Procedure for Governing Oil System

Station: NTPC- Simhadri

BHEL Ref No.PS-DC-186-500-103 NTPC Ref no SIM/1/TS/2/103

Plant area: TURBINE PROCEDURE FOR GOVERNING OIL SYSTEM SLNO

1.0

PLANT DETAILS

2.0

OBJECTIVE

3.0

PROPOSAL

4.0

SERVICES REQUIRED

5.0

SAFETY PERECAUTIONS

6.0

EMERGENCY PROCEDURE

7.0

STAE OF THE PLANT

8.0

TEST METHOD

9.0

COMPLETION CRITERIA

10.0

APPENDICES a. TECHNICAL SPECIFICATION b. DRAWINGS i)

Governing System Drawing

ii)

Governing Characteristic curves

Sheet 1 of 28



Sheet 2

Plant area: TURBINE PROCEDURE FOR GOVERNING GOVERNING OIL SYSTEM SLNO

1.0

STATUS

PLANT DETAILS: Governing Rack Consisting of following.

i) ii) iii) iv) v) vi) vii) viii) ix) x) xi) xii) xiii) xiv)

Emergency trip valve Tripping Device Change over valve Filters in control oil Accumulator. Starting Device Hydraulic Amplifier with set of follow up pistons (HP&IP) Load shedding relay Trimming Device Electro Hydraulic converter with set of follow up pistons (HP & IP) Extraction Relay Oil injection Test Device Vacuum protection Device. Set of solenoids for ATT operation.

HP Front Pedestal consisting of following.

i) ii)

Impeller for primary oil Over speed trip governor

HP Rear Pedestal Consisting of following.

i) ii) iii)

2.0

Thrust protection Device. For brief description of above items, refer to O&M manual HP and IP governing valves.

OBJECTIVE:

To commission the Governing control system for controlling speed and load of the machine. Signatures NTPC

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Sheet 3


3.0

STATUS

PROPOSAL:

Proposed to set the Hydraulic, Electro Hydraulic convertors, to set the characteristics of HP and LP governing valves and to check the operation of emergency stop valves of HP and IP. 4.0

SERVICES REQUIRED:

4.1

Oil system shall be in service.

4.2

Operating man power.

4.3

The following equipments and Instruments. a) Portable vaccum pump one No. b) Hydraulic pressure pump one No. c) Standard pressure gauges with an accuracy of 0.1kg/cm 2 range 0-10 kg/cm 2 4 Nos. 2 1 Nos. “ 0 –20 kg/cm 2 “ 0 – 40 kg/cm 1 Nos d) Standrad vacuum gauge range 0 – 760 mm Hg. e) Dial gauge with Magnetic Base 0-10 mm one No. f) Depth gauge one No. range 0-50 mm g) Slip gauge Box one No. h) Filer gauge 0.05 to 1 mm 1 Set. i) Diffent sizes of spanner set ( double end) j) Ring spanner 3 mm to 27 mm one set. k) Allen Key one set 3 mm to 10 mm. l) Screw driver small to big one set. m) Voltage injection test kit one No. n) Multimeter one No. o) Digital speed indicator one No. 0-4000 rpm range.

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Sheet 4


5.0

STATUS

SAFETY PRECAUTION:

While testing and adjusting the LP Bypass governing no insulation work shall be allowed. Fire fighting equipments shall be made available. The operating personnel shall be aware of the procedure. 6.0

EMERGENCY PROCEDURE:

Refer to Section 6.0 of LP Bypass System. (BHEL Ref.No.PS-DC-186-500-102 NTPC Ref No. SIM/1/TS/2/102)

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Sheet 5


7.0

STATUS

STATE OF THE PLANT:

7.1

AOPs are available for running.

7.2

Control oil, Trip oil & Test oil lines are erected & Hydrotested after oil flushing.

7.3

HP & IP Governing valves are erected.

7.4

Connected Instrumentation and controls are made ready.

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Sheet 6


8.0

STATUS

METHOD:

8.1.1

Initial checks to be carried out before setting of Hydraulic governor.

8.1.2

The components number indicated on the check list is based on Governing Scheme Drg.No.1.1-2192-7279/1 of KWU.

