Shunt trip breaker

[rodriguezandy]

I need to install a 100amp 3 pole breaker with shunt trip accessory in its own enclosure in a xray room that will serve the xray equipment, the breaker is being feed from the main panel. I need an e-stop button to engage the shunt trip coil to trip the breaker incase of an emergency, this shunt trip accessory is rated 120v (same as the breaker.) My question is, can I supply 120v from 1 of the legs on the load side of the breaker to a n/o e-stop which will energize the shunt trip coil and trip the breaker when the button is engaged? The breaker being used is Siemens ED43B100L and the shunt trip accessory is S01ED60. I don't want to have to run a circuit from the main panel for the shunt trip reason being is dedicated circuit breaker for the shunt trip could be manually turned off at the main panel and would disable the emergency power off and won't trip the shunt trip breaker incase of an emergency.

 

[LarryFine]

I don't think there is any prohibition to doing that.

 

[augie47]

Two items come to mind.
You would need some approved method to connecting the conductor to the 100 amp circuit. Doubtful the lugs are rated for that 2nd conductor.
The conductor to the stop would need to be protected at its ampacity.

I would lean more to supplying the e-stop from a dedicated breaker and installing a breaker lock on that breaker.

 

[jim dungar]

You would need some approved method to connecting the conductor to the 100 amp circuit. Doubtful the lugs are rated for that 2nd conductor.

Many breakers that size have lug options for control terminal connections. Some provide a 1/4 'stakon' while others are simply holes drilled and tapped for a screw.
Check with the breaker manufacturer

 

[gadfly56]

We have done this with kitchen systems from time to time. I prefer using contactors with energized relays instead. Break the connection, power off. No need to worry about secondary breakers being turned off, monitoring the power to the shunt coil, or protecting the wire to the shunt coil. Inherently fail safe.

 

[LarryFine]

We have done this with kitchen systems from time to time. I prefer using contactors with energized relays instead. Break the connection, power off. No need to worry about secondary breakers being turned off, monitoring the power to the shunt coil, or protecting the wire to the shunt coil. Inherently fail safe.

And cheaper.

 

[hillbilly1]

We have done this with kitchen systems from time to time. I prefer using contactors with energized relays instead. Break the connection, power off. No need to worry about secondary breakers being turned off, monitoring the power to the shunt coil, or protecting the wire to the shunt coil. Inherently fail safe.

It is definitely failsafe, but I think the humming is what drives engineers to specify other means. K-Mart back in the day used a large latching contactor for the panel, so if you lost control power, it wasn’t going to unlatch.

 

[SceneryDriver]

Use an under voltage release for your breaker, instead of a shunt trip. Wire your E-stop(s) normally closed, powered from a separate breaker (with a lock). That way, a broken wire or damaged switch will cause a trip, and it will fail to a safe state.

E-stops are never wired as normally open - you can't tell the difference between a switch not pressed and a broken wire. A technician could hit the E-stop and the X-ray machine could continue to operate since the shunt trip would never trigger.


SceneryDriver

 

[hillbilly1]

Use an under voltage release for your breaker, instead of a shunt trip. Wire your E-stop(s) normally closed, powered from a separate breaker (with a lock). That way, a broken wire or damaged switch will cause a trip, and it will fail to a safe state.

E-stops are never wired as normally open - you can't tell the difference between a switch not pressed and a broken wire. A technician could hit the E-stop and the X-ray machine could continue to operate since the shunt trip would never trigger.


SceneryDriver

The problem with that, is a power blip or outage may trip the breaker, so the machine would be down until maintenance can reset it. Fresh Market found that out on their deli hoods.

 

[SceneryDriver]

The problem with that, is a power blip or outage may trip the breaker, so the machine would be down until maintenance can reset it. Fresh Market found that out on their deli hoods.

As it should be. I think an X-ray machine definitely counts as a "dangerous machine" that shouldn't be allowed to restart automatically after a power outage. A few indicator lights, and the operator will know that they have to press the RESET button to recover from an E-stop or a power outage.


SceneryDriver

 

[hillbilly1]

As it should be. I think an X-ray machine definitely counts as a "dangerous machine" that shouldn't be allowed to restart automatically after a power outage. A few indicator lights, and the operator will know that they have to press the RESET button to recover from an E-stop or a power outage.


SceneryDriver

But the breaker has to be manually reset. Most places like that only allow maintenance to reset the breaker. Lab tech is not a qualified person.

 

[SceneryDriver]

But the breaker has to be manually reset. Most places like that only allow maintenance to reset the breaker. Lab tech is not a qualified person.

Then use a safety contactor and a safety relay to do a proper E-stop circuit. That way, the operator gets the reset button. 24VDC contactor coil solves the humming while energized issue. I wonder if the X-ray machine might have a dry contact that could be interrupted with a safety relay to shut it down. It would save having to use the contactor.


SceneryDriver

 

[William Johnson]

yes, your idea might be doable, but I’d lean toward using a separate, properly protected circuit for the shunt trip coil to avoid potential lug rating issues and to keep the system safer and code‑compliant.

 

[SceneryDriver]

yes, your idea might be doable, but I’d lean toward using a separate, properly protected circuit for the shunt trip coil to avoid potential lug rating issues and to keep the system safer and code‑compliant.

What do lug ratings have to do with anything?


SceneryDriver

 

[jim dungar]

yes, your idea might be doable, but I’d lean toward using a separate, properly protected circuit for the shunt trip coil to avoid potential lug rating issues and to keep the system safer and code‑compliant.

See post #4. Lugs with control terminations are often a standard option in larger frame and industrial breakers.

 

[Jraef]

See post #4. Lugs with control terminations are often a standard option in larger frame and industrial breakers.

The Siemens breaker that the OP says he has is unfortunately one that does not have that option.

Side issue: I believe that EDB43100 breaker is not of the type that you can add a shunt trip (or UV trip) to in the field, it must be ordered from the factory with it installed. So if you are going to have to go that route, the contactor makes more sense. There are “silent/low hum” contactors available, depending on the actual current you need. This is a 100A breaker, but is the x-ray machine actually using 100A?

 

[rodriguezandy]

These are all great ideas, would've loved just doing a contactor. But the engineer who designed it wanted a shunt trip breaker and an e-stop button. I might just run a separate circuit for the estop and put a breaker lock on the breaker.

 

[rodriguezandy]

Then use a safety contactor and a safety relay to do a proper E-stop circuit. That way, the operator gets the reset button. 24VDC contactor coil solves the humming while energized issue. I wonder if the X-ray machine might have a dry contact that could be interrupted with a safety relay to shut it down. It would save having to use the contactor.


SceneryDriver

This is how it should have been designed, idk why they want a shunt trip breaker having a safety contactor would've been ideal like you said. I could have probably suggested the change to the engineer.