
opening leakage paths through the insulation. Physical damages can be
caused by physical shock, vibration, over-speed, short-circuit forces or
line starting, out-of-phase paralleling, erosion by foreign matter, damage
by foreign objects and thermal cycling.
Ionization effects: Ionization (corona), which may occur at higher
operating voltages, is accompanied by several undesirable effects such as
chemical action, heating, and erosion.
To achieve maximum effectiveness, a direct visual inspection program
initially to those areas that are prone to damage or degradation caused
by the influences listed below. The most suspect areas for deterioration
or damage are 1) ground insulation, which is insulation intended to
isolate the current carrying components from the non-current bearing
components, and 2) support insulation, which includes blocks and slot
wedges and are usually made from compressed laminates of fibrous
materials, polyester, or similar felt pads impregnated with various types
of bonding agents. Check for the following:
Page 31
Deterioration or degradation of insulation from thermal aging:
Examination of coils reveal general puffiness, swelling into ventilation
ducts, or a lack of firmness of the insulation, suggesting a loss of bond
with consequent separation of the insulation layers from themselves or
from the winding conductors or turns.
Abrasion: Abrasion or contamination from other sources, such as
chemicals and abrasive or conducting substances, may damage coil and
connection surfaces.
Cracking: Cracking or abrasion of insulation may result from prolonged
or abnormal mechanical stress. In stator windings, looseness of the
bracing structure is a certain sign of such phenomena and can itself cause
further mechanical or electrical damage if allowed to go unchecked.
Erosion: Foreign substances impinging against coil insulation surfaces
may cause erosion.
Warning: When using cleaning solvents,
ensure adequate ventilation and user
protection.
Cleaning
Exterior: Wipe loose dirt from the exterior with a clean, lint-free cloth.
Remove stubborn accumulations of dirt with a detergent or solvent
that won’t damage the paint or metal surfaces. Use a vacuum to clean
ventilating ports.
Windings, assembled machines: Where cleaning is required at the
installation site and complete disassembly of the machine is unnecessary
or not feasible, pick up dry dirt, dust or carbon with a vacuum cleaner to
prevent the redistribution of the contaminant. A small non-conducting
nozzle or tube connected to the vacuum cleaner may be required to reach
dusty surfaces or to enter into narrow openings. After most of the dust
has been removed, a small brush can be affixed to the vacuum nozzle to
loosen and allow removal of dirt that is more firmly attached.
After the initial cleaning with a vacuum, compressed air may be used to
remove the remaining dust and dirt. Compressed air used for cleaning
must be clean and free of moisture or oil. Air pressure or velocity must
be adequately controlled to prevent mechanical damage to the insulation.
Disassembly of the machine and more effective cleaning by a qualified
Kato technician may be required if the above described field service
cleaning procedures do not yield effective results.
Windings, disassembled machines: Take an initial insulation resistance
reading on the machine to check electrical integrity. The high pressure
hot water wash method of cleaning, which sprays a high velocity
jet of hot water and water containing a mild detergent, is normally
effective in cleaning windings, including those subjected to flooding
or salt contamination. Use multiple sprays with clean water to remove
or dilute the detergent following the detergent spray. Dry the machine
until acceptable insulation resistance values are obtained at room
temperature. See the insulation resistance procedures below for minimum
recommended values.
Page 32
Electrical contacts: Clean electrical contacts, switch contacts and
terminals with an approved contact cleaner. Do not file contacts.
Insulation resistance tests at low voltage
Insulation tests are conducted for two reasons: to discern existing
weakness or faults or to give some indication of expected service
reliability.
Insulation resistance tests are based on determining the current through
the insulation and across the surface when a DC voltage is applied. The
leakage current is dependent upon the voltage and time of application,
the area and thickness of the insulation, and the temperature and
humidity conditions during the test.
The insulation resistance test is used to determine the insulation
condition prior to application of more extensive testing measures. Refer
to the following electrical measurement procedures for testing detail.
Contact Kato Engineering or refer to IEEE Standard. 432-1992 when
more extensive insulation tests are required.
Exciter field (stator) and PMG armature (stator)
1. Disconnect the exciter leads from the terminals in the terminal box or
the voltage regulator.
2. Connect exciter leads to one clamp of 500-volt megger, and connect
the other clamp to the generator frame.
3. Apply 500 V from the megger, and measure the resistance reading
after 1 minute. The reading must be a minimum of 1 megohm. If it is
not, refer to the cleaning or dry out procedures.
