Shunt Trip Brkr

[LarryFine]

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

I usually use them energized closed.

 

[hillbilly1]

KMart would use a latching contactor to shut off the panel. Murphy Oil uses a latching contactor instead of shunttrips for pump emergency shutdown. I didn’t think it would be legal, but could not find anything that would prohibit it.

 

[brantmacga]

I build mostly restaurants; all the kitchen equipment under the hood is on a shunt trip breaker, but we also use shunt trip MCB’s with an e-stop (break glass) outside as an emergency disconnect. We use I-Line gear, and there is a 120v solenoid inside the breaker that hits the trip bar. Also, since most of them are 1200A services we have an additional 12v solenoid connected to a Micrologic trip unit for GFP. Some jurisdictions require us to put an actual disconnect switch outside in lieu of the emergency e-stop.

We used to do shunt trip on individual kitchen equipment breakers, but since the 2017 requires GFCI’s on 3-pole breakers we shunt the feeder to the equipment panels.


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[romex jockey]

I build mostly restaurants; all the kitchen equipment under the hood is on a shunt trip breaker, but we also use shunt trip MCB’s with an e-stop (break glass) outside as an emergency disconnect. We use I-Line gear, and there is a 120v solenoid inside the breaker that hits the trip bar. Also, since most of them are 1200A services we have an additional 12v solenoid connected to a Micrologic trip unit for GFP. Some jurisdictions require us to put an actual disconnect switch outside in lieu of the emergency e-stop.

We used to do shunt trip on individual kitchen equipment breakers, but since the 2017 requires GFCI’s on 3-pole breakers we shunt the feeder to the equipment panels.


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now i'm wondering if i need an E Stop ?

~RJ~

 

[hillbilly1]

I build mostly restaurants; all the kitchen equipment under the hood is on a shunt trip breaker, but we also use shunt trip MCB’s with an e-stop (break glass) outside as an emergency disconnect. We use I-Line gear, and there is a 120v solenoid inside the breaker that hits the trip bar. Also, since most of them are 1200A services we have an additional 12v solenoid connected to a Micrologic trip unit for GFP. Some jurisdictions require us to put an actual disconnect switch outside in lieu of the emergency e-stop.

We used to do shunt trip on individual kitchen equipment breakers, but since the 2017 requires GFCI’s on 3-pole breakers we shunt the feeder to the equipment panels.


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Technically shunt trip mains are not a legal means of disconnect, so that’s why some of the jurisdictions want the outside disconnect. I did have one gear that had a battery backup for the shunt trip button outside, so if utility was partially lost, it still would trip the main. I think that’s why shunt trip mains cannot be used as an emergency disconnect, if one or two phases are lost, it will not trip, leaving the other leg got.

 

[LarryFine]

I build mostly restaurants; . . .

The majority of my fire-suppression wiring has been with updating existing kitchens to comply with newer requirements. I first have to figure out how it's presently wired to add my wiring so the system operates according to the new rules.

It's cheaper and easier to add appliance and receptacle contactors than shunt-trip breakers. One kitchen had a shunt-trip main, but the exhaust fan and alarm still needed power, so I added a small sub-panel using insulation-piercing taps.

 

[gadfly56]

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

~RJ

Power to pull in. The coil runs through the micro switch on the suppression system. When the suppression system head is set, power on. Head tripped, power off, panel off.

 

[LarryFine]

Power to pull in. The coil runs through the micro switch on the suppression system. When the suppression system head is set, power on. Head tripped, power off, panel off.

Right. Better that a defective contactor defaults to the appliance lose power than stay on during a fire.

 

[Alwayslearningelec]

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.

So something else other than the LOAD the breaker is feeding?

 

[LarryFine]

So something else other than the LOAD the breaker is feeding?

A shunt-trip breaker is merely a breaker that can be tripped by remote control.

 

[winnie]

So something else other than the LOAD the breaker is feeding?

Yup. Anything that can supply the shunt voltage can trip the breaker.

Jon

 

[gadfly56]

For kitchen systems, my techs would typically power the shunt coil via one of the hot legs of the breaker itself. This takes care of the issue of powering the coil from a second source which might be switched off by accident. However, if something happened to that little jumper and it was removed or came loose for any reason, you wouldn't know it until the next inspection or worse, system activation during a fire. This is why the source of power is supposed to by monitored.

 

[winnie]

For kitchen systems, my techs would typically power the shunt coil via one of the hot legs of the breaker itself. This takes care of the issue of powering the coil from a second source which might be switched off by accident. However, if something happened to that little jumper and it was removed or came loose for any reason, you wouldn't know it until the next inspection or worse, system activation during a fire. This is why the source of power is supposed to by monitored.

In my one application I intentionally used the undervoltage trip unit instead. If the control circuit lost power then the breaker would trip. The downside is that the breaker needs to be reset after every power outage. Not an issue for my application but I but it would be a deal breaker for many.

-Jon

 

[paulengr]

If you only work with molded case breakers shunt trip might look very strange. But at the switchgear level traditionally a circuit breaker is just a switch able to trip on command rapidly and interrupt high fault currents, nothing more.

All trip functions are implemented by protective relays. There are dozens of different types and configurations. A common one using ANSI numbers is 50/51. In low voltage breakers even if it is done using electronics we still call this “thermal magnetic”. More recently (relatively speaking) two things are happening. The days of the “wall of relays” is done. An entire power generating plant can be done with about 3 multifunction relays. Second we are seeing not only switchgear breakers with built in trip units for simple functions like feeder breakers but the trip units are getting quite sophisticated.

An example of a relatively sophisticated system is main-tie-main. This has 3 switchgear breakers in a row flanked by feeder breakers (for loads). The normal configuration is the tie is open. If a source fails that main opens and the tie closes, restoring power to the side that lost power. This requires both shunt trip and shunt close functions.

In a top of the line switchgear breaker relay a typical set of functions is manual trip and close, lockout (utility “tag out”), instantaneous, thermal, distance relaying, ground fault, negative sequence, reverse direction, tripping on power or power flow, under/over voltage, under/over frequency, various ZSI schemes, battery voltage, various unbalance conditions, and programmable functions, with data recording and full communication. Look at the SEL-751 as an example. Even the fanciest on board relays don’t even come close.

Cost-wise on board trip units are always cheaper but the limited functions make them useless except for simple functions.

 

[LarryFine]

In my one application I intentionally used the undervoltage trip unit instead. If the control circuit lost power then the breaker would trip.

I use contactors for commercial kitchen appliances because it's safer if they fail off.

 

[Open Neutral]

One application:
Gas station Emergency Power Off on the pumps.