Electrical Boards

11 KV Station Board:

OBC ( Station Board)

• Tie to 4BA (Unit Board)
• Tie to OBA (Station Board Unit-3)
• ADPH-2 Transformer
• Drives- MDBFP-4C

OBD

• Tie to 4BB(Unit Board)
• CHP-2 Transformer
• HT to station auxiliary board OCB
• Tie to OBB (Station Board Unit-3)

4BA

• HT to unit auxiliary board 4CA-1
• Tie to OBC
• CEP-4A, 4C
• PA fan -4A,
• FD Fan -4A
• ID fan -4A Ch-1 & Ch-2
• CW pump-4A

4BB

• HT to unit auxiliary board 4CA-2
• Tie to OBD
• CEP-4B
• PA fan -4B
• FD Fan -4B
• ID fan -4B Ch-1 & Ch-2
• CW pump-4B

3.3 KV Boards

OCB(Station Auxiliary Board)

• HT to Station Service Board ODB(unit-4)
• HT to BTST-2
• HT to DMPT-2
• HT to WTPT-2
• HT to CWST-2
• HT to Station Service Board ODB (unit-3)
• HT to ODCT02
• HT to ODCT02
• Tie to OCA

4CA-I (Unit Auxiliary Board)

• HT to CTST-4A
• HT to Unit Service Transformer 4DA
• HT to ESP field Transformer A1, B1, C1, D1
• DRIVES- 

1.  ECW pump (TG)-4A,
2.  ECW pump-4A(SG),
3.  BCW pump-4A, 
4.  Mill-4A,4C,4E,4G,4J, 
5.  IAC-2

4CA-II (Unit Auxiliary Board)

• HT to CTST-4B, 4C
• HT to Unit Service Transformer 4DA
• HT to ESP field Transformer A1, B1, C1, D1
• DRIVES- ECW pump (TG)-4B, ECW pump-4B(SG), BCW pump-4B, BCW pump-4C , Mill-4B,4D, 4F, 4H,4K

4DA(Unit Service Board)

• HT to 4KA
• HT to 4KB
• HT to 4HA
• HT To 4HB
• HT to unit ACDB (4QA)
• HT to Boiler ACDB (4HC)

Ash Water System

INTRODUCTION: -

The ash water system is used to cater water for various utilities in ash handling system. The water is supplied from the ash water tank through the pumps like BALP pumps / BAHP pumps / FW pump / sump jetting water pumps which are located at Ash Water Pump House and are started & stopped from ASPH control room. Ash water tank makeup make is taken from different sources like Raw water makeup from stage 1 & 2 inter connection, Raw water makeup from stage-2, Ash water recirculation, Treated ash water recirculation, Service water blow down and CHP according to the situation and requirement.

Low pressure ash water system caters water at the following areas (BALP pumps):

• Ash slurry sump makeup.
• Ring header for seal trough makeup / flushing.
• Refractory cooling supply.
• Bottom ash hopper makeup / filling.
• Bottom ash hopper window spray.
• Make up to overflow settling bin.

High pressure water pump caters water at the following areas (BAHP pumps):

• Jet pump fitted below the clinker crusher at the bottom ash hopper.
• Jetting water requirement for bottom ash hopper.
• HP line water supply to feeder ejector and slurry box of economizer and economizer bypass system.
• HP line to economizer ash transfer hopper for jetting purposes.
• HP line to jet pump fitted below the economizer ash transfer hopper.
• HP line bypass connection to bottom ash hopper refractory cooling water and ring header for seal trough make up / flushing water line.
• Flushing connections to bottom ash hopper overflow weir boxes.
• Line for flushing sludge pump discharge lines.

Flushing water pump:

• The flushing water pumps are provided for slurry disposal line flushing purpose.

Sump jetting water pumps caters at the following areas:

• Ash slurry sump jetting.
• Common ash slurry trough jetting arrangement. 

