Frequency Distribution of Leakage Current on Silicone Rubber Insulator in Salt-Fog Environments

This paper presents an analysis result of using the frequency distribution of leakage current to monitor insulator performance in salt-fog environments. Experiments have been carried out on silicone rubber insulator by injecting salt fog into an artificial fog chamber with an ultrasonic vibration salt-fog generator and applying an AC voltage of 30 kVrms at 50 Hz as the test voltage. Based on the frequency distribution extracted by a wavelet transform technique, the measured leakage current is separated into the low-, intermediate-, and high-frequency components. Cumulative charge at each frequency component is obtained by a time-integral method and found to correlate the frequency components and the insulator performance. Obtained results show that high-frequency components are more effective than low-frequency components on monitoring insulator performance in salt-fog environments.