Generator Auxliaries PSTI 21.01.10

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• EXCITER MONITORING DURING OPERATION– TEMPERATURE MONITORING SYSTEM

• AIR TEMP MONITORING THRU RTDs

– FUSE MONITORING SYSTEM• THRU STROBOSCOPE

– GROUND FAULT DETECTION SYSTEM• THRU INSTRUMENT SLIP RINGS

– EXCITATION CURRENT MEASUREMENT• THRU QUADRATURE COILS

2

• INDIVIDUAL BAR TEMP MONITORING • DEW POINT BEFORE / AFTER GAS DRIER• ON LINE PARTIAL DISCHARGE • RF MONITOR• GEN END WDG VIBRATIONS DETECTION • GEN CONDITION MONITORING• TEMP RISE CHECKING WITH TAGGING

COMPOUNDS• SHAFT TORSONAL MONITORING• ROTOR WINDING TEMP MONITORING

DIAGNOSTIC FEATURES

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• INDIVIDUAL BAR TEMPERATURE MONITORING SYSTEM– MACHINES OF HIGHER RATINGS LIKE 500MW

ENVISAGE DIRECT COOLING OF STATOR– WINDING BY DM WATER TEMP OF STATOR

WINDING WHEN MEASURED – BY RTDs IN SOME SLOTS MEASURE ONLY THE

BAR SURFACE TEMP AT LOCATION OF RTDs.– OUTLET TEMP AT HEADER ALSO GIVES

AVERAGE TEMP – SCALE FORMATION OR OTHERWISE WATER

FLOW REDUCTION IN ANY BAR CAN CAUSE INCREASE IN TEMP AND MAY LEAD TO

– WINDING FAILURE

5

• INDIVIDUAL BAR TEMPERATURE MONITORING SYSTEM– SPECIAL OUTLET NIPPLES ARE DESIGNED

TO – ACCOMMODATE MINIATURE RTDs – LEADS ARE TAKEN OUT FOR CONNECTION

TO MICROPROCESSOR BASED MONITORING SYSTEM

– CORRECTION FACTORS ARE APPLIED– TEMP IN INDIVIDUAL BAR IS SCANNED

CYCLICALLY– ALARMS ARE GENERATED WHEN PRESET

LIMITS ARE CROSSED

6

• MOISTURE MEASURING SYSTEM– PURPOSE :

• HYDROGEN USED FOR COOLING OF DIFFERENT COMPONENTS OF STATOR AND ROTOR

• H2 DURING CIRCULATION PICKS UP MOISTURE FROM VARIOUS SOURCES

• MOISTURE CAUSES DETORIATION OF INSULATION SYSTEM , STRESS CORROSION IN RETAINING RING, COIL SHORTING , ARCING ETC

7

MOISTURE MEASURING SYSTEM• MEASURING PRINCIPLE :

– BASIC ELECTRODE IS OF ALUMINIUM COUNTER ELECTRODE OF GOLD FILM THRU WHICH WATER CAN PENETRATE

– MOISTURE SENSITIVE ALUMINIUM OXIDE SERVES AS DIELECTRIC

– WATER MOLECULES OF HUMID GAS DIFFUSE THRU PORES OF OXIDE LAYER AND CHANGES IMPEDENCE OF THE CELL

– SIGNAL FROM SENSOR IS PASSED ON TO MOISTURE ANALYSER TO PROVIDE CONTINUOUS MONITORING

8

• ON LINE PD MEASURING SYSTEM– FAULTS AT INCEPIENT STAGE ARE OFTEN REVEALED BY

ELECTRIC DISCHARGE BEFORE CAUSING SERIOUS SHORT CIRCUITS.

– DISCHARGE PRODUCES CURRENT PULSES OF RF SPECTRUM AND CAN BE DETECTED AT GENERATOR NEUTRAL AND PHASES USING RF CURRENT PROBES, HV COUPLING CAPACITORS AND A SPECTRUM ANALYSER

– RF EMISSION DATA GIVES THE HEALTH OF STATOR INSULATION

– RF EMISSION IS DETECTED BY SPECTRUM ANALYSER AND A RF MULTIPLEXER

– RF DATA IS SENT TO PC VIA BUS COMMUNICATION LINK – SOFTWARE DEVELOPED SENDS COMMANDS FROM PC

TO ANALYSER FOR RESET, FREQUENCY , RANGES, SWEEP TIME , READING OF DIFF PEAK AMPLITUDES ETC

9

MESURING METHODS :

