Surge protectors don’t use capacitors.
They use a variable resistance circuit- usually metal oxide varistors. When the supply is at the correct voltage, it just goes through them. When it’s too high (a surge,) the resistance increases and excess voltage is sent out a fork to ground
mvirts@lemmy.world 9 months ago
Oh! Yeah that makes sense… idk why I thought they mainly used a capacitive circuit. So those varistors must dissipate power in normal operation right?
FuglyDuck@lemmy.world 9 months ago
Varistors change their resistance loads depending on the voltage coming into it. the hot wire is connected to ground, and when in normal voltages, they’re very high resistance. electricty follows the path of least resistance- similar to water flowing down hill.
so, when the voltage is normal, the power goes into the plugs does it’s thing. when a surge hits, the MOV’s loose resistance with the increased voltage, letting it flow into the ground wire instead. This brings the voltage going down the hot wire to normal, until the MOV’s go back to being highly resistive, and normal power.
basically, think of it as being a water wheel, when the flow of water is ‘normal’, the sluice gates are open and the water goes down the sluice driving the wheel. when there’s a lot of water coing in, though it spills out and doesn’t make the wheel spin too fast.