PROCEDURES :
 LINE UP PROCEDURE FOR ASH WATER SYSTEM
PRECONDITIONS

• The AWT level is normal.
• Check no PTW is pending on the equipment and system as well as the associated system like BA HOPPER etc.
• Ensure the CW pumps are running and the blow down valves are open from both the units from CW pump discharge header.
• Check the make up water valve to AWT from CW blow down near AWT is closed.
• Ensure the AWR pumps are in service and water is available to AWT. The makeup valve is motor operated and power supply available.
• Ensure the RAW water makeup valve to AWT is available and on auto at ASPH control room and power supply available.
• Ensure the supply normalization of all AW PUMPS at AWMCC END and check both Sections are normalized individually.
• Before starting the system the SCE is to be informed and the open channel level to be checked.

LINE UP PROCEDURE FOR STARTING ANY PUMP

• Before starting any pump ensure the down stream line is lined up i.e near the BA Hopper or ASPH.
• Check the respective pump suction valve is opened and the pump is vented properly.
• Keep the discharge valve crack open before starting otherwise it will be difficult to open the valve after pump starts.
• Ensure that the DV is not opened fully otherwise the pump will draw high starting current for a longer period and may trip on overload. It is quite detrimental for the motor life.
• Check the EPB is released.
• Now the pump is ready to take start.

AFTER THE PUMP STARTS

• Slowly open the DV till it opens full.
• Check the pump current in ASPH control room that it is with in limits. Other wise check for any other valve opening/closing
• If the pump is not vented properly then it may draw low current. If the other pump discharge valve is open and NRV is not holding then also it may draw high current.
• Check the discharge pressure.
• Check the other pump DV is closed and pump is not rotating in reverse direction.
• Check for any gland leakage/pump or motor abnormal vibration/bearing temperatures. If any immediately inform the ASPH control room/UCB.

ROUTINE CHECKS

• Check running pump has no gland leakage.
• All stand by pump EPBs are released.
• All stand by pump discharge valves are open.

ISOLATION PROCEDURE

• Close pump suction valve
• Close pump discharge valve
• Isolate the power supply.
• Press EPB locally
• Open the pump vent

Screw Chiller

INTRODUCTION : -
Various spaces in stage -II main power house building are air-conditioned by one number centralized chilled water type air-conditioning plant consist of 2 nos 300TR capacity vapor absorption  machine (VAM) for normal service and 2 nos of 300TR ‘screw chilling’ units for backup standby. The inside conditions of the control rooms are maintained with room temperature 24.4°C ±1°C and RH 50% ± 5% for all spaces except programmer room for which temperature maintained 22°C ±1°C and RH at 50% ± 5%.The VAM and screw chillers are having in built capacity control management which is operated through microprocessors interface with main PLC control panel.
Normally main plant A/C system will be in operation continuously as it is covering cooling areas related to all unit # 3, 4, 5 and 6 CER & CCR. Whenever maintenance is required on screw chiller unit # 1 / 2, the availability of VAM to be ensured and will be kept in operation.

The main plant A/C system provides air conditioning to
1. Control equipment room (CER) at 17mtr.
2. UPS and Marshalling panel at 8.5mtr.
3. Centralized control room at17mtr.
4. Programmers room 17mtr.
5. SWAS room at 0mtr.
6. C & I work shop, shift C & I Engineer, Shift In-charge &Record rooms etc. (at17.0m).
7. Viewing Gallery.
8. Digital Conference Room.  

STARTING / STOPPING PROCEDURE OF SCREW CHILLER
STARTING PROCEDURE FOR SCREW CHILLER :-1 Check and line up all available condenser pumps, chiller pumps, CT fans, AHUs.
2 Check and normalize the power supply of all available condenser pumps, chiller pumps, CT fans, AHUs.
3 Check and normalize the power supply of screw chiller control panel, compressor motors.
4 Check the oil level in CT fan.
5 Check and fill water level in CT sump. Open inlet v/v for filling and observe the water level in the other CT sumps if they are in service.
6 Start and ensure CT fan ‘ON’ indication. Like wise start at least 4no.s CT fans.
7 Now condensate pump ready to start will come. Start condensate pump and ensure ON feed back and
open condensate inlet motorized v/v. Run at least 4no.s condensate water pumps.
8 Now chiller water ready to start will come. Start chiller water pump and open chiller water inlet motorized valve.
9 Now start Screw chiller either from CRT or from skid mounted A/C control panel.
10 Check for any abnormality.
11 Check ready status of respective AHU. Start AHU and ensure ON feedback. Check three way mixing
valve operation. Its operation is interlocked with room temperature and Relative humidity set points.
12 Make sure that in case of any fire, fire damper closed and AHU switched off.

