Acoustic emission detection of partial discharges in polymeric insulation

Abstract

Defects in the polymeric insulation will produce partial discharge (PD) activity, which in turn may lead to the eventual breakdown of the insulation. It is important that partial discharge behavior is detected and identified so that defects can be localized and eliminated. When a partial discharge occurs, there is a rapid release of energy, some of which is emitted as acoustic energy. The use of acoustic transducers bonded to the outer screen of the polymeric insulation in order to detect partial discharges by their acoustic emission (AE) is attractive on a number of counts: the test equipment is small; no additional high voltage capacitors are required; it is not necessary for the power supply to be disconnected, thus it is suitable for on-line monitoring; acoustic detection is free from electrical interference and external discharges will not be detected. The long-ten aim of this project is to develop an online PD monitoring system for high voltage cable joints capable of determining the accurate location, and type of partial discharge using acoustic emission techniques. In order to achieve this objective, the characteristics of acoustic emission signals travelling through the polymeric insulation have been investigated. This paper presents the preliminary study on the detection and signal analysis of partial discharges from a void within polymeric insulation model, using acoustic emission techniques.