* FAULTS IN GENERATORS GET ANNOUNCED BY PD BRIDGING PART OF HV INSULATION AND ARE DETECTABLE DUE TO RF SIGNAL COMPONENTS* DISTRIBUTION OF PD w.r.to PHASE ANGLE OF GEN VOLTAGE IS CHARACTERISTIC FOR CAUSE OF DISCHARGE AND ALLOWS FOR CONCLUSION TO FURTHER OPERATION OF GENERATOR* RF COUPLERS ARE INSTALLED AT BUS DUCT FOR 3 PHASES OF GENERATOR TO DETECT DISCHARGES

ON LINE PD MEASURING SYSTEM

10

DETECTS FAULTS IN HIGH VOLTAGE EQPT OF POWER PLANTS :1. SPARKING OF GROUNDING BRUSHES ON GENERATOR SHAFT WITH SECONDARY DAMAGES ON BEARINGS 2. BROKEN GROUND CONNECTION ON GEN STATOR WDG CIRCUIT / BAR3. DEFECTIVE GENERATOR BUSHING4. BROKEN LEAD IN VOLTAGE TRANSFORMER WINDING/ PROTECTION EQPT5. HIGH CORONA DISCHARGE IN A 400 KV GROUNDING SWITCH6. HV DISCHARGE INSIDE MAIN TRANSFORMER WINDING7. PD ON PHASE BUS SUPPORTS8 PD DUE TO DAMAGED PHASE BUS BUSHING

RF MONITORING SYSTEM

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BLOCK SCHEMATIC DIAGRAM :

RF MONITORING SYSTEM

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PURPOSE :

* LONG UNSUPPORTED PORTION OF STATOR WINDING

* OVERHANGS ARE FIXED WITH THE HELP OF BRACINGS AND SUPPORT BRACKETS / RINGS

* HIGH VIBRATIONS CAN CAUSE INSULATION FAILURE DUE TO RUBBING OF CONDUCTORS AND FATIGUE

END WINDING VIBRATION MONITORING SYSTEM

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PRINCIPLE :

* INSULATION WHEN HOT BEYOND SAFE LIMITS GENERATES SMALL PARTICLES BEFORE ACTUAL BURNING TAKES PLACE* THESE PARTICLES ARE MADE TO PASS THROUGH ION CHAMBER OF GCM * UNDER NORMAL CONDITION IONS PASS FROM CATHODE TO ANODE IN CHAMBER AND FLOW OF IONS IS MEASURED IN CURRENT AS 100%* PARTICLES WHEN PRESENT REDUCE THE FLOW & HENCE THE CURRENT * LOW CURRENT BELOW PRESET VALUE GENERATES AN ALARM

ALARM VALIDATION :* ION CHAMBER BYPASSED , IF CURRENT RETURNS TO 100% VALUE , THE ALARM IS GENUINE . OTHERWISE IGNORE THE ALARM

GENERATOR CONDITION MONITORING SYSTEM

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INTERPRETATION :

•AFTER ALARM VALIDATION PARTICLES PRESENT IN COOLING MEDIUM (H2) IS PASSED THRU AN EXTREMELY FINE MESH FILTER

* SAMPLE COLLECTED IN FILTER ANALYSED BY GAS CHROMOTOGRAPH

* ANALYSIS IS IN THE FORM OF VERTICAL LINES CALLED FINGER PRINTS

* FINGER PRINT MATCHING DONE WITH LIBRARY BUT IS TEDIOUS, COSTLY AND TIME CONSUMING

* TAGGING COMPOUNDS ARE APPLIED ON VARIOUS PARTS OF GENERATOR TO IDENTIFY WHICH PART IS ACTUALLY HOT

* ANALYSIS OF SAMPLES IN IN FILTER NOT POSIBLE IN INDIA

GENERATOR CONDITION MONITORING SYSTEM

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SHAFT VOLTAGE GETS DEVELOPED DUE TO :* STATIC CHARGES* CAPACITIVE COUPLED EXCITATION VOLTAGE

SYSTEM CONTAINS :* MAIN UNIT* DISPLAY UNIT* LOCAL JUNCTION BOX

SHAFT GROUNDING SYSTEM

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FEATURES :

* MEASURES SUPERIMPOSED VOLTAGE* MEASURES GROUND LOOP CURRENT* MEASURES RESULTANT OR ACTUAL SHAFT VOLTAGE* ALARM FOR: a. FUNCTION FAILURE b. BRUSH DEGRADATION / LOSS OF CONTROL c. BRUSH BOUNCE CONDITION d. BEARING PEDESTAL INSULATION FAILURE

SHAFT GROUNDING SYSTEM

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•CALCULATES SHAFT FATIGUE AND EXPENDED LIFE OF TG SHAFT FOR EACH SHAFT SECTION

•PROVIDES ALARM TO WARN THE OPERATOR WHEN SHAFT TORQUE EXCEEDS A LOW LEVEL GROWING OSCILLATIONS.