SHUT DOWN PROCEDURE FOR SCREW CHILLER:1 Stop Screw chiller to be stopped one at a time.
2 Ensure ‘OFF’ feedback of screw chiller and closing of inlet motorized valves of condenser water and
chiller water of respective screw chiller.
3 ‘ON’ close feed back of chiller / condenser water shutoff valves, Stop chiller water pumps if not required
for running of VAM / Stop condenser water pumps if not required for running of VAM (Normally any two
out of 2 screw chillers and 2 VAM are in service, For that 4 CT fans, 4 Condenser pumps, 4 chiller pumps
will be in operation).
4 Stop excess CT fans as per requirement and ensure ‘Off’ feedback.
5 Stop excess AHUs as per the requirement.
6 Close chiller / condenser outlet manual valves for issuing PTW.
7 Isolate the compressor power supply for issuing PTW.

NORMAL OPERATION CHECKS:-1 CT sump level and CT fan oil level in oil cup.
2 Check expansion tank level in every shift.
3 Chiller water / condenser water inlet and outlet temperatures / flow  

Fly Ash System

 INTRODUCTION : 

In coal fired boilers ash is collected in two forms, bottom ash and fly ash. BA
constitutes around 20% of the total ash and remaining 80% is collected in the form of fly ash. Fly
ash evacuation is done online using vacuum pumps either in dry ash mode or in wet mode. In
wet mode we use collecting towers which sprays water on ash going to vacuum pump suction
and makes it slurry which will be discharged in to seal box and then to slurry trench. In dry mode
we collect dry ash in buffer hoppers there by with the help of transport air it will be carried to
hoppers in the ash dyke and from there it is stored and distributed to different users. 

ISOLATION PROCEDURE FOR FLY ASH SYSTEM :

SHUT DOWN CHECKS:

1. Before shut down of fly ash system, ensure all hoppers are empty by checking their vacuum in MHV open condition, if not. Pock the hoppers and empty them 
2. After ensuring emptiness of all hoppers and no ash slurry is observed in CT flash box, stop all the vacuum pumps and isolate their cooling sealing water line and isolate the unit CSW line v/v to ensure adequate pressure to other running units.
3. Check all the MHV’s and line header valves are closed.
4. Stop the fluidizing blower and isolate the heater supply.
5. Stop the fly ash pump and isolate its makeup valve from BALP discharge.
6. Empty the settling bin by sludge pump and stop the sludge pump after level becomes low.

START-UP CHECKS FOR FLY ASH SYSTEM: 

1. After getting all the clearances from AHD and EMD for running the fly ash system line up the FA water pump, seal water pump, BALP water pumps, vacuum pumps, cooling sealing water pumps.
2. Check for availability of at least one collecting tank in each pass with all mechanical fittings.
3. Check the hopper plate valve of each hopper is in open condition.
4. Check all the drains of settling bin are closed and open manual isolation v/v’s of settling bin make up v/v from BALP discharge.
5. Check the ash water tank level is adequate and start minimum number of BALP pumps for filling the settling bin and check ash water tank is getting makeup from at least one of its sources (ash water re circulation, raw water st-1, raw water st-2, CW blowdown)
6. Ensure sludge p/p is mechanically normalized and start it after ensuring settling bin is in filled condition.
7. Check the availability of at least one pair of vacuum pump and collecting tank in each pass and ensure ash intake v/v, water v/v, vacuum line v/v and vacuum pump suction v/v are in open condition.
8. Check both clean water tank levels are high and ensure they are getting makeup either from CW blow down or from BALP discharge.
9. Start at least one CSW pump for one unit and one seal water pump.

