# Shunt Trip Coils?



## HARRY304E (Sep 15, 2010)

KTodderM said:


> I'm just wondering if there is a limit or a not to exceed time on the coil of an energized shunt trip breaker?
> 
> I installed 2- 100A/2pl Shunt trip cut-hammer BR's. These are both mains for sub panels. 1 feeds 3 submersible motors in fuel tanks, the other feeds 8 switched neutral breakers for fuel dispensers. That part may not be relevant to the question, but the 2 E-Stop switches are both N.O. with maintained mushrooms. So is it OK to energize those shunt coils for an extended amount of time?
> They have been tested and approved by the fire marshall but im worried that if they are tripped in the future how long can the coils of the breakers run before they burn up?
> Thanks for looking at my question. I can give any details needed.


Well I'll bet those coils are rated to run for a good amount of time unless they are overloaded.

Welcome to the forum..:thumbup:


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## micromind (Aug 11, 2007)

Shunt trip coils will burn up in just a few seconds if left energized. That's why most (if not all) breakers that have these coils also have a switch inside to de-energize the coil once the breaker has tripped. 

Even if the breaker didn't have such a switch, if the shunt trip control circuit is powered downstream of the breaker, the coil will not be energized when the breaker is tripped.


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## Bbsound (Dec 16, 2011)

to avoid that issue, feed the shunt trip control circuit from the breaker you are shunting


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## KTodderM (Dec 1, 2012)

Hey thanks a lot guys, I had already planed on changing out the push buttons to momentary rather than the maintained. I really like the idea of moving the control circuit to one of the panels it opens. 
So most if not all shunt trips will open their own internal control circuit when tripped? Hey thanks again for the help! And quick too!


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