•PROVIDES CHART OUTPUTS FOR RECORDING VARIOUS INPUT PARAMETERS SHAFT OSCILLATIONS WITH FACILITY FOR EXTERNAL CONNECTIONS

TORSIONAL STRESS ANALYSING SYSTEM

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ROTOR WINDING TEMP MONITORING

•INDIRECT, APPROXIMATE METHOD•QUADRATURE AXIS V/S CURRENT CHARACTERISTICS•SHOP TEST RESULTS FOR FIELD CURRENT V/S ROTOR WINDING TEMP•EXTRAPOLATION OF DATA•REALISATION IN DCS BY CURVE FITTING FOR QUAD. VOLTAGE V/S TEMP RISE OVER COLD GAS

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FORCED COOLING WATER SYSTEM FOR AIR COOLED GENERATORS

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PRIMARY WATER SYSTEM

1. PRIMARY WATER TANK2. PRESSURE REGULATOR3. WASTE GAS TO ATM.4. PUMP5. COOLER6. FILTER7. BYPASS LINE8. CW FOR STATOR WDG.9. ION EXCHANGER10. CW FOR BUSHINGS11. TEFLON HOSE12. C W MANIFOLD

Losses in wdg, bushings, bus bar are dissipated

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HYDROGEN COOLED GENERATORS

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•DIRECT HYDROGEN COOLING OF STATOR CORE AND ROTOR WINDING

•INDIRECT COOLING OF STATOR WINDING

DESIGN FEATURES

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HYDROGEN/WATER COOLING SYSTEM

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•DIRECT WATER COOLING OF STATOR WINDING AND DIRECT AXIAL HYDROGEN COOLING OF ROTOR WINDING

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AIR COOLED GENERATORS

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AIR COOLED GENERATORS

# DIRECT COOLING OF STATOR CORE AND ROTOR WINDING

# INDIRECT COOLING OF STATOR WINDING

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TYPE OF AUXILIARY SYSTEMS

BASIC SYSTEMS : 1. Seal oil system 2. Stator water system 3. Gas system

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PURPOSE OF SYSTEMS

Seal Oil System :

Prevents H2 escape from Generator body by maintaining a continuous oil film between Generator body and Rotor journals at both the ends.

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PURPOSE OF SYSTEMS

Stator Water System :

Stator water system used to dissipate heat losses arising in the generator stator winding by supplying cooled water.

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PURPOSE OF SYSTEMS

Gas System :

Gas system used to cool the rotor winding by supplying cooled Hydrogen gas.

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TYPE OF AUXILIARY SYSTEMS

1. Primary water system 2. Seal oil system 3. Gas system 4. Waste gas system 5. Waste fluid system

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(A) PRIMARY WATER SYSTEM

Primary water system comprises the following equipments.

1. Primary water pump & filter unit 2. PW Coolers 4. Instrument rack 5. Primary water tank 5. Necessary Piping, Valves and Instruments

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PRIMARY WATER SYSTEM

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PRIMARY WATER PUMP & FILTER UNIT-Comprises the followings

1. 2X100% AC Pumps2. PW Filters3. Mixed bed ion exchanger4. Alkalyser unit

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(B) SEAL OIL SYSTEM (DOUBLE FLOW)

Seal Oil System is double flow seal oil system & have two seal oil supply circuits. 1. Air side seal oil supply circuit 2. H2 side seal oil supply circuit

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(B) SEAL OIL SYSTEM (DOUBLE FLOW)

seal oil supply system comprises followings equipments. 1. Seal oil unit 2. Seal oil pump unit 3. Seal oil valve rack 4. Seal oil storage tank 5. Necessary piping, valves and Instruments

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SEAL OIL UNIT- Comprises the followings. 1. 2X100% AC air side seal oil pumps (Air side) 2. 1X100% DC air seal oil pump (Air side) 3. 1X100% Ac Seal oil pump( H2 side) 4. Seal oil tank 5. 2 nos. DPR Valves (Air side) 6. 1 no. DPR Valve (H2 side) 7. 2X100% Seal oil coolers (Air side) 8. 2X100% Seal oil coolers (H2 side) 9. Duplex oil filter (Air side) 10. Duplex oil filter (H2 side)

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(C) GAS SYSTEM

Gas system comprises the following equipments 1. Gas unit 2. H2 Distributor 3. Co2 Distributor 4. N2 Distributor 5. Gas drier 6. Co2 vapouriser 7. Necessary piping, valves and Instruments

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(D) WASTE GAS SYSTEM

Waste gas system comprises the followings.