Starting Permissive for CSW pump:

1. Emergency stop push button at field is in released condition.
2. Module is healthy.
3. O/L of MCC in normal condition (RESET).
4. Emergency stop button from MCD not pressed.
5. Overhead tank – 1 (Stage-1 side) level high.
6. Selected in operation mode. (Oprn/maint).
7. Start command from MMI given.
8. Emergency stop push button at field is in released condition.

Auto Start Condition:

1.  The pump selected on auto will take start if any of the running pump trips subject availability of the permissive as stated above.

Tripping Conditions: -

1. Pump will tripped automatically if any one of the following conditions is satisfied 
2. Emergency stop push button at field is in pressed condition
3. Emergency stop button at MCD pressed
4. Module is not healthy
5. MCC module is overloaded
6. Overhead Tank level – 1 level low

Starting Permissive for FAW pump: -Pump will take start from MMI page if all of the following permissive are available

1. Pump selected in manual mode. (Auto/man)
2. Emergency stop push button at field is in released condition
3. Module is healthy
4. 4 O/L of MCC in normal condition
5. Emergency stop button from MCD not pressed
6. BA settling tank level high
7. Any one seal water pump is running
8. Seal water pressure is normal (1.5 ksc)
9. Start command from MMI given

Tripping conditions:

Pump will trip automatically if any one of the following conditions is satisfied

1. Emergency stop push button at field is in pressed condition
2. Emergency stop button at MCD pressed
3. Module is not healthy
4. MCC module is overloaded
5. Seal water pressure is low (1.5 ksc)
6. Seal water pump is not running 10 sec time delay
7. BA settling tank level DANGER LOW, 5 sec time dela

Starting Permissive for SEAL WATER pump:

Pump will take start from MMI page if all of the following permissive are available

1. Pump selected in manual mode. (Auto/man)
2. Emergency stop push button at field is in released condition
3. Module is healthy
4. O/L of MCC in normal condition
5. Emergency stop button from MCD not pressed
6. Clean water tank level is high

Tripping conditions:Pump will trip automatically if any one of the following conditions is satisfied

1. Emergency stop push button at field is in pressed condition
2. Emergency stop button at MCD pressed
3. Module is not healthy
4. MCC module is overloaded
5. Clean water tank level low

Starting Permissive for VACUUM pump: -

Pump will take start from MMI page if all of the following permissive are available:-

1. Pump selected in manual mode. (Auto/man) Suction valve and seal water solenoid valve of selected pump will open when pump is selected in operation mode.
2. Emergency stop push button at field is in released condition
3. Module is healthy
4. O/L of MCC in normal condition
5. Emergency stop button from MCD not pressed
6. Suction valve of pump is open and Suction valve of other pump is close.
7. Instrument air pressure at selected air receiver is adequate (>5.5 ksc)
8. Any one cooling sealing water pump is running
9. Cooling sealing water flow at cooling sealing water station is adequate.
10. Cooling sealing water pressure at cooling sealing water station is adequate.(1.5 ksc)
11. Vacuum breaker of selected tower is open condition.
12. Vacuum line header valve of selected tower is open and Vacuum line header valve of other tower is close.
13. Fly ash intake valve of selected tower is open and Fly ash intake valve of other tower is close.
14. Buffer hopper vacuum line valve of dry ash system is close
15. Any one Fly ash water pump is running and Fly ash water pressure of selected tower WH is adequate (>5.5 ksc).

