/diy/ - Do It Yourself

>>1664138
True, but not all of them have a MOV. When they do, the MOVs are usually small and can't take too many joules during their lifespan. They will explode easier with violent surges, especially if the circuit is simple and doesn't include fast acting thermal fuses beside the MOV. Small MOVs also tend to have a shorter lifespan when used in power delivery for 220V AC, because, like I said, they have a very limited capacity for transient absorption. As a MOV takes each transient hit, it degrades and it's clamping (operating suppression) voltage is reduced. It will eventually overheat at nominal operating voltage, and explode or catch fire if not protected by a thermal fuse. Plus, one MOV is not enough. You need at least three for basic protection. This is because to achieve both common mode surge suppression and differential mode surge suppression, you do need at least three MOVs. See pic related.