Study of high frequency characteristics of Metal Oxide Surge arrester

Metal Oxide Surge arresters are subjected to continuous operating voltages and transient voltages. In the gapless metal oxide surge arresters a leakage current flows through the arrester at working voltages. The leakage current increases as the temperature of the arrester block increases. In the present study the arrester is subjected to a sinusoidal voltage of variable frequency ranging from 10Hz to 2MHz. The leakage current, phase angle between the leakage current and applied voltage are measured. The measurements indicate that the magnitude of leakage current increases and the phase angle decreases from about 90°leading to zero as the frequency is increased. The experiments were repeated for different block temperatures. The frequency response of the arrester blocks is obtained from this which could be useful as diagnostic parameter and also for modeling the arrester behavior at high frequencies.