generator auxiliary system
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4 August 2011 PMI Revision 01 1
GENERATOR
AUXILIARY
SYSTEM
4 August 2011 PMI Revision 01 2
Generator Auxiliary System
• GENERATOR AUXILIARIES CAN BE BROADLY
DIVIDED INTO THREE SYSTEMS
• A) Stator water system
• B) Seal oil system
• C) Gas system
4 August 2011 PMI Revision 01 3
STATOR WATER SYSTEM
DIFF PRESS SWITCH
VACUUM PUMPS
POLISH UNIT
FILTERS
COOLERS
PUMPS
GAS TRAP
FLOW METERS
CONDUCTIVITY
EXPANSION TANK
MAKE UP
FSI
I DIFF PRESS.
MAGNET FILTER
4 August 2011 PMI Revision 01 4
Stator Water System
• Stator water cooling is a closed loop system
• There are two full capacity single stage centrifugal pumps with change over facility
• The pumps are driven by 3Ph. 415V A.C. motors
• The stator water cooler is shell and tube type heat exchanger
• DM water flows through shell
4 August 2011 PMI Revision 01 5
Stator Water System
• There are two mechanical filters and one magnetic
filters
• Mechanical filters are of wire mesh type
• Magnetic filter is having permanent magnet
• The expansion tank is a hermetically sealed
container made of S.S.
4 August 2011 PMI Revision 01 6
Stator Water System
• Float valve is there in the expansion tank to
maintain water level in the tank which act as
suction storage tank for stator water pumps
• Polishing unit (mixed bed ion exchanger) is there to
maintain conductivity of stator water to desired level
4 August 2011 PMI Revision 01 7
Stator Water System
• For commissioning the system the system has to
be filled up first
• Prerequisites for filling the cooling circuits
a) circuit should be flushed
b) hydraulic testing
c) installation of pump and motors after O/H
d) filters cleaned and boxed up
4 August 2011 PMI Revision 01 8
Stator Water System
e) coolers and all other components are boxed up
f) ion exchanger is ready and is in service
g) all instruments and measuring devices are in
position after their callibration
4 August 2011 PMI Revision 01 9
Stator Water System
• System should be lined up for filling
• Complete stator water system should be filled with
DM water having required quality
• All air should be vented from the system before
starting of the pump
4 August 2011 PMI Revision 01 10
Stator Water System
• Take trial of the water pumps
• Check the stand by pump for automatic starting
• Adjust level regulator in the expansion tank
• Check all the signalling devices for proper
functioning
4 August 2011 PMI Revision 01 11
Stator Water System
• Check all the instruments and meters for their proper
functioning
• Adjust make up water pressure around 2.0Kg/cm2
• Adjust small water flow through the gas trap
• Check there is no leakage of water in the system
• Take ejector into service
• Take one cooler into service
4 August 2011 PMI Revision 01 12
Stator Water System
• Check emergency switching in circuit of the stand by water pump
• Check high and low alarm of the expansion tank
• Check high conductivity alarm and tripping
• Check pump discharge pr., filter diff. pr., conductivity, flow, inlet winding pr., winding diff. pr., vacuum in expansion tank, motors current
4 August 2011 PMI Revision 01 13
SEAL OIL SYSTEM
OIL COOLER
FILTERS
DPRV
CONSTANT PRESS. REGULATORS WITH ORFICE PLATES
VACCUM PUMP
BEARG
DRAINS
TG
1 2
EE BEARING TE BEARING
GAS EXHAUST
FROM GAS SYSTEM
IOT
VACUUM
TANK
SOST
SOP SOP-3 DC
DP SW
TS ES
FR
FLOW M. PS PG
4 August 2011 PMI Revision 01 14
SEAL OIL SYSTEM
• Generator shaft seals are supplied with
pressuerised seal oil to prevent hydrogen escape
at the shaft
• Maintains continuous oil film between Seal Ring
and rotor journal
• Oil pressure is kept higher than the gas pressure
• There are one AC seal oil pp. and one DC seal oil
pp. which feed oil to the seal through cooler and
filter
4 August 2011 PMI Revision 01 15
SEAL OIL SYSTEM
• Both the seal oil pumps are 100% capacity screw type pump
• A vacuum pump is provided to maintain vacuum in seal oil tank
• There is a additional facility to supply seal oil from governing oil
• The seal oil pressure to the seal is controlled by DPR which maintain specified DP between oil and hydrogen
4 August 2011 PMI Revision 01 16
SEAL OIL SYSTEM
• Thrust oil is there to hold the seal ring in position
against gas pressure
• Two seal oil coolers having 100% capacity is
provided to cool the oil
• Duplex filter is provided in the oil line
• Vacuum pump evacuates gases from SOT
4 August 2011 PMI Revision 01 17
SEAL OIL SYSTEM
• Commissioning of seal oil system will be required when the
1) generator to be filled with hydrogen or air.
2) machine to be put on barring gear
• Prior to commissioning make sure that all instruments and devices are ready for operation after callibration, overhauling and trial.
