Repetitive fast voltage stresses-causes and effects

In this article, we have seen how high-frequency system resonances, triggered by power electronic devices, may enhance both electrical and thermal stress on an insulation system. An important lesson from this study is that even an insulation system that is very well designed according to present standards may fail if it is subjected to stresses that were never considered in the design. The root cause of such failures is thus not within the failed part, and it can only be found by studying the entire system where the failed part is used. With the examples given here, we hope that the reader may more easily recognize situations which may warrant a deeper study and perhaps some extra precautions.