STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 1 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
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.
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
The elementary conductors are Rosbel transposed in the
slot portion to minimize eddy current losses. The coil
sides are 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 nonmagnetic 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.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
FIELD WINDING:
The field winding is made from hard drawn silver bearing
copper. The winding is held in position and by nonmagnetic 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.
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
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.
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
the stator body. They are made
with coiled copper wire wound on
as to expose maximum surface area
coolers are mounted in
out of admiralty brass
them staggered form so
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.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
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.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
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
------------------
------
-------
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
2. TESTING OBJECTIVE :
TO TEST THE GENERATOR AND MAKE IT READY FOR SYNCHRONIZATION.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
3.0 PROPOSAL
3.1
Tests
as
detailed
in
item-8
shall
be
carried
out
on
generator, confirming the manufacturers test reports.
3.2
Generator short circuit test will be carried out and the
values will be recorded.
3.3
The current based relays will be dynamically tested for
their function and the values will be recorded.
3.4
Generator open circuit test will be carried out and
the
values will be recorded.
3.5
The voltage based relays will be dynamically tested for
their function and the values will be recorded.
3.6
The synchronizing circuit will be checked and the phasing
out will be carried out.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
4. SERVICES REQUIRED
4.1
Laboratory equipments/test sets for measurement of
electrical parameters required.
4.2
Illumination at required locations.
4.3
240 V A.C power supply for testing.
4.4
Communication facility at test area.
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TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
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
location, and probable duration of the tests.
5.3
The other agencies working in the test area are informed
about the test in progress.
nature,
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NTPC REF NO: SIM/1/TS/ 2 / 008
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6.
EMERGENCY PROCEDURE :
6.1
Shock treatment
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.
Such 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.
chart
and
first
aid
box
shall
be
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
7.
7.1
STATE OF PLANT :
Generator Erection complete and satisfactory.
erection test results/log sheets available for
following :
-
Mounting of embedded parts and foundation plates.
-
Erection of stator.
-
Gas tightness and Hydraulic tests.
-
Measurement
of
insulation
resistances
of
All
the
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.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
7.2
Following
Testing/Commissioning
schedules
satisfactorily and results/records available :
completed
-
Generator Gas Tightness Test.
-
Hydraulic test and oil flushing of seal oil system.
-
Seal Oil System – Circulation
-
Hydraulic test and flushing of primary water system.
-
Generator test schedule
-
Generator, generator bay protection test schedule
7.3
All the systems mentioned in 7.2 are in totally normalised
condition and available for generator testing.
7.4
Fire protection system (CO2 system) is made available.
7.5
For carrying out short circuit test, short generator
transformers HT terminals R,Y,B together at 400 KV side by
earth switch or by the links capable of carrying 1500A
current. Isolate 400 KV supply and earth.
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NTPC REF NO: SIM/1/TS/ 2 / 008
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
1.
The following measurement circuits to be made through for
monitoring and taking readings :
a.
b.
c.
d.
e.
f.
g.
h.
Generator Voltage – RY, YB, BR
Generator Current – R, Y, B
Excitation Voltage
Excitation Current
Active Power
Reactive Power
Power Factor
Energy meter
Synchronising circuits and protection circuits also to be
kept ready alongwith recommended settings set in the
protection relays.
2.
Testing / measuring equipments to measure PMG Voltage(3
Phase AC), main exciter Voltage (DC) and PMG’s phase
sequence in AVR are to be kept ready.
3.
Excitation Circuit :

Fuses of PMG input to AVR and main exciter input from AVR
output are to be checked for their healthiness.

Cables of PMG and main exicter are to be cnfirmed that
they are properly
connected and are free
from earth
short or any other faults.

Winding resistances of PMG and main exciter are to be
taken only to check their healthiness.

Healthiness of stroboscope
and DAVR to be checked.
trip should
come from DAVR.
4.
Ensure that Gen PTS are racked in and Gen bus duct are in
pressurised
condition.
