Shunt Trip

[Bobhook149]

Could someone explain how one of these work. Where would you use it? From what i understand it is a low voltage indicator to trip the breaker or something like that?

 

[crazyboy]

120v to the coil shuts off the breaker. Commonly used in commercial kitchens to shut down the electrical under the hood when the extinguishing system goes off, also commonly used for emergency stops etc.

 

[480sparky]

Shunt trip breakers are just like normal breakers but they can be turned off electrically. There is a mechanism built into them that turns them off if power is applied to the mechanism.

Shunt trip breakers usually require an extra 'space' in the panel for the mechanism. Here are some typical 1-, 2- and 3-pole shunt trips:

 

[ohmhead]

Could someone explain how one of these work. Where would you use it? From what i understand it is a low voltage indicator to trip the breaker or something like that?

Well on a commercial building there is a shunt trip button installed outside some times there maybe more than one button its a building fire code rule the fire dept will use it to shut down electric in that building in the event of a fire condition .

In orlando they mount at 7 foot above grade to center of button .

Its for the firemen putting out the blaze so no one gets electrocuted the button is a break glass type when you break the glass it sends 120 volts to the coil located in the main breaker or main disconnect to that building shutting down power .

Yes you can have a 24 volt shunt trip coil what ever voltage you need .

These are also on emergency generators for fire dept .

 

[Aledrell]

Could someone explain how one of these work. Where would you use it? From what i understand it is a low voltage indicator to trip the breaker or something like that?

They are breakers in commerical kitchen that generally go to ovens, grills, and hoods. They can be turned off by an electric signal ussually sent from a fire panel. In my experience these require some coordination with fire sprinkler contractor, because you need to run your shunt wire to the fire panel.

 

[magictolight.com]

Don't forget computer rooms!

 

[ohmhead]

Well i guess we should give the op more good examples next time you get gas look outside the gas station you will see shunt trip buttons for the gas pumps emergency shut down .

In the kitchens as stated there for a fire under the hood a grease fire its by the egress exit door of that kitchen .

Any elevator in a building has a shunt trip breaker if a fire is in the elevator shaft or in the elevator machine it will be shunt tripped by you fire alarm heat detectors in pit or shaft .

there are many reasons and locations for these lots of uses even in a plant or factory for shut down of equipment.

 

[Bobhook149]

are they required by code? If so, where?

 

[480sparky]

are they required by code? If so, where?

Fire & building codes, not an NEC requirement.

 

[LarryFine]

Could someone explain how one of these work. Where would you use it? From what i understand it is a low voltage indicator to trip the breaker or something like that?

Simple explanation: it's a breaker that can be tripped by remote control.

You could use one when you need a circuit to de-energize when one of any number of alarm or emergency events occur, such as to shut down electrical equipment under a commercial kitchen exhaust hood when a fire occurs.

 

[LarryFine]

More info: Often, the electromagnetic coil in the breaker cannot withstand continuous energization. If the circuit that trips it is powered by the same breaker, that takes care of it automatically. Otherwise, the tripping power must be a momentary voltage.

Sometimes, there is an extra contact in the breaker body that is in series with the coil, and sometimes, there is an auxillary contact set (or even two sets) that can be wired to break power to the coil and/or for remote signaling about the breaker tripping.

 

[SG-1]

Shunt Trips

Shunt Trips

When a medium voltage breaker is closed the CLOSING SPRING(S) forces the primary contacts CLOSED and charges the OPENING SPRING(S) When voltage is applied to the shunt trip, which is little more than a relay coil without any contacts, it "pulls a trigger" by moving it's plunger or actuating arm. This releases a latch & the energy stored in the OPENING SPRING opens/trips the breaker.

Low voltage breakers work in a simular way. The resistance you feel while closing the breaker is cocking the OPENING SPRING. The mechanical stored energy can now be released by the thermal trip unit ( detecting a overcurrent), hand operation, or the shunt trip to open/trip the breaker.

As stated before these devices are energized for a few cycles only.



Steve

 

[hurk27]

Any elevator in a building has a shunt trip breaker if a fire is in the elevator shaft or in the elevator machine it will be shunt tripped by you fire alarm heat detectors in pit or shaft .

I thought they would have to stop at the next floor first?

 

[Bobhook149]

yeah i see that being a problem if it does not

 

[hurk27]

yeah i see that being a problem if it does not

Sure let's trap them in the elavator and cook them too:roll:

 

[jeremysterling]

I have a question about shunt trip breakers. In post #3, the first breaker pictured says, "Internal contacts open coil circuit when circuit breaker or interrupter is in any open position". Is this true of all or even most shunt trip breakers?

In the directions for installing a trip coil in an I-line breaker, I did not see any labels like the one on 480sparky's breaker.

 

[hurk27]

I have a question about shunt trip breakers. In post #3, the first breaker pictured says, "Internal contacts open coil circuit when circuit breaker or interrupter is in any open position". Is this true of all or even most shunt trip breakers?

In the directions for installing a trip coil in an I-line breaker, I did not see any labels like the one on 480sparky's breaker.

almost all the ones I use it does, because it remove the triggering power after the breaker has tripped, if it didn't the coil would burn up. but from what I have read on here I guess there are some that can stay energized?

the one in 480's post is a Square D QO, I just hate when the installer doesn't knock out the space covering that label in the panel cover, and you think you have an extra space to steal for an extra circuit:roll:

 

[jeremysterling]

Thanks for answering my question Wayne. I installed a shunt trip breaker that was tested once and I don't know if the one-time test burned up the coil or not. My crappy meter said the coil was open, with the breaker shut. This meter has read open on other (good)coils, so I'm not real worried.

 

[hurk27]

Thanks for answering my question Wayne. I installed a shunt trip breaker that was tested once and I don't know if the one-time test burned up the coil or not. My crappy meter said the coil was open, with the breaker shut. This meter has read open on other (good)coils, so I'm not real worried.

As I said there are some that can stay energized and if you don't provide a cut off or a momentary voltage it can burn up.

I would schedule a time so it could be tested, I would not want it to fail if it is used for life safety. and get a new meter, never let your meter keep you guessing, or you or someone will get hurt. only do test with a known good test equipment, or your just second guessing.

 

[LarryFine]

In post #3, the first breaker pictured says, "Internal contacts open coil circuit when circuit breaker or interrupter is in any open position". Is this true of all or even most shunt trip breakers?

It is definitely not prudent to presume, let's say. I had to replace a 225a 3p shunt-trip ITE breaker because it had been left energized to trip. The malfunctioning fire-suppression system was stuck on, because an emergency manual push-button was pushed in and latched.

The breaker had a built-in auxillary contact set (NO-COM-NC) for just that purpose, and can also be used for remote signalling; I've even seen DPDT aux. contacts before. The contact wires were still neatly coiled up, unused, on back of the breaker in the power panel section. :roll:


Added: The reason they need to break the circuit, at least in the case of the 225a above, is the coil is rated for 120v through 480v, as long as it's a momentary pulse. If the breaker is supplying its tripping circuit, it stops automatically; in my case, it wasn't.