RC FEEDER INTERLOCK & PROTECTION 1
INDIABULLS POWER LIMITED
BOILER-PROTECTION & INTERLOCK
2RC FEEDER INTERLOCK & PROTECTION
PROTECTION& INTERLOCKCLASSIFICATION OF BOILER
PROTECTIONS & INTERLOCKS
BOILER AUXILIARIES INTERLOCK & PROTECTION
This system takes care of sequence of starting protection & interlock of boiler auxiliaries like 1) ID fans2) FD fans3) PA fans4) APH5) MILL6) RC FEEDER7) REHEATER Protection
FURNANCE SAFEGAURD SUPERVISORY SYSTEM(FSSS)
This system takes care of interlocks required for starting, supervising the operating & safe shutdown of the equipments connected with fuel firing system like1) Purge Interlock2) LOTV control & supervision3) HOTV control & supervision4) Pulveriser interlocks5) SADC- on/off & supervision6) Flame Intelligence & checking7) Boiler flame failure protection8) Boiler Trip protection
3RC FEEDER INTERLOCK & PROTECTION
Furnace safeguard Supervisory System
It is designed to ensure the execution of safe, orderly operating sequence in
start up and shutdown of fuel firing equipments and to prevent error of
omission and commissioning in following such a safe operating procedure.
• FSSS system supervises, controls and monitors the preparation,
distribution and admission of fuel & air into the furnace and execution
and enforcement of pre-established safe firing procedure.
• The FSSS provides permissive interlocks only to ensure safe start up
sequence of equipment.
Introduction to FSSSFurnace Safeguard Supervisory System(FSSS)
4RC FEEDER INTERLOCK & PROTECTION
FSSS is designed to perform the following functions:
• Prevent any fuel firing unless a satisfactory furnace purge sequence has
first been completed.
• Prevent start-up of individual fuel firing equipment unless certain permissive
interlocks have first been satisfied.
• Monitor & control the proper sequence (Manual or Automatic) during start-
up and shutdown of fuel firing equipment.
• Make continued operation of fuel firing equipment subject to certain safety
interlocks remaining satisfied.
• Provide status feedback to the operator and in some cases, to the unit
control system.
• Provide flame supervision when fuel firing equipment is in service and affect
a fuel trip upon certain adverse operating conditions.
• Initiate a fuel trip when certain abnormal operating conditions exist.
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FSSS’s Operational Function:1) FURNACE PURGE SUPERVISION.
2) LIGHT OIL ON/OFF CONTROL & SUPERVISION.
3) HEAVY OIL ON/OFF CONTROL & SUPERVISION.
4) PULVERISER CONTROL & SUPERVISION.a. Pulveriser discharge valve control.b. Pulveriser ignition permissive.c. Pulveriser ready permissive.d. Pulveriser on/off control.e. Hot air gate open/close controlf. Feeder start/stop control.
5) SADC - ON/OFF CONTROL & SUPERVISION.
6) FLAME SCANNER INTELLIGENCE & CHECKING.a. Scanner air fan control.b. Flame scan output indication.c. Flame failure trip.
7) BOILER TRIP PROTECTIONRC FEEDER INTERLOCK & PROTECTION
6RC FEEDER INTERLOCK & PROTECTION
FSSS’s Operational Function:• Furnace Purge
Before any fuel firing can take place, (initially or after a boiler trip) a
successful furnace purge cycle must be completed. To start furnace purge
cycle
• Establish AC/DC supply to FSSS equipments.
• Bring normal water level in drum.
• Take at least one ID&FD fans in service.
• Establish airflow between 30% to 40% of MCR
PURGE READY
AND
Press “START PURGE” button
START PURGEPURGING
5 minute count down timer ON
7RC FEEDER INTERLOCK & PROTECTION
FSSS’s Operational Function:• Furnace Purge
If PURGE READY signal is not available, then check the following
conditions are satisfied• Light oil trip valve is proven closed.• Light oil nozzle valves are proven closed.• Heavy oil trip valve is proven closed.• Heavy oil nozzle valves are fully closed.• All PA fans are off.• All feeders are off.• All hot air gates are fully closed.• All the flame scanners show “NO FLAME”• No boiler trip command is present.• Airflow between 30% & 40% MCR.• All auxiliary dampers are modulating.
