Degradation Processes of Voids in Silicone Rubber under Applied AC Fields

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Description/Abstract

This paper is concerned with an experimental study into the degradation processes that occur when voids in solid dielectric materials experience high applied electric fields. A method has been developed for manufacturing 2mm thick samples of silicone resin that contain a single void of 1mm diameter . Five Samples are simultaneously electrically stressed under an applied ac sinusoidal voltage of 12kV for 6 hours that is then increased to 15kV until a sample fails. During the stressing period, PD data is regularly acquired [1]. The remaining 4 samples are then inspected for signs of degradation. A typical result of a degraded sample is shown in Figure 1. The experiment is repeatable and the obtained degraded samples have been analysed using Raman spectroscopy to identify the chemical content of the degraded areas at the void /silicone rubber interface. Initial results indicate that the degradation is a pre-cursor to the development of a bow-tie electrical tree [2] , although further research is required to confirm this.