Analysis of Australian power transformer failure and retirement statistics

Analyzing the probability of power transformer failure is challenging, because to observe a sufficient number of failures requires a fleet size larger than is often operated by one utility. Parametric distributions have been applied to small data sets to model failure. However, an assumption is that the failure follows the chosen distribution. Reliability data from 97% of the 6,057 power transformers operating in mainland Australia and Tasmania was collected and analyzed to develop a more accurate understanding of failure statistics. Information on 564 failures and retirements occurring between 2000 and 2015 was collected, stratified into; distribution, subtransmission, and transmission voltage class units, and then analyzed. The useful life of the three different populations was estimated, and the relationship between age and different failure types was investigated