The MOVs are commonly used in AC primary circuits to suppress voltage transient surges. However, the MOV can also be subjected to continuous abnormal overvoltage caused by poor power grid quality or loss of neutral-to-ground connection in power transformer wiring. If a standard/conventional MOV is subjected to the above conditions, it may go into thermal runaway, resulting in overheating, smoke and potentially catastrophic failure. The TMOV is designed to address this kind of situation.