Evaluation of a Functional Life Test Model for Power Transformers

A power transformer life model and its related, test procedure have been evaluated and found to provide more meaningful information on retained operational capability of the winding insulation than can be derived from simple material tests. Both paper and enamel conductor insulation demonstrated retained functional ity after aging for time periods in excess of 5 times the life defined in industry loading guides. In addition, valuable knowledge was revealed about the behavior of conductor turn insulation with free gas entrapment, where the gas source was either oil supersaturation with dissolved gas or thermal evolution from overheated cellulose.