Effects of Temperature on Partial Discharge and Breakdown Characteristics of an Ester Liquid under AC stress

This paper presents a study on effects of temperature on partial discharge (PD) characteristics and breakdown voltages of a synthetic ester liquid under AC stress. In this study, a needle-to-plane electrode configuration was employed to perform the PD measurement and breakdown voltage tests at four temperatures, i.e. 20 °C, 40 °C, 60 °C and 80°C. The experimental results showed that both PD and breakdown behaviors of the synthetic ester are temperature dependent. Both the magnitude and repetition rate of positive PDs, those occurred at the positive half cycles, increase gradually with the increase of temperature. However, both the magnitude and repetition rate of negative PDs, those occurred at the negative half cycles, drop significantly with the increase of temperature. In addition, it is observed that the AC breakdown voltage decreases slightly with the increase of temperature.