Measurement techniques to reveal arrester MOV response during steep-front impulsing

Steep-front, high current tests have been performed on 10 kV and 15 kV MOV (metal oxide varistor) and gapped SiC (silicon carbide) distribution arresters. Arrester voltage responses to steep-front, nearly rectangular current pulses exhibited a large voltage overshoot or initial spike. A considerable part of this overshoot voltage was the induced voltage in the voltage divider due to time-changing magnetic field generated by the rapidly rising arrester current. The overshoot voltage was estimated by replacing the test arrester with a similarly sized aluminum tube. Noises have been filtered out of the voltage and current waveforms by software filtering to determine the maximum rate of rise of the arrester current. The arrester peak voltages and the peak responses of the arrester materials are related linearly to the maximum rate of rise of the arrester currents.<>