Visualisation of electrical transient using the wavelet transform”, proc. of AISTA.pdfVIP

Visualisation of electrical transients using the wavelet transform David Cornforth and Rick Middleton Dep artment of Electrical and Comp uter Engineering, University of Newcastle, NS W, Australia Joe Tusek Electrical Plant Testing, Pacif ic Power International, University of Newcastle, NS W, Australia Abstract. High voltage insulation suffers from aging processes caused by the electrical, mechanical and thermal stresses of normal operation. Failure of equipment containing high voltage insulation can be sudden and catastrophic, leading to risk of injury to personnel and damage of expensive equipment. On line monitoring of electrical signals has been shown to provide useful diagnostic information. The processing of such information is a complex problem. The wavelet transform can be used to provide a method of analysis and visualisation of transient electrical signals obtained from on line monitoring. 1. Aging and degradation of insulation The electricity supply industry relies on equipment that utilises high voltage insulation, predominantly made of paper and insulating oil. As much of this equipment was installed more than 20 years ago, it has already exceeded its planned working life. The insulation deteriorates under normal operating conditions, and this is accelerated due to short or long term overloads, lightning or switching surges, and moisture. These stresses break down the insulation system both chemically and mechanically, which leaves the impaired insulating system subj ect to further deterioration due to electrical breakdowns [1, 2]. These bre