RC FEEDER INTERLOCK & PROTECTION 8
FSSS’s Operational Function:LIGHT OIL TRIP VALVE CONTROL(LOTV)
• Conditions to be fulfilled to open LOTV after successful purging Light oil supply pressure is adequate All LO nozzle valve proven closed in AB elev
•Conditions leading to close LOTV automaticallyMFT
Any Light oil nozzle valve not closedLight oil header pressure very low
Any light oil nozzle valve not closedAtomizing air pressure very lowNo light oil Start/Stop in Elevation AB
LOTV
FM To AB elevation burners
AIR
LDO LOFCV
Tripping command to close LOTVand or
and
AND “LOTV OPEN”
Permissive ok
RC FEEDER INTERLOCK & PROTECTION 9
FSSS’s Operational Function:HEAVY OIL TRIP VALVE CONTROL(HOTV)
• HOTV opening conditionsHORTV is fully openHOTV close command is not present
All heavy oil nozzle valves are closedNo MFT condition is presentHO supply pressure is adequateHO supply temperature is adequateHOTV close command is not present
HFO
Return line to tanks
FM To AB,CD,EF elevation burnersHOTV
HOFCV
SteamHORTV
“HOTV OPEN” permissive satisfied
and
or
and
and
RC FEEDER INTERLOCK & PROTECTION 10
FSSS’s Operational Function:HEAVY OIL TRIP VALVE CONTROL
• HOTV closing conditions
Master fuel trip
HO Recirculation valve is not closed
If any of the conditions exist for more than 5 sec
Atomizing steam pressure very low
No HO start or stop in any elevation
Any HO nozzle valve not closed
HO header pressure very low
Any HO nozzle valve not closed
HO header temperature very low
Any HO nozzle valve not closed
*Also HO commanded to close under loss of 220VDC
CLOSE command to HOTV
or
and
and
and
and
or
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PULVERISER CONTROLPULVERSISER DISCHARGE VALVE CONTROL:
•The pulveriser discharge valve can be opened manually by depressing the push-button on the console insert. •The valve can be manually closed by the push-button on the console insert only when the pulveriser is off. The corresponding indications are available on the console insert as Red and Green lamps for open and close positions respectively
FSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
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PULVERISER CONTROL PULVERISER IGNITION PERMIT:Prior to starting any feeder, the feeder ignition energy must be adequate to support coal firing. This is accomplished all 6 elevations as follows:PULVERISER "A“A minimum of 3 of the 4-elevation “AB“ oil nozzle valves proven open Boiler loading is greater than 30%Feeder “B” is in service at greater than 50% loading
PULVERISER "B“A minimum of 3 of the 4-elevation “AB“oil nozzle valves proven open Boiler loading is greater than 30% Feeder “A” is in service at greater than 50% loading.Feeder “C” is in service at greater than 50% loading.
PULVERISER "C" A minimum of 3 of the 4-elevation “CD“oil nozzle valves proven open Boiler loading is greater than 30%Feeder “B” is in service at greater than 50% loadingFeeder “D” is in service at greater than 50% loadingA minimum of 3 of the 4-elevation “AB“oil nozzle valves proven openFeeder “B” is in service at greater than 50% loading.
FSSS’s Operational Function:
Permit signal to start PULVERISER A
andor
Permit signal to start PULVERISER Cand or
or
and
Permit signal to start PULVERISER Band or
or
RC FEEDER INTERLOCK & PROTECTION
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PULVERISER "D" A minimum of 3 of the 4-elevation “CD“ oil nozzle valves proven open. Boiler loading is greater than 30%Feeder “C” is in service at greater than 50% loading.Feeder “E” is in service at greater than 50% loading.
PULVERISER "E“A minimum of 3 of the 4-elevation “EF“oil nozzle valves proven open Boiler loading is greater than 30%Feeder “D” is in service at greater than 50% loading.Feeder “F” is in service at greater than 50% loading. A minimum of 3 of the 4-elevation “CD“ oil nozzle valves proven openFeeder “D” is in service at greater than 50% loading.
PULVERISER "F“A minimum of 3 of the 4-elevation “EF“oil nozzle valves proven open. Boiler loading is greater than 30%Feeder “C” is in service at greater than 50% loading
FSSS’s Operational Function:
Permit signal to start PULVERISER D
RC FEEDER INTERLOCK & PROTECTION
and or
or
Permit signal to start PULVERISER E
oror
and
and
Permit signal to start PULVERISER F
or
and
PULVERISER CONTROL PULVERISER IGNITION PERMIT:
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PULVERISER CONTROLHOT AIR GATE(HAG) CONTROL:
• CONDITIONS FOR HAG OPENPULVERISER ON
PULVERISER AUTO START
MANUAL MODEOPEN HAG FROM PUSH BOTTON
• CONDITIONS FOR HAG CLOSE
CLOSE HAG COMMAND EXIT>30 SECSPULVERISER OFFLOSS OF 24V DC IN ELEVATION
FSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
orCLOSE COMMAND TO HOT AIR GATE
OPEN COMMAND TO HOT AIR GATEor
and
and
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FSSS’s Operational Function:
MASTER FUEL TRIP
• If some abnormal condition occurs(like less than 30% air ), Master Fuel Trip
Relay acts and ensures the closure of Heavy Oil Trip valve (HOTV) and all
light Oil Nozzle Valves (LONV), thus cutting off total oil supply.
• Thus MFT ensures a safe shut down of the boiler in case of any abnormal
conditions in boiler/ furnace.
• It also ensures the stopping of all pulverizer systems and Primary Air (PA)
fans, cutting off total coal supply to boiler. The various abnormal operating
conditions under which Master Fuel Trip occurs are as follows:-
RC FEEDER INTERLOCK & PROTECTION
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FSSS’s Operational Function:
MASTER FUEL TRIP CONDITIONS
1. Drum level very low > 5 seconds.
2. Drum level very high > 10 seconds.
3. Both FD Fans off.
4. Both ID Fans off.
5. Air flow is less than 30% (318.03Tons/Hr )
6. Furnace pressure very low.
7. Furnace pressure very high.
8. Loss of all fuel trip.
9. Unit flame failure trip.
10. Loss of 220V DC for more than 2 seconds
11. Less than fire ball and loss of 110V AC at any elevation in service.
12. Loss of Reheater protection.
13. Both emergency trip Push Buttons pressed (Operator initiated boiler trip).
14. Spare trip.
RC FEEDER INTERLOCK & PROTECTION
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FSSS’s Operational Function:MASTER FUEL TRIP CONDITIONS
When MFT acted, simultaneous impulses shall be given for :-
1)Closing all the nozzle valves (LONV/HONV) and trip valves (LOTV/HOTV).