No
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
5. Systems :
i.
ii.
Stator water cooling system is to be kept on line.
Rotor cooling is to be confirmed by parameters of H2
temp.
iii. Seal oil circulation in service is to be confirmed.
iv. All RTDs are to be monitored in control room.
v.
Busduct pressuring unit must be in service.
vi. Rotor earth fault circuit to be made ready and kept
on line.
vii. Operation of UT-A&B-11KV breakers and GCB are to be
checked and found OK. UT-A & B breakers are to be
put in test position.
6.
Following modifications to be carried
out
normalised after synchronisation of generator.
i.
ii.
iii.
iv.
v.
and
to
be
Excitation system on manual
Auto channel in blocked condition.
Field breaker closing from ATRS inhibited.
Auto synchronised isolated from circuit.
Turbine trip from generator trip removed.
GRP TB3 – 9 & 10
GRP TB3 – 11 & 12
7.
LBB LINKS
to be kept out
8.
Interlock between
be defeated.
9.
GT differential protection
input CT Sec. Links.
switchyard isolated and field beaker to
to
be
disabled
by
shorting
At 3000 rpm Measure PMG voltage frequency and phase sequence .
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7.6
Excitation system panels are kept in ON condition.
7.7
The steam turbine run
start-up procedure.
7.8
The spill currents in the CT terminals in the relay
panel,control panel& AVR panels are first checked when the
machine is at 3000rpm.
to
3000rpm
after
following
the
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8.0
TEST METHOD :
8.1
8.1.1
8.1.2
Short circuit characteristics test :
AVR in manual mode.
FB is off and no trip from tripping relays and AVR.
Hence, FB close permissive available.
Close GCB in dead circuit.
Measure CT secondary current of GT CT at switchyard.
Control room.
Switch on the excitation
Slowly raise excitation till generator current reaches
500 A and note the
readings of field voltage,
current,
generator
excitation
current,
terminal
voltage and stator currents in three phases.
Slowly
raise
excitation
and
measure
the
above
parameters at diff. Stator
currents till the rated
stator current.
Draw a graph between field current and gen. Current.
8.1.3
8.1.4
8.1.5
8.1.6
8.1.7
8.1.8
S.No
01.
02.
03.
04.
05.
06.
07.
08.
09.
10.
11.
12.
13.
14.
15.
16.
17.
Gen.Field
Current
(Amps)
Gen.
current
500
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
15000
16000
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Exciter
field
voltage
Exciter
field
current
Gen.
Termina
l
Voltage
AVR
control
Voltage
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9
Find overall
Transformer.
8.2
1.
short circuit ratio of Generator and Generator
PROTECTION CHECKING:
Proving of Rotor Earth Fault protection (64E) :
At machine stand still condition, connect the ground fault
detection brush to earth and ensure that rotor earth fault
relay operates (Refers 3-562-006-0357 / Rev.2, Sheet-37).
Either TE or EE side (TB1-40 OR TB1-41 to be earthed).
2.
When GCB closed and ,
out.
a.
the following checks can be carried
Proving of negative phase sequence (46G).
Change the polarity of anyone phase of 3
Phases currents by interchanging relay terminals A5
and A6 or A7 and A8 or A9 and A10 (sheet 36).
i. Ensure that the relays flags are reset.
ii.
Close field breaker and slowly raise excitation till
the current is about __________ alarm will appear
after 5 Seconds trip will occur at K1 times operating
time. Operating time depends on the current setting
I23 .
iii. Reduce excitation and switch off FB.
iv. Normalise wires on relays terminals.
b.
Proving of Generator field failure protection (40G1 &
40G2).
i.
Set K1K5 to the maximum setting.
ii. Check K3 + K4 = K2.
iii. The Voltage across terminals 7 & 8 of the relay and
current through terminal 6.
iv. Close FB and slowly raise the excitation. Check
relay operates at Vs = 2I (K1K5 + (K3+K4)
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v.