Tripping conditions:Pump will tripped automatically if any one of the following conditions is satisfied:-

1. Emergency stop push bottom at field is in pressed condition
2. Emergency stop bottom at MCD pressed with accept PB of alarm pressed
3. Module is not healthy
4. MCC module is overloaded
5. Suction valve of pump is close
6. Suction valve of other pump is open.
7. Instrument air pressure is low
8. Any one cooling sealing water pump is not running (5 sec time delay).
9. Cooling sealing water flow at cooling sealing water station is low. (5 sec time delay).
10. Cooling sealing water pressure at cooling sealing water station is not adequate (5 sec time delay).
11. Any one Fly ash water pump is not running (5 sec time delay)

GETTING STARTED:

1. After collecting towers and vacuum pumps are lined up, start the FA water pump, check for its discharge pressure and observe water is coming in each seal box.
2. After all the permissives for vacuum pump are satisfied start the vacuum pumps in each pass and observe water flow in each seal box.
3. Start the fluidizing blower and check for its discharge pressure (>0.4ksc). Check the heater is mechanically normalized and is taking auto cut-on and cut-off.
4. Check the hopper temperature is maintaining between 90-1200C
5. Check for vacuum in vacuum breaker open condition, in better condition it should be <100mmwc.
6. Check for shut off vacuum in each pass (should be >400mmwc) and ensure vacuum breaker is getting opened at vacuum>450mmwc otherwise inform to C&I for adjustment in VB setting.
7. Check for line vacuum in individual line, for better operating conditions it should be with in 70-90 mmwc. If line vacuum is low check for any line leakages and to be tightened.
8. If all the checkings are satisfied then check the individual hopper empty condition by opening MHV (material handling valve) one at a time in each pass and by observing the drop in vacuum.
9. After coal firing was started in boiler and oil guns are removed fields have to be charged and after ash got accumulation we can observe increase in vacuum once ash flow is established by opening individual MHV’s.

ROUTINE CHECKS DURING RUNNINGCONDITION:

1. In each shift check for proper line vacuum, shutoff vacuum and vacuum in VB open conditionwhich ensures cleanness of vacuum suction line.
2. Check each seal box for adequate slurry or water flow, if sufficient water flow was not observed then its water nozzles might got choked and change the CT and go for same procedure.
3. If vacuum in VB open condition is high (>100mmwc) then vacuum suction line might got choked and go for water washing by stopping the vacuum pump in that pass.
4. After ensuring CT performance and vacuum settings, start the ash evacuation by opening one MHV in each pass after opening that line header v/v.
5. Check for steady line vacuum in case no MHV is opened. If the line vacuum is not steady and hunting widely, check for the MHV passing of any hopper otherwise it will choke the vertical line due to sudden rush of ash.
6. Check for any ash carryover to the vacuum pump suction by observing VP discharge. If slurry is observed in the pump discharge because of improper CT function due to its water nozzles choking and go for CT change over.
7. Check each hopper is getting emptied and check for the hopper temperature also. If the hopper temperature is maintaining low (<900C), inform to EMD.

 

Operation of PA Fan

Prestart checks and starting of lube oil system:

1 Check the lube tank level is normal (>50% in upper gauge glass, Two gauge glasses are
provided).
2 Check the lub oil system is properly lined up (one cooler & one filter).
3 Check all the instruments are fixed and the root valves are open.
4 Check the lub oil coolers are charged from SGECW side.
5 EPB’s of LOP are released.
6 Check recirculation valve is crack open.
7 Give clearance to UCB to start one lub oil pump.
8 After the LOP is started from UCB, feel the oil flow in recirculation line and close recirculation
valve after two minutes of pump starting.
9 Check the return oil flow from bearings and check the oil pressures. The Normal control oil
pressure after the cooler & filter is > 10.00 Ksc & Lub Oil pressure is 2ksc.
10 Check for any oil leakage from inside the fan casing.
11 If control oil pressure is < 9.5 ksc, BMD to be informed to adjust relief valve setting.
12 Check for any abnormal sound from the pump.

