A discussion on the dependence of partial discharge inception voltage on supply voltage waveform: sinusoidal and modulated AC

Aside from a trend to develop insulation system designs free of partial discharges (PD) and/or to monitor partial discharges to evaluate electrical asset component health conditions, there is still confusion on the impact of supply voltage waveform on partial discharge inception voltage (PDIV). The literature presents contrasting information about how voltage waveform characteristics (frequency, shape, dv/dt) impact PDIV. This paper aims at discussing the effect of modulating AC voltage supply on paradigmatic capacitive and inductive test objects. It is shown that the major factors affecting the PDIV are how the electric field distribution behaves with frequency and slew rate and how the assumption on which PD inception field models are generally based, i.e., deterministic phenomenon, holds in practice. As a matter of fact, one can mostly expect PDIV to increase with frequency and slew rate in capacitive objects, the opposite in inductive components.