Powergrid Experience on Failure Prevention of Transformers & Reactors

Large power transformers are expensive and critical elements of a utility transmission system. Some transformers are so important that consequences of their failure are tremendous e.g. 765 kV Transformers and Converter Transformers of HVDC System which are transmitting bulk power from remote generating stations to load centers. POWERGRID is operating and maintaining about 650 Power Transformers, 90 converter transformers and 1000 shunt reactors installed in 190 substations across the country. Present task in front of POWERGRID is to maintain serviceability of such a large fleet of Transformers/Reactors which are critical considering the ageing fleet, large addition of new Transformers/Reactors especially at 765 kV level and significant effect on the grid due to any outage.

During Operation and Maintenance of Transformers & Reactors in POWERGRID, various problems/failures are observed. These failures were analyzed in detail and various measures are taken to improve the serviceability of Transformers & Reactors. In this paper, few case studies are brought out where failure prevention of Transformers & Reactors are achieved based on past failures/problems encountered in POWERGRID.