PI 3Q.23-2
Electrical Equipment - Course PI 30.2
GENE~TOR
AUXILIARY SYSTEMS
OBJECTIVES
On completion of this module the student will be able to:
I.
State the purpose of the generator stator cooling system.
2.
List and briefly explain five operational reqUirements of the generator
stator cooling system.
3.
Given a simplified diagram of a typical stator cooling system:
a)
b)
c)
Label each flagged component;
Identify the flow direction of the demineralized cooling water
us"; ng arrows.
Briefly explain the function of each component in a stator cooling
system.
4.
State the purpose of the generator hydrogen seal.
5.
State three operational reqUirements of the generator hydrogen seal.
6.
Given a cross-sectional diagram of a typical generator hydrogen seal:
a)
b)
Briefly explain its operation;
State the direction of flow of the seal oil within the seal.
7.
State the purpose of the generator hydrogen seal oil system.
8.
List and briefly explain six operational reqUirements of the generator
hydrogen seal oil system.
9.
Given a simplified diagram of a typical generator hydrogen seal oil
system:
a)
b)
Label the flagged components correctly;
Briefly explain the function of each component.
10.
State the purpose of the generator hydrogen cooling system.
II.
List and briefly explain seven operational requirements of a generator
hydrogen cooling system.
January 1990
I
ITPO.OI
PI 30,23·2
12. Given a simplified diagram of a large AC generator:
a)
b)
c)
Label the components related to, or cooled by the hydrogen cooling
system;
Briefly explain the function of each of the components you
identified in (a).
Indicate with arrows, the flow paths of the hydrogen gas.
13. List and briefly explain six precautions with respect to the
generator auxiliary systems discussed in objectives 1 to 13 inclusive.
14. aJ
bJ
List and briefly explain five advantages of choosing hydrogen
rather than air as a cooling medium for large generators;
List and briefly explain two disadvantages of choosing hydrogen
rather than air as a cooling medium for large generators.
2
ITPO.OI
PI 30.23-2
1.0 INTRODUCTION
This module will introduce the trainee to:
(a) The generator stator cooling system.
(b) The generator hydrogen seal.
(c) The generator hydrogen seal oil system.
(d) The generator hydrogen cooling system.
(e)
Precautions relating to generator cooling systems.
(f) The advantages and disadvantages of hydrogen, compared to air, as a
coolant.
2.0 THE GENERATOR STATOR COOLING SYSIEM
2.1 Puroose of The Cenerator Stator Cooling System
The purpose of the generator stator cooling system is to maintain
the copper stator bars and the end core magnetic screen plates
within their proper operating temperature range under all operating
conditions, by passing cooled, demineralized water through them.
2.2 Operational Requirements of the Generator Stator Cooling System
To ensure safe operation of the generator, five operational
requirements must be met. These are:
(i)
(ii)
To provide demineralized cooling water to the generator
stator windings and the end core magnetic screen plates, at a
controlled pressure below that of the hydrogen pressure,
thereby ensuring that any leaks which may occur will result
in hydrogen gas entering the stator coolant rather than water
entering the generator.
To detect and alarm if the conductivity of the demineralized
The demineralized water
must not allow any fault to ground.
water goes up to an unsafe level.
(iii) To prOVide filtration to remove any particulates which could
plug the very.small bores of the stator tubes.
(iv)
To provide venting to atmosphere for any hydrogen gas that
becomes entrained in the stator coolant.
(v)
To prOVide for addition of demineralized coolant into a head
tank to make up for any loss due to leaks or evaporation from
the stator cooling system.
1
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PI 30.23-2
2.3 A TYPical Stator Cooling System
Figure 2 is a simplified diagram of a typical stator cooling system,
showing typical system components and the direction of the coolant
flow. The follOWing are brief explanations of the functions of the
major components of the system:
(i)
ac Pumps - PM I, PM 2
Two 100% duty pumps, operating on Class IV ac power, are
provided. Either of these pumps can prOVide 100% of the
required flow. Therefore, one pump is in service and the
other is on standby.
(i i )
Emergency pump - PM 3
The emergency pump is a 50% duty pump, meaning it is capable
of supplying only 50% of the required full power flow. It is
powered from Class I and starts automatically if both ac
pumps fail. Some stations may not have an emergency pump.