4 August 2011 PMI Revision 01 18
SEAL OIL SYSTEM
• Seal oil system has to be filled with oil
• Prerequisite for oil filling
1) set all level switches
2) close all stop and non-return shut off valves
3) open all pressure gauge and pressure switches
isolating valves
4 August 2011 PMI Revision 01 19
SEAL OIL SYSTEM
4) open pressure transducer isolating valves
5) open isolating valves of impulse lines of
differential pressure regulator
6) bearing lube oil system is in service
4 August 2011 PMI Revision 01 20
SEAL OIL SYSTEM
• Open isolating valve of seal oil storage tank to seal
oil system. Oil will start filling the seal oil system
• Open valves in oil flow path
• Take coolers and filters into service
• After oil is filled up into the system level will be
visible in the gauge glass of the SOT
4 August 2011 PMI Revision 01 21
SEAL OIL SYSTEM
• Take governing oil system into service
• Start AC seal oil pump
• To clear air locking seal oil pump should be
switched on and off till its discharge pressure
gauges shows a constant pressure
• Vent DPRV-A and DPRV-B
4 August 2011 PMI Revision 01 22
SEAL OIL SYSTEM
• Vent both the coolers one by one
• Vent filters
• Vent pressure gauges, pressure switches and
transmitters
• Set seal oil pressure by DPRV-A
• Stop AC seal oil pump and set DPRV-B
(<0.3Kg/cm2 from DPRV-A)
4 August 2011 PMI Revision 01 23
SEAL OIL SYSTEM
• Set thrust oil pressure (0.5 Kg/cm2 more than seal
oil pressure)
• Take vacuum pump into service and adjust SOT
vacuum as recommended
• Check all the meter readings are within limit
• Check seal oil flow is as per system requirement
4 August 2011 PMI Revision 01 24
SEAL OIL SYSTEM
• Check automatic starting of stand by DC seal oil pump by
different interlocks including alarm
• Check function of level switch of SOT, seal oil storage tank
and pre-chambers
• After seal oil temperature reaches 300C start cooling water
flow to seal oil cooler and adjust the flow in such a way so
that the seal oil temperature is maintained at 400C
4 August 2011 PMI Revision 01 25
H2 DISTRIB
HYDROGEN
CO2 VAPOURIZER
TO SEALOIL DPT
H2 DRIER
HYDROGEN GAS SYSTEM
CO2
ANALYZER
DRAIN
AIR
FILTER
OP
DPI
4 August 2011 PMI Revision 01 26
GAS SYSTEM
• Overhauling of gas drier has been carried and the
drier is boxed up
• Check all instruments are in position after
calibration
• Functionally check the gas drier system
• Check the availability of adequate no of CO2 filling
point and adequate no of co2 cylinders
4 August 2011 PMI Revision 01 27
GAS SYSTEM
• Check availability of adequate no of Hydrogen
filling points and cylinders
• Functionally check the LLD system
• Check whether the relief valves in the high
pressure valves are alright
• Check the generator is completely boxed up
• Check the seal oil system is in service
4 August 2011 PMI Revision 01 28
GAS SYSTEM
• Check generator air tightness test is successfully
completed
• Start purging air with CO2 till the purity of CO2
inside casing reaches above 95%
• After CO2 purity reaches as desired start purging
CO2 with Hydrogen
• Continue purging till hydrogen purity reaches above
98%
4 August 2011 PMI Revision 01 29
GAS SYSTEM
• Pressurise generator casing with hydrogen up to its
design value
• Recheck hydrogen leakages by detector
• Take drier into service
• Take gas coolers into service
• Vent the coolers and establish flow
4 August 2011 PMI Revision 01 30
Checks Before Generator Synchronisation
• Before final commissioning of Generator following are to be ensured
a) all work on Generator has been completed
b) all electrical measurement and tests has been completed
c) checking and setting of temperature measuring points, protection and other signalling scheme has been completed
4 August 2011 PMI Revision 01 31
Checks Before Generator Synchronisation
• Safety precautions including fire fighting
equipments are available
• Oil supply to generator bearing and seal has been
established and quality/flow of oil is as per
specification
• Generator is filled with hydrogen of desired purity
and up to rated pressure
4 August 2011 PMI Revision 01 32
Checks Before Generator Synchronisation
• Generator stator winding is charged with distillate of desired quality. The other parameters of distillate is as per norms
• Generator gas coolers are charged and the parameters are normal
• Generator circuit breaker is in open condition after testing
• All switchyard equipments has been tested and normalised
4 August 2011 PMI Revision 01 33
Checks Before Generator Synchronisation
• All protection and control schemes are in service
after callibration and testing
• Excitation system has been tested, normalised and
field breaker has been kept in open condition.
• Mode of excitation system has been selected
(auto/man)
4 August 2011 PMI Revision 01 34
Checks Before Generator Synchronisation
• After ensuring completeness of checks and
availability of all equipments the set should be
started as per starting instruction and gradually to
be brought to rated speed
• During course of running up all parameters to be
noted and to be checked
4 August 2011 PMI Revision 01 35
Checks Before Generator Synchronisation
• When generator reaches rated speed check the
following
a) bearing and seal temperatures
b) performance of brush gear
c) vibrations
d) any gas, oil or water leakages
e) any abnormalities in generator performance
4 August 2011 PMI Revision 01 36
Checks Before Generator Synchronisation
• Switch on excitation system and check for various parameters and functioning of excitation system
• After ensuring all parameters are all right and machine behavior is normal match the generator’s electrical parameters with the grid and synchronise the machine when permissive for the same is available
• Load the machine gradually. During loading also monitor all parameters
4 August 2011 PMI Revision 01 37
THANK YOU
4 August 2011 PMI Revision 01 38
4 August 2011 PMI Revision 01 39
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