WHAT IS PERMISSIVE, PROTECTION & INTERLOCKS OF ID FAN

INTERLOCK system and PROTECTION are mostly used in every power sector for preventions of any physical damage of equipment or human life. PERMISSIVE is also an important for startup and proper running of machines. 

Here you are going to learn about ID FAN Permissive, Protections and It's Interlocking systems.

ID FAN is stand for Induced Draft Fan its's always set near stack for collections of dust from ESP outlets of light dust and drafted through stack in the atmosphere.

ID FAN PERMISSIVES:

1. ID FAN REGULATING DAMPER (IGV) MIN POSITION (< 5%).

2. ID FAN OUTLET GATE - FULL CLOSED.

3. ID FAN INLET GATE - FULL CLOSED.

4. LUBE OIL PRESSURE ADEQUATE  (> 0.8 ata) [TAG - HNV10CP001 & HNV10CP002 (SEL)]

5. ID FAN BEARING TEMP NOT HI  (< 770 °C) -------- ON DELAY 2 SEC

6. MOTOR BEARING TEMP NOT HI   (< 850 °C) -------- ON DELAY 2 SEC

7. MOTOR WINDING TEMP NOT HI   (< 1250 °C, ALL 6) ------ ON DELAY 2 SEC.

8. ANY ONE FLUE GAS PATH (A/B/C/D) IS AVAILABLE.

9. LUBE OIL TANK LEVEL ADEQUATE (1LS).

10. LUBE OIL TEMP AFTER COOLER ADEQUATE    <77 °C (TO BE REVIEWED).

11. ANY LOP IN SERVICE.

12. FLUE GAS PATH AVAILABLE:

➢ ANY EP PATH AVAILABLE. 

➢ FD FAN O/L GATE & BLADE PITCH CTRL MAX.

➢ ANY ONE APH AVAILABLE WITH SEC SCAPH I/L AN O/L DAMPER OPEN OR EC SCAPH BP DAMPER OPEN.

➢ ALL AUX AIR DAMPER MODULATING.

10. VFD SYSTEM AUXILLARY CONTROL SUPPLY IS HEALTHY.

11. VFD SYSTEM ‘CHANNEL 1 READY ‘AND ‘CHANNEL 2 READY.

ELECTRICAL PERMISSIVES :

➢ 11 KV SUPPLY.

➢ NO SWITCHGEAR DISTURBANCE.

➢ MASTER TRIP RELAY NOT OPERATED.

➢ SWITCHGEAR (SWGR) AVAILABLE.

➢ SOURCE BRKR CLOSE PERMISSIVE AVAILABLE.

➢ LT UNIDIRECTIONAL (CH1 AND CH2).

 

PERMISSIVE:

SOURCE BREAKER CLOSING PROCESS IN 10 SEC.

➢ CH1 AND CH2 SOURCE BREAKER NOT DISTURBED AND ON FROM SWGR END.

➢ NO ALARM FROM VFDD FAN.

➢ CH1 AND CH2 READY FROM VFD.

➢ START PERMISSIVE AVAILABLE FROM VFD.

➢ NO FAULT FROM VFD.

➢ IGV MIN POSITION AND I/L,O/L GATE CLOSED FOR BOTH CHANNELS.

 OR

CH2 SPEED > MIN (30 SEC) FROM VFD FOR CH1 START PERM.

CH1 SPEED > MIN (5 SEC) FROM VFD FOR CH2 START PERM.

➢ LOP A OR B ON FROM MCC.

➢ EXCITER WINDING TEMP NOT HIGH (<500C) 2SEC TD.

INTERLOCKS :

1. STAND BY LOP STARTS (WITH DELAY 30 SEC.)

➢ IF FAN IS RUNNING AND LUB OIL PRESURE   < 0.6 ATA [TAG – HNC10CP001 OR 002]

(INSTANTANEOUSLY)

OR

➢ IF FAN IS RUNNING AND RUNNING LOP TRIPS AND OTHER LOP IN STANDBY.