(iii)
Check Valves - NV24 and Others
Various check valves are provided to prevent reverse rotation
of the pumps and to ensure correct flow direction of the
stator coolant.
(iv)
Stator Water Coolers - HXI, HX2
In order to minimize demineralized water cost and to prevent
ingress of impurities, the demineralized water ;s
recirculated through the stator conductors and the cooling
system in a closed loop. Two 100% duty heat exchangers,
cooled by low pressure service water, are provided in a
parallel configuration. These heat exchangers are vented at
their high points.
(v)
Strainer and Filter - STRI, FRI
A strainer and filter are provided to remove any particulates
from the coolant. Both may be instrumented for differential
pressure drop across them and bypassed for maintenance.
2
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PI30.23-2
VENTS
VENTS
COOI.ANf
HEADER
TANK
ENOCORE
MAGNETIC
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ts
,~ RESIST,ANCE.Jf'
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" "COlUMNS"".
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WATER
SUPPLY
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,.,
i.,
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GAS
CHAMBER
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VENT
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~50% '100% ~100%
,
j,1M3 lpUMP i,PuMPI
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(DUTY 'DUTY
........
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STATOR
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I
PM3
PM2
PM'
(I)
('V)
(IV)
COOI.ANf
STRAINER
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t.. . .~ ...............:.:
o.clxygenetlng
FIgure 2:
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(X§ Q§ <:B
• PUMP...
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COOLWATER
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~
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,.,
DETRAINING
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,,
t
SCREEN
GENERATOR
STATOR
SERVICE IiO
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LS_TR...,j'
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FA,
Slmpllfled DIagram of a TypIcal Stator CoolIng System
ITPO.OI
PI
(vi)
30.Z3-Z
Deexygeoating Unjt and IX CQlumn - IXI
In Qrder to prQvide the required insulating prQperties, the
statQr water cQnductivity must be held belQw preset limits.
A typical Qperating cQnductivity is in·the 0.5 ~s/cm range.
Since cQnductivity will tend tQ rise during QperatiQn, an IX
cQlumn and deQxygenating unit are prQvided tQ scrub the
demineralized water circulating in the stator cQQling system.
(vii)
Vents
Vents are prQvided as shQwn, at variQus high pQints in the
statQr cQQling system, tQ permit bleeding Qff Qf any gases
(OZ, NZ, HZ) that might accumulate and cause an "air-1Qck" tQ
fQrm.
(viii) CQQlant Header Taok
The cQQlant header tank hQlds a supply Qf demineralized water
at a relatively cQnstant head pressure fQr the stator cQQlant
system. It is impQrtant tQ keep the statQr cQQling system
filled with demineralized water in Qrder tQ minimize the
cQrrQsiQn and Qther fQrms Qf contaminatiQn that will arise if
the statQr cQQling system is repeatedly Qpened tQ the
atmQsphere.
(ix)
Resistance Colymns
The resistance columns carry the stator cooling water into or
Qut Qf the generatQr while electrically iSQlating the statQr
cQQling system frQm the statQr cQnductQrs. StatQr cQnductQr
vQltages are as high as Z4 kV.
(x)
Gas Detrainjng Chamber
The heated QutflQW frQm the statQr cQnductQrs and the end
CQre magnetic screen plates at each end Qf the generatQr gQeS
tQ the gas detraining chamber. Any hydrQgen that may have
leaked intQ the demineralized cQQling water (PH2 > PHZO) is
separated and vented tQ atmQsphere.
4
ITPO.OI
PI 30.23-2
3.0 THE GENERATOR HYDROGEN SEAL
3.1 purpose of the Generator Hydrogen Seal
Hydrogen seals are prOVided at each end of the generator to ensure
that there is a minimum of hydrogen leakage between the rotating
generator shaft and the stationary end cover of the stator. This
requires maintaining a continuous seal for operating periods of a
year or more, at hydrogen working pressures of 300 - 400 kPa(g), at
generator rotor speeds ranging from stationary to I SOO RPM.
3.2 Operational Regyirements of a Generator Hydrogen Seal
Three operational requirements of a generator hydrogen seal are:
(i)
It must provide a seal between the generator rotor and the
stationary end cover of the generator.
(ii)
It must accommodate significant axial movement of the rotor
shaft with respect to the generator end cover.
(iii)
It must minimize the ingress of oil and/or air to the
generator cavity.
