Use of low frequency harmonic components as a signature to detect arcing on HTV silicone rubber in salt-fog

This paper presents the results of using the low frequency harmonics of leakage current as a measure of dry band arcing in salt-fog. Sleeved high temperature vulcanized (HTV) silicone rubber rods were tested under 0.25, 0.40 and 0.60 kV/cm in salt-fog at two different salinities, i.e. 1000 and 2500 muS/cm. The leakage current was measured and analyzed using fast Fourier transform (FFT). The results show that as the electric field increases, the fundamental component of the leakage current decreases and both the third and fifth harmonic components increase. Also, increasing the salinity of the fog increases both the third and fifth harmonic components with no significant change in the fundamental component. In general, harmonic components increased only when arcing occurred, thus providing a signature for the dry band arcing activities.