Comparison of air corona PD characteristics under low and power frequency voltage by impulse-current method

For partial discharge test of electrical equipment with large capacitance, applying low frequency test voltage can effectively reduce the capacity, cost and volume of test power, especially the transportation cost for field test. The characteristics of partial discharge at low frequency are necessary to be studied to form diagnosis method of insulation defect. This paper measures and analyzes the characteristics of corona discharge in air at 50 Hz, 40 Hz, 30 Hz, 15 Hz, 10 Hz and 5 Hz including inception voltage, repetition rate of pulse, maximum and average magnitude of discharge, phase resolved partial discharge pattern etc. The similarity and difference of characteristics at power and low frequency is discussed with experiments and theory, which can be a suggestion for partial test at low frequency.