4. Ground the exciter field leads to the generator frame for several
minutes after the megger has been disconnected. This will allow the
voltage build up to be properly discharged.
Caution: The insulation resistance tests are
usually made on all or parts of an armature
or field circuit to ground. They primarily
indicate the degree of contamination of the
insulating surfaces or solid insulation by
moisture and other conducting influences
and will not usually reveal complete or
uncontaminated ruptures.
Note: The insulation resistance value
increases with decreasing winding
temperatures. All readings must be
corrected to winding temperatures. Use
Table 4 for converting megger readings to
other temperatures (e.g., 100 megohms at
50º C is converted to 170 megohms: 1.7 x
100).
Winding
Temp
(ºC)
Conversion
factor
10
20
30
40
50
60
70
80
90
100
110
120
0.23
0.37
0.6
1
1.7
2.7
4.5
7.5
14
23
38
61
Table 4: Temperature conversion
factor for resistance readings
Warning: Never apply the megger to the
rotating rectifier, the voltage regulator, or
generator accessories (e.g., temperature
detectors, space heaters).
Page 33
Exciter armature
1. Disconnect the exciter armature leads from the rotating rectifiers.
2. Connect the leads of the exciter armature to one clamp of a 500-volt
megger, and connect the other clamp to a suitable connection on the
shaft.
3. Apply 500 V from the megger, and measure the resistance reading
after 1 minute. The reading must be a minimum of 1 megohm. If it is
not, refer to the cleaning or dry out procedures.
4. Ground the exciter leads to the shaft after disconnecting the megger.
This will allow the voltage build up to be properly discharged.
Main rotor
1. Disconnect the generator field leads from the positive and negative
terminals of the rotating rectifier assembly.
2. Connect the positive and negative leads to one clamp of the 500-volt
megger, and connect the other clamp to the shaft.
3. Apply 500 V from the megger, and measure the resistance reading
after 1 minute. The reading must be a minimum of 1 megohm. If it is
not, refer to the cleaning or dry out procedures.
4. Ground the field leads to the shaft after disconnecting the megger.
This will allow the voltage build up to be properly discharged.
Main stator
1. Disconnect power connections and all control apparatus from the
generator terminals.
2. Measure insulation resistance of each phase separately with the two
other phases shorted to the frame.
3. Use a 500-volt megger connected between the lead(s) of the phase to
be measured and generator frame. The minimum 1-minute insulation
resistance must not be less than that given by the following formula:
Resistance
in megohms =
(
)
Rated generator voltage
1000
+1
If it is less than above, refer to the cleaning or dry out
procedures.
4. Ground the leads to the frame after the 1-minute megger test. This
will allow the voltage build up to be properly discharged.
Page 34
Dry out procedures
If the insulation resistance readings are below the recommended
minimum values specified previously, use one of the dry out procedures
described below. Select the procedure based on the size and location
of the unit, available equipment, and experience of personnel. Before
drying, remove the voltage regulator, and cover all inlet and discharge
openings. Provide an opening at the top of the machine, preferably at the
fan end, for moisture to evaporate.
Drying with external heat: Place heat lamps, space heaters (in addition
to the ones already supplied) or a steam pipe near the windings. Monitor
winding temperatures. Raise winding temperature gradually at a rate
of 50° F (10° C) per hour up to 200° F (93° C). Measure insulation
resistance at 1-hour intervals. Typically the insulation resistance will
slowly drop while the temperature is coming up, and then gradually
increase and level out.
Drying with AC current in the armature: Short circuit the generator
terminals. Provide DC excitation to the brushless exciter field winding.
Insert a current transformer and an ammeter to read full load current.
Run the generator at rated speed. Apply excitation to the exciter field
until rated current is developed. Monitor winding temperatures until they
stabilize. Continue running until insulation resistance values level off.
Monitor winding temperatures. Raise winding temperature gradually at
a rate of 50° F (10° C) per hour up to 200° F (93° C). Measure insulation
resistance at 1-hour intervals. Typically, the insulation resistance will
slowly drop while the temperature is coming up and then gradually
increase and level out.
Bearing lubrication
Shielded or sealed ball bearings: Shielded or sealed ball bearings are
factory packed with lubricants and generally can be operated several
years without requiring replenishment or change of the grease. If
repacking the grease is necessary, disassemble the machine, clean the
bearings, and repack the bearings about 1/2 full using a high quality ball
bearing grease, which must be capable of lubricating satisfactorily over a
temperature range of the lowest ambient temperature to 250º F.
