instruction manual - BHEL Bhopal

3.2.1 GENERAL
Check the following:
Sl.No. Description
1. Breather Silicagel (Blue when dry)
2. Oil in the Breather housing cup.
3. All valves for their correct opening and closing sequence.
4. Oil level in conservator tank.
5. Oil in cooling system.
6. Oil level in bushings.
7. Release air, wherever necessary.
8. Cooling accessories (Pump motors, Fan motors etc.) for direction and O/L
setting.
9. Buchholz, oil level indicator, pressure gauges, thermometer,Temp. indicators
etc. for operation.
10. Earthing of main tank M.Box T/C driving gear, diverter, Pump Fan motor etc.
11. Neutral earthing.
12. Earth Resistance of Electrodes.
13. Earthing of bushing test tap.
14. Check oil leakage for 24 hrs.
15. Check Auxiliary circuit voltage (415 V).
16. Calibration of OTI/WTI with hot oil.
17. Check Working of WTI/RTD repeaters at control room.
18. IR of core to earth.
3.2.2 INSULATION RESISTANCE TEST
Sl. Description Date Time Megger IR Temp. Remarks
No. in Hrs used Value o C
1. Control wiring
2. Tap Changer
a) Motor
b) Control
3. Cooling system
a) Motor Fan
b) Motor pump
c) Control wiring
4. Main winding
a) HV/E+LV
b) IV/E+HV
c) LV/E+HV+IV
d) HV/IV
e) IV/LV
f) HV/LV
(Not less
than 500 V
megger)
(Not less
than 1000V
megger)
NOTE :
(1) While checking these values no external line, lightning arrestors etc. should
be in circuit.
(2) Special care should always be taken while meggering the transformer
winding to ensure that there is no leakage in the leads.
Prepared By Samvet Lahari, Bhopal. Phone- 5277412