Reasons for Transformer Failure
Contrary to popular belief, transformers do experience short circuits and
abnormal electrical conditions that result in their failure.
As transformers become older, the likelihood of failure increases as insulation begins to deteriorate.
An example of one such abnormal condition is overexcitation.
Many industry experts have concluded that overexcitation and through faults are more detrimental to transformer life than load-associated aging [1].
Through-fault failures were a major industry concern in the United States during the late 1970s and 1980s, when the industry experienced an unusually large number of through-fault failures due to design deficiencies.