Generator

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STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 1 OF 18

1. PLANT DETAILS : The 500 MW generator is coupled to the 500 MW KWU turbine. The rated parameters of the generator are listed in plant details (Section-1) of Testing schedule for generator protection and generator bay. The design and constructional features are outlined briefly below. Generator manual supplied by the manufacturer may be referred for details of above. STATOR BODY : The stator body is a totally enclosed gas tight fabricated structure suitably ribbed internally to ensure high rigidity. Hydrogen coolers are housed longitudinally inside the stator body. Rigid end shields close the casing and support the fan shields. STATOR CORE : The stator core is made up of segmental varnish insulated punchings of cold rolled grain oriented silicon gel and is assembled in an interleaved manner on core bars. Steel spacers for ventilating ducts are provided for radial cooling of core by hydrogen. The core is held pressed by means of heavy non-magnetic steel press rings which are bolted to the ends of the core bars. Additional support is provided to the teeth portion. In order to isolate the stator body and thus the foundations from magnetic vibrations, the core bars are designed to provide elastic suspension of the core in the stator frame. STATOR WINDING AND INSULATION: The stator has a three phase, double layer short corded bar type windings having two parallel paths. Each coil side consists of glass insulated solid and hollow conductors with cooling water passing through the latter. The elementary conductors are Rosbel transposed in the slot portion to minimize eddy current losses. The coil sides are

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 2 OF 18

firmly held in position by fibrous slot wedges. The overhang portion of the coil is securely lashed with glass chord to bondage rings and special brackets of non-magnetic steel, which are in turn fixed to the core press rings. DISTILLATE HEADERS: Ring type water headers, made of copper are provided separately for distillate inlet and outlet in the stator on turbine side. The headers are supported on insulators and isolated from stator body. The winding ends are solidly soldered into the coil legs which are then ultrasonically tested. Individual bars are provided with water inlet/outlet connections made of P.T.F.E Hoses, The bar heads are insulated by fiber molded covers. TERMINAL BUSHINGS: Water cooled terminal bushings are housed in the lower part of the stator on the slip ring side, Porcelain insulators are provided to insulate the terminal bars from the stator body. Effective sealing is provided between the terminal bushings and the stator body to avoid any possible leakage of hydrogen. Terminal bushings are housed inside a chamber made of non-magnetic steel plates. Three phase terminals and three neutral terminals are brought out. The terminal plate of the end terminals, where bus bar connections are made is silver plated. ROTOR The rotor is of cylindrical type; the shaft and body being forged in one piece from chromium nickel molybdenum and vanadium steel. The rotor with all the details assembled is dynamically balanced to a high degree of accuracy subjected to 20% over speed for 2 minutes. FIELD WINDING: The field winding is made from hard drawn silver bearing copper. The winding is held in position and by non-magnetic

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 3 OF 18

rotating ring in the overhang portion. Gap pickup method is used for direct hydrogen cooling of rotor. The main slot insulation is of glass cloth impregnated with Epoxy resin. The inter turn insulation consists of layers of prepped glass cloth glued to the bottom of each conductor. The end windings are packed with blocks of glass laminates to separate and support the coils and to restrict their movement under stress. The end windings are insulated from the retaining rings with the help of glass epoxy molded segments. SHAFT MOUNTED FANS For circulating the cooling gas inside the generator two propeller type fans are shaft mounted on either end of the rotor body. Fan hubs are made of alloy steel forging and are a shrunk fit on the rotor shaft. The alloy steel cast fan blades are machined in the tail portion to suit the fan hub and held in position with the help of conical pins. The blades can be easily removed from or assembled in the fan hub. Fan shields fixed to the end shields guide the gas flow. RETAINING RINGS: The end windings are held in position by retaining rings of floating type shrunk fit on the rotor body. The rings are screwed to prevent axial movement by locking nuts. SLIP RINGS: The slip rings consists of helically grooved alloy steel rings shrunk on the rotor shaft and insulated from it. They are mounted on a single, common steel bush, which has an insulating jacket pre-molded on it. The complete bush with sliprings are provided with inclined holes for self ventilation. The helical grooves cut on the outer surface help improve the brush performance.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 4 OF 18