8.1.3

Check whether erection of all fluid pipe lines are completed.

8.1.4

Check whether the isolation valves before the filter MAX 42 BT 001 – 003 is kept opened for speed control rack.

8.1.5

Check whether the test valves of HP and IP for stop valve MAX 47 AA 001 – 014 and MAX 47 AA 021 – 024 respectively are kept closed fully.

8.1.6

Ensure that the isolating valves before the 32 bar control fluid filters MAX 32 BT 011-012 for HP control valves and filters MAX 32 BT 021 – 022 for IP control valves are kept opened fully.

8.1.7

Ensure whether the isolating valves in control fluid lines MAX 32 AA 511,512,516,517 and MAX 32 AA 521,522,526,527 and secondary oil lines MAX 45 AA 511-514 band MAX 45 AA 521524 are kept fully opened for HP and IP control valves.

8.1.8

Check whether the isolating valves in EHC circuit in HP secondary fluid MAX 45 AA 501 and IP Secondary fluid MAX 45 AA 502 is closed, while setting the hydraulic controller.

8.1.9

Close the control fluid line isolating valve MAX 42 AA 621 and Secondary fluid line isolating valve MAX 45 AA 566 of CRH NRV slide valve MAX 42 AA 001.

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Sheet 7


STATUS

8.1.10

Ensure closing of the trip fluid line isolating valve MAX 51 AA 527 and MAX 51 AA 530 of extraction NRV slide valve MAX 51 AA 048 and MAX 51 AA 051.

8.1.11

Fix a dial gauge 0-10 mm underneath bellow KA 09 in the hydraulic speed Governor MAX 46 By 001.

8.1.12

Fix three standard gauges in Auxiliary secondary fluid HP secondary oil and IP secondary fluid lines. (0-8 kg/cm 2 to read upto 0.1 kg/cm 2 accuracy).

8.1.13

Open the top cover of Hydraulic amplifier MAX 45 By 011 to measure the power piston KA 08 lift.

8.1.14

Ensure that the Boiler stop valve is fully closed and the main steam line is not charged with steam.

8.1.15

Check whether solenoid MAX 42 AA 051 of the trimming device KA 10 is in energized condition.

8.1.16

Check that the solenoids MAX 51 AA 202 and MAX 51 AA 201 are in the de-energised condition and ensure that the change over valve MAX 51 AA 211 is in normal position and not in Test position.

8.1.17

Ensure starting device MAX 47 By 001 in closed condition.

8.1.18

Keep the speeder gear in maximum set positions.

8.1.19

Check whether control fluid pump is running and a control fluid pressure of 32 kg/cm 2 and 8 kg/cm 2 is available.

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Sheet 8


temperature

in

control

fluid

tank

STATUS

8.1.20

Maintain fluid 500 C / 550 C.

8.1.21

Check the load shed relay solenoid MAX 46 AA 011 is in deenergised condition and aux. Secondary fluid doesn’t drain through the load shed relay solenoid.

8.1.22

Ensure that the main trip valve MAX 51 AA 005-006 is in reset conditions.

8.1.23

Switch off ATRS panel supply, so that hydraulic governor can be checked when boiler is not in service.

8.1.24

Check the following pressure in the rack.

8.1.25

Control fluid pressure

- 8 kg/cm 2

8.1.26

Start up fluid pressure

- 7 kg/cm 2

8.1.27

Aux. Start up fluid pressure

- 7 kg/cm 2

8.1.28

Trip fluid pressure

- 7-7.5 kg/cm 2

8.1.29

Aux. Trip fluid pressure

- 7-7.5 kg/cm 2

8.1.30

Control fluid pressure to control valve

- 32 kg/cm 2

8.1.31

Ensure that the respective governor characteristics is used while setting the governor.

around

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Sheet 9


8.2

STATUS

Procedure for checking and setting of Hydraulic Governor.

8.2.1

Note down the initial reading of starting device when the starting device is in full closed condition.

8.2.2

Operate starting device MAX 46 By 001 gradually from Minimum to Maximum position and carry out the following checks.

