Report of Indian Institute of Public Administration ... - Ministry of Power

Maharashtra
The total number of such transformers in the transmission company is less than
one thousand. Assuming that an average of four feeders are emanating from each
such transformer and one for sub-station auxiliaries and further assuming that
none of these have already been provided with an energy meter, the maximum
number of energy meters required to be fixed on priority would only be 7,000
Nos. With high priority, the job of fixing these energy meters can be completed
in a couple of months. This activity will help energy accounting in respects of
not only a transmission company but distribution company as well.
Similarly if there is a common feeder for supply to auxiliaries and sub- station
colony then reading of energy meter on the feeder must match with sum of
energy meter readings of sub-station auxiliaries and colony. These readings
could be checked on hourly basis as all these sub-stations have operating staff for
24 hours. Any deviations in the above comparisons should be investigated and
corrected on priority.
iii) Presently in many sub-stations, in which energy is received from generating
plants, energy meter is not provided in the generator bay for measurement of
energy input on the EHV busbar. The energy supplied to the transmission
company by the generator, is computed from the difference between the readings
of energy meters on the LV side of the generator transformer and on the unit
auxiliary transformer and the losses in the generator step up transformer go to
MESTCL’s account. To avoid this, direct measurement of energy input on the
busbar would be required and an energy meter of class 0.2 accuracy and current
transformers having metering core of 0.2 accuracy class be provided for this
purpose in each generator transformer bay.
iv) Transformer is very important equipment in transmission and distribution of
energy. Failure of EHV transformer leads to large-scale disruption in the
transmission system besides considerable costs involved in repairs/replacement.
It is therefore very prudent to provide on-line and off-line ‘condition monitoring
devices’ to prevent failure of EHV transformers. This aspect needs to be given a
higher priority while procuring transformers and their subsequent maintenance in
service.
v) In 400 kV and major 220 kV sub-stations, it would be very useful to provide
sequence of events recorders and numeric relays to enable proper analysis of
faults.
10.35