Shunt trip breaker

[Joshua L. Frederick]

Can someone explain these a little better to me? I have a general idea on there purpose, but I was wondering about the inspection part of it. I have no idea what its protecting, should I just disclaim and say its present? Or how do you report on them if found?

BTW, Very small commercial building.

Thanks in advance.

[rmaday]

From http://www.maintenanceresources.com/...ircbreak5.html


SHUNT TRIP

Some times it is advantageous to turn a breaker off from a remote location. To facilitate this task, an accessory called a shunt trip feature is installed by the manufacture inside of the breaker. This device consists of an electro-magnetic trip coil that is connected in series with an external field wired switch. When the switch contacts are closed, power is passed to the shunt trip coil causing the breaker’s mechanical latch to move to the open position. Re-closing the breaker is done by physically going to the breaker and manually moving the operating handle to the on–closed position.
When opened by use of the shunt trip coil, the breaker’s operating handle moves to the off (maximum handle travel) and not the tripped (short of full handle travel) position. Knowing this can help when trying to determine if the breaker tripped off due to an overcurrent condition or was remotely turned off.


HTH

[Joshua L. Frederick]

Yeah, I read this one already, but I thank you anyway. I was wondering exactly what they're usually installed for and why.

[Michael Larson]

Often used to shut down supply air to the structure in the event of a fire.

[Frank P. Newman]

In industrial/commercial power systems almost all large circuit breakers use shunt trip circuitry. This allows multiple relays to monitor conditions in a circuit (overcurrent, ground fault, open phase, bus differential, etc.) and trip the applicable breaker(s) when required. There is very little true need for shunt trip breakers in the typical residence, but some will be found from time-to-time, employed mostly for convenience sake.

[Harry F. Johnson, II]

Originally Posted by mlarson

Often used to shut down supply air to the structure in the event of a fire.

elevators are another example