They feared some undetected trace of poison.

他们担心一些未被识破投毒痕迹。

This heating helps to break down weak spots in the dielectric that otherwise might pass through the electrode undetected, only to fail during a later spark or hipot test.

这热量帮助击穿电线绝缘较薄地方﹐否则线材通过电极而没有被到﹐结果在以后火花试和高压绝缘试验将会失效。