3.3 A Typical Generator Hydrogen Seal
Figure 3 is a simplified sectional diagram of a typical generator
hydrogen seal. The cool, clean seal oil is supplied to the
stationary oil feed chamber at a pressure somewhat greater than the
hydrogen pressure in the generator. A preset spring loading, aided
slightly by the oil pressure provides an axial force which
continuously holds the seal ring toward the shaft ring face. On the
front of the seal ring is the soft metal continuous seal face. The
oil pressure causes the seal oil to flow through the oil ports to
the continuous seal face, where the majority of the oil flows
outwards between the seal face and the seal ring and the remainder
flows inwards toward the rotor shaft. This flow pattern results in
a continuously oil wetted and cooled seal between the rotor shaft
and the generator end cover.
Most of the oil flow is required for lubrication and cooling of the
seal face. After flOWing outwards to the low pressure side of the
seal, it is discharged to the bearing drains in the bearing
pedestal. Since the oil flow to the hydrogen side is small, the
quantity of entrained air released inta the hydrogen is very small.
It is, therefore, not necessary to vacuum treat the seal oil to
remove entrained air. Hydrogen purity is normally maintained
without extensive make-up. The small amount of oil which flows to
the hydrogen side is drained to the hydrogen detraining tank.
5
ITPO.OI
PI30.23-2
...SUl. ...TlOf,I
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."
.....
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----~
Figyre 3: A Section yf a TYPical Generator Seal
6
ITPO.Ol
PI 30.23-2
3.4 Radial HydrQgen Seals
The radial Qil seal shQwn in Figure 4 is a newer fQrm Qf hydrQgen
seal having nQ SQft metal seal faces. Oil is pumped tQward the
shaft frQm two sets Qf hQles in a statiQnery ring surrQunding the
generatQr shaft, fQrming tWQ rings Qf Qil between the mQving shaft
and the statiQnary ring. A central vacuum ring extracts the Qil
frQm the seal area. These rings Qf Qil accQmmQdate bQth axial and
radial shaft mQvement while cQntinuQusly sealing the hydrQgen within
the generator.
VACUUMOIL OUT ---:::'" PRESSURE ..
,OIL IN
...+__/
I I
+ "
t
SEALING'RING
HOUSING,
QIL
SEAL
SEALING RING
-+- HOUSING
H2 PRESSURE
INlice
AIR OUTSIDE GENERATOR
_QE_N_ER_'_TGR_--!./.:..~""
~
OIL SEAL
GENERATOR SHAFT
- - - - - - ..
END VIEW
~ii--
SIDE VIEW
Figure 4; A Typical. Simplified. Radial HydrQgen Oil Seal
4.0 GENERATOR HYDROGEN SEAL OIL SYSIEM
4.1 PurpQse Qf the GeneratQr HydrQgen Seal Oil System
The purpose Qf the generatQr hydrQgen seal oil system is tQ clean,
lubricate and CQQl the hydrQgen seal face while prQviding the
required sealing pressure.
4.2 OperatiQnal Reqyirements gf the GeneratQr HydrQgen Seal Oil System
It was indicated in SectiQn 3.3 abQve that the seal Qil flows
thrQugh the seal tQ the seal face in Qrder tQ CQQl and lubricate the
seal face and prQvide the dynamic, hydrQgen seal. Six QperatiQnal
requirements Qf the seal Qil system are;
(i)
TQ prQvide sufficient Qil flow tQ keep the seal face
lubricated and cQQled under all Qperating cQnditions.
(ii)
TQ maintain the Qil at a predetermined differential pressure,
greater than the hydrQgen pressure in the generator, and
thereby prQvide the actual hydrQgen seal.
7
ITPO.O!
PI 30.23-2
(i i i)
To maintain the seal oil at the correct operating temperature
under all operating conditions.
(i v)
To provide filtration to remove any particulates which could
score the soft metal seal face.
(v)
To remove entrained hydrogen from the oil and vent the
hydrogen safely to atmosphere.
(vi)
To provide an emergency oil supply in the event of failure of
the main seal oil pumps.
4.3 A Typical Generator Hydrogen Seal Oil System
Figure 5, is a simplified diagram of a typical generator hydrogen
seal oil system, showing the system components and the direction of
the oil flow. The following is a brief description of the function
of the major components:
4.3.1 Oil From Main Turbine Oil System
The seal oil is normally supplied from the main turbine
lubricating oil system via a turbine shaft driven pump and
pressure relief valve (PRY).
