Testing Shunt trip breakers - Electrician Talk - Professional Electrical Contractors Forum

Mr. Sparkle · 11-06-2009, 08:31 PM

Why you no reset Shunt trip breaker?

Anyone ever tested a Shunt system and had a breaker not reset afterwords?

Just wondering because this was an existing system in good shape that was tested today and all the sudden one of the breakers went to sh*t after testing.

480sparky · 11-06-2009, 08:33 PM

Did it open because the control system activated the shunt mechanism, or did the circuit powered by the breaker experience an overload/short?

Mr. Sparkle · 11-06-2009, 08:36 PM

Control system activated, just testing it. No short.

480sparky · 11-06-2009, 08:40 PM

Maybe the coil voltage is still being applied?

Selectric · 11-06-2009, 08:42 PM

Is the switch that is used for the S/T control a momentary or maintained contact? Is it possible that it is one of those big mushroom switches that need to be pulled back out?

Mr. Sparkle · 11-06-2009, 08:56 PM

This was an Ansul system in a kitchen, another EC I was helping today tested it from the Kitchen location and all the shunts tripped but one will not reset. I am not very familiar with the system, I am just trying to help him troubleshoot prior to purchasing a new breaker.

wildleg · 11-06-2009, 08:58 PM

what's the brand/model# ?

rewire · 11-06-2009, 09:00 PM

maybe bad contacts or faulty relay

nolabama · 11-06-2009, 09:07 PM

maybe bad shunt trip breaker

Selectric · 11-07-2009, 09:57 AM

Remove the S/T control wiring from the breaker in question and try to reset the breaker. In addition, test for voltage on the S/T control wiring that you removed from the breaker.

Zog · 11-07-2009, 10:50 AM

Amazing, all sorts of bad advice on how to "test" a breaker when we don't even know what type of breaker this is. There is no such thing as a "shunt trip breaker", a shunt trip is an accessory.

Please, don't do anything stupid like bypass protective functions and reset this breaker, that type of miove will get you killed and/or do some serious damage to equipment.

Post the breaker type and cat# and any other nameplate info so we can give you some real advice.

TOOL_5150 · 11-07-2009, 10:56 AM

Quote:

Originally Posted by Zog

Amazing, all sorts of bad advice on how to "test" a breaker when we don't even know what type of breaker this is. There is no such thing as a "shunt trip breaker", a shunt trip is an accessory.

Please, don't do anything stupid like bypass protective functions and reset this breaker, that type of miove will get you killed and/or do some serious damage to equipment.

Post the breaker type and cat# and any other nameplate info so we can give you some real advice.

What, Really? There is no such thing as a shunt trip breaker? What the heck are these other guys talking about with breakers that have an additional wire coming off of them, labeled as shunt trip breakers?

~Matt

TOOL_5150 · 11-07-2009, 10:58 AM

By the way, That was an honest question. All the breakers I have seen that are labeled as shunt trip, sure do not look like it is an accessory, they look to be part of the breaker itself.

~Matt

drsparky · 11-07-2009, 11:34 AM

Quote:

Originally Posted by Zog

Amazing, all sorts of bad advice on how to "test" a breaker when we don't even know what type of breaker this is. There is no such thing as a "shunt trip breaker", a shunt trip is an accessory.

Please, don't do anything stupid like bypass protective functions and reset this breaker, that type of miove will get you killed and/or do some serious damage to equipment.

Post the breaker type and cat# and any other nameplate info so we can give you some real advice.

Sorry Zog, but they are selling a lot of imaginary breakers, here are a few examples.
http://www.grainger.com/1/3/shunt-trip-circuit-breaker

wildleg · 11-07-2009, 11:46 AM

if you take the cover off the breaker you will find that the shunt trip is generally an optional part. shunt trip breakers are often ordered with the feature already installed, so it may not be obvious to you if you have never taken one of those breakers apart. I am no expert tho - there may very well be breakers what have them built in, but I have no knowledge of that.

Mr. Sparkle · 11-07-2009, 11:50 AM

Its an Ansul system in a kitchen that controls a few 1 pole SQ D breakers with shunts attached to them. We did not get a chance to even start troubleshooting it, just looking for advice on some common points to check in the system before I assume it is the shunted breaker.

Zog · 11-07-2009, 01:19 PM

Quote:

Originally Posted by TOOL_5150

By the way, That was an honest question. All the breakers I have seen that are labeled as shunt trip, sure do not look like it is an accessory, they look to be part of the breaker itself.

~Matt

And it was an honest answer, a shunt trip is an accesory added to a breaker. It would be like calling your car an air conditioned car. It's not a type of car but just a feature. Symantics I suppose.

micromind · 11-07-2009, 01:54 PM

I've always called them 'shunt-trip breakers' too. Though this term is not exactly technically correct, everyone knows what I'm referring to.

Interesting though, I usually call a breaker with an undervoltage trip coil a ' breaker with undervoltage trip'.

Since the breakers in question are 120 volt branch circuit breakers, the easiest way to test them would be to remove the panel cover, disconnect (and isolate) one of the trip coil wires, disconnect the load wire, and try to re-set the breaker. This is about as safe as you're going to get without removing it from the panel, which I consider completely unnecessary.

Wait a sec here!!! Since removing the panel cover could be considered hot work, you'll need to shut down the entire national power grid in order to be in complete compliance with all safety regulations. No hot work! ever! Rules are rules!

Seriously, lets be at least somewhat reasonable with safety here.

Rob

Selectric · 11-08-2009, 09:50 AM

Like micromind and I said if you remove the S/T control lead from the breaker and it resets then there is a problem with the control. If it does not reset then it is the breaker itself.

Zog is part correct some of the larger breakers have the S/T as an accessory that can be field replaced and/or installed. I have never seen a small breaker like a SqD QOB that was not a factory made S/T.

Without looking at the problem I would suspect a bad breaker or control relay. Since you stated that all breakers tripped on that Ansul system and all but that one would reset. Most of the Ansul systems that I worked on have 120 control power to the dry contact switch at the Ansul bottle. From the Ansul bottle switch to a hoffman box with relays to control all the safety devices connected to the system, S/T breakers, gas valves, exhaust fans etc.

220/221 · 11-08-2009, 12:27 PM

Quote:

Symantics I suppose

Ya think?

Perhaps shunt tripped would be more appropriate but....shut up.

The term shunt trip breaker is commonly used therefore there is such a thing.

Quote:

Post the breaker type and cat# and any other nameplate info so we can give you some real advice

I am going to go out on a limb here and suggest that most shunt trip breakers that we are talking about here are all the same.

I am just guessing here from what I've seen but, voltage (120 in the ones I've installed) goes thru a coil in the shunt portion tripping a spring loaded lever which turns the breaker off via the tie bar.

Anyway....all I can suggest is the obvious. Remove the shunt wire and try to reset. Maybe take the tie bar off and try to rest it??