8.2.3

Check whether the start up and Auxiliary start up fluid pressure drops.

8.2.4

Operate the starting device gradually and increase the Auxiliary secondary fluid pressure to 2.3 kg/cm 2 and note down HP and IP secondary fluid pressure.

8.2.5

Check when starting device is fully opened, note down the starting device lift. The lift should be 24.5mm and auxiliary secondary fluid pressure should be 4.4 kg/cm 2 or above.

8.2.6

If the aux. Secondary fluid pressure is not obtained, adjust Auxiliary follow up piston KA 08 which is in service of MAX 46 By 001 to obtain aux. Secondary fluid pressure of 4.4 kg/cm 2 and above, when starting device is fully opened conditior.

8.2.7

Note down the HP and IP secondary fluid pressure corresponding to 4.4 kg/cm 2 of Auxiliary secondary fluid pressure.

8.2.8

Bring back the starting device gradually towards the closing position and check the trip point of aux. Secondary fluid pressure. The trip point should be around 2.1 kg/cm 2 approximately. At least under 2.3 kg/cm 2 . Note: Trip point of Auxiliary follow up piston is the pressure at which auxiliary secondary fluid pressure suddenly falls to zero.

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Sheet 10


STATUS

8.2.9

Bring back the starting device to fully closed position.

8.2.10

Ensure the starting device is in closed condition.

8.2.11

Fix the dial gauge below the bellow and adjust it to read zero mm.

8.2.12

Note down the initial reading of power piston KA 08 of MAX 45 By 011 by a depth gauge.

8.2.13

Note down the starting device initial readings.

8.2.14

Operate the starting device gradually to open position till the auxiliary secondary fluid pressure increases to 2.3 kg/cm 2 .

8.2.15

At 2.3 kg/cm2 of Auxiliary secondary oil pressure check whether the HP secondary fluid pressure is 3.0 kg/cm 2 .

8.2.16

If the value is not achieved, adjust the three follow up pistons KA 01 of MAX 45 By 011 of HP secondary fluid pressure equally.

8.2.17

Check the lift of power piston KA 08 of MAX 45 By 011 is around 6 to 7 mm (approx.), when the HP secondary fluid pressure is around 3.0 kg/cm 2 .

8.2.18

If the value is not achieved, adjust the start up opening of pilot valve KA 07 of MAX 45 By 011.

8.2.19

Increase the aux. Secondary fluid pressure to 2.55 kg/cm 2 HP secondary fluid pressure will be 3.24 kg/cm 2 . The IP secondary fluid pressure should be 3.5 kg/cm 2 .

8.2.20

If the IP secondary fluid pressure value is not achieved, adjust the three follow up pistons KA 02 of MAX 45 By 011 equally to get 3.5 kg/cm 2 of IP secondary oil pressure.

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Sheet 11


STATUS

8.2.21

Note down the values of followings:-

8.2.22

Starting device travel.

8.2.23

Lift of the bellow.

8.2.24

Power piston lift of Hydraulic controller.

8.2.25

Aux. Secondary fluid pressure, HP secondary fluid pressure and IP secondary fluid pressure.

8.2.26

Increase the Auxiliary secondary fluid pressure to 4.4 kg/cm 2 and check whether HP secondary fluid pressure reaches 5.0 kg/cm 2 .

8.2.27

If the value is not achieved, adjust the proportionality adjuster KA 09 of MAX 45 By 011 to get HP secondary fluid pressure of 5.0 kg/cm 2 when auxiliary secondary fluid pressure is around 4.4 kg/cm2 .

8.2.28

Check by closing the isolating valve MAX 42 BT 001 and MAX 42 BT 002 and MAX 42 BT 001 of speed control rack and note at what pressure of trip fluid, Tripping device MAX 51 AA 006, MAX 51 AA 005 and emergency trip valve MAX 52 AA 005 trips suddenly.

8.2.29

Trip device sand emergency trip valve should trip at 3 bar of trip fluid pressure. If it is not achieved, adjust the spring tension to get the set value.

8.2.30

After checking and ensuring that trip devices and emergency trip valve trips at 3 bar, bring down starting device from open position to closed position.

