Saturable reactor insulation is currently stressed by an exponential decay pulse voltage under normal operating conditions. The partial discharge (PD) characteristics of epoxy resin under an exponential decay pulse voltage were studied here and were compared at 25 and 110°C. In addition, this study compares these PD characteristics with those under a sinusoidal voltage to better measure the insulation design margin of the saturable reactor under an exponential decay pulse voltage. Finally, this study explains the PD mechanism based on the three-capacitor circuit model and space charge accumulation. Compared with the sinusoidal voltage, a higher amplitude, a higher inception voltage and fewer PDs are obtained under the pulse voltage. The reason may be related to the accumulation of space charge. Due to the duality of the space charge effect, the promotion effect of space charge accumulation on the PD under the pulse voltage is dominant, and an increase in temperature will weaken the promotion effect. In contrast, the inhibitory effect of space charge accumulation on the PD under the sinusoidal voltage is dominant. The experimental results can provide a basis for the optimal design of saturable reactor insulation under an exponential decay pulse voltage.

当前，在正常工作条件下，饱和的反应堆绝缘受到指数衰减脉冲电压的压力。本文研究了在指数衰减脉冲电压下环氧树脂的局部放电（PD）特性，并在25和110°C下进行了比较。此外，本研究将这些PD特性与正弦电压下的PD特性进行了比较，以更好地测量指数衰减脉冲电压下可饱和电抗器的绝缘设计裕度。最后，本研究基于三电容器电路模型和空间电荷积累来解释PD机制。与正弦电压相比，在脉冲电压下可获得更高的幅度，更高的起始电压和更少的PD。原因可能与空间电荷的积累有关。由于空间电荷效应的双重性，在脉冲电压下，空间电荷积累对PD的促进作用占主导，温度升高会削弱促进作用。相反，在正弦电压下，空间电荷积累对PD的抑制作用占主导。实验结果可为在指数衰减脉冲电压下可饱和电抗器的优化设计提供依据。