These varistors were protecting a transformer when they died. The transformer was protected as the fuse blew – thanks to the varistors. Credit: bhungy
Category Archive: Varistor
Dec
11
Varistor on UPS cracks
The burned part shown appears to be a MOV (Metal-oxide Varistor). The purpose of a MOV is to have a very high resistance until a certain voltage is reached at which point it will conduct current, in this case from “Hot” to “Neutral.” This property is useful for surge protectors. Original poster says this UPS …