Estimation of partial discharge onset characteristics in gases around a triple junction

A new method of estimating partial discharge onset conditions in gases around a triple junction is proposed. The effectiveness of the method based on the Paschen curve and the potential distribution along the interface between a solid insulator and gas is confirmed experimentally in air at room temperature. The partial discharge onset conditions in air and SF₆ gas under different pressures at room temperature and in cryogenic nitrogen and helium gases at saturation temperature and atmospheric pressure are estimated. The partial discharge intensity is discussed on the basis of the proposed method.