连续方波脉冲电压下温度对聚酰亚胺薄膜局部放电特性的影响

为了评估温度对局部放电(partial discharge,PD)特性的影响,对连续方波脉冲电压条件下的局部放电测试系统进行了改进,并采用该系统测试变频电机用聚酰亚胺纳米复合薄膜在不同温度条件下的局部放电特性,分析了不同温度下的局部放电散点图、放电次数及绝缘寿命。试验结果表明:局部放电多集中在方波脉冲的上升沿及下降沿附近,且在电压负半周期平顶区内,出现了大量放电;同时,随着实验温度的增加,局部放电次数及放电幅值虽然降低,但聚酰亚胺的绝缘寿命也逐渐降低,这说明局部放电只是引起聚酰亚胺纳米复合薄膜绝缘失效的原因之一,高温条件下活性电子的入陷、脱陷过程及空间电荷造成的电场畸变可能是诱导绝缘失效的另一个因素。

Effect of Temperature on Partial Discharge Properties of Polyimide Film Under Continuous Square Impulse Voltage

In order to evaluate the influences of temperature on partial discharge(PD) properties,a PD testing system with variable test temperature was improved.The PD characteristics of polyimide nanocomposite films used in inverter-fed motors were investigated.The amount,amplitudes,and scatter diagrams of PD pulses which were obtained under different testing temperatures were presented.The results show than most of the PD pulses appear near the rising and falling edge of the continuous square impulse voltage.Some PD pulses are observed during the flat zone of negative semi-period of continuous square impulse voltage.However,PD pulses could hardly appear during the flat zone of positive semi-period.Although the amount and amplitudes of PD pluses decrease gradually with the increase of testing temperature,the life time of polyimide nanocomposite films also reduces.It is demonstrated that PD is only one of the factors which causes the damage of polyimide nanocomposite films.Under high temperature,the trapped and de-trapped processes of active electron and the distorted local field caused by space charge are the other reasons which induce the insulation damage.