Prestart checks and starting of PA fan1 Ensure that there is no pending PTW against the fan / lube oil system, ducting, dampers and
motor.
2 Check and release EPB at local.
3 Ensure that there is no reverse rotation of the fan.
4 Ensure that the lube oil system is in service.
5 Check air path is available. At least one PAPH is ON and air path of the APH available (APH air
I/L & O/L dampers are open), for second PA fan both PAPH must be on.
6 Check that the SCAPH inlet / outlet damper are open bypass damper is closed incase of cold
start up and SCAPH line isolated and bypass damper are open in case of hot start up.
7 Remote / local selector switch of blade pitch mounted on the actuator is selected in remote and
the blade pitch is in minimum position.
8 Check that the outlet (discharge) damper is in closed position and in remote.
9 Check the PA fan discharge duct drain valve is in closed position .After shut down with air preheater water washing this duct drain should be opened first to check any water accumulation inside fan casing, before taking PA fan into service.
10 Locally check all manholes are closed at 0 mtr.
11 Keep cold air gate damper of at least two mills open so that minimum air flow is assured.
12 Check the fan bearing oil temperatures and oil flow through the bearing outlet lines.
13 Check all permissive satisfied in the start permissive window.14 Start the fan with blade pitch minimum position and ensure opening of discharge damper fully.
Then gradually increase the blade pitch position to load the fan.
15 Check for any abnormal sound, vibration of fan / motor.
16 Check for any oil / air leakage.

STARING OF SECOND PA FAN:

1 Both PAPH must be ON and its inlet and outlet damper open.
2 At least three mills be in service.
3 Put blade pitch of 1st PA fan in CAS and PA header pr. In auto with set point 850 mmwcl – 900
mmwcl.4 Start 2nd PA fan and put blade pitch of 2nd PA fan a command of 10-15% as the discharge
damper starts opening and close feed back disappears.

NORMALISATION, STARTING AND LOADING OF ID FAN

PRE CONDITION OF THE UNIT:
  
1. Unit is running at full load (500MW) with 7 mills in operation.
2. Both TDBFPs are in service and Feed water control in auto.
3. MDBFP # C is available on auto (Rapid start up mode).
4. Airflow control is in auto with both FD fans in service.
5. Both PA fans in service in CAS mode.
6. Unit control is in CMC mode.
7. Both ID fans in service and furnace draft control in auto.

ENSURE THE FOLLOWING:  

1. Revise the station DC as per the planned shut down programme.
2. Bypass FD fan discharge gate close permissive from remote when fan in running condition to trip the fan
on fan running and discharge gate close protection.
3. FD fan trip from ID fan trip and ID fan trip from FD fan trip protections are to be bypassed.
4. Ensure the running contact of other set ID fan & FD fan .
5. Availability of atomizing steam and HFO at requisite pressure & temp (oil: 100ºC / 17-18 kg/cm², Steam:
200 – 210ºC / 6.5 kg/cm²).
6. Completion of WB/LRSB operation before starting the load reduction.
7. Availability of PAPH / SAPH soot blowers for operation.
8. Ensure the power supply healthiness of the ID fan inlet and outlet dampers.
9. Best communication between control room and local.
10. TDBFP- A/ B recirculation valve auto-closing protection is to be taken care

PROCEDURE FOR ID FAN UNLOADING, STOPPING AND ISOLATION: 

