
MEP 660 - Trouble shooting Manual
Doc No.: IM – 51
Rev.2.0
Print: October 2008
90
PARAMETER
DESCRIPTION
FAULT CODE
1086
FAULT MESSAGE P21 stuck closed. Run Auto/manual test.
RESTRICTIONS
Motoring in series prohibited
ALARM BELL
30 seconds
RESET LEVEL
Low, Manual
After manual reset if the fault still present, the fault will be generated
again.
FAULT
RECOVERY
Automatic when P21 auxiliary contact is detected as open.
PROBABLE
CAUSES
1. Low control air pressure can cause delayed operation of power
contactor and cause this fault.
2. P21 power contactor main contact tips welded.
3. P21 power contactor auxiliary contact tips welded.
4. Defective wiring.
5. Defective Digital output card 1 MLSD16 in slot No. 14.
6. Defective Digital input card 2 MDIP16 in slot No. 10.
FAULT
ISOLATION
1. Most probably this fault is logged due to delayed operation of the
power contactor. Fault may not exist while testing. If so
A. Ensure proper over travel of the auxiliary contacts.
B. Ensure control air pressure is 5 Kg./Sq.Cm.
2. Check the status of Green LED 4 on digital input card in slot 10. If
both Green and yellow LEDs 4 are glowing.
A. Check status of P21 power contactor. If found in energized
position, check the status of magnet valve.
B. If magnet valve is not energized, then the power contactor tips
are welded. Separate them.
C. If magnet valve is energized, then the digital output card 1 in
slot 14 is defective. Replace the card and check
3. Check for welding of P21 power contactor auxiliary contact tips. If
welded change the auxiliary contacts.
4. If auxiliary contacts are not welded,
A. Check the status of Green LED 4 on digital input card 2 in slot
10.
B. If green LED is glowing with power contactor de-energised, then
defective wiring. P21FB wire is getting wrong supply. Check
continuity of wiring.