The Coin Inside Your Power Strip That Stops Surges

A nearby lightning strike or a big machine switching can send a sudden high voltage down the power line. Surge protected power strips and power supply inputs often use a varistor (MOV) to handle it. A varistor sits across line and neutral. At normal voltage its resistance is very high, so almost no current flows. Once the voltage passes its rated level, its resistance drops sharply, the surge current takes the varistor path instead of your device, and the voltage at the device is clamped to a safer level. Varistors wear a little with every big surge, and a very large surge can short one and make it hot. That's why they are usually paired with a fuse or a thermal fuse that disconnects a failed varistor. In many power strips, power stays on after that, but the surge protection is gone. #Electronics #SurgeProtector #Varistor #Shorts