Manish Dhruw Asst Manager 14843 Cpp-540
Boiler Interlock - A Boiler Interlock is an arrangement of heating controls. It ensures the boiler does not fire when there is no demand for heat. Protection of boiler – Boiler protection are provide to detect the abnormal condition by constantly measuring the various parameter under normal and faulty condition. If any abnormality happened trip the boiler to prevent from major damage. Need of Interlocks & Protection
◦ ◦ ◦ ◦
To avoid operational faults To avoid equipments damage. To avoid accidents to individuals. To avoid system disturbances
Master Fuel Trip - it produces trip signal for fuel systems from operation , then trip the boiler out of service away from danger. this relay needs many conditions to operate , these conditions will be found at the following points. • 9. Unit flame failure. 1. Both ID fan trip. • 10. Loss of fuel. 2. Both FD fans trip. • 11. Loss of scanner cooling air (Scanner air 3. Emergency manual trip. pressure<2 KPa with 5 min time delay). 4. Turbine tripped and HPLP bypass not opened (RH protection act). • 12. Both APH tripped. 5. Drum level low low low (<-325mm • 13. Oil burner light off failed. with 5 sec delay). 6. Total air flow<30%. • Other than MFT 7. Furnace pressure low low low (<-254 • 1. MS temperature≥5850C (5 sec time mm of H2O). delay). 8. Furnace pressure high high high • 2. RH temperature≥5850C (5 sec time (>+330 mm of H2O). delay).
Interlocks cum protections
1. If one ID fan trips, one FD fan will trip in the same sequence. 2. If one FD fan trips, one ID fan will trip in the same sequence. 3. If one APH trips, one ID fan, one FD fan and one PA fan will trip in the same sequence. 4. In case of GCB opening, top elevation mill or non adjacent mill will trip. 5. If drum level≥200 mm, EBD will open. 6. If drum level≤150 mm, EBD will close. 7. Feed water flow<50 TPH, Economiser recirculation MOV will open. 8. Feed water flow>80 TPH, Economiser recirculation MOV will close. 9. If superheated steam pressure is higher than 14.86 MPa ERV will open and if pressure is lower than the value ERV will close (if kept in service).
1. Boiler drum pressurea) Higher than 17.24 MPa LHS safety valve will lift and it will reset @ 16.35 MPa. b) Higher than 16.74 MPa RHS safety valve will lift and it will reset @ 16.21 MPa. 2. Superheated steam pressurea) Higher than 15.29 MPa, LHS safety valve will lift and it will reset @ 14.765 MPa. b) Higher than 15.2 MPa, RHS safety valve will lift and it will reset @ 14.747 MPa. 3. CRH steam pressurea) Higher than 3.058 MPa, LHS safety valve will lift and it will reset @ 2.947 MPa. b) Higher than 2.963 MPa, RHS safety valve will lift and it will reset @ 2.867 MPa. 4. HRH steam pressurea) Higher than 2.817 MPa, LHS safety valve will lift and it will reset @ 2.726 MPa. b) Higher than 2.75 MPa, RHS safety valve will lift and it will reset @ 2. 62 MPa.
Drum level 1. Level>125 mm: high priority alarm. 2. Level>-125 mm: high priority alarm. 3. Level>250 mm: emergency priority alarm. 4. Level>-250 mm: emergency priority alarm. Furnace pressure 1. Pressure>30 mm of H2O: high priority alarm. 2. Pressure>-30 mm of H2O: high priority alarm. 3. Pressure>50 mm of H2O: emergency priority alarm. 4. Pressure>-50 mm of H2O: emergency priority alarm. MS flow 1. MS flow>200 TPH: high priority alarm. 2. MS flow>450 TPH: emergency priority alarm.
