Shunt Trip Brkr

[Alwayslearningelec]

What the purpose(s) of a shunt trip breaker? These always seem to be stand-alone and not a breaker within a panel with other breakers.

 

[ramsy]

Had to look it up. I suppose to stop letting the smoke out.

 

[bwat]

It just means that something else can trip the breaker, other than the breaker itself.

Silly example: Let’s say the breaker is feeding power to a location that could possibly have a water leak. You install a leak detection sensor in that area and design it such that if the sensor detects water, it send a signal to the breaker to trip via the shunt trip.

 

[gadfly56]

What the purpose(s) of a shunt trip breaker? These always seem to be stand-alone and not a breaker within a panel with other breakers.

These are standard devices for shutting down power in commercial kitchens to electrical appliances in the event of a fire on the cook line, or shutting down elevators before sprinkler activation

 

[jim dungar]

Probably the most common shunt trip breakers, an electrical would install, are for fire protection systems (i.e. Ansul).

For miniature molded case breakers the shunt trip takes up an additional pole space. It is not uncommon to find them in separate enclosures near the equipment they control.

 

[ptonsparky]

Hazardous areas such as propane, gasoline, etc. Shunt trip an entire panel with one breaker.

 

[infinity]

We recently installed one one a feeder to a panel in a boiler room. They had a break glass switch at each door in case they needed to shutdown the boilers from outside the room.

 

[petersonra]

They are a handy way to shut down power without having to do it with a contactor. I don't use them real often but they can be real handy in the right circumstance. I think the last one I used was to shut down the power to a transformer that fed the exciter to a genset.

 

[mikeames]

Wired one in a school Shop. All the equipment was fed from one panel. A shunt trip main was used and wired to a series or mushroom e-stop switches around the shop. If for example someone had a sweatshirt string being pulled into a machine anyone could push any of the e-stop switches and kill the power. The e-stope required a key to reset. Or the instructor could essentially lock out the equipment while away.

 

[don_resqcapt19]

What the purpose(s) of a shunt trip breaker? These always seem to be stand-alone and not a breaker within a panel with other breakers.

Everyone I have installed was in a panel...sometimes a main to shut down the complete panel and sometimes a breaker to shut down a specific piece of equipment.

 

[Buck Parrish]

It just means that something else can trip the breaker, other than the breaker itself.

Silly example: Let’s say the breaker is feeding power to a location that could possibly have a water leak. You install a leak detection sensor in that area and design it such that if the sensor detects water, it send a signal to the breaker to trip via the shunt trip.

Where could I find a leak detector that would do that ?. I suppose it would have a LV wire to the shunt. That's exactly what I've been looking for.

 

[hbiss]

Where could I find a leak detector that would do that ?. I suppose it would have a LV wire to the shunt. That's exactly what I've been looking for.

Security and alarm suppliers like ADI normally have them. Names like Water Bug, etc. These are low voltage devices with NO and NC contacts on the output. Since the shunt-trip coil on most shunt trip breakers is line voltage (actually will operate on 120-240V), you are going to have to provide a relay with a 12 or 24VAC coil to control line voltage to operate the shunt trip.

-Hal

 

[hillbilly1]

Shunt trips are available in lower voltages such as 24 volts, but keep in mind a lot of them have a high current pull when first energized. Most have clearing contacts, so once activated, coil voltage is removed once breaker opens. One reason they are used, it requires a manual reset of the breaker, cannot be reset automatically regardless if E-Stop or other control is reset. They are also used for shutting off power to UPS units in case of fire or other malfunction.

 

[winnie]

There is a similar device called an under voltage trip. As the name implies you have to supply voltage to the device to prevent tripping.

Can be used in similar situations to a shunt trip, and may save a pair of wires for some applications.

Jon

 

[Jraef]

To explain it further;
Inside of all breakers is a "trip bar", a mechanism that is directly coupled to the latching mechanism that hold the contacts closed when you turn it on. Then the "trip sensors" are either magnetic or thermal elements that act to "hit" that trip bar and release the mechanism, opening the breaker.

A Shunt Trip (ST) is simply an additional electro-magnet coil that you can control from the outside that acts on that same trip bar inside of the breaker. So is an Under Voltage Release (UVR) mechanism, except it is ALWAYS energized and DE-energizing it causes it to act on the trip bar. In some smaller breakers, there is no room inside of the breaker housing itself to add a ST or UVR, so they are made as "side cars" that attach NEXT to the breaker. You don't see them used in panels much because they consume a breaker mounting space and those are always in demand. Hence them being put in stand-alone enclosed breaker package in most cases. On larger 2 and 3 pole breakers, the ST or UVR coil could be installed inside, so all you see are two small wires coming out. In the past, these had to be mounted at the factory, so you had to order them that way, but in recent years most breaker mfrs have changed to having "accessory pockets" on the front of the breaker under the face plate that allow you to add a ST or UVR to an existing breaker. Those have made it easier to add them after the fact.

 

[LarryFine]

Also to add, unless the circuit(s) being opened also supply the tripping power, make sure the trip can withstand constant power.

 

[jim dungar]

Also to add, unless the circuit(s) being opened also supply the tripping power, make sure the trip can withstand constant power.

Or have integral coil clearing contacts, as is common on molded case breakers.

 

[romex jockey]

These are standard devices for shutting down power in commercial kitchens to electrical appliances in the event of a fire on the cook line, or shutting down elevators before sprinkler activation

yup, doing one now , shunt fed subpanel for anything under the 'hood' when it activates


~RJ~

 

[gadfly56]

yup, doing one now , shunt fed subpanel for anything under the 'hood' when it activates

View attachment 2557536
~RJ~

That's the smart way to do it. I've seen panels full of 6 or so shunt trip breakers for the appliances. I'd still rather use a contactor.

 

[romex jockey]

That's the smart way to do it. I've seen panels full of 6 or so shunt trip breakers for the appliances. I'd still rather use a contactor.

hmmmmm, yeah but, a contactor that lives activated 'open' Gad???

~RJ