Development Of Detection System Based On Negative Sequence Current Against Internal Faults Of Transformers

The internal fault of transformer is one of  those problems which are very difficult to trace in beginning. A transformers suffering internal fault for a long interval results as transformer failure either by  damage the insulation provided in between windings of transformer or by heating of transformer oil above permissible limit. These conditions are cause to make power supply failure in large scale. This problem of internal fault detection become more difficult for lower ratting transformers. Buchholz Relays are use for detecting the internal faults but this method is not as effective as require in present days scenario.

This paper deals with a new technique based on negative sequence current for detecting internal fault with the help of differential relay connect both side of the transformer winding which compare the phase difference   of negative sequence current between both side of transformer.