15-10-2014, 12:01 PM
Abstracts: 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.