Reliability analyses and calculations for distribution transformers

This paper discusses methods for estimating reliability parameters of distribution transformers. The data analysis techniques presented have been developed through operating records provided for the period 1970 to 1993 by an Electric Utility Department in the USA. Calculation results show that the failure mode of distribution transformers can be represented by Weibull distribution. Both useful calculation methods and results of failure rates as well as MTTF (mean time to failure) are given in the paper.