Record Vop =
Iop =
Volts
Apms.
vi.
Reduce the excitation and trip FB.
C.
Proving of Generator Trasnformer Differential
Protection (87GT R,Y,B)
Keep Relay setting in the minimum value so as to avoid
generator to run in fault condition for a long time and for the
maximum fault current
R phase: with machine in de-excited condition, block
contribution
of
current
to
differential
relay
by
shortcircuiting CT secondary wires on GRP 7 TB1-1&4 (wire nos.
A411, A470) and monitor differential current at relay terminal
27. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current . Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
Y phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP 7 TB1-2&4 (wire nos.
A431,A470) and monitor differential current at relay terminal
27. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
PHASE
R
Y
B
OPERATING CURRENT
GENERATOR CURRENT
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D.
Proving of Generator Differential Protection (87G1)
R phase: with machine in de-excited condition, block
contribution of current to differential relay by shortcircuiting CT secondary wires on GRP1 TB1-1&4 (wire nos.
A11,A70) and monitor differential current at relay terminal 6.
Switch on excitation & slowly raise till generator current is
around 2000A. Record the values of operated current and
Generator current . Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
Y
phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP1 TB1-2&4 (wire nos.
A31,A70) and monitor differential current at relay terminal 8.
Switch on excitation & slowly raise till generator current is
around 2000A. Record the values of operated current and
Generator current . Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
B phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP1 TB1-3&4 (wire nos.
A51,A70) and monitor differential current at relay terminal 10.
Switch on excitation & slowly raise till generator current is
around 2000A. Record the values of operated current and
Generator current . Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
E.
Proving of Gen. Trf HV winding Diff Protection (87HV)
R phase: with machine in de-excited condition, block
contribution
of
current
to
differential
relay
by
shortcircuiting CT secondary wires on GRP2 TB1-22&25 (wire nos.
A511,A570) and monitor differential current at relay terminal
6. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
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PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
Generator current . Switch off Excitation and
breaker. Normalise TB wirings and relay settings.
trip
field
Y phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP2 TB1-23&25(wire nos.
A531, A570) and monitor differential current at relay terminal
8. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
B phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP2 TB1-24&25 (wire nos.
A551,A570) and monitor differential current at relay terminal
10. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
F.
Proving of Generator Differential (87G 2R,Y,B)
R phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP6 TB1-1 & 4 (wire nos.
A111,A170) and monitor differential current at relay terminal
27. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current. Switch off Excitation and trip
field
breaker. Normalise TB wirings and relay settings.
Y phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP6 TB1-2&4 (wire nos.
A131, A170) and monitor differential current at relay terminal
27. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current . Switch off Excitation and trip
field
breaker. Normalise TB wirings and relay settings.
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TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
B phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP6 TB1-3&4 (wire nos.
A151, A170) and monitor differential current at relay terminal
27. Switch on excitation & slowly raise till generator current
is around 2000A. Record the values of operated current and
Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
G.
Proving of GT overhead connection Diff (87TL R,Y,B)
R phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP2 either TB1-1 & 4
(A211,A270) or TB1-6&9(A221&A280) or TB1-11&14(A311&A370) or
TB1-16&19 (A321&A380) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
Y phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP2 either
TB1-2 & 4
(A231,A270) or TB1-7&9(A241&A280) or TB1-12&14(A331&A370) or
TB1-17&19 (A341&A380) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker.Normalise TB wirings and relay settings.
B phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP2 either TB1-3 & 4
(A251, A270) or TB1-8&9(A261&A280) or TB1-13&14(A351&A370) or
TB1-18&19 (A361&A380) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current . Switch off Excitation and trip field
breaker.Normalise TB wirings and relay settings.
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 23 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
H.