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Sheet 12


STATUS

8.2.31

Operate the starting device from closed position and once again check at 2.3 kg/cm 2 of Auxiliary secondary fluid pressure, the HP secondary fluid pressure is 3.0 kg/cm 2 .

8.2.32

Increase the auxiliary secondary fluid pressure in steps of 0.2 kg/cm2 and note down the following.

8.2.33

HP secondary fluid pressure.

8.2.34

IP secondary fluid pressure.

8.2.35

Power Piston lift of Hydraulic converter.

8.2.36


8.2.37

Check that a closing and opening reserve of 3.5 mm, is available for power piston KA 08 Hydraulic Amplifier MAX 45 By 011.

8.2.38

Check the bellow travel KA 09 of MAX 46 By 001 between auxiliary secondary fluid pressure of 2.3 to 4.4 kg/cm 2 , should be approx. 5 mm.

8.2.39

Check the total travel of Amplifier power piston. It should be 50 mm approximately, from fully closed position to fully open condition of starting device MAX 47 By 001.

8.2.40

Plot the following curve.

8.2.41

Power piston lift versus Auxiliary secondary fluid pressure.

8.2.42

Bellow lift versus auxiliary secondary fluid pressure.

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Sheet 13


STATUS

8.2.43

Bellow lift versus HP secondary fluid pressure.

8.2.44

Bellow lift versus IP secondary fluid pressure.

8.2.45

Bring the starting device to minimum position, to set HP and IP control valves.

8.2.46

Adjust the local position transmitter to indicate zero mm for both HP and IP control valves.

8.2.47

Bring the starting device to a position where HP secondary fluid pressure is 3.0 kg/cm 2 .

8.2.48

Adjust the start of opening of HP control valves 1-4, just to open at 3.0 kg/cm 2 of HP secondary fluid pressure.

8.2.49

Bring the starting device to a position where IP secondary fluid pressure is 3.5 kg/cm 2 .

8.2.50

Adjust the start of opening of IP control valves 1-4, just to open at 3.5 kg/cm2 of IP secondary fluid pressure.

8.2.51

Increase the Auxiliary fluid pressure in steps of 0.2 kg/cm 2 and note down the following upto the maximum position of starting device.

8.2.52


8.2.53


8.2.54

HP control valve lift.

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Sheet 14


STATUS

8.2.55

IP control valve lift.

8.2.56

Plot the curve for the following.

8.2.57

HP secondary fluid pressure versus HP control valve lift 1-4.

8.2.58

IP secondary oil pressure versus IP control valve lift 1-4.

8.2.59

If the lifts of control valves are not coming equal adjust the fulcrum point of lever 12 feed back linkage as shown in O&M manual KWU Drg.1.1-2321-0006/1.

8.2.60

Open the test valve of HP stop valve number one fully and check whether stop valve opens fully.

8.2.61

Fully close the test valves of HP stop valve number one and check whether the stop valve closes fully.

8.2.62

Repeat the same test 2.24.0. and 2.24.1 for HP stop valve number Two, Three & Four and IP stop valve number One, Two, Three and Four.

8.2.63

Ensure full lift of HP stop valve about 92 mm and IP stop valve about 176 mm which are the design values.

8.2.64

Now open HP stop valve number one by opening the test valve fully and ensure that the stop valve has opened fully.

8.2.65

Energise solenoid valve MAX 48 AA 201 and MAX 48 AA 202, to admit auxiliary start up fluid to Main trip valve MAX 51 AA 005 and Main trip valve MAX 51 AA 005 and MAX 51 AA 006.

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Sheet 15


STATUS

Note: Do not energise longer than 30 minutes.

8.2.66

Check by closing the isolating valve MAX 42 BT 001 MAX 42 BT 002, and MAX 42 BT 003 in control fluid system to speed control rack.

8.2.67

Note down at what trip fluid pressure HP stop valve number one suddenly closes.

8.2.68

Repeat the operation 2.27.0. for HP stop valve number Two, three and Four and IP stop valve number one and two, three and four. Note down the trip fluid pressure at which stop valve closes.