1. Take the unit control to manual from CMC mode. (Turbine on limit pressure control and Boiler master on manual).
2. Take airflow control to manual.
3. Take fuel master to manual and gradually reduce the load to 400MW by slowly unloading and removing 7th running mill. Adjust airflow according to the load (1650T/ hr corresponding to 400MW).
4. Take HFO support in one elevation corresponding to any running mill according to the mill combination (At least 3 oil guns in one elevation).
5. Gradually reduce the load to 350 MW by slowly unloading and removing 6th running mill. Adjust airflow according to the load (1450T/ hr corresponding to 300MW).
6. Reduce MS pressure set point according to the load during the process of load reduction.
7. Check the loading and suction flow of TDBFP A / B. If suction flow is low corresponding to the speed, Then keep open any one TDBFP- A / B recirculation valve.
8. Probably kept five consecutive mills in service to ensure stable combustion.
9. Adjust the burner tilt position to maintain MS & HRH temperature up to maximum possible (540C).10. Take blade pitch control of corresponding FD fan into manual and slowly unload and, then stop the fan from fan running and discharge gate close protection by giving close command to its discharge gate.
11. Take IGV / speed control of the ID fan (which is to be stopped) into manual and gradually unload the fan by observing furnace draught and running ID fan will take load in auto.
12. Gradually unload the ID fan (which is to be stopped) and stop it. Other ID fan takes some load in auto. If required, It can be further loaded manually by observing the furnace draught, speed and current.
13. Ensure the auto closing operation of ID fan inlet and outlet dampers after stopping the fan. If not closed in auto, immediately close it from local. Then isolate the power supply of suction damper & discharge damper and lock it mechanically.
14. Check the furnace to wind box DP and furnace combustion stability.
15. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.
16. Start PAPH – A / B and SAPH – A / B soot blowing. (This is to be done at least twice in a shift as long as oil guns in service).
17. After stopping one of the ID fan, Gradually increase the load up to 350MW with 5 mills operation and simultaneously increase the loading of the running ID fan, which is having reserve margin with both channels in service (Check current, vibration, speed and bearing temperature).
18. Close one of the TDBFPs recirculation valve, which was kept opened previously after sufficient loading of TDBFPs.
19. Remove oil support after stabilisation of load at approximately 350MW with 5 mills operation.
20. Isolate the Main motor channel 1& 2 power supply (Both source breaker ). Depending on the
requirement the control supply to VFD can be isolated .
21. Press the local EPB.
22. Isolate the inlet guide vane (IGV) actuator power supply.
23. Stop lube oil system and isolate as per requirement.
24. Issue PTW after ensuring proper isolation according to PTW procedure.

PROCEDURE FOR NORMALISATION, STARTING AND LOADING OF ID FAN: 

1. Ensure the cancellation of PTW and clearance from maintenance BMD/EMD/C&I, then normalise the fan motor power supply. (Both channel 1 & 2)
2. Revise the station DC as per the planned programme.
3. Remove the ID fan suction and discharge damper mechanical locking and normalise the power supply.
4. Normalise the IGV power supply. Release the local EPB.
5. Line up lube oil system and take it into service.
6. Line up and charge cooling water for motor, fan bearings and lube oil coolers.
7. Reset all alarms in VFD room if any thing is pending .
8. Start the ID fan with IGV minimum position and ensure opening of suction and discharge gates .
Gradually load the ID fan by increasing IGV position and speed, simultaneously observe the furnace
draught (Other running ID fan will unload in auto). If required maintain furnace draft by taking draft control into manual.
9. Balance the loading of the two ID fans by adjusting their IGV & Speed and put them in CAS mode.
10. Start second FD fan and load it slowly.
11. Put airflow control in auto.
12. Take 6th mill into service and gradually increase the load to 450MW.13. Adjust the MS pressure set point according to the variation of load.
14. Take 7th mill into service and increase the load to full (500MW).15. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.
16. Adjust the burner tilt to maintain M S & HRH temperature up to maximum possible (540C).17. Normalise the TDBFP – A / B recirculation control valve auto close protection.
18. Normalise the FD fan to ID fan trip and ID fan trip to FD fan trip protections.
19. Normalise FD fan discharge gate close permissive from remote when fan in running condition which wasbypassed to trip the fan on fan running and discharge gate close protection.
20. Put fuel master in auto.
21. Take unit control in to CMC mode.

Steps to do Over-speed Test for Main turbine

Steps to do Over-speed Test for Main turbine

 