4.3.2 AC Seal Oil Pump
If the turbine shaft driven pump is unable to provide
suitable seal oil pressure, a Class IY ac pump is used. The
combination of shaft driven and/or ac pumps will vary from
station to ·station.
4.3.3 QC Seal Oil Pump
If the main oil pump and ac oil pump are unable to provide
suitable seal oil pressure, a Class I de pump starts
automatically. The filters and coolers are bypassed by the
oil which flows from the de seal oil pump to the seals. Some
stations will have alternate backup/emergency oil supplies.
Note that the provi:sion of redundant oil pumps and different
pump motor power supplies helps to ensure that the hydrogen
seal will be maintained and kept properly cooled and
lubricated whenever the generator is in any operating state
other than shutdown and air filled.
4.3.4 Pressure Controls and Alarms
Various pressure controls and alarms are provided to maintain
the seal oil pressure at a fixed differential above the
hydrogen pressure, to provide alarms for low oil pressure and
to start pumps when required.
8
ITPO.OI
PI30.23-2
TURBINE
END SEAL
SUPRING
END SEAL
GENERATOR
~t
..
r-----.J
SEAL
t~
SEAL
..1--..--_ _--,
+
SEAL
OL
<XlClI.ER
HXl
tOIL
HVDRJGEN
TRAP TP1
-
SEAL
SERVICE
WATER
OIL
<XlClI.ER
HX2
FILTER
FR1
A
PRV
H~4:::>I<l-- -
OIL FROM
"10 em
t
OlLAND
SOMEH2
DIAM
PRESSt.JRO
BAlANCE
LINES
IX:
PUMP
Cll
AC
PUMP
CIIV
SHAFT DRIVEN
PUMP
AIR AT SLIGHT NEGATIVE PRESSURE
OIL
TURBINE OIL TANK TK1
2
HYDFOGEN
DETRAINING
TANKTK2
FIgure S:
SImplIfIed CIrcuIt of the Seal 011 System
9
ITPO.OI
PI 30.23-2
4.3.5 Seal Oil Filters and Coolers
The seal oil filters are provided to remove any particulates
from the oil before it is supplied to the generator hydrogen
seals. The filters are instrumented for high AP across the
input/output lines. The coolers cool the oil before it flows
through the seals, thereby maintaining the soft-metal seal
faces within their operating temperature range. The seal oil
temperature is controlled via the seal oil coolers which are
supplied by manually operated service water valves.
Thermocouples embedded in the seal face are used to monitor
for high seal face temperatures.
4.3.6 Detrainjng Tank
The major portion of the seal oil flow drains to the bearing
sumps and then to the turbine and seal oil tank.
The small amount of seal oil that flows inwards to the
hydrogen side then drains down to the hydrogen detraining
tank via a sight glass and ~ 10 cm diameter pressure balance
line. In the detraining tank, the entrained hydrogen
separates from the oil. The oil is forced up to the hydrogen
trap by the generator hydrogen pressure.
4.3.7 Hydrogen Trap and Extraction Fan
Any hydrogen remaining in the oil is removed in the hydrogen
trap and is safely vented to atmosphere by an extraction fan.
The seal oil flows by gravity down to the turbine and seal
oil tank.
4.3.8 Turbine and Seal Oil Tank
This large tank prOVides a sump for all of the oil used in
the turbine lubricating and seal oil systems.
10
ITPO.OI
PI 30,23-2
5.0 GENERATOR HYDROGEN COOLING SYSTEM
5,1 purpQse Qf the GeneratQr HYdrpgen CQQling System
The purpose of the generator hydrogen cooling system is to maintain
the generatQr rQtQr and the statQr irQn within their prQper
Qperating temperature ranges under all Qperating cQnditiQns,
5,2 OperatiQDal Requirements Qf the GeDeratQr HydrQgen CQQling System
As was indicated in PI30.23-1 heat is remQved frQm the generatQr
rQtQr and the statQr irQn by cQntinuQusly passing hydrQgen gas
thrQugh them. Seven QperatiQnal requirements Qf the generatQr
hydrQgen cQQling system are:
(a)
(b)
(c)
(d)
(eJ
(f)
(g)
5.3
TQ cQntinuQusly recirculate the hydrQgen gas within the
generator.
