基于方波脉冲电压绝缘寿命实验的漏电流检测

Leakage Current Detection for the Insulation Life Experiment Based on Square-Wave Pulse Voltage

在脉冲电应力绝缘加速老化实验中,为消除试样电容过渡过程电流对绝缘材料和结构绝缘失效判定的影响,提高实验结果的准确性和可靠性,设计一种漏电流检测电路。在双极性高频脉冲电压下电容过渡过程电流主要集中在脉冲边沿5μs以内,12μs后过渡过程基本结束,此后试样回路电流主要是绝缘漏电流;利用此特性,通过控制电路控制电子开关,在每个脉冲边沿切除电容过渡电流而代以前一时刻的漏电流保持值,而12μs后再切换回电流检测信号。理论分析和实验结果表明,该漏电流检测方法可以有效的消除试样等效电容过渡过程电流对漏电流检测的影响,其相对偏差率小于3.03%,可以较好的满足脉冲电应力绝缘寿命加速老化实验的要求,且提高实验结果的可靠性。

In the experiment of the stress pulse insulation accelerated ageing, a leakage current detection circmt is designed in order to eliminate the effect of the sample capacitor transition cu^ent on the insulation failure judgment of insulating material and structure and to improve the reliability and accuracy of the experiment results. Under the high-frequency bipolar pulse voltage, the capacitor transition current mainly focuses on the edge of pulse within 5μs. Beyond 12μs the transition basically ends, and then the remaining part is chiefly insulation leakage current.By using this characteristic, the electronic switch is controlled by the controlling circuit. At each pulse edge, the capacitor transition current replaced by the leakage current value of the last cycle, while beyond 12μs the circuit can switch back to the current detection signal. Theoretical analyses and experimental results showed that this method of leakage current detection could effectively eliminate the influence of the sample equivalent capacitor transition current on the leakage current detection circuit; and the relative deviation rate of the circuit was less than 3.03 percent. It could meet the requirement of the experiment of the stress pulse insulation accelerated ageing,and improve the reliability of the experiment result.