1. Vapour Exhausters 2. Necessary piping, valves and Instruments

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(D) WASTE FLUID SYSTEM

Waste fluid system comprises the followings.

1. Drain oil collector 2. Necessary piping, valves and Instruments

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TG COMMISSIONINGGenerator commissioning includes commissioning of following systems– Generator– Brush Less Exciter– Seal Oil System– Gas System– Stator Water System– Excitation System– Protection System– Control & Instrumentation System

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Stator Water SystemALARMS / INTERLOCKS– Stator water outlet header temp. – HIGH– Conductivity after ion exchange – HIGH– Conductivity in Stator Water – HIGH– DP across Stator water filter – HIGH– SW temp. after cooler – HIGH - TRIP– SW flow through main winding – LOW – TRIP– SW flow through terminal bushing – LOW – TRIP– SW inlet pressure in Winding – LOW– SW temperature after stator winding – HIGH– SW temperature after Terminal Bushing - HIGH– Pressure in Stator Water Tank - HIGH

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Gas SystemPerformance expected from Gas System– Maintain constant gas pressure in Generator casing.– Monitor Gas purity under all operating conditions– Scavenging Air and filling H2– Purging H2 and filling Air– Moisture free Gas supply

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Gas SystemALARMS / INTERLOCKS– H2 Gas purity in Generator casing – LOW– H2 Gas pressure in casing – LOW– Presence of Oil/Water in Liquid Level Detector(LLD) -

HIGH

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AVR & Metering PT / CT

Generator +

If

Generator Circuit

Breaker

Isolator 2

Generator Transformer

Isolator 1

Earth Switch

ProtectionCT

Metering & Protection PT / CT

UATField

CT

Electrical Schematic Diagram

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3 PHASE REVOLVING BRIDGE

POWER DIODE,WITH HIGH PIV,HIGH MECHANICAL STRENGTH.

EMPLOYS RC NETWORKS FOR OVER VOLTAGE PROTECTION OF DIODES.

FUSES FOR DIODE FAILURE INDICATION.

FINNED ALUMINIUM SECTION FOR DIODE MOUNTING.

STROBOSCOPIC METHOD OF FUSE FAILURE INDICATION

COMPRISES OF

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3 PHASE BRIDGE CIRCUIT

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GENERATOR

CONTROL &

INSTRUMENTATION-

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• GENERATOR INSTRUMENTATION• EXCITER INSTRUMENTATION• GENERATOR SEAL OIL SYSTEM• GENERATOR PW COOLING SYSTEM• GENERATOR GAS SYSTEM• GENERATOR WASTE GAS SYSTEM• GENERATOR WASTE FLUID SYSTEM

GENERATOR SYSTEMS

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• MEASUREMENT / MONITORING• CONTROLS• ALARMING• PROTECTION• DIAGNOSTICS

C&I FUNCTIONS

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• SEAL OIL PRESSURE• H2 PRESSURE (CASING / MANIFOLD) • SEAL OIL / H2 DIFF PR.(TE/EE)• SEAL OIL INLET TEMP• H2 PURITY IN AIR ( THERMAL

CONDUCTIVITY BASED) • H2 PURITY IN CO2 (DURING FILL/PURGE)• CO2 IN AIR ( DURING FILL/PURGE)

MEASUREMENT CIRCUITS

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• PW CONDUCTIVITY AFTER FILTER• PW CONDUCTIVITY AFT. ION EXCHANGER• PRIMARY WATER FLOW THRU WDGs.• PW FLOW THROUGH R,S,T BUSHINGS• PW TEMP AT INLET TO WDGs• DP ACROSS STATOR WDGs• STATOR WDG TEMP• STATOR CORE TEMP