Regreaseable ball or roller bearings: In applications where regreaseable
bearings are used, grease fill fittings and relief valves are incorporated
into the bearing housing. Lubricate the bearings in accordance with the
lubricating instructions attached to the generator.
Sleeve bearings: Lubricate the bearings in accordance with the
lubricating instructions attached to the generator and the bearing
lubrication instructions, which are provided in the manual package as
supplementary material.
Page 35
Caution: Do not apply heat too rapidly. It
could damage the windings.
Rectifier tests
If a failure of a rectifier is suspected, remove the exciter cover. Remove
the nut and washer holding the rectifier in the heat sink, and remove the
diode lead wire. Lift the rectifier from the heat sink (see figure 20 for
an overview). Test the entire rectifier with an ohmmeter or test lamp as
follows:
Negative
Positive
Positive
Figure 20: Rectifier
Ohmmeter: Connect the ohmmeter leads across the rectifier in one
direction (see Figure 21). Note the meter reading. Reverse the leads, and
note the meter reading. The meter should indicate a low resistance when
the leads are across the rectifier in one direction and a high resistance
when the leads are across the rectifier in the opposite direction. A low
resistance in both directions indicates a short. A high resistance in both
directions indicates an open rectifier.
Cathode
Ohmmeter
Anode
Reverse
diode
Standard
diode
Figure 21: Testing the rotating rectifier with an
ohmmeter
Page 36
Test lamp: Connect the leads of a test lamp, consisting of standard
flashlight batteries and a flashlight and built, as shown in Figure 22,
across the rectifier in one direction. Then reverse the leads. The light
should light in one direction but not the other. If the light lights in both
directions, the rectifier is shorted. If the light does not light in either
direction, the rectifier is open.
Figure 22 Test lamp
Replace defective rectifiers with rectifiers of the same operating
characteristics as rectifiers installed in the generator at the factory. Order
rectifiers by part number, including the model and type of exciter as well
as the generator serial number.
Surge protectors may be included on the rotating rectifier assembly.
Disconnect one lead of the surge protector, and connect the leads of an
ohmeter or makeshift test lamp, consisting of standard flashlight batteries
and a flashlight and built as shown in Figure 21, across the surge
protector in either direction.. If the light comes on, the surge protector
is defective. Order surge protectors by part number, including the model
and type of exciter as well as the generator serial number. Following
replacement, make sure that the revolving field, exciter armature, and
rotating diode leads are properly secured.
Page 37
Note: The following procedures are meant
to be a general guide. Procedures for your
unit may vary.
Warning: Ensure the generator has stopped
and is de-energized before disassembly.
Warning: Use a hoist and slings or chains
to support components during removal. Use
lifting devices that are selected for generator
component weights. Be extremely careful
not to damage components.
Disassembly
Overall disassembly
1. Remove the terminal box cover, and disconnect the load leads and
all other leads. Tag the leads to ensure they are correctly connected
when the generator is reassembled.
2. Remove the bolts securing the generator to the base and prime
mover, and move the generator to an area that allows sufficient room
for disassembly.
3. Remove the coupling or drive plates.
4. Remove the exciter cover.
5. Remove the clips securing the exciter field leads to the exciter frame
and endbracket. Disconnect the leads and remove the exciter frame/
stator and/or exciter-PMG frame/stator.
6. Remove the (optional) PMG and exciter armature as described
below.
7. Support the shaft. Remove the exciter-end endbracket bolts, and
remove the endbracket. Tap lightly with a rubber or fiber mallet
to loosen the endbracket if necessary. Repeat with the drive-end
endbracket (if applicable).
8. Remove the fan from the hub where applicable. If necessary, make
sure to mark the location of the fan for reinstallation.
Warning: Make sure the pipe is strong
enough to support the weight of the rotor
and that it does not have rough edges on
the inside, which could damage the shaft.
Caution: To prevent tension on the shaft,
put the slings around the largest shaft step
possible.
9. Float out the rotor (see Figure 23). First attach a pipe over the shaft
on the drive end. Attach slings around the pipe on one end and
around the shaft on the opposite end. Lift up the rotor, and move it
out, resting the rotor as the slings are moved down the pipe for the
next lifting stage.