TQ CQQl the hydrQgen tQ the required temperature,
TQ dry the hydrQgen tQ the required dewpQint.
TQ maintain the CQrrect hydrQgen gas pressure in the
generatQr by prQviding make-up hydrQgen tQ cQmpensate fQr
1eaks,
TQ prQvide an alarm fQr liquid Qil Qr water within the
generatQr cavity,
TQ mQnitQr the hydrQgen gas purity,
TQ prQvide C02, Air and H2. fQr purging and charging the
generator.
ATypical
GeneratQr HydrQgen CpQ]ing System
Figure 6 is a simplified diagram Qf a typical, large generatQr
shQwing the directiQns Qf the hydrQgen flQW within the generatQr,
The fQllQwing are brief explanatiQns Qf the functiQns Qf the majQr
cQmpQnents Qf the generatQr hydrQgen cQQling system,
5.3,1 Centrifugal Fans, Hydrogen F1QW Paths
The centrifugal fans lQcated at each end Qf the rQtQr draw
hydrogen from the "air gap" between the rotor and stator and
blQW it thrQugh the cQQlers lQcated within the generatQr
YQke, FrQm the cQQlers the hydrQgen is directed tQ bQth the
statQr irQn and tQ the rQtQr, The CQQl hydrQgen passes
thrQugh ducts in the statQr irQn and enters the air gap frQm
the centre pQrtiQn Qf the statQr irQn. The cQQled hydrQgen
is alsQ directed tQ the rQtQr ends by sheet metal shrQuding
and enters the end bells, percQlates thrQugh and alQng the
rQtQr windings and emerges intQ the air gap alQng the centre
pQrtiQn Qf the rQtQr,
II
!TPO,Ol
BULK H2
SUPPLY &
PRESSURE
CONTROL
H2
DRYERS
H2 GAS
PURITY
ANALYSERS
I
•. .
H2COOLERS
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IIQ9
COOLED H2
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N
- -......• .......
+++. --+....ffif-.+--+----. - - - - ...1-
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Figure 6:
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CENTRIFUGAL
FAN
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'"0
;-l:" .,
A Typical Generator Hydrogen Cooling System
r-,
-
PI 30.Z3-Z
5.3.Z Hydrogen Coolers
The hydrogen coolers are long, finned, U-tube units mounted
axially in compartments located in the generator yoke.
(Also, see Figures 5 and 6 of PI30.Z3-!). Service water is
circulated through the cooler tubes. The hot hydrogen passes
over the finned tubes, loses its heat to the service water
and then flows on to cool the stator iron and rotor
conductors. The hydrogen temperature is controlled by
automatically regulating the flow of service water to the
coolers, using RTDs within the stator to measure the hydrogen
temperature.
5.3.3 Gas Supplies - HZ, COZ and Air
Hydrogen from a bulk storage system is fed to the generator
via a pressure regulating valve. The HZ pressure within the
generator is held relatively constant by the hydrogen make-up
system.
COZ from portable bottles is used to purge hydrogen or air
from the generator when required. The COZ is then displaced
by clean, dry air if the generator is to be opened for
maintenance.
5.3.4 Hydrogen Dryer
Typically, the hydrogen dryer will be a twin tower type using
beds of activated alumina. Cycle times are adjusted to suit
the drying load. Refrigeration type driers are used in some
stations.
5.3.5 Hydrogen Gas Analyzer
The gas analyzer unit analyzes the HZ purity when the
generator is at operating speed. A low purity alarm is
prOVided. A portable gas analyzer is used when charging and
discharging the generator.
The primary significance of hydrogen purity is the
requirement to avoid an explosive Hz/Air mixture, ie, HZ
content must be above 96% or below 5%.
!3
ITPO.O!
PI 30.23-2
6.0 PRECAUTIONS
There are six major precautions related to the generator cooling systems
discussed in this lesson. This section is a review and consolidation of
the previous material.
(a)
Stator Cooling Water Conductivity
Since the large generators used in NGS operate at 18 000 volts ac or
above, it is absolutely essential that the stator cooling water
conductivity be kept low enough to provide adequate electrical
insulation. This is both a personnel and an equipment concern.
(b)
Hydrogen/Ajr Concentrations
The hydrogen/air concentration must be kept outside the explosion
range to avoid serious damage to equipment and possible fire injury
to personnel.
