I. Introduction
Partial discharge (PD) detection and location techniques using acoustic signals are well-established for power transformers and outdoor insulation. They have been applied also to other power apparatus such as air-insulated and gas-insulated switchgear or high voltage capacitors. It appears to be common wisdom that acoustic methods are not well suited for PD detection in high voltage cables [1] [2]. This seems counterintuitive for anyone who has heard the characteristic crackling sound when testing a faulty cable termination in a quiet test room. Despite some trials, acoustic techniques for PD detection in cables have not been widely implemented probably because of the various shortcomings associated with the use of traditional, electroacoustic-type sensors. Acoustic sensors based on photonic techniques [3] bring new possibilities because of their non-conducting nature and their ability of broadband signal detection. A sensor of this type is currently being developed
This work has been funded from the Australian Strategic Technology Programme of Energy Networks Association.
In this context, an investigation by computer modelling was carried out to determine the nature of acoustic signal from partial discharges in a model insulation system containing materials commonly used in cable terminations.