Comparison of ultrasonic, electrical and UHF characteristics of partial discharge emission in oil/paper insulation systems

Abstract

In this paper, partial discharge measurements on artificial specimens simulating corona, surface and internal partial discharge in paper/oil insulation systems are discussed. Focus is made on a comparative analysis of signals derived through both conventional (conducted electrical signals) and unconventional (acoustic and UltraHigh Frequency emission) techniques. The results indicate that unconventional techniques can provide evidence of partial discharge activity, but are not sufficient to assess the severity of the detected phenomenon. This requires apparent charge measurements conducted through conventional detectors. In the case streamers are observed, narrowband detection (with bandwidths below 50 kHz) must be used to get an accurate estimate of apparent charges.