2)All fuel inputs are stopped by tripping all the mills.
3)Closing all hot air gates(HAG).
4)Tripping all the feeders.
5)All fuel air dampers are opened 100% and transferred to manual.
6) All auxiliary air dampers are opened 100% and transferred to manual.
RC FEEDER INTERLOCK & PROTECTION
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FSSS’s Operational Function:
•During light up and until any main fuel (coal) is in service at a fire condition, the flame scanners do not take part in the overall flame failure protection system.
•A fire ball condition is established for coal firing when either or both the adjacent feeders are proven
.AND. 2 out of 4 fireball scanners show flame.
RC FEEDER INTERLOCK & PROTECTION
FLAME SCANNER INTELLIGENCE AND CHECKING SCANNER AIR FLOW CONTROL FLAME SCANNER OUTPUT INDICATION FLAME FAILURE PROTECTION
19RC FEEDER INTERLOCK & PROTECTION
FSSS’s Operational Function:
Two scanner air fans (1 AC main + 1 DC stand-by) are provided for the unit.
1)AC scanner fan will automatically start if following condition are fulfilled:
2)DC scanner fan will automatically start:
3)In the event of 24VDC failure or all FD fans off, scanner’s atmosphere emergency suction damper will open(at normal condition suction from FD discharge)
FLAME SCANNER INTELLIGENCE AND CHECKING SCANNER AIR FAN CONTROL
AC scanner fan does’t start >5secs
AC scanner fan trips
Low DP across Furnace to Scanner Duct> 10 secs
OR
LOGIC
Start cmd to DC Scanner Fan
AND LOGIC
AC Scanner Fan will automatically start
After completion of PURGE
ON MFT
20RC FEEDER INTERLOCK & PROTECTION
FSSS’s Operational Function:
For AB elevation
Feeder B proven
Elv. AB 2/4 FB scanner show flame
Feeder A proven
*Same similar flame indication logic for BC,CD,DE,EF
FLAME SCANNER INTELLIGENCE AND CHECKING FLAME SCANNER OUTPUT INDICATION
AND
LOGICOR
LOGIC
ELE AB FLAME
Arming signal to “FLAME
FAILURE TRIP PROTECTION”
>2secs
RC FEEDER INTERLOCK & PROTECTION 21
FSSS’s Operational Function:FLAME SCANNER INTELLIGENCE AND CHECKING FLAME FAILURE PROTECTION:
•An elevation voting for "No Flame" condition is as described below for the respective coal and oil elevations.
ELEVATION “A”Feeder “A” is not provenElevation AB- 3/4 Fireball scanners shows no flameElevation AB HO/LO- 2/4 nozzle valves not openElevation AB started and loss of 110V AC power
ELEVATION “B”Feeder “B” is not proven. Elevation AB- 3/4 Fireball scanners shows no flameElevation AB HO/LO- 2/4 nozzle valves not open Elevation AB started and loss of 110V AC powerElevation “BC” 3/4 fire ball scanners show no Flame
ELEVATION “C”Feeder “C” is not proven.Elevation CD- 3/4 Fireball scanners shows no flameElevation CD HO- 2/4 nozzle valves not open.Elevation CD started and loss of 110V AC power.Elevation “BC”- 3/4 fire ball scanners show no Flame
FSSS
and or
ELEVATION BVOTED NO FLAME
andor
and
ELEVATION CVOTED NO FLAME
and
and
or
ELEVATION AVOTED NO FLAME
and or
RC FEEDER INTERLOCK & PROTECTION 22
FSSS’s Operational Function:
ELEVATION “D”Feeder “D” is not provenElevation CD 3 out of 4 Fireball scanners shows no flameElevation CD HO 2 out of 4 nozzle valves not openElevation CD started and loss of 110V AC powerElevation “DE” 3 out of 4 fire ball scanners show no Flame
ELEVATION “E”Feeder “E” is not provenElevation EF 3 out of 4 Fireball scanners shows no flameElevation EF HO 2 out of 4 nozzle valves not openElevation EF started and loss of 110V AC powerElevation “DE” 3 out of 4 fire ball scanners show no Flame
ELEVATION “F”Feeder “F” is not proven.Elevation EF 3 out of 4 Fireball scanners shows no flameElevation EF HO 2 out of 4 nozzle valves not openElevation EF started and loss of 110V AC power
ELEVATION DVOTED NO FLAME
andor
and
ELEVATION E VOTED NO FLAME
and
and
or
ELEVATION F VOTED NO FLAME
and or
FLAME SCANNER INTELLIGENCE AND CHECKING FLAME FAILURE PROTECTION(cont):
RC FEEDER INTERLOCK & PROTECTION 23
FSSS’s Operational Function:FLAME SCANNER INTELLIGENCE AND CHECKING FLAME FAILURE PROTECTION(cont):
Any of feeder proven
Elv. F voted no flame
Elv. E voted no flame
Elv. D voted no flame
Elv. C voted no flame
Elv. B voted no flame
Elv. A voted no flame
ANDLOGIC
UNIT FLAME FAILURE TRIP
SIGNAL
All elevation voting for “No Flame" as described above will cause a unit trip on Flame Failure trip, provided the flame failure circuit is armed. (Unit Flame failure Trip circuit is armed 2 seconds after any coal elevation is put into service. i.e. any feeder proven
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SADC CONTROLFSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
Secondary Air Damper Control includes both auxiliary & fuel air Damper control
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FSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
Auxiliary air damper position at above & below 30% boiler load.
