Protecting contacts

Typically to protect contacts from inductive kickbacks in AC, a snubber
network is used. As an alternative, can a MOV provide a reliable function
for the same purpose, i. e. will the MOV survive repeated strikes even if
chosen properly from the energy absorption viewpoint?
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MOV's degrade with repeated surge currents (since it has to act like a short circuit when it fires, localizied heat build up within the MOV will eventually cause the whole MOV to fail).
I had better luck with gas tubes when we turned on large inductors on/off and resulting L di/dt caused several hundred volt surges on 48VDC rail which would kill components left & right. Gas tube can light up millions of times (it is also a great visual indicator to let you know if it is still working or not) without failing. I built an automated tester which would cause an inductive surge every minute & the test ran 24 hours per day, and even on weekends (so om one year, we created 24 hours x 60 minutes x 200 days of operation = 288,000 times). Even after 3 years (nearly 1 milliion firings), the gas tube held up just fine - it was awesome !!!
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Nam Paik

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