8.2.69

De-energise the solenoid MAX 48 AA 201 and MAX 48 AA 202 after completing the test on stop valves.

8.2.70

Bring back the starting device to full close condition.

8.2.71

Operate the starting device gradually from minimum to maximum position.

8.2.72

Check whether HP stop valve opens first, and IP stop valves opens later as per the indications marked on the starting device scale and note down the start up fluid pressure for opening of HP and IP stop valves.

8.2.73

De-energise solenoid MAX 42 AA 051 of the trimming device KA 10 of Hydraulic Amplifier MAX 45 By 011.

8.2.74

Bring back the starting device to closed position.

8.2.75

Check the dial gauge below the bellow is set at zero.

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Sheet 16


STATUS

8.2.76

Note down the intial reading of starting device.

8.2.77

Open gradually the starting device from fully closed position to fully open position and note down the following.

8.2.78

Bellow lift.

8.2.79

Auxiliary secondary fluid pressure.

8.2.80


8.2.81


8.2.82


8.2.83

Plot the following curve Bellow travel versus Auxiliary secondary fluid pressure. Bellow travel versus HP secondary fluid pressure. Bellow travel versus IP secondary fluid pressure.

8.2.84

Energise the trimming device solenoid MAX 42 AA 051.

8.2.85

Load shed relay MAX 46 AA 011 get energized whenever generator breaker trips on fault. The duration of operation is only two seconds.

8.2.86

During the actuation of load shed relay check whether Aux. Secondary fluid pressure drops down to zero and comes back, to the value at which the load shedding relay was actuated.

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Sheet 17


STATUS

8.2.87

Switch on the ATRS supply.

8.2.88

Check the Main trip valve trips immediately and all the stop valves and control valves closes immediately.

8.2.89

Check the Auxiliary secondary fluid pressure, HP secondary fluid pressure, IP secondary fluid pressure, trip fluid pressure, trip fluid pressure and Auxiliary trips fluid pressure reads zero.

8.2.90

Switch off ATRS panel supply.

8.2.91

Ensure and check it is as per step number 2.38.2.

8.3

Initial checks to be carried out before setting of ElectroHydraulic Converter.

8.3.1

Normalise the isolating valves MAX 45 AA 501 in HP secondary fluid line and MAX 45 AA 502 in IP secondary fluid line from EHC, which was kept closed while checking the hydraulic controller.

8.3.2

Keep the starting device MAX 47 By 001 in maximum position.

8.3.3

Ensure that the trip fluid line isolating valves MAX 51 AA 511 is kept opened.

8.3.4

Ensure that control fluid line isolating valve MAX 42 AA 611 is kept opened.

8.3.5

Ensure a pressure gauge 0 to 8 kg/cm 2 in the pressure gauge point provided before EHC MAX 45 By 001 in trip fluid line.

8.4

Procedure for checking and setting of EHC

8.4.1

Feed through set point voltage, a fixed voltage in co-ordination with C & I Engineer.

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Sheet 18


STATUS

8.4.2

Check whether the voltage in moving coil MAX 45 CG 001 T is around minus volts.

8.4.3

The Equilibrium voltage should be between minus 8 volts to minus 1.2 volts.

8.4.4

If it is not, adjust the moving coil by loosening the three locking screws to such a position where the equilibrium voltage is around minus 1 volt.

8.4.5

After adjusting as said in 4.1.3. feed zero volt through set point and note down the power piston lift. (minimum reading)

8.4.6

Feed 10 volts through set point voltage and note down the power piston lift. (Max. reading)

8.4.7

The difference in lift between maximum and minimum lift should be approximately 50mm.

8.4.8

Vary the controller from minimum to maximum position and note down the out put of Collins I and II in the minimum and maximum position.

8.4.9

The Collins I and II out put should be –7.5V to +7.5V. adjust the Collins MAX 45 CG 001A, MAX 45 CG 001K to get this voltage, if it is not achieved.

8.4.10

Increase the set point voltage and hold the power piston lift KA 08 of EHC MAX 45 By 001 about 6 to 7mm as obtained in Hydraulic Governor setting.