Note:During furnace purge, all auxiliary air dampers are in 100% open condition
Auxiliary Air Damper PositionBoiler load<30%(opening) Boiler load>30%(closing)
1) When boiler load below 30% MCR all auxiliary air dampers are opened 100%
2) Furnace to Wind box DP is maintained approximately 40mmwc
1) Auxiliary air dampers associated with non service elevation will close from top to bottom with 10secs time sequence
2) Furnace to Wind box DP is increased with respect to oil header pressure.
SADC CONTROLA) Auxiliary Air Damper Control:
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SADC CONTROLA) Auxiliary Air Damper Control:
FSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
1)Conditions leading to Manual control & automatically open of Auxiliary Air Damper:
All ID fans OFF
All FD fans OFF
MFT
Loss of 24V DC
2) Conditions leading to Manual control :
DP trans. deviation very high
Failure of selected DP trans.
Furnace to Wind Box DP very
High >240mmwc
OR
Logic
Commanded to 100% open
+ Manual control
OR
LogicThrown to
Manual control
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FSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
Fuel air dampers are modulated with respect to feeder rate
Feeder ON signal
Feeder OFF signal
Note:During purging all fuel air dampers are in 100% open position.
SADC CONTROLB) Fuel(Coal) Air Damper Control:
50 seconds > OPEN cmd to fuel air damper
50 seconds > CLOSE cmd to fuel air damper
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SADC CONTROLFSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
1)Conditions leading to Manual control & automatically open of Fuel Air Damper:
All ID fans OFF
All FD fans OFF
MFT
Loss of 24V DC
2) Conditions leading to Manual control :
Feeder rate signal failed
open cmd from FSSS
close cmd from FSSS
OR
Logic
Commanded to 100% open
+ Manual control
OR
LogicThrown to
Manual control
SADC CONTROLB) Fuel(Coal) Air Damper Control:
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SADC CONTROLFSSS’s Operational Function:
RC FEEDER INTERLOCK & PROTECTION
C) Over fire Air Damper Control:
Over fire air dampers are used to control SOx & NOX
1. Lower Over fire air damper will open when boiler load >50% MCR
2. Upper Over fire air damper will open when boiler load>75%MCR
RC FEEDER INTERLOCK & PROTECTION 30
BOILER AUXILIARIES INTERLOCK & PROTECTION
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BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTION
Conditions existing when the unit is shutdown and prior to starting of ID Fans:
1)ID fan A & B are OFF.
2)Regulating dampers of fans A & B are fully open.
3)Inlet gates of ID fans A & B open.
4)Outlet gates of ID fans A & B open.
5)The regulating dampers and hydraulic coupling will be on manual control
during shutdown and impulse from furnace draft control to
regulating dampers of ID fans disconnected.
RC FEEDER INTERLOCK & PROTECTION
32
BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan A (ID Fan B is OFF):
A) ID fan A shall be prohibited from starting till the following conditions are satisfied:
1)Regulating dampers of ID FAN - A in minimum position.
2)Hydraulic coupling scoop tube for ID FAN - A in minimum position &
manual.
3)Outlet gate of ID FAN – A closed.
4)Intel gate of ID FAN – A closed.
5)ID FAN - A’s fan & motor bearing temperature not very high.
6)Motor winding temperature not very high.
7)One of APH is running with its inlet & Outlet dampers in open position.
8)Lube oil permissive satisfied(any LOP on & pressure >0.8 ata).
9)Hydraulic coupling of ID Fan-A’s oil level O.K and cooler ready for
operation.
10)Flue gas path available(dampers across APH,ESP & FD fan o/l damper
open).
RC FEEDER INTERLOCK & PROTECTION
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BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan A (ID Fan B is OFF):
B) When ID fan A is started , impulses shall be given for :-
1)Opening the inlet gate of ID Fan- A after the motor reaches rated speed.
2)Connecting the regulating dampers/scoop tube control of ID Fan – A to
auto control
3)Closing the inlet gate and the outlet gate of ID Fan – B and bring the
regulating dampers/scoop tube control to minimum position
4) Permission to start either FD Fan – A or B
*Same similar interlocks for Starting ID Fan B (ID Fan A is OFF)
RC FEEDER INTERLOCK & PROTECTION
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BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan A (ID Fan B is OFF):
A) ID fan A will trip automatically under following conditions:-
OR LOGIC
ID fan A’s fan bearing temp too high>90’c >10secs
ID fan A’s motor bearing temp too high>90’c >10secs
ID fan A’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec
FD fan’s tripping interlock to ID fan
ID fan A’s motor winding temp too high>130’c >10secs
ID fan A ON & its I/T gate closed>30secs
ID fan A’s working oil temp very high>110’c>2secs
ID fan A’s motor protection, eg- earth fault, short-circuit
Trip signal to ID fan A
RC FEEDER INTERLOCK & PROTECTION
35
BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan A (ID Fan B is OFF):
B) When ID fan A trips simultaneous impulse will be give for :-
1) Tripping signal to working FD fan.
2) Tripping signal to Boiler through FSSS.
3) Disconnecting the impulse from auto control to regulating damper and
Hydraulic coupling control.
4) Opening of inlet & outlet gate of ID fan B.
5) Commanded to wide open of regulating damper of ID A & B.
