Mechanism of electrical discharge development in transformer oil in the Setup of insulated electrodes

The results of research intended to reveal the role of insulation wrapping on HV electrode in the mechanism of electrical discharges in transformer oil under lightning impulse (0,83/50 μs) of both polarities are presented in this paper. This role is determined by analysis of the parameters characterizing the discharges and also by observation of their spatio-temporal development and oscillograms of the light emitted by their channels. The research was performed for two model electrode configurations: an electrode with paper insulation and a bare electrode which had the same outer geometric dimensions as the insulated one.