FIELD LEAD: The slip rings are connected to the field winding through semi-flexible copper leads and current carrying bolts, placed radially in the shaft. Two semicircular hard copper bars insulated from each other and from the rotor shaft are placed in the central bore or the rotor joining the two sets of current carrying bolts with special profiled precision conical threads. GAS COOLERS Four longitudinally mounted gas coolers are mounted in the stator body. They are made out of admiralty brass with coiled copper wire wound on them staggered form so as to expose maximum surface area to hydrogen. BEARINGS: Generator bearings are of pedestal type with spherical seating to allow self alignment and are supported on a separate pedestal on slip ring side and in the L.P casing on the turbine side, Bearing bush is of cast steel lined with white metal. Oil catchers and deflectors are provided to prevent axial leakage of oil. To prevent shaft currents slip ring side bearing and connecting pipes are insulated from earth. SHAFT SEALS: In order to prevent leakage of hydrogen from the generator casing radial thrust type shaft seals are provided on either side where the shaft extends out from the generator. The seal consists of seal liner with babbit pressing against the shaft caller of the rotor. Seals are defined in testing schedule of seal oil system.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 5 OF 18

NAME PLATE DETAILS RATED DATA & O/P APPARENT POWER ACTIVE POWER CURRENT VOLTAGE FREQUENCY PF STATOR WDG CONN HYDROGEN PRESS CONT PERM UNBAL LOAD RATED FIELD VOLTAGE CURRENT TURBO GEN. 588 MVA 500 MW 16166 A 21 + 1.05 KV 50 HZ 0.85(LAG) YY 3.5 BAR 8 % 340 V 4040 A MAIN EXCITER -----3780 KW 6300 A 600 V -----------------------------PILOT EXCITER 65 KVA -----195 A 220 + 22 V 400 HZ ------------------------

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 6 OF 18

2. TESTING OBJECTIVE : TO TEST THE GENERATOR EQUIPMENT AND MAKE IT READY FOR EXCITATION AND SYNCHRONIZATION.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 7 OF 18

3.0 PROPOSAL 3.1 3.2 3.3 3.4 3.5 3.6 Tests as detailed in item-8 shall be carried out on generator, confirming the manufacturers test reports. Insulation resistance tests on generator rotor, stator and bearing pedestals shall be carried out. Winding resistances for both stator and rotor will be measured and recorded. Impedance of rotor windings shall be measured and recorded. Checks/Tests shall be carried out all the embedded resistance temperature detectors. The brush gear assembly shall be checked tested as per its standard checklist and test procedure.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 8 OF 18

4. SERVICES REQUIRED

4.1

Laboratory equipments/test sets for measurement of electrical parameters required in specific tests (5KV motorized megger, Kelvins bridge or micro ohm meter).

4.2 4.3 4.4

Illumination at required locations. 240 V A.C power supply for testing. Communication facility at test area.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 9 OF 18

5.0

S A F E T Y PRECAUTIONS:

5.1

The test area shall be clearly defined and cordoned off.

5.2

The test team leader is fully aware of the nature, location, and probable duration of the tests.

5.3

The other agencies working in the test area are informed about the test in progress.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 10 OF 18

6. 6.1

EMERGENCY PROCEDURE : Shock treatment chart and first aid box shall be

available. 6.2 Emergency telephone numbers of fire and hospital shall be prominently displayed near by. 6.3 The test in progress shall immediately be stopped and all line apparatus disconnected and equipment suitably earthed in case of a accident or abnormality. instruction will be received from the team leader. 6.4 The test team is fully aware of measures to be taken in the event of injuries to any personnel / damage to any machinery. Such