MEASURING CIRCUITS - Continued

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• BEARING VIBRATIONS IN X,Y PLANES• SHAFT VIBRATIONS IN X,Y PLANES• BEARINGS TEMP• H2 PURITY ( DENSITY BASED) • PW TANK LEVEL • COLD GAS TEMP • HOT GAS TEMP • EXCITER HOT AIR TEMP

• DP AMONG PW / COLD GAS TEMP

MEASURING CIRCUITS - Continued

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• GEN TERMINAL BOX LIQUID LEVEL MONIROTING

• SEAL OIL LEVEL MONITORING IN TANKS• OIL LEVEL IN PRECHAMBERS• PW TANK PRESSURE MONITORING• MCBs MONITORING• H2 PRESSURE AT MANIFOLD• ALKALISER DOSING TANK LEVEL• FLOW THRU BYPASS FOR DOSING

MONITORING CIRCUITS

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• AC SEAL OIL PUMP-1,2 (AIR SIDE)• DC SEAL OIL PUMP -3 (AIR SIDE)• AC SEAL OIL PUMP (H2 SIDE)• BEARING CHAMBR EX.BLOWER-1,2• CO2 VAPOURISER• PRIMARY WATER PUMP-1,2• GAS DRIER HEATER & BLOWER• EXCITER ANTICONDENSATION HEATERS &

BLOWER

- Continued

CONTROL CIRCUITS

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• COLD GAS TEMP CONTROL • PRIMARY WATER TEMP CONTROL• ALKALISER DOSING

CONTROL CIRCUITS - Continued

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• LOCAL ALARMS• WINDOW ALARMS• CRT ALARMS

ALARMING

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• ELECREICAL PROTECTIONS• GENERATOR MECHANICAL PROTECTIONS

GENERATOR PROTECTIONS

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• DIFFERENTIAL ( 0.2-0.4 In, t < 60ms)• STATOR EARTH FAULT (t< 1s , I <15A)• ROTOR EARTH FAULT ( 2 STAGE)• UNDER EXCITATION• OVER CURRENT ( 1.3 In, 6-8 S max) { additional as inverse time lag

impedance based)• LOAD IMBALANCE PROTECTION ( 2 STAGE)• RISE-IN VOLTAGE (Instant trip at 1.45 Un , delayed trip for low rise till 1.2

Un)• UNDER FREQUENCY PROTECTION• REVERSE POWER (50-80% of reverse power, 20-4 s dly)• OVER VOLATGE (surge arrestors, 1.2-1.4Un, power freq spark over voltage

2*Un,impulse spark <4Un))

GEN . ELECTRICAL PROTECTIONS

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• PW FLOW THRU STATOR WDGs EMERGENCY LOW• PW FLOW THRU TERMINAL BUSHING “R”• PW FLOW THRU TERMINAL BUSHING “S”• PW FLOW THRU TERMINAL BUSHING “T”• PW TEMP AFTER COOLERS EMERGENCY HIGH• COLD GAS TEMPERATURE EMEREGENCY HIGH• LIQUID IN TERMINAL BUSHINGS• SEAL OIL TEMPERATURE EMERGENCY HIGH• EXCITER HOT AIR TEMPERATURE EMERGENCY HIGH

GEN . MECHANICAL PROTECTIONS

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EXCITATION SYSTEM

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MAIN COMPONENTS OF EX. SYSTEM• PILOT EXCITER • BRUSHLESS EXCITER• ROTATING DIODES AND FUSES• RC CIRCUITS• QUADRATURE AXIS COILS• CJN CABINETS (THYRISIEM 03-4)• AVR ( 1 AUTO + 1 MANUAL)• ROTOR TEMP MEAS. THRU INDIRECT

METHOD• CONSOLE INSERT AT CONTROL DSK• DIODES/ FUSE MONITORING

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* GENERATORS USE H2 FOR COOLING THEREBY IMPROVES OPERATING EFFICIENCY

* CONTAMINATION OF H2 BY OIL VAPOUR , WATER OR AIR INCREASE THE WINDAGE LOSSES

* 1% REDUCTION IN H2 PURITY CREATES A 12 % INCREASE IN WINDAGE LOSSES

* H2 MAKES AN EXPLOSIVE MIXTURE WITH AIR BETWEEN 4 TO 74 % BY VOLUME

HYDROGEN PURITY MEASURING SYSTEM

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Types of Excitation Systems

• High Frequency Excitation system•Static Excitation System•Hybrid AVR type Excitation system•Brushless Excitation System•SEE with Digital AVR

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Design Features of Excitation System

