The Shift-in-charge shall check the following
in case of MOCB / ABCB /SF-6 breakers:-
i. The oil level and oil leakage shall be checked in case of MOCB. If the level is less or
leakage is there, it shall be reported to the Incharge (GSS).
ii. The closing spring of 132 kV BHEL make HLD type breaker should be kept in
charged condition when the breaker is in service so as to keep second trip coil also in
operation.
iii. The pressure of nitrogen in case of 132 kV HLR breaker of M/s BHEL, shall not be
below 5.4 kg/ cm2 as indicated by the pressure gauge on the top dome of each pole.
If found low, Incharge (GSS) be informed.
iv. Air pressure in case of ABCB and SF-6 breakers shall be checked and if low, it shall
be maintained at correct level. The normal operating pressure for some of the
breakers is given below:-
a. 220 kV SF-6 ABB make 20.5 kg/cm2
b. 220 kV SF-6 NGEF make 32 kg/cm2
c. 220 KV ABCV DLF ABV make 31 kg/cm2
d. 132 kV SF-6 HBB/ABB make
i) 20.5 kg/cm2
ii) 16.0 kg/cm2
e. 132 kV DCF/DCvF ABCB, HBB make 16.0 kg/cm2
f. 132 kV ABCB DLF HBB make 30.0 kg/cm2
g. 132 kV ABCB Voltas make 17.0 kg/cm2
Note:- The Shift-in-charge shall verify the correct operating pressure of the breaker installed at his grid sub station.
v. Air pressure in the central compressed air plant shall be checked. If low, it shall be
maintained at the correct level. Some typical values are given below:-
132 kV HBB DCF/ DCvF ABCB 40 - 30/16 kg/cm2
220 kV/132 kV HBB DCF/DLF ABCB 50 - 60/30 kg/cm2
132 kV TMG ABCB 40 - 35/17 kg/cm2
vi. Hydraulic oil pressure in case of hydraulic oil operated breakers, shall be checked
and, if low, shall be maintained at the correct level. The normal operating pressures
for some of the breakers are given below:-
400 kV BHEL make breaker - 305 – 320 kg/cm2
132 kV Jyoti make breaker - 305 -- 336 kg/cm2
vii. The Shift-in-charge, on assuming the charge of shift, shall get the moisture drained
from the air bottles of the SF-6 breakers and compressed air plant installed in compressor room.
viii. If any leakage is observed in hydraulic / pneumatic system, it shall be reported to the
Incharge (GSS) for immediate action.
ix. If the SF-6 low alarm is observed in Annunciator panel, it shall be immediately
reported to the Incharge (GSS).