New MOV Failure Mode Identification Invention

This patent pending technology relates, generally, to surge protection devices. More particularly, it relates to a surge protection device that relies on the capacitive properties of the metal oxide varistor (MOV) as a part of an impedance network for failure identification. Unlike other designs that rely on thermal fusing to identify MOV operability, in this design the MOV is used as part of a capacitive network that would operate at a frequency other than 60 Hz. During normal operation (no failure), every capacitive impedance, including the MOV, will exhibit a voltage drop across them. On the other hand when the MOV fails as an open circuit then the current in this network will be zero and as a result zero voltage drops will be across the capacitive impedances. The reason only open circuit failure will be detected is because MOVs initially fail as a short circuit but eventually they fail as open circuit, due to continuous conduction .