• MS & RH Temperature • 1. MS temperature>5450C: high priority alarm. • 2. MS temperature>5500C: emergency priority alarm. • 3. RH temperature>5450C: high priority alarm. • 4. RH temperature>5500C: emergency priority alarm. • Others • 1. APH flue gas inlet temperature<3000C: high priority alarm. • 2. O2<1: high priority alarm. • 3. O2 zero: emergency priority alarm. • 4. Furnace DP≥90 mm of H2O: high priority alarm. • 5. Furnace DP≤10 mm of H2O: high priority alarm.
1. No ID fan A/B converter/ device fault. 2. No ID fan protection acted. 3. ID fan A/B inlet & outlet damper closed. 4. ID fan IGV in minimum position. 5. APH A/B flue gas inlet & outlet damper open. 6. APH A/B running 1. ID fan A/B breaker protection acted. Or 2. BMS trip ID fan A/B. Or 3. FD fan A/B tripped. Or 4. APH A/B tripped. Or 5. ID fan A/B temperature protection acted. 6. ID fan A/B vibration protection acted. 7. ID fan A/B running and fan outlet damper closed.
AND
Start enable Interlock:
OR
TRIP enable Interlock:
ALARM 1. Fan/ motor bearing temperature≥750C: high priority alarm. 2. Fan/ motor bearing temperature≥800C: emergency priority alarm. 3. Fan bearing vibration≥6.3 mm/sec: high priority alarm. 4. Fan bearing vibration≥11mm/sec: emergency priority alarm. 5. Motor winding temperature≥1100C: high priority alarm. 6. Motor winding temperature≥1200C: emergency priority alarm TRIP 1. Motor winding temperature≥1300C (2 out of 6 temperatures with 60sec time delay). 2. Fan/ motor bearing temperature≥900C (with 60 sec time delay). 3. Fan bearing vibration≥11mm/sec ( with 60 sec time delay). 4. ID fan motor protection (over current, earth fault, negative sequence, phase fault etc) acted. 5. BMS trip ID fan. 6. FD fan trip to ID fan trip. 7. ID fan running and fan discharge damper closed. 8. APH trip to ID fan trip.
1. No FD fan A/B converter/ device fault. 2. No FD fan protection acted. 3. FD fan A/B outlet damper closed. 4. FD fan IGV in minimum position. 5. APH A/B flue gas inlet & outlet damper open. 6. APH A/B running. 7. ID fan A/B running.
1. FD fan A/B breaker protection acted. Or 2. BMS trip FD fan A/B. Or 3. ID fan A/B tripped. Or 4. APH A/B tripped. Or 5. FD fan A/B temperature protection acted. 6. FD fan A/B vibration protection acted. 7. FD fan A/B running and fan outlet damper closed.
AND
Start enable Interlock:
OR
TRIP enable Interlock:
ALARM 1. Fan/ motor bearing temperature≥750C: high priority alarm. 2. Fan/ motor bearing temperature≥800C: emergency priority alarm. 3. Fan bearing vibration≥6.3 mm/sec: high priority alarm. 4. Fan bearing vibration≥11mm/sec: emergency priority alarm. 5. Motor winding temperature≥1100C: high priority alarm. 6. Motor winding temperature≥1200C: emergency priority alarm. TRIP 1. Motor winding temperature≥1300C (2 out of 6 temperatures with 60sec time delay). 2. Fan/ motor bearing temperature≥900C with 60 sec time delay. 3. Fan bearing vibration≥11mm/sec with 60 sec time delay. 4. FD fan motor protection (over current, earth fault, negative sequence, phase fault etc) acted. 5. BMS trip FD fan. 6. ID fan trip to FD fan trip. 7. FD fan running and fan discharge damper closed
1. No PA fan A/B converter/ device fault. 2. No PA fan protection acted. 3. PA fan A/B outlet damper closed. 4. PA fan IGV in minimum position. 5. APH A/B flue gas inlet & outlet damper open. 6. APH A/B running. 7. ID fan A/B running. 8. FD fan A/B running. 9. No boiler trip command. 1. PA fan A/B breaker protection acted. Or 2. MFT trip PA fan A/B. Or 3. ID fan A/B tripped. Or 4. FD A/B tripped. Or 5. PA fan A/B temperature protection acted. 6. PA fan A/B vibration protection acted. 7. PA fan A/B running and fan outlet damper closed
AND
Start enable Interlock
• OR
Trip enable Interlock:
ALARM motor bearing temperature≥750C: high priority alarm.
