Effect of Low Temperatures on Partial Discharges in C4F7N/CO2 Gas Mixtures

In order to study the partial discharge characteristics of C4F7N/CO2 gas mixture at low temperatures, and to investigate the effects of temperature, mixing ratio and air pressure on the partial discharge characteristic, this paper carries out the partial discharge test of C4F7N/CO2 gas mixture in the temperature range of -20–20℃ based on the pulsed current method, and obtains the partial discharge characteristics of C4F7N/CO2 gas mixture at different temperatures, different mixing ratios and different air pressures. The partial discharge characteristics of C4F7N/CO2 gas mixture were obtained at different temperatures, different mixing ratios and different air pressures, and the influence of temperature on the local discharge of C4F7N/CO2 gas mixture was analysed. It was found that the partial discharge initial voltage of C4F7N/CO2 gas mixture decreased and the amount of the discharge increased with the increase of temperature, while the frequency of the discharge did not undergo a regular change. The study can provide a reference for the design, operation and maintenance of electrical equipment using C4F7N/CO2 gas mixture as insulation medium.