Failure anticipation in oil-paper insulation

Characteristics of partial discharges (pd) in oil-paper insulation models were studied. Such information is required as part of a larger project to develop apparatus to warn of an impending failure of oil-paper insulated high voltage transformers in normal service. Progressive growth of partial discharges from inception to failure of the insulation was monitored using a pulse height analyzer. The partial discharges have very large magnitudes (approximately 100 000 pC) during a period lasting from a few minutes to a few hours before the insulation fails. Hence it is feasible to give a warning of an incipient failure in oil-paper insulated station equipment using pd detection methods.