Design Help required! Metal Oxide Varistor - in-circuit health Monitoring

[aju11]

We have some applications (single/Three AC and DC) which have several MOVs connected in common mode (i.e. Line to Earth).

We wish to monitor the health these MOVs and report the status over a data link (like RS485/232).

Intension here is to predict the MOV failure event and take action before actual MOV failure occurs.

I came across iTMOV series from Little fuse. But is it the only way?

Can we monitor standard MOVs and GDTs?

[coppercone2]

its a leakage test circuit, they are put into whole home surge protection systems. MOV increases leakage as it gets worn. I don't know the circuit though. Basically a light that turns on when it gets outside of specs.