On the character of different forms of partial discharge and their related terminologies

Experimentally obtained partial discharge pulse forms are compared with those derived theoretically, using a mathematical model of a short gap. The calculations indicate that, with overvolted short gaps, the apparent absence of the protracted ion current tail in the overall pulse form is due to the large excess of the electron current component generated by strongly enhanced cathode emission by the photoeffect and other phenomena. Under conditions of high overvoltage the ion-impact-induced emission, the ion fluxes and, consequently, the ion current component are greatly reduced as compared to the electron current. The long ion current tail, representing not more than a few percent of the total current, passes undetected. Pulseless and pseudo-glow discharges are considered. Preferred terms to designate the different forms of partial discharges are suggested.>