INTRODUCTION
The aim of this project is to analyze and upgrade existing transformer protection system in BPCL Kochi Refinery. Transformers are static devices totally enclosed and generally oil immersed. Therefore, chances of faults occurring on them are very rare.” However the consequences of even a rare fault may be very serious unless the transformer is quickly disconnected from the system. This necessitates providing adequate automatic protection for transformer against possible faults.Small distribution transformers are usually connected to the supply system through series fuses instead of circuit breakers. Consequently, no automatic protective relay equipment is required. However, the probability of faults on power transformers is undoubtedly more and hence protection is absolutely necessary.
The transformer is major and very important equipment in power system. It requires highly reliable protective devices. The protective scheme depends on the size of the transformer. The rating of transformers used in transmission and distribution system range from a few kVA to several hundred MVA . For small transformers of medium size over current relays are used. For large transformers differential protection is recommended.
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We analyzed and studied the existing transformer protection relays used in BPCL. [There different types of protection employ different types of relays.
With the technological advances being made in generation protection section, the [generator protection using new methods have gathered momentum. Here we have studied about functioning of transformer protection using numerical relays.
