Surge Protector Selection

If you will investigate a bit, I think you will be able to answer your own questions. I like to shop here for components but you may have some other distributor closer to you.

These devices protect by providing a short circuit path for excessively high voltages up to their current rating but only for a very short time. Fortunately, most surges are in fact, very short. But, if they persist, the MOV will burn out (we like to call that "letting its smoke out"). Unfortunately, you will only know this has happened if you check.

Some manufacturers have a detection circuit to determine the status of the MOV. I would expect it to be some form of pulse injection but I don't have any real design information.

I can tell you that the most common mistake made with surge protection is placing it too far away from the source or the actual load you intend to protect. You want the MOV to be installed one of the shortest paths between power conductors. On a Main Panel, this would be right where the power cables are attached. On a distribution board, this woulld be right where the power comes in.

By the way, because these are so inexpensive, it is better to have a few extra in parallel. That will assure a longer service life.

Please refer to IEC 60364-4-443