EFFECT OF CHANGES IN ELECTRODE SURFACE ON PD BEHAVIOUR IN SF6 GIS

Insulation degradation of high voltage equipment in general and in gas insulated systems (GIS) in particular is one of the major concerns of electricity supply industries. Partial discharge detection is one of the most effective diagnostic tools for monitoring the condition of GIS. However, the influence of the change that takes place on GIS electrode surfaces with regard to the behaviour of partial discharge is an area which needs to be studied. The computerbased partial discharge data acquisition system that has been developed at the University of New South Wales along with other techniques for analysing the surface of the electrode such as scanning electron microscopy (SEM) will be used for the purpose of this research. The computer-based M system provides a very sensitive monitor of M characteristics and is able to indicate very subtle changes in behaviour. In this paper a general background of a series of experiments will be presented, along with, some of the preliminary results.. The first series of experiments will be conducted in SF6 in a 1 litre chamber, the electrodes will be a point-plane geometry stressed by negative DCHV.