Question Doubt surge protector and varistor

[cloudff7ps1]

I have a surge protector 220v, it uses 3 x 20mm varistors When a varistor bursts or explodes or at the end of its useful life, the protection is lost but the surge protector sockets continue to operate without protection? 3 varistors F-N, F-T, N-T

 

[hotaru.hino]

If the varistor fails over time, it generally fails to short circuit. If it fails violently, then it's open circuit.

 

[bill001g]

Yes that is the way it works most the time. You can't tell if you actually have good protection or not, the strip will provide power to your ends units no matter if the varistors are good or bad. All the varistor does is provide another path for voltages that are too high. If the varistor is burned out or fails for other reason then your end devices will see these voltage spikes.

There is no simple way to test this you have to unsolder the varistors so you never really know if they are still working and protecting your stuff.