1. Fan/ 2. Fan/ motor bearing temperature≥800C: emergency priority alarm. 3. Fan bearing vibration≥6.3 mm/sec: high priority alarm. 4. Fan bearing vibration≥11mm/sec: emergency priority alarm. 5. Motor winding temperature≥1100C: high priority alarm. 6. Motor winding temperature≥1200C: emergency priority alarm. TRIP 1. Motor winding temperature≥1300C (2 out of 6 temperatures with 60 sec time delay). 2. Fan/ motor bearing temperature≥900C with 60 sec time delay. 3. Fan bearing vibration≥11mm/sec with 60 sec time delay. 4. PA fan motor protection (over current, earth fault, negative sequence, phase fault etc) acted. 5. MFT trip PA fan. 6. ID fan/ FD fan A/B trip to PA fan A/B trip. 7. PA fan running and fan discharge damper closed.
1. No fan converter/ device/ breaker fault. 2. Any one PA fan running. 3. Fan IGV in minimum position. 4. In case of one fan running & other fan standbya) If running fan getting tripped due to any protection acting then stand by fan will start in interlock if selected. b) If seal air pressure becomes low (<6 KPa), then standby fan will start by interlock. 4. During unit start up fan start enable will come with the start of any PA fan if selected in fan auto start interlock. **Command will go to Seal air fan IGV for 60% opening in auto with the start of the fan. 1. Fan breaker protection acted. Or 2. Both PA fans are stopped (after 2S fan will stop).or 3. In case of both seal air fan running and seal air header pressure>22 KPa then one seal air fan will stop in auto if selected in interlock (discharge pressure
Start enable interlock
• AND
• OR
Trip enable interlock:
1. Seal air fan current>200 Amp: high priority alarm. 2. Seal air fan current>260 Amp: emergency priority alarm. 3. Seal air discharge pressure<800: high priority alarm. 4. Seal air discharge pressure<600: emergency priority alarm. 1. Seal air fan current≥ 284Amp. 2. Both PA fans stopped/ tripped (fan trip after 2Sec). 3. Seal air fan breaker protection acted. 4. Seal air header pressure>22 KPa (in case of both fans are running), trip one fan.
ALARM
TRIP
1. No motor or breaker protection acted. 2. Fan is in remote. 3. In case of one fan is running and the other is in stopped conditiona) By interlock input if one fan is stopped/ tripped, standby fan will start in auto. b) If scanner air header pressure<2 KPa for 5 sec, then standby fan will start in auto by interlock input.
AND
Start Enable Interlock
1. Scanner air header pressure< low switch acting: emergency priority alarm. 2. Scanner air fan trip: emergency priority alarm.
Alarm
1. Scanner air fan breaker protection acted. 2. Scanner air fan motor protection acted.
Trip
1. No breaker/ motor protection acted. 2. Lube oil pressure normal for > 5 minutes. 3. No MFT acted. 4. Boiler drum pressure>3.4 kg/cm2. 5. Secondary air temperature>1770C. 6. Total air flow<40% (230TPH). 7. MDVs are open. 8. Mill outlet temperature<1150C. 9. Cold air gate is open. 10. Coal feeder is in remote. 11. PA permit satisfied. 12. Mill ignition permit satisfied.
