Easiest method of determining contact sequence

[lester mcmanaway]

easiest method of determining contact sequence on LV breaker.
light circuit
slow close
c...
d...
I feel like this ones a little misleading. the light circuit is useless unless you slow close the breaker(which is incorrect apparentlly).

[Sanjayo]

what is the alternate method if you don't use a light circuit?

[lester mcmanaway]

what is the alternate method if you don't use a light circuit?

In our shop we slow close them and use a pin gage set with the arc chutes off to ensure the contacts make within manufacturers spec. (typically an 1/8 as the article reads.) I feel like there is no diffinitive way to tell how much of a variance you have if the lights don't turn on at the exact same time. Its going to be a judgement call that leaves room for error I feel.
Aside from that how do you use a light circuit if you don't slow close the breaker? I just think they should both be the correct answer if nothing else.

[Sanjayo]

Removing the arc-chutes can be a real pain on some models. The procedure you described seems much harder than hooking up a proper light circuit to the primary stabs and doing the simple slow close...

[lester mcmanaway]

harder but if asked by a customer i'm certain they are correct with my method. But thats kind of besides the point, not really what i was getting at. One of the answers is slow close and one is a light circuit. If slow closing is not a viable method than a light circuit is irrelevant because it would be useless without slow closing the breaker. Regardless of how you measure the touching of the arcing contacts you still have to slow close it to check when the contacts touch. I just think the question needs reworded.

[Sanjayo]

No doubt your method is better but the question is which way is easiest. My point is that the slow close doesn't determine the contact sequence, its the act of verifying contact either physically (by looking or measuring) or electrically (using lights).

[lester mcmanaway]

The light method just does not seem accurate to me. So if you turn the handle on an akr, 1 light lights up move the handle a quarter inch and the second and third lights come on, is that in spec? It would just be a guess really. Im sure its a pretty rare occasion to see the lights come on exactly simultaneously. I feel like even just looking at the contacts with arc chutes off (slow closing) and not even measuring I would have a better chance of telling you if your contacts are in spec than just by guessing if the variance in the lights its ok.

[lester mcmanaway]

I also hope the arc chutes are coming off anyway during inspection and testing. I was under the impression that was pretty much an industry standard when field testing and cleaning a breaker?

5 posts :D

[SecondGen]

Light circuit is used to find out which contact touches first, then you measure the other two, which requires pulling arc-chutes. There should be no more than the 0.032” or whatever manufacturer specifies.


Removing the arc-chutes can be a real pain on some models. The procedure you described seems much harder than hooking up a proper light circuit to the primary stabs and doing the simple slow close...

[SecondGen]

I also hope the arc chutes are coming off anyway during inspection and testing. I was under the impression that was pretty much an industry standard when field testing and cleaning a breaker?

Related -> http://testguy.net/threads/2758-Do-you-always-pull-arc-chutes

[andykaster]

Related -> http://testguy.net/threads/2758-Do-you-always-pull-arc-chutes

I normally take off arc chutes unless they are old asbestos ones. I never touch them or use compressed air on those.