Study on Evolution Patterns of Power Frequency Arc Discharges in Transformer Oil

This study investigate the intricate evolution patterns of arc discharges and shock wave phenomena occurring in transformer oil under the influence of power frequency AC voltage. By conducting a series of experimental investigations specifically targeting arc discharges in transformer oil under power frequency AC voltage, the research meticulously scrutinized the alterations in discharge patterns, voltage-current evolution, and the development of shock waves. The experimental outcomes unveiled a phenomenon wherein multiple discharges take place between the electrodes during arc discharges in oil under power frequency AC voltage, resulting in the generation of pulsed voltage and current. Moreover, the escalation of pressure within the arc channel and bubbles instigates the compression of the surrounding liquid, consequently leading to the outward propagation of numerous shock waves. The experiments reveal that when the electrode gap is 2 mm, five shock waves are generated, while for electrode gaps of 1 mm and 3 mm, two and seven shock waves are observed respectively. Apart from the losses in the transformer and discharge circuit, the energy of the arc will transfer to the internal energy of the plasma-gas mixture, the mechanical energy consumed by the expansion of the arc channel and bubbles, the heat conduction at the boundary of the channel, and the transfer of radiative energy to the outside. Based on the Braginskii fluid kinetic energy balance equation, the maximum transfer ratio of internal energy is calculated to be 29.3%, the maximum transfer ratio of mechanical energy is 15.9%, and the maximum transfer ratio of radiative and conductive heat transfer is 6.5%. This comprehensive research significantly contributes to elucidating the developmental patterns and characteristic parameter variation mechanisms of arc discharge in transformer oil.