AND
Start Enable Interlock
1. Feeder trip and no mill ignition permit. 2. MFT. 3. MDVs closed. 4. Lube oil pressure low (2 out of 3 lube oil pressure
AND
TRIP Enable Interlock
1. Mill lube/ hydraulic oil tank temperature>750C: high priority alarm. 2. Mill lube oil thrust pad oil temperature>600C: high priority alarm. 3. Mill lube oil thrust pad oil temperature>700C: emergency priority alarm. 4. Mill motor front/ rear bearing temperature>750C: high priority alarm. 4. Mill motor winding temperature>1000C: high priority alarm. 5. Mill outlet, roller bearing temperature>900C: high priority alarm. 6. Mill current>60 amp: high priority alarm. 7. Mill inlet PA flow< 50 TPH: high priority alarm. 8. Mill hydraulic pressure>150 kg/cm2: high priority alarm. 9. Mill hydraulic pressure<70 kg/cm2: high priority alarm. 10. Seal air header pressure<800 mm of H2O: high priority alarm. 11. Seal air header pressure<600 mm of H2O: emergency priority alarm.
Alarm
1. Mill motor protection (over current, earth fault, negative sequence, phase fault etc) acted. 2. MFT trip mills. 3. MDVs closed trip mill (2 out of 4 MDVs). 4. Mill lube oil pressure low (2 out of lube oil pressure
Start enable Interlock: 1. No breaker or motor protection acted. 2. Respective mill ignition permit. 3. Feeder speed (VFD command) minimum. 4. No mill trip command. 5. Feeder is in remote.
1. Mill trip/ emergency stop. 2. MFT. 3. Feeder running and no coal. 4. Mill outlet temperature<540C and HAG closed and feeder VFD command<2%.
AND
OR
Start Enable Interlock
Stop/Trip Enable Interlock:
1. Belt deviation of feeder switch act: high priority alarm. 2. No coal switch act: high priority alarm. 3. Coal jam switch act: low priority alarm. 4. Feeder cleaner motor fault: low priority alarm. 5. Coal flow zero: low priority alarm.
1. Mill trip to feeder trip. 2. MFT to feeder trip. 3. Feeder motor/ breaker protection acted. 4. Feeder running and no coal. 5. Mill outlet temperature<540C and HAG closed and feeder VFD command<2%.
Alarm
Trip
Mill Lub Oil Pump Interlock & Protection
1. No breaker or motor protection acted. 2. LOP is in remote. 3. Oil pool temperature of lube oil>600C.
1. Oil pool temperature of lube oil<450C. 2. After LOP starting if oil pool temperature of lube oil<450C and mill not running (30 mins time delay). 3. After mill stopping after 4 hrs time delay stop command will go for LOP.
AND
Start enable Interlock
OR
Stop/trip enable Interlock
1. Lube oil pump stopped: emergency priority alarm. 2. Lube oil pressure: 750C high priority alarm. 4. Lube oil thrust liner sump temperature>: 600C high priority alarm. 5. Lube oil thrust liner sump temperature>: 700C emergency priority alarm. 1. LOP motor/ breaker protection acted. 2. Oil pool temperature of lube oil<450C. 3. After LOP starting if oil pool temperature of lube oil<450C and mill not running (30 mins time delay). 4. After mill stopping after 4 hrs time delay stop command will go to LOP.
Alarm
Trip
1. No breaker or motor protection acted. 2. APH is in remote. 3. Guide and support bearing oil pump running for minimum of 300 sec (for U#2 APH). 1. APH flue gas inlet temperature<800C and fans (ID, FD & PA) are running. 2. For APH auxiliary motor, with the start of APH main motor trip command will go.
AND
Start enable Interlock
OR
Stop/trip enable Interlock:
• Other Interlocks: • 1. Start command will go for APH auxiliary motor (DC) with the tripping of APH main motor. • 2. In case of APH main motor VFD getting bypassed due to any fault, APH main motor DOL supply will pick up. • 3. For U#2 APH• a) If APH support/guide bearing temperature> 540C, lube oil pump will start. • b) If APH support/guide bearing temperature< 500C, lube oil pump will stop
