The relationship between power of arc discharge in transformer oil and peak value of the shock wave

Abstract

Since 2018, there have been seven incidents of explosions and fires in ultra‐high voltage transformers in China, which are caused by internal arc discharge in transformer oil. Various pressure measurement experiments have been conducted to explore the laws of discharge pressure. However, differences in experimental conditions, discharge energy, and current peak values have led to discrepancies in the discharge power and pressure laws in these experiments. Thus, it is crucial to investigate the relationship between arc discharge power and pressure peak in transformer oil. An arc discharge test platform was established to measure pressure waveforms based on the RLC circuit. Additionally, a shadow optical path observation system was implemented to record the development process of discharge arc, bubble pulsation, and shock waves. The study reveals the positive relationship between the average power and the peak value of the shock wave; the former refers to the breakdown and expansion stage of the arc channel, and the latter is generated by the discharge, respectively. Overall, the pressure generation mechanism of arc discharge in transformer oil and the relationship between arc discharge power and peak value of discharge pressure are revealed.