Proving of Unit Transformers Differential (87 UTA
R,Y,B & 87UTB R,Y,B)
UNIT TRANSFORMER - A
R phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP3 either TB1-1 & 4
(A111A, A170A) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
Y phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP3 either TB1-2 & 4
(A131A,A170A) and measure differential current at relay
terminal 27. Switch
on excitation & slowly raise till
generator current is around 2000A. Record the
values
of
operated current and Generator current. Switch off Excitation
and trip field breaker. Normalise TB wirings and relay
settings.
B phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP3 either TB1-3 & 4
(A151A, A170A) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
UNIT TRANSFORMER - B
R phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP3 either TB1-16 & 19
(A111B,A170B) and measure differential current at relay
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 24 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
Y phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP3 either TB1-17 & 19
(A131B, A170B) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
B phase: with machine in de-excited condition, block
contribution of current to
differential
relay
by
shortcircuiting CT secondary wires on GRP3 either TB1-18 & 19
(A151B, A170B) and measure differential current at relay
terminal 27. Switch on excitation & slowly raise till generator
current is around 2000A. Record the values of operated current
and Generator current. Switch off Excitation and trip field
breaker. Normalise TB wirings and relay settings.
I.
Proving of Backup Impedance(21GRY,YB,BR)
Excite the machine and slowly raise the current till the
relay operates. Measure current at relay terminal 5 & voltage
across 7 & 8. Note the values of Operating
current
and
Voltage.
iii) Normalise Generator Transformer HT terminals. Open
Generator Circuit Breaker.
8.3
Open Circuit Characteristic Test
1. Keep DAVR in manual
2. Ensure that no trip from protection panel as well as
DAVR are not present.
3. Field breaker close permissive is available
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 25 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
4. Close field breaker
5. Excite slowly upto Generator Terminal Voltage reaches 2
KV. Note down the values of Field voltage,field
current,Generator field current and Generator current
against Generator terminal voltage.
6. Increase the excitation in steps of stator terminal
voltage 2 KV and note down the above values.
7. Tabulate the values noted and draw a graph between
Generator field current Vs Generator terminal voltage.
8. Find Characteristic impedance of Generator
Gen.
Termina
l
voltage
2000 v
4000 v
6000 v
8000 v
10000 v
12000 v
14000 v
16000 v
18000 v
20000 v
21000 v
8.4
Exciter
field
voltage
Exciter
field
current
Gen.
current
S.No.
Gen.Fie
ld
Current
(Amps)
AVR
control
Voltage
01.
02.
03.
04.
05.
06.
07.
08.
09.
10.
11.
Proving of Stator earth fault (64G1 & 96G)
64 G1
1.
Earth any one of the phases at 400 KV side.
2.
Keep stator Earth fault relay settings at minimum
value.
Close FB and slowly raise the excitation. Note the
values of voltage operated and current flown through
earthed phase when relay operates.
Normalise the earth and relay setting connection
after reducing excitation and tripping FB.
3.
4.
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 26 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
96G :
1.
Earth the point where neutral grounding
transformers and generator neutral connected
together.
2.
Set the relay setting in minimum in order to avoid
over strain of generator.
Close FB and slowly raise excitation fill relay
operateds note the values of current operated.
Reduce excitation, trip FB and then normalise the
earth connection made for testing as said in point
No.1.
3.
4.
a. Proving of Over voltage(59G) & under voltage (27G1,27G2)
Excite the machine & reach the rated terminal Voltage
across Generator stator terminals i.e.21 KV . Measure the
voltage across 9 & 10 of 27G1 & 27G2. Reduce the voltage to the
set value percentage of the above relays and check that the
relays are operated.
Increase the terminal voltage further above rated voltage
by 5 or 10 %. Check over voltage relay 59 G1 operated
CAUTION: KEEP AS MINIMUM SETTINGS AS POSSIBLE SO THAT
GENERATOR STATOR TERMINALS WILL NOT OVERSTRAIN FOR SUDDEN
VOLTAGE FLUCTUATIONS DURING TESTING.