*Same similar interlocks for ID Fan B(ID Fan A is OFF)
RC FEEDER INTERLOCK & PROTECTION
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BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan B (ID Fan A is ON):
A) ID fan B shall be prohibited from starting till the following conditions are satisfied:
1)Regulating dampers of ID FAN - B in minimum position.
2)Hydraulic coupling scoop tube for ID FAN - B in minimum position &
manual.
3)Outlet gate of ID FAN – B closed.
4)Intel gate of ID FAN – B closed.
5)ID FAN - B’s fan & motor bearing temperature not very high.
6)ID FAN - B’s Motor winding temperature not very high.
7)Lube oil permissive satisfied(any LOP on & pressure >0.8 ata).
8)ID Fan-B’s Hydraulic coupling oil level O.K.
RC FEEDER INTERLOCK & PROTECTION
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BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan B (ID Fan A is ON):
B) When ID fan B is started (ID fan A is ON), impulses shall be given for :-
1)Opening the inlet gate of ID Fan- B after the motor reaches rated speed.
2)Connecting the regulating dampers/scoop tube control of ID Fan – B to
auto control
3)Permission to start another FD Fan.
*Same similar interlocks for Starting ID Fan A (ID Fan B is ON)
RC FEEDER INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION 38
BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan B (ID Fan A is ON):
A) ID fan B will trip automatically under following conditions:-
OR LOGIC
ID fan B’s fan bearing temp too high> 90’c >10sec
ID fan B’s motor bearing temp too high> 90’c >10sec
ID fan B’s fan (12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec
FD fan’s tripping interlock to ID fan
ID fan B’s motor winding temp too high130’c>10sec
ID fan B ON and I/T gate not open>30sec
ID fan B’s hydraulic coupling lub oil pressure very low<0.6Bar
ID fan B’s hydraulic coupling working oil temp very high>110’c for 2sec
Trip signal to ID fan B
ID fan B’s motor protection, eg- earth fault, short circuit
39
BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan B (ID Fan A is ON or vise versa):
B) When ID fan B trips simultaneous impulse will be give for :-
1) Disconnecting the impulse from auto control to regulating damper and
Hydraulic coupling control.
2) Bring the regulating damper of ID fan B to minimum position.
3) Bring the hydraulic coupling scoop tube position to minimum.
4) Commanded to close inlet & outlet gate of ID fan B.
5) Tripping signal to one working FD fan( 2 FD fans working).
6) Initialization of Partial load relay to reduce boiler load to 60%MCR.
*Same similar interlocks for ID Fan A(ID Fan B is ON)
RC FEEDER INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION 40
BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S LUBRICATION OIL PUMPS:
• There are 2x100% LOPs(1W, 1S) are provided for each ID fans
LOPs will automatically start under following condition(when ID A is ON):
LOP A or B will automatically stop under following condition(when both LOPs are ON):
TRIP CMD TO ANY ONE LOP A or B
LOP A tripped >30secs
LOP A is ON & pressure<0.6ATA >30secs
ORLOGIC
START CMD TO LOP B
LOP B tripped
LOP B is ON & pressure<0.6ATA
ORLOGIC
START CMD TO LOP A>30secs
>30secs
LOP B ON
Lub Oil pressure>0.8ATA
>5secs
LOP A ON AND
LOGIC
*same similar interlocks for ID fan B’s LOPs
41RC FEEDER INTERLOCK & PROTECTION
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTION
Conditions existing when the unit is shutdown and prior to starting of FD Fans:
1)FD fan A & B are OFF
2)FD fan A & B blade pitch in maximum position.
3)FD fan blade pitch control disconnected.
4)Lub Oil pumps of FD fans off.
5)Outlet dampers are fully open.
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BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan A (FD Fan B is OFF):
A)FD fan A shall be prohibited from starting till the following conditions are satisfied:
1)ID fan either A or B is ON.
2)FD FAN – A blade pitch control in minimum position.
3)Outlet damper of FD FAN – A closed
4)Intel gate of FD FAN – A open
5)FD FAN - A’s fan & motor bearing temperature not very high
6)Motor winding temperature not very high
7)FD fan’s Lube oil permissive satisfied(any LOP on & pressure >13bar)
RC FEEDER INTERLOCK & PROTECTION
43
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan A (FD Fan B is OFF):
B) When FD fan A is started (FD fan B is off), impulses shall be given for :-
1)Opening the outlet gate of FD Fan- A after the motor reaches rated speed.
2)Outlet damper of FD Fan – B to close & impeller blades of FAN-B to be
driven to minimum position.
3)Connecting the blade pitch control of Fan – A to auto control.
*Same similar interlocks for Starting FD Fan B (FD Fan B is OFF)
RC FEEDER INTERLOCK & PROTECTION
44
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan A (FD Fan B is OFF):
A) FD fan A will trip automatically under following conditions:-
OR LOGIC
FD fan A’s fan bearing temp too high> 105’c >10sec
FD fan A’s motor bearing temp too high> 110’c >10sec
FD fan A’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec
ID fan trips
FD fan A’s motor winding temp too high> 130’c >10sec
FD fan A ON and its O/T gate not open>120sec
Trip signal to FD fan A
FD fan A’s motor protection, eg- earth fault, short circuit
RC FEEDER INTERLOCK & PROTECTION
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BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan A (FD Fan B is OFF):
B) When FD fan A trips simultaneous impulse will be give for :-
1) Disconnecting the blade pitch of FD fan A & B to the maximum.
2) Opening the outlet damper of fan B.
