generator auxiliary system

4 August 2011 PMI Revision 01 1

GENERATOR

AUXILIARY

SYSTEM


Generator Auxiliary System

• GENERATOR AUXILIARIES CAN BE BROADLY

DIVIDED INTO THREE SYSTEMS

• A) Stator water system

• B) Seal oil system

• C) Gas system


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


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


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.


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


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


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


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


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


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


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


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


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


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


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


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.


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


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


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


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


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)


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


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


H2 DISTRIB

HYDROGEN

CO2 VAPOURIZER

TO SEALOIL DPT

H2 DRIER

HYDROGEN GAS SYSTEM

CO2

ANALYZER

DRAIN

AIR

FILTER

OP

DPI


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


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


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%


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


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



• 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



• 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



• 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)



• 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



• 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



• 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


THANK YOU

generator auxiliary system

Documents

stator water

seal oil system

seal ring

expansion

gas pressure

pmi revision

seal

oil