8.4.11

Check the HP secondary fluid pressure, and adjust the three follow up pistons KA 01 of EHC MAX 45 By 001 equally to get HP secondary fluid pressure of 3.0 kg/cm 2 when power piston lift is 6 to 7mm as obtained in Hydraulic Governing setting.

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Sheet 19


STATUS

8.4.12

Increase set point voltage and hold the HP secondary fluid pressure at 3.24 kg/cm 2 .

8.4.13

At 3.24 kg/cm2 of HP secondary fluid pressure adjust, follow up pistons KA 02 of EHC MAX 45 By 001 equally to get 3.5 kg/cm 2 of IP secondary fluid pressure.

8.4.14

Note down the power piston lift of EHC.

8.4.15

Increase the set point voltage in steps on one volt and note down Collins out put I and II and power piston lift.

8.4.16

Check whether the HP secondary fluid pressure and IP secondary fluid pressure obtained are equal to the hydraulic governor characteristics set earlier.

8.4.17

Ensure by plotting the curve, that a closing and opening reserve of 3 to 5 mm is available for power piston KA 08 of EHC MAX 45 By 001.

8.4.18

Ensure the start of opening of HP and IP control valves remains at 3.0 kg/cm 2 of HP and 3.5 kg/cm 2 IP secondary fluid pressures respectively, as set earlier during hydraulic controller adjustement.

8.4.19

Check and ensure that the HP and IP control valves open with respect to HP and IP secondary fluid pressure as per the governor characteristics, from full close to full open position.

8.4.20

Plot the following curves.

8.4.21

Set point voltage versus Collins I and II voltage.

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Sheet 20


STATUS

8.4.22

Set point voltage versus HP and IP secondary fluid pressure.

8.4.23

HP and IP secondary fluid pressure versus control valve lift.

8.4.24

Power piston lift versus HP and IP secondary fluid pressure.

8.4.25

After drawing the charecteristic curves of EHC and Hydraulic compare the slope of these curves. Both should be equal.

8.5

CHECKING AND SETTING OF NON-RETURN VALVES ON EXTRACTION AND COLD REHEAT. Extraction Relay MAX 51 AA 001

8.5.1

Check and ensure that all the drain valves in trip fluid lines are kept closed.

8.5.2

Open isolating valve MAX 51 AA 527 and MAX 51 AA 530 to test valve MAX 51 AA 048 and MAX 51 051 to extraction NRV is opened.

8.5.3

Check whether test valve MAX 51 AA 048 and MAX 51 AA 051 are in open condition.

8.5.4

Check whether solenoid valve MAX 51 AA 028 and MAX 51 AA 028 and MAX 51 AA 031 are in de-energised condition.

8.5.5

Check whether isolating valve MAX 45 AA 509 accumulator MAX 45 BB 001 in HP secondary fluid line is opened.

8.5.6

Ensure a pressure gauge is provided on the trip fluid lien after the extraction valve relay.

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Sheet 21


STATUS

8.5.7

Adjust at HP secondary fluid pressure of 3.25 kg/cm 2 the pilot valve spring tension of KA 01 and KA 02 to open the extraction valve A2, A3, A4 and A5.

8.5.8

Increase the HP secondary fluid pressure above 3.25 kg/cm 2 and check the following.

8.5.9

Check by energizing the solenoid MAX 51 AA 028 and MAX 51 AA 031 the NRV’s A2. A3. A4 and A5 closes.

8.5.10

De-energise th e solenoids and check the NRV’s A2, A3, A4 and A5 opens back.

8.5.11

Check by closing the test valve MAX 51 AA 048 and MAX 51 AA 031 the NRV’s A2, A3, A4 and a5 closes.

8.5.12

Ensure by opening the test valve, the NRV’s A2, A3, A4 and A5 opens back.

8.5.13

Ensure by reducing the HP secondary fluid, all the extraction NRV’s closes and note down the HP secondary fluid pressure at that position.

8.5.14

All the extraction NRV’s should close not later than 3.0 kg/cm 2 of HP secondary fluid pressure.

8.6

Cold Reheat Non-Return valve

8.6.1

Check and ensure that all the drain valves in control fluid lines are kept closed.