• Open the Top cover of pilot valves KA02 and KA03 of MAX62AA001 .
• Press the pilot valve KA02 fully and observe the Aux. start-up fluid pressure. lf pressure is ok slowly release the valve.
• Press the pilot valve KA03 fully, to isolate the Auxiliary trip fluid from main trip valve to over-speed trip test device and keep in pressed down till the completion of the test.
• Note down the Aux Trip Fluid Pressure
• Rotate the hand wheel KA01 of over-speed trip test device in clockwise direction for admitting the test fluid to the over speed Bolts.
• The actuation of over speed bolt is indicated on the test rack by lamps for limit switches MAY10CG001 and MAY10CG002, provided on the LHS of front bearing pedestal. Alarm in control room is to be ensured.
• Check whether Auxiliary trip fluid pressure goes to zero.
• Note down the test fluid pressure when over speed bolts acted and ensure alarm in UCB.
• Rotate the hand wheel KA01 of over-speed test unit in the anticlockwise direction where the test fluid gets cut off, to the over speed bolts
• Press the Pilot valve KA02 of over-speed test device, to reset over speed bolts 1 and 2
• Check whether Auxiliary trip fluid pressure builds up and it is as per the recorded value
• Slowly release Pilot valve KA02, of over speed test device. Aux startup fluid Pressure become to zero.
• Repeat last 2 steps to ensure resetting of over-speed trip device bolts.
• Wait for 1-2 minutes (approx.) & allow auxiliary trip fluid pressure to be steady at around 5.0 Kg/cm2.
• Slowly release the knob of pilot valve KA03, of over-speed test device & OBSERVE RISE lN AUX TRIP FLUID
• Press the pilot valve KA03 fully, of over-speed fest device if any drop in Auxiliary trip oil pressure or Load during the releasing of pilot valve KA03.
  
  
  

 

 

 

 

 

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CEP Protection

CEP

START PERMISSIVE

  1.       CEP Suction valve open  AND

            Hotwell level not low (>-250 mm)  2/3  AND                                  

Swgr. available  AND

            Swgr. not disturbed  AND

            Thrust bearing temp  < 100 degc  AND        

            Motor bearing temp. < 85 degc   AND

            Motor winding temp.  < 125 degc  AND                                         

Recirculation valve  40% open  AND

            Vent valve open  AND

            [[CEP Standby selected AND Its disch v/v open ]  OR 

CEP  discharge valve closed ]

2)  TRIP PROTECTION

1)         Hotwell Level very low  ( < - 1850 mm )       2/3

2)         CEP ON AND  Discharge press. low ( < 18 ksc )

3)         CEP ON for 10 sec  AND  Flow through CEP low ( < 300 tph) TD5s

4)         Thrust bearing temp. very high ( > 105 degc)

5)         Motor bearing temp. very high ( > 90 degc)

6)         Motor winding temp. very high ( > 130 degc)

7)         Suction valve not open

8)         Electrical protection acted

3)  AUTO START

1)         Pump Selection  Standby AND

            Other Running pump Tripped

2)         Pump Selection  Standby    AND

            Any other pump  ON for 30 sec  AND

            Discharge header press. low (<20 ksc)

3)         Command from CEP startup sequence step # 103

4)  AUTO STOP

1)         Command from CEP shutdown sequence step # 201

CEP  DISCHARGE VALVE

1)  AUTO OPEN

1)         CEP ON   AND   Discharge press.   > 18 ksc  TD2s

2)         CEP Discharge press.  > 18 ksc   AND 

            Any other CEP ON   AND

            CEP Standby Selected  TD5s

3)         Command from CEP Startup sequence step # 106

2)  OPEN RELEASE

1)         Discharge Valve I.B.V Open

3)  CLOSE RELEASE

1)         CEP OFF

4)  AUTO CLOSE

1)         CEP Standby Selected AND             Discharge hdr. press.  < 20 ksc  TD2m

2)         CEP OFF

3)         Command from CEP Startup sequence step # 102

4)         Command from CEP Shutdown sequence step # 202

5)  DISCHARGE VALVE  I.B.V AUTO OPEN

1)         CEP ON  AND  Discharge press. > 18 ksc  TD2s

2)         CEP discharge press.  > 18 ksc   AND

            Any other CEP ON  AND

            CEP Standby Selected TD5s

6)  DISCHARGE VALVE  I.B.V AUTO CLOSE

1)         Discharge valve opened

CEP  VENT VALVE

1)  AUTO OPEN

1)         CEP discharge press.  > 18 ksc  AND

            Any other CEP ON AND CEP Standby Selected TD5s

2)         CEP OFF

3)         Command from CEP Startup sequence step # 103

4)         Command from CEP Shutdown sequence step # 202

2)  AUTO CLOSE

1)         CEP ON

3)  OPEN RELEASE

1)         CEP OFF