2. ID FAN INLET AND OUTLET GATE WILL OPEN ON AUTO, IF

➢ ID FAN IS RUNNING (60SEC DELAY) [IF OTHER FAN IS NOT RUNNING GATE WILL OPEN

IMMEDIATELY]

 OR

➢ ID FAN A & B ARE NOT RUNNING. (TO BE INCLUDED)

3. ID FAN INLET /OUTLET GATE CLOSE PERMISSIVE WILL BE AVAILABLE ONLY WHEN FAN NOT RUNNING.

4. ID FAN INLET/OUTLET GATE WILL CLOSE AND IGV GOES TO MINIMUM POSITION ON AUTO IF ID FAN TRIPS AND OTHER ID FAN IS RUNNING & ONE FD FAN WILL BE IN SERVICE. (BOILER LOAD WILL COME TO 50% MCR) 

WHEN STOP CMD IS GIVEN TO CH 1 & 2 IT TAKES 30 SEC AND 60SEC TO CLOSE GATES AND IGV AT MIN POSITION.

5. AFTER START COMMAND

➢ SELECTED FAN MOTOR STARTS

➢ OUTLET & INLET GATE CLOSE, IGV WILL GO FOR MINIMUM FOR STAND BY FAN IF IT IS NOT IN SERVICE

➢ OUTLET GATE OPENS & THEN INLET GATE OPENS AND IGV/VFD IN AUTO MODE FOR

THE STARTED FAN.

PROTECTIONS:

ID FAN TRIP TO INLET GATE-1 & GATE-2 CLOSE OR OUTLET GATE-1 & GATE-2 CLOSE GETS ARMED 120 SEC AFTER RESPECTIVE ID FAN ON FEEDBACK.

SN	DESCRIPTION	VALUES			TIMER (SEC)
		NORMAL	ALARM	TRIP & ALARM
1.	ID FAN BRG TEMP (DE & NDE) 0C	≤77	>77	≥82	2
2.	ID FAN MOTOR BRG TEMP (DE & NDE) 0C	≤85	>85	≥90	10
3.	ID FAN BRG VIBRATION DE & NDE (MM/SEC)	≤6.3	>6.3	>12.6	10
4.	MOTOR BRG VIBRATION DE & NDE (MM/SEC)	≤4.5	>4.5	>9
5.	ID FAN EXCITER WINDING TEMP ( 0C )	<50	>50	>60	2
6.	ID FAN MTR WDG TEMP (0C) (1/6)	≤125	>125	>130 (2/6)	2
7.	POST PURGE FAN TRIP FROM FSSS *	- 5	+ 75	-175 / +150	-

➢ CH-1 FAULT THEN CH1 WILL TRIP.

➢ CH-2 FAULT THEN CH2 WILL TRIP.

➢ MASTER TRIP RELAY OPTD FROM SWGR.

➢ IF ID FAN A AND B ON & ALSO FD FAN A AND B ON , IF FD FAN TRIPPED ,THEN CH-1 

AND CH2 OF SAME SERIES ID FAN WILL TRIP(5 SEC. OFF DELAY).

➢ CH-1 & CH-2 BOTH SOURCE BREAKERS AND BOTH LOAD BREAKERS WILL TRIP IF EPB OPERATED VFD CHANNEL FAULT CAUSES.

1. LOSS OF EXHAUST BLOWER FOR VFD PANEL.

2. EXCITER UNDER VOLTAGE.

3. EXITER OVER CURRENT.

4. MOTOR COOLING WATER LEAKAGE.

5. MOTOR COOLING WATER FLOW ADEQUATE.

6. SOURCE BREAKER TRANSFORMER TRIP.

• BUCCHOLZ RELAY OPERATE.

• PRV OPERATED.

• WINDING TEMPERATURE VERY HIGH.

• OIL TEMPERATURE VERY HIGH.

• CONSERVATOR OIL LEVEL LOW.

• RECTIFIER DOOR OPEN.