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Old February 9th, 2018, 01:25 PM   #4
United States

mk42 is offline
Join Date: Jun 2013
Location: MI
Posts: 2,092
Originally Posted by Timeismoney08 View Post

So I'm designing a motor circuit that will have E-stops running to a AB safety relay.

What keeps the Contactor that the safety relay will pull in safe? How do I prevent a contactor from becoming welded?

I've went over some historic drawings of other machines I've seen and the safety relay is always force guided and control reliable, but it always seems as if the contactor were welded shut, nothing would ever know.

Thanks in advance!

Generally, you use TWO contactors, so that if one welds shut, the other will still break the circuit. You should also be using contactors with an auxiliary feedback contact, to report status back to the system/safety relay.

I believe it is usually required to have a periodic test carried out (once a shift, once a day, once a week, depending), to check for hidden faults. This is often procedural, not automated.
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