聚合物绝缘特性分析中的热刺激电流测量

本文设计了一个pA级的热刺激电流测量系统。文中充分讨论了各种干扰和温度漂移对测量结果的影响,选择性能优异的超低偏置电流元件和差分电路,微电流测量部分采用多次滤波设计、分层布局、特殊的屏蔽环和接地设计等技术。通过这些手段可将仪器的电流测量范围扩展到pA量级,电路噪声降至0．1 pA。并以此装置实测了变频电机用纳米复合绝缘电介质的热刺激电流,以此了解绝缘老化和击穿的微观表现。

TSC measurement in polymer insulation characteristic analysis

A measurement system of pA level thermally stimulated current(TSC)was designed to measure the TSC of the polymer and investigate the space charge accumulation and the trapping parameter in polymer.The influences of various interferences and temperature drift on measurement results are thoroughly discussed.Some effective methods(e.g.,ultra low bias current amplifier,differential circuit,multiple tilting,independent PCB design,and input guarding)are used, which expands the current measurement range down to pA level and decreases the circuit noise down to 0.1pA.The designed device was used to measure TSC curves of nano composite insulation dielectric used in inverter motors,and through which the microphenomenons of insulation aging and breakdown are understood.