Shunt trip breakers

[mtymartin]

Could someone please tell me how a shunt trip breaker works? Such as a fryer hookup, does the ansul system nc switch provide continuos nuetral so that when it goes into alarm the breaker LOOSES a nuetral and shuts down?

 

[celtic]

Real basic description here...
A shunt trip breaker(STB) is simply a breaker that can be tripped from a remote location at will.

The shunt is a 120v coil...just like a contactor has - an electro-magnet, for example.

On the STB will be 3 screws...one is for the actual load - to your fryer. The other two recieve 120v (for the coil to operate) BUT applying 120v will keep the STB from ever suppling the fryer with power. The coil needs to be broken..switched.

Depending on how the system is installed (Ansul, under hood requirements, FA connect, etc) will dictate if a NO or NC point is used on the Ansul micro switch.
In my experiences, I have used a NO point. When the Ansul goes into "alarm" state, the micro switch will CLOSE the 120v circuit to the STB - OPENING the circuit that feeds the fryer.

Does that help at all?

 

[LarryFine]

To add: if the STB cannot withstand a continuous voltage on the coil, you must either power it from itself or make sure it contains auxillary contacts you can wire in series with the coil.

 

[celtic]

To add: if the STB cannot withstand a continuous voltage on the coil, you must either power it from itself or make sure it contains auxillary contacts you can wire in series with the coil.

Nice catch Larry....I mentioned the silly fryer so many times I negelected to mention the S on the STB could get fried by constant power :grin:

 

[zog]

A shunt trip is a feature on a breaker, not a type of breaker.

 

[mtymartin]

Yes that is excellent info and pretty much like I thought. More than likely here I need the NO switch, but will be sure to check for continuos operation. Thanks gentlemen so much.