Caution: Make sure the rotor does not
rest on the stator during the stages of
movement. Make sure the rotor does not hit
the stator.
Page 38
Figure 23: Floating the rotor
Exciter armature and PMG removal (see Figure 24)
1. Remove the exciter cover.
2. Remove the retaining bolt and washer.
3. Disconnect the field wires on the rotating rectifier assembly.
4. If the generator has a PMG, pull it off separately using hand force.
Wrap the PMG rotor in plastic to avoid contamination with metal
filings.
5. Slowly pull the armature assembly off of the generator shaft. If the
exciter can not be pulled off by hand, use a hydraulic jack as shown
in Figure 25.
6. Remove the key from the keyway in the generator shaft.
Page 39
Caution: Ensure the generator field wires
are flat in the wireway so they don’t tear
during pulling. Do not pull on the edges of
the heat sinks or on the exciter armature
windings.
Warning: Pull the PMG off straightly. The
assembly may pull toward other steel
components. Be careful that your fingers or
hands do not get pinched.
PMG aligning
pin
PMG
Retaining
washer
Hole in sleeve for field wires
(some models may have a
slot)
Rectifier
Retaining
bolt hole
Field leads
Retaining
bolts
PMG rotor
aligning
slot
A
B
A
B
Wire slot
Keyway
Key
Exciter armature
Shoulder
Exciter armature
sleeve
B-B cutaway view of
shaft
A-A end view of
exciter
Wire slot
Bolt holes
Shoulder
Key
Keyway
Figure 24: Exciter armature assembly
Plate
Hydraulic jack
Exciter sleeve
Threaded rod
Figure 25: Pulling the armature assembly
Page 40
Bearing removal
1. Remove the endbracket(s) to expose the bearing(s).
2. Use a puller to remove the bearing from the shaft end with a cap. If
the bearing is going to be used again, make sure the puller supplies
pressure only against the bearing inner ring (see Figure 26).
Cap to protect shaft end
Puller against
bearing
Outer ring
Inner ring
Figure 26: Pulling the bearing
Assembly
Bearing installation (done prior to installing the rotor)
1. Heat the bearing to 220º - 250º F in a clean oven or with an induction
heater.
2. Start the heated bearing on the shaft. Then use a fiber or soft metal
tube to tap the bearing into place.
3. Ensuring that pressure is applied only to the bearing inner ring,
press the bearing onto the shaft until the inner ring seats against the
bearing shoulder on the shaft. Assemble the rest of the generator after
the bearing has cooled.
Page 41
Caution: Make sure all components are
clean before assembly.
Note:: Torque fasteners to the values specified in Table 3 unless otherwise specified.
Overall assembly
1. Float in the rotor until the rotor and stator laminations line up.
Position the rotor such that a full pole face is at the bottom.
2. Install the endbrackets. Support the rotor during installation. Put an
corrosion inhibitor on the bare mating surfaces to prevent rust.
3. Install the exciter armature and optional PMG as described below.
4. Install the covers.
5. Install the coupling or drive plates.
6. Reconnect the load leads and exciter leads.
Exciter armature and PMG installation (see Figure 24)
1. Clean the shaft and inside of the exciter sleeve.
2. Place the key in the slot in the shaft.
3. Lay the generator field wires flat in the wireway with the wire ends
protruding past the end of the shaft.
4. Position the exciter armature assembly in line with the shaft, and turn
the assembly to the position where the keyway in the exciter sleeve is
in line with the key in the generator shaft.
Caution: Do not pound on the rectifier or
armature windings.
5. With hand force, push the exciter armature assembly over the shaft,
so the end of the sleeve is against the shoulder on the shaft. When
it is part of the way onto the shaft, start the field lead wires through
the wire hole or slot in the exciter sleeve. It may be necessary to tap
lightly on the exciter sleeve in order to move the assembly over the
key. Use a fiber or rubber mallet. If installation is still a problem, use
a heat gun to expand the exciter sleeve.
6. Connect the exciter armature wires to the rectifier terminals.
7. If the generator has a PMG, place it onto the end of the exciter
sleeve. Make sure it is aligned with the pin slot in the end of the
exciter sleeve.
8. Install the retaining washer and bolt, and torque (60 ft-lbs for a 1/2inch diameter bolt; 200 ft-lbs for a 3/4-inch diameter bolt).
