How and Why Varistor Failure Occurs; Including the Effects of Structure, Processing and Multipulse Surges
In 2011 a triggered lightning experiment had an unexpected result. In this experiment an instrumented power line was hit by a lightning flash having multiple return strokes; and the unanticipated result was that an MOV in equipment connected to the power line was damaged, even though the Imax rating of the MOV was much higher than the recorded lighting peak current.
How could this happen? More importantly, is this something that can happen more generally; and is it something we should be concerned about? To help answer these questions this presentation discusses what an MOV is, how the way it is made influences its behavior when surged, how and why failures occur, and how multipulse surges differ from single surges in their effect on MOV properties.