An Analysis of VEPCO´S 34.5 KV Distribution Feeder Faults as Related to Through Fault Failures of Substation Transformers

A study of Vepco´s 34.5 kV distribution feeder faults was conducted by installing fault recording equipment in some of their substations. The data was analyzed on a statistical basis and provided information relating to the magnitude, frequency, duration and types of faults seen by the substation transformers. Consideration of the high number of substation transformer failures, the cumulative aging effects of short circuits and their operating experience with instantaneous reclosing brought about changes in Vepco´s standard reclosing practices. These changes should reduce the number of short circuits on these transformers and thereby decrease the probability of failure.