The detection of partial discharges in power transformers using computer aided acoustic emission techniques

A computerized measurement and analysis system developed within the Electricity Commission of New South Wales which has proved to be both sensitive and accurate is described. The system was designed to facilitate the detection and location of partial discharges in power transformers during normal service operation. The system is now being used as a front-line diagnostic tool and a useful complement to dissolved gas analysis. It has been shown that electrical discharge pulses can be measured during normal service operation by correlating the electrical signal with the acoustic emission. The system has identified 15 transformers with insulation faults. Nine of these transformers have been inspected and/or repaired. This test has had a considerable impact on maintenance practice. The known location of the partial discharge source has allowed maintenance and repair decisions to be made before opening the transformer. Most repairs have been effected on site, and in some cases the location of the source has permitted transformers to remain in service due to the noncritical nature of the fault