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 11 OF 18

7. 7.1

STATE OF PLANT : Generator erection Erection test complete and satisfactory. available for All the

results/log

sheets

following : Mounting of embedded parts and foundation plates. Erection of stator. Gas tightness and Hydraulic tests. Measurement of insulation resistances of various parts of generator, D.C. resistances and impedances. Continuity, D.C. resistance and IR checks of RTDs. Purge tests of rotor ventilation canals. Rotor insertion tests. Bearing adjustment tests. Alignment or generator rotor. Inclination or shaft journal test results. Coupling alignment results of generator and LP rotor. Magnetic Axis adjustment results. Fan and shield clearance results. DTI checks on generator rotor. Shaft seal adjustment results. Temperature monitoring system. Centering and offset-setting of brush gear. Fixing of brush holder and brushes.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 12 OF 18

7.2

Following

Testing/Commissioning

schedules

completed

satisfactorily and results/records available : Generator Gas Tightness Test. Hydraulic system. Seal Oil System – Circulation Hydraulic system. 7.3 All the systems mentioned in 7.2 are in totally test and flushing of primary water test and oil flushing of seal oil

normalised condition and available for generator testing. 7.4 Fire protection system (CO2 system) is made available.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 13 OF 18

8. 8.1

T E S T METHOD : INSULATION RESISTANCE OF GENERATOR WINDINGS : Measure and record insulation resistance of

8.1.1

stator windings. Megger used : __________ KV Motorized Serial NO. : __________ Range : _______

Ambient Temp. __________________ Relative Humidity : _______________ (if practical) BETWEEN C1 – E C2 – E C3 – E VOLTAGE APPLIED I.R. 1 MIN. IR 10 MIN. IR10 P.I.=-------IR1

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 14 OF 18

8.1.2

Measure

&

record

rotor

winding

insulation

resistance. Megger used Motorized/Hard Serial NO. Ambient Temp. BETWEEN Rotor Terminal& earth :_____________ KV :_____________ :_____________ :_____________ INSULATION RESISTANCE

VOLTAGE APPLIED

8.2. RESISTANCE MEASUREMENT OF GENERATOR WINDINGS : Using a Kelvins bridge/suitable test set measure and record generator winding resistances. Test set used and details of test set. Measured between Temperature Resistance Corrected Resistance at oC Test Certificate value.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 15 OF 18

C4 – C1 C5 – C2 C6 – C3 ROTOR W I N D I N G S NOTE : Rotor Winding resistance measurement to be taken from main exciter winding terminals REMARKS : 8.2 Test on Generator continuity of embedded resistance and Record temperature Insulation observation detectors. Measure below : Megger used ______________ Ohm meter used ____________ Sl. NO. RTD No. LOCATION CONTI NUITY RESISTANCE IR REMARKS resistance RTDS. resistance Generator

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 16 OF 18

Sl. NO.

RTD No.

LOCATION

CONTI NUITY

RESISTANCE

IR

REMARKS

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 17 OF 18

9. COMPLETION CRITERIA : 9.1 THE RECORD VALUES OF TESTING CARRIED OUT ON GENERATOR ARE COMPLETED AND KEPT ALONG WITH THIS TESTING

SCHEDULE. 9.2 GENERATOR AUX SYSTEM FOR RUNNING GENERATOR ARE LISTED AND KEPT ALONG WITH THIS SCHEDULE. 9.3 GENERATOR IS READY FOR COMMISSIONING.

STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500NTPC REF NO: SIM/1/TS/ / PLANT AREA : ELECTRICAL SYSTEM TESTING SCHEDULE : 500 MW STEAM TURBINE GENERATOR

SHEET 18 OF 18

10. APPENDICES DRAWINGS: I. SCHEMATIC DRAWINGS OF : 1. Generator RTDs 2. Primary water system. 3. Hydrogen Gas filling. FACTORY TEST REPORT OF GENERATOR :

II. LOG SHEETS : I) II) III)

IR VALUES, WR VALUES OF GENERATOR LIST OF PROTECTIONS INCLUDED READINESS OF AUX. SYSTEMS

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