High frequency harmonic components of leakage current for monitoring insulator performance in cold fog

High harmonic components of leakage current are often ignored from the analysis of insulator performance, whether they are effective for monitoring insulator performance or not needs better investigation. In this paper, experiments have been carried out on SIR insulators in cold fog and harmonic components of leakage current are extracted for monitoring the surface performance. The leakage current is separated into the low frequency, the intermediate frequency and the high frequency harmonic components. The results show that the high frequency harmonic components are well in accordance with discharge activities on the insulator surface. With the application in cold-fog environments, the high frequency harmonic components are found to be more effective than the low frequency harmonic components for monitoring the insulator performance.