8.6.2

Check the isolating valve MAX 42 AA 621 in control fluid line to slide valve MAX 42 AA 001 is kept opened.

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Sheet 22


STATUS

8.6.3

Check the isolating valve MAX 45 AA 566 in secondary fluid lines is kept opened.

8.6.4

Adjust the slide valve MAX 42 AA 001 spring tension to open the NRV at 3.3 kg/cm 2 , HP secondary fluid pressure.

8.6.5

Check by reducing the pressure of HP secondary fluid below 3.3 kg/cm2 and ensure whether NRV is closed fully. NOTE: - The opening of CRH NRV and extraction NRV had to be set as per the customer consultants requirements. If it is not given, it can be set in the above said value.

8.7

Ensure the following settings in coordination with C&I / electrical Engineers.

8.7.1

Ensure the starting device percentage position at control room indication from 0 to 100% matches with full close to full open position.

8.7.2

Adjust the four number of limit switches provided on the starting device for 1%, 42%, 56% and 100% respectively of starting device opening.

8.7.3

Ensure the speeder gear percentage position at control from indication, crom 0 to 100% matches with full close to full open position.

8.7.4

Adjust the limit switches in full open direction and full close direction for four number of HP stop valves and four numbers of IP stop valves.

8.7.5

Ensure the open and close indication is appearing for all the stop valve at control room.

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Sheet 23


STATUS

8.7.6

Adjust the percentages position of the Four control valves of HP and Four control valves of IP indicates at control room the full open and full close directions.

8.7.7

Ensure the local scale indicator mounted on the body of Four numbers of HP control valve and Four numbers of IP control valve in the fully open and fully closed directions.

8.7.8

Adjust the limit switch of cold reheat NRV in the fully open and fully closed direction and check the open and closed indication is appearing at control room.

8.7.9

Ensure that the potentiometer for extraction valves A2,A3,A4 and A5 indicating the valve opening position is calibrated.

8.7.10

Ensure the extraction NRV solenoid MAX 51 AA 028 and MAX 51 AA 031 for A2, A3, A4 and A5 indication at control room for energized and de-energised condition.

8.8

Testing of overspeed Bolts by injecting overspeed test device MAX 62 AA 001.

oil

through

CONDUCT THE FOLLOWING CHEKS AT 300 RPM

8.8.1

Release the lock of pilot valve KA 02 and KA 03 of MAX 62 AA 001.

8.8.2

Check whether the turbine speed is exactly 3000 rpm.

8.8.3

Press the pilot valve KA 03 fully, to isolate the Auxiliary trip fluid from main trip valve to overspeed trip test device and keep in pressed down. Note down the Auxiliary trip fluid pressure.

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Sheet 24


STATUS

8.8.4

Rotate the handwheel KA 01 of overspeed trip test device in clockwise direction for aditting the test oil (mineral oil) to the overspeed Bolts.

8.8.5

Check at what pressure of test oil, the overspeed Bolts act.

8.8.6

The actuation of overspeed bolt is indicated on the test rack by lamps and can be observed by the actuation of limit switches MAX 10 CG 001 + 002, provided on the LHS of front bearing pedestal.

8.8.7

Check whether Auxiliary trip fluid pressure goes to zero.

8.8.8

Note down the test oil pressure at which overspeed, bolt number one comes out and overspeed bolt number Two comes out.

8.8.9

Rotate the handwheel KA 01 of overspeed test unit in the anticlockwise direction where the test oil gets cut off, to the overspeed bolts.

8.8.10

Press the Pilot valve KA 02 of overspeed test device, to reset overspeed bolts One and Two.

8.8.11

Check whether Auxiliary trip fluid pressure builds up and it is as per the recorded value at 8.3.0.

8.8.12

Release Pilot valve KA 02, of overspeed test device.

8.8.13

After ensuring auxiliary trip fluid pressure is steady, release the knob of pilot valve KA 03, of overspeed test device.

8.8.14

Repeat the test two to three times as per the steps 8.2.0 to 8.9.0 and check whether test oil pressure comes to a steady valve.