3) To open the scanner air emergency suction damper.
4) Tripping signal to Boiler through FSSS
5) The outlet damper of FD fan A shall remain open.
*Same similar interlocks for FD Fan B(FD Fan A is OFF)
RC FEEDER INTERLOCK & PROTECTION
46
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan B (FD Fan A is ON):
A)FD fan B shall be prohibited from starting till the following conditions are satisfied:
1)Two ID fans should be ON.
2)FD FAN – B blade pitch control in minimum position.
3)Outlet damper of FD FAN – B is in closed position.
4)FD FAN - B’s fan & motor bearing temperature not very high
5)Motor winding temperature not very high
6)FD fan’s Lube oil permissive satisfied(any LOP on & pressure >3BAR)
RC FEEDER INTERLOCK & PROTECTION
47
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan B (FD Fan A is ON):
B) When FD fan B is started (FD fan A is on), impulses shall be given for :-
1)Opening of outlet damper of FD Fan- B after the motor reaches rated
speed.
2)Connecting the blade pitch control of Fan – B to auto control.
*Same similar interlocks for Starting FD Fan A (FD Fan B is OFF)RC FEEDER INTERLOCK & PROTECTION
48
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan B (FD Fan A is ON):
A) FD fan B will trip automatically under following conditions:-
RC FEEDER INTERLOCK & PROTECTION
OR LOGIC
FD fan B’s fan bearing temp too high> 105’c >10sec
FD fan B’s motor bearing temp too high> 110’c >10sec
FD fan B’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec
Any one or both ID fan trips
FD fan B’s motor winding temp too high> 130’c >10sec
Trip
signal to FD fan B
FD fan B’s motor protection, eg- earth fault, short circuit
FD fan B ON and its O/T gate not open>120sec
49
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan B (FD Fan A is ON):
B) When FD fan B trips simultaneous impulse will be give for :-
1) Disconnecting FD fan B the blade pitch control from auto.
2) Bringing the FD fan B blade pitch control to minimum position.
3) Closing the outlet damper of Fan B.
4) Initiation of partial load relay for 60% MCR
*Same similar interlocks for FD Fan A trips (FD Fan B is OFF)
RC FEEDER INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION 50
BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S LUBRICATION OIL PUMPS:
There are 2x100% LOPs(1W, 1S) are provided for each FD fans
LOP will automatically start under following condition(when FD A is ON):
LOP will automatically stop under following condition(when both LOPs are ON):
*same similar interlocks for FD fan B’s LOPs
ORLOGIC
START CMD TO LOP BLOP A tripped >30secs
LOP A is ON & pressure<9BAR >60secs
LOP B tripped
LOP B is ON & pressure<9BAR
ORLOGIC
START CMD TO LOP A>30secs
>30secs
LOP B ON
Lub Oil pressure>13BAR
>5secs TRIP CMD TO ANY ONE LOP A or B
LOP A ON AND
LOGIC
51RC FEEDER INTERLOCK & PROTECTION
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTION
Conditions existing when the unit is shutdown and prior to starting of PA Fans:
1)PA fan A & B are OFF
2)PA fan A & B blade pitch in maximum position.
3)PA fans blade pitch control disconnected.
4)Lub Oil pumps of PA fans off.
5)Outlet dampers are fully open for PA Fan A & PA Fan B.
52
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan A (PA Fan B is OFF):
A)PA fan A shall be prohibited from starting till the following conditions are satisfied:
1)Either FD fan A or B is ON.
2)PA FAN – A blade pitch control in minimum position.
3)Purge completed
4)PA FAN - A’s fan & motor bearing temperature not very high
5)Motor winding temperature not very high.
6)APH should be in service with one gas & air inlet and outlet damper
opened.
7)PA fan’s Lube oil permissive satisfied(any LOP on & pressure >0.8 ata)
RC FEEDER INTERLOCK & PROTECTION
53
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan A (PA Fan B is OFF):
B) When PA fan A is started , impulses shall be given for :-
1)Opening the outlet damper of PA Fan- A.
2)Connecting the blade pitch control of PA Fan – A to auto control
3) Bringing the blade pitch of PA fan B to minimum position.
4)Closing of outlet damper of PA fan B
5) Permission to start 3 lower coal elevations through FSSS
*Same similar interlocks for Starting PA Fan B (PA Fan A is OFF)
RC FEEDER INTERLOCK & PROTECTION
54
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan A (PA Fan B is OFF):
A) PA fan A will trip automatically under following conditions:-
RC FEEDER INTERLOCK & PROTECTION
OR LOGIC
PA fan A’s fan bearing temp too high> 105’c >10sec
PA fan A’s motor bearing temp too high> 90’c >10sec
PA fan A’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec
Both FD fan trips
PA fan A’s motor winding temp too high>120’c >10sec
Trip
signal to PA fan A
PA fan A’s motor protection, eg- earth fault, short circuit
MFT acted
PA fan A ON and its O/T gate not open>120sec
55
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan A (PA Fan B is OFF):
B) When PA Fan B trips simultaneous impulse will be give for :-
1) Disconnecting the blade pitch control from auto.
2) Bringing the PA fan A blade pitch control to minimum position.
3) Closing the outlet damper of PA Fan A.
4) Tripping all the operating mills (through FSSS)
*Same similar interlocks for PA Fan B(PA Fan A is OFF)
RC FEEDER INTERLOCK & PROTECTION
56
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan B (PA Fan A is ON):
A) PA fan B shall be prohibited from starting unless following condition are satisfied
1)Both FD fans ON.