(c) Hydrogen to Seal Oil Differential pressure
The seal oil pressure must be greater than the hydrogen pressure to
prevent leakage of hydrogen from the generator. Again the concern
is for personnel and hardware.
(d) Hydrogen to Stator Water Differential pressure
To prevent leakage of liquid water from the stator system into the
hydrogen, the hydrogen pressure must be greater than the stator
cooling water pressure.
Liquid water inside the generator
represents a physical impact hazard to the spinning rotor and is
also potentially an electrical short circuit hazard if it picks up
impurities.
(e) Hydrogen Dryness
To prevent condensation and possible ground faults within the
generator, the hydrogen gas which is circulating in the generator
must be kept dry enough to always be above the dewpoint. To assist
in the prevention of condensation, the stator cooling water
temperature must always be above the hydrogen temperature.
(f)
Drajns
Any leakage of liquid, oil or water into the generator can cause
severe physical damage. The drains from the bottom of the generator
must be operational.
14
ITPO.01
PI 30.23·2
7.0 HYDROGEN GAS AS A COOLANT
Five advantages relating to the choice of hydrogen rather than air as a
cooling medium in large NGS generators are discussed very briefly below:
(aJ Density
Hydrogen gas has a lower density than air, so windage losses are
less and less fan power is required for circulation. This low
density permits higher working pressures thereby increasing heat
removal capability.
(bJ Soecific Heat Caoacity
Hydrogen has approximately seven times the specific heat capacity of
air.
(cJ Mass Flow
The cooling capability and, hence, the output of the machine is
significantly increased, without a corresponding increase in windage
losses, by pressurizing the hydrogen.
(dJ
Insylation Life
When a machine is hermetically sealed and kept free of oxygen, the
interior is less subject to contaminants. This prolongs insulation
life.
(el
Fire
A,fire hazard jDsjde the generator is eliminated because the pure
hydrogen atmosphere inside the generator will not support
combustion.
Disadvantages relating to the use of hydrogen as a cooling medium are:
(aJ
Explosion Hazard
Hydrogen in air is explosive, between 5% and 96% concentration. The
hydrogen/air ratio must not be permitted to reach the explosion
range either inside or outside the generator.
Systems must be provided to achieve this criteria.
(bJ Hydrogen Sea1s/Sypp1y
The provision and maintenance of rotating seals increases both
design complexity and maintenance requirements.
A bulk hydrogen supply is required to fill and pressurize the
machine with clean, dry hydrogen.
15
ITPO.OI
PI 30.23-2
ASSIGNMENT
(Il
With respect to the generator stator cooling system shown in the attached
diagram:
(a) State its purpose.
(b)
List and briefly explain five operational requirements of the stator
cooling system.
(c)
Identify the numbered components.
(d)
Briefly explain the function of each component identified in (c).
(e) Using arrows, identify the flow direction of the stator cooling
water.
'
(2) With respect to the generator hydrogen seal shown in the attached
diagram:
(a)
State its purpose.
(b)
State three operational requirements of the seal.
(c)
Briefly explain its operation.
(d)
State the flow directions of the seal oil.
(3) With respect to the generator hydrogen seal oil system shown in the
attached diagram:
(a) State its purpose.
(b)
List and briefly explain six operational requirements of the system.
(c)
Identify the numbered components.
(d)
Briefly explain the function of each component identified in (c).
16
lTPO.O!
PI 30.23-2
(4)
With respect to the generator hydrogen cooling system shown in the
attached diagram:
(a)
State its purpose.
(b)
List and briefly explain seven operational requirements of the
system.
(c)
Identify the numbered components.
(d)
Briefly explain the function of each component identified in (c).
(e)
Using arrows, identify the flow paths of the hydrogen gas.
(5)
List and briefly explain six precautions related to the generator cooling
systems used with the large turbo-generators in NGS.
(6)
List and briefly describe five advantages and two disadvantages related
to the use of hydrogen as a coolant in large generators in NGS.
17
ITPO.OI
PI 30.23-2
QUESTION n
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18
ITPO.OI
PI 30,23-2
QUESTION #2
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Sectlon of a Generator Hydrogen Seal
Section of a Generator Hydrogen Seal
19
ITPO,OI
PI 30.23-2
QUESTIQN #3
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Simplified Circuit of a Typical Seal Oil System
20
ITPO,Ol
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