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Sheet 25


8.8.15

8.9

STATUS

Lock the Pilot valves KA 02 and KA 03 of overspeed testing device, after completing the test. Testing of 7% regulation of Hydraulic Governor.

8.9.1

Check the machine is running on electro hydraulic or Hydraulic.

8.9.2

If it is running on Electro Hydraulic change over to Hydraulic.

8.9.3

Ensure after changing over to hydraulic, the isolating valves MAX 51 AA 501 and MAX 51 AA 502 in secondary Fluid lines of Electro Hydraulic converter is kept closed.

8.9.4

Ensure the starting device in maximum position.

8.9.5

Increase the speeder gear to full open condition and check the speed increases to 3210 rpm at fully open condition.

8.9.6

If the speed is not achieved, loosen the lock nut and increase the compression of spring item No.13 of component compression of spring item No. 13 of component drawing in O&M manual, Drg. No. 1.1-2210-0004/1, of hydraulic speed governor, to get the required speed.

8.9.7

After starting 7% of rated speed, at speeder gear and starting device in maximum position, lock, the lock nut, if Hydraulic speed governor.

8.10

Actual overspeed Test 10 to 12% of rated speed.

8.10.1

Ensure before carrying out actual overspeed test, the both overspeed governors are operative by conducting oil injection test as explained in 8.0.0

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Sheet 26


STATUS

8.10.2

Ensure that all speed indicators and recorders are indicating the samespeed when the machine is at 3000 rpm and at 3210 rpm.

8.10.3

Ensure that turbine is running at a speed of 3210 rpm with starting device and speeder gear in maximum position.

8.10.4

Press continuously the overspeed testing lever KA 07 provided in the start and load limiting device MAX 46 by 001, by watching the speed indication.

8.10.5

Ensure the speed raise is steady and the machine trips at 3300 rpm (approx.) by the actuation of overspeed governors.

8.10.6

Both the overspeed governors should operate between 10 to 12% of rated speed. Note: Release the lever if the overspeed governor is not acting at 12% of the rated speed. Adjust the overspeed governor bolt to act 10-12% of rated speed.

8.10.7

Record the speed at which overspeed governors 1 and 2 acts.

8.10.8

After trip out when machine reaches 3000 rpm, note down the coasting down time from 3000 rpm, to turning gear speed at 100 rpm interval.

8.10.9

Bring back the machine to the rated speed for further checks.

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BHEL Ref No.PS-DCNTPC Ref no SIM/

Sheet 27


STATUS

8.11

Testing of Hydraulic low vacuum trip MAG 01 AA 011 at 3000rpm.

8.11.1

Ensure that the control fluid and Auxiliary trip fluid are available to the low vacuum trip unit.

8.11.2

Ensure whether primary oil pressure is available in the low vacuum trip unit.

8.11.3

Ensure a calibrated vacuum gauge is fixed in between the solenoid valve MAG 01 AA 201 and low vacuum trip unit, on the vacuum impulse line.

8.11.4

Energise the solenoid MAG 01 AA 201 and what the vacuum gauge, for drop of vacuum.

8.11.5

Record at what value of vacuum, the low vacuum trip acts.

8.11.6

The low vacuum trip should act at 0.3 bar.

8.11.7

If low vacuum trip has not acted at 0.3 bar, adjust the spring tension number 7, by means of adjusting screw number 5 as shown in component drawing in O&M Manual Draing number 1-13400-009/1.

8.11.8

Lock the adjusting screw.

8.11.9

Bring back the machine to the rated speed and release for carrying out generator dryout. Note:- Hydraulic low vacuum trip can be test even on turning gear by jacking the disc No.2 O&M Manual Drg No.1.1-3400-0009/1 with the help of locking screw.

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Sheet 28


9.0

STATUS

COMPLTION CRITERIA:

The characteristic of governing valves shall match with design valves closely. 10.0

APPENDICES:

a)

Technical Specification

b)

Drawing i)

Governing System Drawing.

ii) Governing Characteristic Curves.

Note: O&M Manual of Turbine to be referred for 10. 0 a) & b)

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PROCEDURE FOR GOVERNING OIL SYSTEM

Procedure for Governing Oil System

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