8.5
Proving of Under frequency Protection(81G1)
1. Short GRP4 TB1-11 &12 to bypass GCB close temporarily.
2. Increase the relay setting above 50 HZ for testing so
that it senses normal frequency as under frequency.
3. Excite the machine and maintain rated terminal voltage
4. Once terminal voltage is reached, underfrequency relay
will operate.
5. Normalise TB shortings and relay settings as
recommended.
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 27 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
b. Proving of Gen overfluxing (99G)
1.
2.
3.
8.6
8.6.1
8.6.2
8.6.3
8.6.4
8.6.5
8.6.6
8.6.7
8.6.8
Keep the setting to minimum of 1.o
Excite the machine such that the secondary voltge of
PT at the relay terminals is 110V.
Relay will operate. After that reduce exdcitation
and trip field breaker.
SYNCHRONISING:
Now set all the relays as per the recommended values.
The following are the steps for synchronizing the
generator to the Grid:
Excite the generator to the rated voltage.
Switch the synch.selector switch to Manual position
and also switch on the
synchroscope.
By monitoring the double voltmeter, match the generator
voltage by raising or lowering the excitation. The
generator in coming voltage to be marginally greater
than the running bus voltage.
No check that the phase sequence of the running bus and
the incoming bus are same.
Now raise or lower the speed such that
the
synchroscope
pointer
rotates
in
the
clockwise
direction at a rate such that the check sync. Relay
operates when the pointer is about 12’ O clock
position.
Close the generator breaker, when the ‘Check sync in’
lamps glows.
Now, manually load the generator to 5 % of the rated
load by giving raise command to the speed reference.
Further loading of the generator is done from the
turbine control panel.
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 28 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
9.
COMPLETION CRITERIA :
9.1
THE RECORD VALUES OF TESTING CARRIED OUT
ARE
COMPLETED AND
ON GENERATOR
KEPT ALONG WITH THIS TESTING
SCHEDULE.
9.2
GENERATOR AUX SYSTEM FOR RUNNING GENERATOR ARE LISTED
KEPT ALONG WITH THIS SCHEDULE.
9.3
GENERATOR IS READY FOR SYNCHRONIZATION.
AND
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 29 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
10. APPENDICES
Drawings :1. Schematic Diagram of Gen, GT & UT protection (3562-006-0357) Rev.02
2. Schematic diagram Electrical control panel-1. (3659-0050610) Rev.
3. Line 1 & line 2 diameter circuits isolator
interlock (3-562-006-0296) Rev.02.
4. Schematic diagram of 400 KV bus-1&2 protection
(TBDG 1865100101/02)
MANUALS : 1.
2.
Relay manuals (Volume – I to Volume IV)
500 MW Turbo Generator O&M manual.
GENERATOR SYNCHRONIZATION CIRCUIT
Sl
Source
location
phases
No.
values
Phase
sequenc
e
1
400 KV
Bus 1
2
400 KV
Bus 2
ECP1
TBG-23a & 24a
R - Y
TBG-24a & 25a
Y – B
TBG-25a & 23a
B – R
ECP1
TBG-27a & 28a
R – Y
TBG-28a & 29a
Y – B
TBG-29a & 27a
B – R
STATION: NTPC SIMHADRI BHEL REF NO : PS-DC-186-500-0020
NTPC REF NO: SIM/1/TS/ 2 / 008
SHEET 30 OF 30
PLANT AREA : ELECTRICAL SYSTEM
TESTING SCHEDULE : GEN. TESTING PROCEDURE FOR FIRST SYNCHRONISING
3
Generator
GRP1
VT 2 (LV
VT
TB1-23 & 27
SIDE)
TB1-27 & 31
R - Y
TB1-31 & 23
Y – B
GRP8
B - R
TB1-36 & 38
VT 4 (HV
TB1-38 & 40
SIDE)
TB1-40 &36
R – Y
ECP1
Y – B
TBG-31a & 32 a
B – R
TBG-32a & 33a
TBG-33a & 31a
R – Y
Y – B
B – R
`