Partial discharge analysis of a narrow dielectric gap with repetitive half-sine pulses

Partial Discharge (PD) tests are carried out in a narrow dielectric gap between spherical electrodes at arbitrary voltage stimulus by a time-resolved measurement system. The usual AC voltage sinusoidal waveform application is compared with a new method based on repetitive half-sine voltage pulses, with either alternating or unipolar polarity. The half-sine pulse with duration T₁ is followed by a pause period of zero voltage of duration T₂ before the reversed polarity half-sine pulse. The effect of the pause period on the discharge activity is investigated. The results are shown for the case of 10 ms duration of the half-sine pulse, i.e. 50 Hz-like, but a pause between every two half-sine pulses can be varied. The PD signals are acquired with a Scope Corder that makes pulse sequential analysis possible. The differences between the two methods and the influence of a pause between two half-sine voltage periods to PD behavior is investigated.