2)Blade pitch control of PA fan B in min. condition.
3)PA fan B & Motor bearing temp not very high(<90oC)
4) Motor winding temp. not very high(<80oC).
5)Both APH are running with their gas and air inlet and outlet dampers
opened
6)Lube oil permissives satisfied
*Same similar interlocks for Starting PA Fan B (PA Fan A is ON)
RC FEEDER INTERLOCK & PROTECTION
57
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan B (PA Fan A is ON):
B) When PA fan B is started (PA fan A is ON), impulses shall be given for :-
1)Opening the outlet damper of PA fan B after the motor ON (TD = 30 sec.).
2)Connecting the damper control of PA fan B to auto control.
3)Permission to put in service remaining coal elevation through FSSS.
*Same similar interlocks for Starting PA Fan A (PA Fan B is ON)
RC FEEDER INTERLOCK & PROTECTION
58
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan B (PA Fan A is ON):
A) PA fan B will trip automatically under following conditions:-
RC FEEDER INTERLOCK & PROTECTION
PA fan B ON and its O/T gate not open>120sec
OR LOGIC
PA fan B’s fan bearing temp too high> 105’c >10sec
PA fan B’s motor bearing temp too high> 90’c >10sec
PA fan B’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec
Both FD fans OFF
PA fan B’s motor winding temp too high>120’c >10sec
Trip
signal to PA fan B
PA fan B’s motor protection eg- earth fault, short circuit
MFT acted
59
BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan B (PA Fan A is ON):
B)When PA Fan B trips simultaneous impulse will be give for :-
1) Disconnecting the blade pitch control of PA fan B from auto.
2) Bringing the PA fan B blade pitch control to minimum position.
3) Closing the outlet damper of PA Fan B.
4) Initiation of partial load relay for 60% MCR
*Same similar tripping interlocks for PA Fan A(PA Fan B is ON)
RC FEEDER INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION 60
BOILER AUXILIARIES INTERLOCK & PROTECTION
• There are 2x100% LOPs(1W, 1S) are provided for each PA fans
LOP will automatically start under following condition(when PD A is ON):
LOP will automatically stop under following condition(when both LOPs are ON):
*same similar interlocks for PA fan B’s LOPs
ORLOGIC
START CMD TO LOP BLOP A tripped >30secs
LOP A is ON & pressure<13BAR >30secs
LOP B tripped
LOP B is ON & pressure<13BAR
ORLOGIC
START CMD TO LOP A>30secs
>30secs
LOP B ON
Lub Oil pressure>20BAR
LOP A ON AND
LOGIC>5secs TRIP CMD TO ANY ONE LOP A or B
PA FAN’S LUBRICATION OIL PUMPS:
61RC FEEDER INTERLOCK & PROTECTION
BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTIONConditions existing when the unit is shutdown and prior to starting of APH:
1)All AHs are off (both electric motor and air motor).
2)The inlet and outlet dampers of flue gas path, Secondary Air path,
Primary Air path are in full open condition.
Starting Air Heater – A (Air Heater – B is OFF)
One electric motor and one air motor have been provided for APH drive system.3) Air Heater – A electric main motor is started if the sump oil temperature
of the bearings measured through RTD is less than 70oC
4)Impulse shall be given for closing of the inlet and outlet dampers for air & gas side of Air Heater B which is off
*same similar interlocks for starting APH – B(APH – A is OFF)
62
BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTIONTripping of APH-A (APH-B is OFF):
1)APH electric motor fault.2)Whenever the sump oil temperature of support/guide bearing is greater
than 70oC an alarm shall be initiated through RTD to the operator. The operator shall check the circulation pump operation & the coolant flow at local to bring down the sump oil temperature. In case if the temperature of sump oil is unable to be brought down, APH electric motor/air motor shall be tripped manually.
When APH’s electric motor trips simultaneous impulse will be give for :-
3)To start Air motor with 5 secs delay
*same similar interlocks for starting APH – B(APH – A is OFF)
RC FEEDER INTERLOCK & PROTECTION
63
BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTION
Tripping of APH-A (APH-B is ON) or vise versa:1) Gas I/L & O/T damper, Secondary air O/T damper, and PA I/L & O/T damper
of the tripped AH shall be automatically closed.2) Boiler load reduced approx 60 %MCR
Tripping of both APH A & B3) Operator may try for restarting the APHs. 4) If any one of the APH is not started within 5 minutes the operator shall
manually trip the boiler.5) All Gas I/L & O/T damper, Secondary air O/T damper, and PA I/L & O/T
damper should be opened
RC FEEDER INTERLOCK & PROTECTION
64
BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTION
Interlocks for Oil Circulation Pumps of support bearings(SB) of Air heaters:2 x 100% oil circulation pump have been provided for the support bearing. Anyone of the two oil circulation pumps can be pre selected as main pump and the other as standby.
Following interlocks shall be provided for Oil Circulating Pumps
APH ON
SB LOP1 OFF>2SECAND
APH ON
SB LOP1 ON
LOW FLOW>30SECS
AND
START CMD TO OTHER LOP
OR
RC FEEDER INTERLOCK & PROTECTION
65
BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTION
Interlocks for Oil Circulation Pumps of guide bearings(GB) of Air heaters:2 x 100% oil circulation pump have been provided for the guide bearing. Anyone of the two oil circulation pumps can be pre selected as main pump and the other as standby.