9. Install the exciter frame/stator and/or exciter-PMG frame/stator.
Install the clips securing the exciter field leads to the exciter frame
and endbracket and connect the leads.
Page 42
10. Measure the air gap between the exciter armature and exciter field
and between the PMG rotor and PMG stator. If the air gap of the
armature is less than specified in Table 5 or if the air gap of the PMG
is less than 0.020 inch, check 1) generator-engine alignment, 2)
check for bearing wear, 3) check for misalignment of the armature,
PMG or stator.
Exciter armature Minimum air gap
diameter (in.)
(in.)
5 3/4
9 7/8
12 1/2
16 1/4
Note: To measure air gap, measure completely around the gap between the exciter
armature and exciter field with a feeler
gauge. Keep the gauge at the tightest point,
and turn the generator over to measure the
air gap as the rotor turns.
Caution: Do not pry on the fan.
0.014
0.014
0.018
0.035
Table 5: Exciter air gap
11. Install the exciter cover.
Storage
If the generator is not installed in its operating location as soon as
received, store it in a clean, dry area, not subject to vibrations or sudden
temperature or humidity changes. Make sure the storage area temperature
is between 10º F and 120º F and the relative humidity is less than 60%. If
possible, storage should be in an ambient temperature of approximately
normal room temperature. Protect the shaft from corrosion by applying
an anti-corrosion agent. Cover the unit with a durable cover.
Prepare units that cannot be stored in a temperature and humidity
controlled area as follows:
Install desiccant bags in the exciter cover and inside the end bells.
Vacuum seal the unit in a covering of plastic or other material designed
for that purpose.
Adequately tag the generator to ensure that preservative greases and
desiccant bags are removed before the unit is placed in operation.
If space heaters are supplied, energize them to keep condensation from
the windings.
For storage longer than 2 months, rotate the shaft a minimum of 10
revolutions every 60 days.
Page 43
Warning: If necessary, remove the covers
around the space heaters to reduce the risk
of fire.
Caution: Grease used in ball and roller
bearing generators is subject to time
deterioration. Before placing the unit into
service after long-term storage, check the
bearings for corrosion, and replace the
grease.
Troubleshooting Guide
(corrective maintenance)
Between regular preventive maintenance inspections, be alert for any
signs of trouble. Correct any trouble immediately. See Table 6 for
symptoms, causes and remedies.
Warning: Problems left uncorrected can
result in injury or serious damage, which can
result in costly repairs and downtime.
Symptom
Cause
Remedy
No Voltage
Open voltage regulator, circuit breaker or
fuses
Check. Reset the circuit breaker or replace
fuses if open.
Overvoltage, undervoltage, or overload
devices tripped (when protective devices
are incorporated into the circuit)
Check for the cause of the abnormal condition.
Correct any deficiencies. Reset devices.
Check the generator nameplate for nominal
operating values.
Open circuit in exciter field
Check continuity of shunt field and leads
to voltage control. (Use ohmmeter or
wheatstone bridge) If open in field coils,
remove exciter field assembly and return
assembly to factory for repair.
Loss of residual magnetism in exciter
field poles
Restore residual magnetism or flash field. When
the voltage regulator is a model that requires
flashing, install an automatic field flashing
system.
Open circuit in stator windings
Check for continuity in the windings. Return the
generator to the factory for repair if open.
Malfunction of automatic voltage
regulator
See troubleshooting of voltage regulator.
Correct deficiencies.
Short-circuited generator output leads
Clear lead to restore voltage buildup.
Open in rotating rectifiers
Check rotating rectifiers, and replace if
open.
Open in generator field
Check for continuity and return rotor to
factory for repair if field coils are open.
Shorted or grounded surge protector
Check for shorts or grounds. Replace .
Shorted or grounded rotating rectifier
Check for shorts grounds. Replace or repair.
Shorted or grounded exciter armature
Check for shorts or grounds. Replace or repair.
Shorted leads between the exciter armature
and generator field
Test and repair.
Incorrect stator connections
Check the connections, and reconect
Low voltage
Page 44
Symptom
Cause
Remedy
Low voltage
(cont.)
Improper adjustment of voltage adjust
rheostat
Adjust rheostat.
Excessive load
Reduce load. With three-wire, single-phase and
four-wire, three-phase generators, the load on
each leg must be as evenly balanced as possible
and must not exceed the rated current on any leg.
Line loss
Increase the size of the line wire.