• Fast response for better stability•Inertia free control of power electronics•Facility for manual operation•Bumpless transfer from auto to manual•Minimum power drainage •High MTBF

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Objectives of Excitation System•Good response in voltage and reactive power control•Satisfactory steady state and dynamic stability•Transient stability for all stated conditions•Quick voltage recovery after fault clearance

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Technical Particulars for Excitation System

•Range of voltage control in Auto 90-110% Un

•Frequency range of operation Fn +-5%•Transformer drop /droop compensation: upto 15%•Maximum change in Gen Voltage during changeover from auto to manual : 1%•Range of exciation control in manual: 0-110% Ifn

•Accuracy of voltage control : +/- 0.5% Un

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Main subassemblies of SEE•Rectifier transformer•Thyristor bridges•Control electronics•Field flashing•Field Suppression•Over voltage protection•Digital AVR •Digital Limiters

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Main subassemblies of B’less Ex. system

•Rectifier transformer•Thyristor bridges•Control electronics•Field Suppression•Digital AVR •Digital Limiters

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Limiter Functions

•Field current limitation•Stator current limitation ( for both leading and lagging stator current)•Load angle limitation•Power system stabiliser

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Main subassemblies of B’less Ex. system

•Rectifier transformer•Thyristor bridges•Control electronics•Field Suppression•Digital AVR •Digital Limiters

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Excitation System Monitoring

•Actual values signals for Gen voltage & current•Voltage reference for excitation build-up circuit•V/f monitoring•Pulses monitoring

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Protection & Monitoring in Excitation System

•Excitation transformer over current protection•Rectifier transformer temp monitoring•Thy. Bridges over current protection•Thyristors Hole storage protection ( dv/dt)•Protection against high inrush current to Thyristors •Air flow monitoring•Field over voltage protection

April 8, 2023 75PMI Revision 00

GENERATOR & ITS AUXILIARY SYSTEM


• GENERATORS AND ITS AUXILIARY CAN BE BROADLY DEVIDED INTO THREE SYSTEMS

• A) Stator water system• B) Seal oil system• C) Gas system • D) Generator


STATOR WATER SYSTEM

DIFF PRESS SWITCH

VACUUM PUMPS

POLISH UNIT

FILTERS

COOLERS

PUMPS

GAS TRAP

FLOW METERS

CONDUCTIVITY

EXPANSION TANK

MAKE UP

FSIIDIFF 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 circuitsa) circuit should be flushedb) hydraulic testing c) installation of pump and motors after O/Hd) filters cleaned and boxed up


Stator Water System

e) coolers and all other components are boxed upf) ion exchanger is ready and is in serviceg) 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

OILCOOLER

FILTERS

DPRV

CONSTANT PRESS. REGULATORS WITH ORFICE PLATES

VACCUM PUMP

BEARGDRAINS

TG

1 2

EEBEARINGTEBEARING GAS

EXHAUST

FROM GASSYSTEM

IOT

VACUUMTANK

SOST

SOPSOP-3 DC

DPSW

TS ESFR

FLOW M. PS PG


SEAL OIL SYSTEM

• Generator shaft seals are supplied with pressuerised seal oil to prevent hydrogen escape at the shaft

• 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 switches2) close all stop and non-return shut off valves3) open all pressure gauge and pressure switches isolating valves


SEAL OIL SYSTEM

4) open pressure transducer isolating valves5) open isolating valves of impulse lines of differential pressure regulator6) 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

CO2VAPOURIZER

TOSEALOIL 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


GENERATOR

• Before final commissioning of Generator following are to be ensureda) all work on Generator has been completedb) all electrical measurement and tests has been completedc) checking and setting of temperature measuring points, protection and other signalling scheme has been completed


GENERATOR

• 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

• 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


GENERATOR

• 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)


GENERATOR

• 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


GENERATOR

• When generator reaches rated speed check the followinga) bearing and seal temperaturesb) performance of brush gearc) vibrationsd) any gas, oil or water leakagese) any abnormalities in generator performance

110

GENERATOR• 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

111

• Protection of generators:– General protections provided are:

• Generator differential protection • Stator earth fault protection• Negative phase sequence • protection against unbalanced loading• Interterm fault protection• Reverse power protection• Field failure protection• Rotor earth fault protection• Temperature sensors in slots• Over current relays in stator and rotor circuits• Surge arresters for surge overvoltage• RC surge suppressors

Generator Auxliaries PSTI 21.01.10

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Transcript of Generator Auxliaries PSTI 21.01.10