Following interlocks shall be provided for Oil Circulating Pumps
APH ON
GB LOP OFF>2SECAND
APH ON
GB LOP1 ON
LOW FLOW>30SECS
AND
OR START CMD TO OTHER LOP
RC FEEDER INTERLOCK & PROTECTION
66
PULVERISER INTERLOCKS & PROTECTION
Conditions existing when the unit is shutdown and prior to starting of MILL:
1)Mill Motor off
2)LOPs for Mills off
RC FEEDER INTERLOCK & PROTECTION
BOILER AUXILIARIES INTERLOCK & PROTECTION
67
Starting of Mill:
A)MILL shall be prohibited from starting till the following conditions are satisfied:1) Bunker Outlet Gate open2) Feeder Inlet Gate open3) Mill Discharge valves open(4nos)
4) Seal air valve is open5) Mill start permit from Pulveriser Lub Oil System6) Mill outlet temp not high <94˚C7) Cold air Gate open8) Tramp Iron Hopper Valve open9) Mill/Oil elevation start permit.
10) Nozzle tilts placed in the horizontal position(for 1st pulveriser only).11) Primary air pressure is adequate(>650mmwc)12) Pulveriser Bowl DP Adequate >200 mmwc13) MILL status off & ignition permit available
PULVERISER INTERLOCKS & PROTECTIONBOILER AUXILIARIES INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION
68
Starting of Mill:
B) When MILL is started, impulses shall be given for :-
1)Permission to open the hot air gate(HAG) & impulse to regulate HAG
2)Permission to start the Raw Coal Feeder.
*Same similar interlocks for Starting all other Mills
PULVERISER INTERLOCKS & PROTECTIONBOILER AUXILIARIES INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION
69
Tripping of Mill:A) Mill will trip automatically under following conditions:-
Motor winding temperature too high>130oC >5sec
Motor bearing temperature too high>85oC >5sec
Mill vibration too high>9mm/s> 15 sec
Mill trip from Pulveriser Lub Oil System(PLOS)
Mill bearing temperature too high> 90oC>5sec
OR LOGIC
Trip
signal to Mill
motor
MFT acted
Mill discharge damper not open
Both PA fans trips
Ignition energy disappears before 180 secs from feeder start
PULVERISER INTERLOCKS & PROTECTIONBOILER AUXILIARIES INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION
Seal air header pressure very low>60secs
70
Tripping of MILL:
B) When MILL is tripped, simultaneous impulses shall be given for :-
1)Signal to trip the feeder’s motor
2)To close the hot air gate.
3)To bring cold air damper to minimum position
*Same similar interlocks for other Mill tripping.
PULVERISER INTERLOCKS & PROTECTIONBOILER AUXILIARIES INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION
71
RAW COAL(RC) FEEDER INTERLOCKS & PROTECTION
RC Feeder Starting:
A) RC Feeder motor is prohibited from starting till the following conditions are
satisfied:
1)No boiler trip condition prevails.
2)Elevation AC&DC available
3)Ignitor energy is available
4)Pulveriser is ON
5)Hot air gate is open
BOILER AUXILIARIES INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION
72
RC FEEDER INTERLOCKS & PROTECTION
RC Feeder Starting:
B) RC Feeder motor is simultaneous impulse shall be give for :
1)To include feeder output in totalizing circuit after 15secs
2)To release feeder speed control to auto after 50secs
3)To modulate fuel air dampers according to feeder speed after 50secs
BOILER AUXILIARIES INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION
73
RC FEEDER INTERLOCKS & PROTECTIONTripping of RC feeder motor:
RC feeder motor will trip automatically under following conditions:-
Boiler Trips
Elevation DC fails >2secs
Pulveriser trips
RC motor’s electrical trip
Elevation AC failsOR
LOGIC
Trip
signal to RC motor
Loss of coal flow & pulveriser amps low
Ignition energy disappears before 180 secs from feeder start
RC FEEDER INTERLOCK & PROTECTION
BOILER AUXILIARIES INTERLOCK & PROTECTION
74
BOILER AUXILIARIES INTERLOCK & PROTECTIONREHEATER PROTECTION
This protection is provided to protect the Reheater against starvation of steam flow during abnormal conditions. To take care of Reheater protection, the Boiler shall be tripped after 10 seconds, when any of the following conditions occur.
Reheater protection will armed automatically under following conditions:
DRUM PRESSURE >8ata
ANY FEEDER ON
BOILER FIRING SIGNAL FROM FSSS
OR
LOGIC
AND
LOGIC
REHEATER PROTECTION ARMED
RC FEEDER INTERLOCK & PROTECTION
75
BOILER AUXILIARIES INTERLOCK & PROTECTIONREHEATER PROTECTION
Reheater protection will automatically enable under following conditions:
REHEATER PROTECTION ACTED(Boiler Trip)
HPBP OR LPBP OPENED<2%
AND
LOGIC
GENERATOR CKT BREAKER OPENED
REHEATER PROT ARMENDOR
LOGIC
10SEC >
AND
LOGIC
IF ANY OF 1 OR MORE VALVES CLOSED1. HPSV1 5. IPSV12. HPCV1 6. IPCV13. HPSV2 7. IPSV24. HPCV2 8. IPCV2
HPBP OR LPBP OPENED<2%
REHEATER PROT ARMEND
RC FEEDER INTERLOCK & PROTECTION
RC FEEDER INTERLOCK & PROTECTION 76
T H A N K S