High resistance connections (hot)
Make better connections.
Shorted main or exciter field
Test the field coils for possible short by
checking resistance with an ohmmeter or
resistance bridge. Return the rotor assembly
to the factory for repair if field coils are shorted.
Low power factor
Reduce inductive (motor) load. Some AC
motors draw approximately the same
current regardless of load. Do not use
motors of larger horsepower rating than
is necessary to carry the mechanical
load.
Weak field due to operating in a warm
temperature
Improve the ventilation of the generator.
Field current can be increased providing
the generator temperature rating
stamped on the nameplate is not
exceeded.
Defective rectifiers in rectifier assembly
(stationary)
Check rectifier assembly. Replace
defective fuses or rectifiers.
Excessive load
Reduce load to rated value.
Defective bearing
Replace the bearing.
Improper speed of engine driven
generator set due to defective governor,
ignition system, or carburetor
Check and correct deficiencies.
Voltage regulator not operating properly
Check the regulator. Adjust, repair or replace.
Prime mover speed fluctuating
Check frequency and voltage of incoming
power when the generator set is motor
driven. Check engine governor on
engine-driven generator sets.
Loose internal or load connections
Tighten all connections.
Generator overloaded
Reduce load to rated value.
DC excitation voltage fluctuating
Trace DC excitation circuit. Correct any
defects.
Overspeed
Correct speed of prime mover.
Voltage regulator not operating properly
Check the regulator. Adjust, repair or replace.
Improper adjustment of voltage adjust
rheostat or voltage regulator
Adjust rheostat and/or voltage regulator.
Voltage regulator not operating properly
Check the regulator. Adjust, repair or replace.
Fluctuating
voltage
High voltage
Page 45
Symptom
Cause
Remedy
Overheating
Clogged ventilating screens and air
passages
Clean all screens and air passages.
Dry or defective bearings
Replace defective bearings.
Coupling misaligned
Align the generator set.
Generator field coils shorted or
grounded
Test field coils for shorts. Replace
shorted rotor or return it to the factory for
repair.
Unbalanced load or overload, low PF
Adjust load to nameplate rating.
Defective or dry bearings
Replace defective bearings.
Misalignment of generator and prime
mover
Align the generator set.
Generator not properly mounted
Check mounting. Correct defective
mounting.
Transfer of vibration from another
source
Isolate the generator set from the source of
vibration by installing vibration dampeners
between generator set base and foundation.
Vibrations
Table 6: Troubleshooting
Page 46
Appendices
List of equipment required for installation and maintenance:
Test equipment
Ammeter
Multimeter
Thermometer
Megger
Resistive Bridge
Notes
Clamp-on, 0 to 500 amp range for measuring of electrical current.
Digital, for measuring voltage, current, frequency and resistance.
For measuring temperature in Celsius
To measure insulation resistance.
To measure resistance of windings.
Special tools
Bearing puller
Exciter puller
For changing bearing.
For pulling exciter armature
Standard tools
Cable tool
Flashlight
Grease gun
Hammer
Lamp (incandescent)
Screwdrivers
Screwdrivers
Wrench
Wrench
Wrench set
Wrench set
Wrench set
Vacuum
Crimping
As required
For lubricating bearings
Soft-faced
Safety light
Standard, sized as required
Phillips, sized as required
Adjustable, 12-inch
Torque 0 to 100 ft-lb
Allen, 1/8 to 1/2 inch
Socket, 1/4 to 1 Inch with 3/8 and 1/2 inch drive
Standard, open-end/box-end combination sized 1/4 to 1 inch
Electric with nonmetallic nozzle
Materials
Air
Corrosion inhibitor
Covering material
Detergent
Gloves
Gloves
Heaters
Plastic
Rags
Water
Tags
Compressed, dry.
Nox-Rust VC #10 Oil or equivalent
Waterproof desiccant bags for protection from
moisture during long-term equipment storage
As required for cleaning
Chemical-protective
Electrical-protective
Space Heater, for eliminating excess moisture in damp areas and dry
out of motor or generator windings
Protection for long-term storage
As required for cleaning
Warm and clean, for cleaning
Warning and cautions
Page 47
Main part location
Exciter cover
Exciter stator
Lead connection
box
Fan
Drip proof
cover
Rectifier
Adapter
Exciter
armature
Endbracket
Rotor
Coupling
hub
Stator windings
Feet
Bearing
Page 48