Shunt Trip Breaker circuit possibly wired wrong

[jim dungar]

I have found that some devices, like protective relays, do not always follow the 'laying on the table' method of NO and NC.
One thing they have in common is a source of control power with a 'fail safe' set of contacts (effectively the contacts are held active, like with a normally 'made' limit switch), they are usually intended to replace an '2-state' mechanical set of contacts.

 

[T.M.Haja Sahib]

I have found that some devices, like protective relays, do not always follow the 'laying on the table' method of NO and NC.
One thing they have in common is a source of control power with a 'fail safe' set of contacts (effectively the contacts are held active, like with a normally 'made' limit switch), they are usually intended to replace an '2-state' mechanical set of contacts.

Are you talking about electrically operated but mechanically held contacts?

 

[T.M.Haja Sahib]

I am glad you finally understand.

It is the OP who need to understand and not me.
Anyway,please reread the first sentence in post#13....:lol:

 

[jim dungar]

Are you talking about electrically operated but mechanically held contacts?

No. These are more like electrically operated, electrically held.There is no standard which must be followed, so we find contact designations that were created by 'electronics' people, rather than ones trained in industrial nomenclature.

 

[gadfly56]

I said about contactor for illustrative purpose.
The contacts of limit switch or whatever it may be should be NO initially.

Not necessarily. In the case of kitchen systems and the use of contactors, almost certainly NOT. IMHO, shunt trips are not the preferred method of interrupting power for a UL300 suppression system. A contactor that has to be energized to allow power to the cooking equipment is more preferable. In that case, you run through the NC and C contacts, as defined by the Automan control head in the "set" position. Absent some truly freaky condition, any failure is most likely to be in the "safe" state.

 

[hurk27]

Not necessarily. In the case of kitchen systems and the use of contactors, almost certainly NOT. IMHO, shunt trips are not the preferred method of interrupting power for a UL300 suppression system. A contactor that has to be energized to allow power to the cooking equipment is more preferable. In that case, you run through the NC and C contacts, as defined by the Automan control head in the "set" position. Absent some truly freaky condition, any failure is most likely to be in the "safe" state.

If you have several electric deep fryers then 6 or 7 120 volt receptacle circuit, and a make up air unit that all have to be shut down your saying that you would prefer to install all those contactors verses installing a subpanel with a shunt trip main with a 24 volt coil fed from a small class-2 transformer, way less for the money:? and labor wise also, I have never seen a shunt trip that required power to maintain but if one is made then you could have the best of both worlds, I do see your point and I understand that fail safe is better, but some of those deep fryers are 30-40 amps and contactors would be expensive.

Of course you could feed a sub panel from a contactor and have the fail safe also.

It is also easy enough to to use the NC contacts of a small Ice cube relay that would do the samething as it would fail safe to shunt trip the breaker and still use the NC contacts in the Ansel system to turn off the relay.

 

[jim dungar]

...I have never seen a shunt trip that required power to maintain ....

This would be called an 'undervoltage trip'.

Every major manufacturer of breakers uses these terms:
shunt trip means remote power must be applied to open device
undervoltage trip means remote power must be applied to keep breaker closed

 

[gadfly56]

This would be called an 'undervoltage trip'.

Every major manufacturer of breakers uses these terms:
shunt trip means remote power must be applied to open deviceundervoltage trip means remote power must be applied to keep breaker closed

And for that reason, hurk, you can wind up in the hurt locker right quick if the power to the shunt coil - which is usually from a separate 15 amp breaker - fails. Now what you are supposed to do is monitor the power to the coil, and notify someone when it drops out. Otherwise you only know when the suppression system tech does his check that the shutdown isn't operable. And the really uncomfortable question is, "Has it only been down one minute, or down for 6 months minus one minute?" I'd just as soon not have to entertain the question.

 

[gadfly56]

If you have several electric deep fryers then 6 or 7 120 volt receptacle circuit, and a make up air unit that all have to be shut down your saying that you would prefer to install all those contactors verses installing a subpanel with a shunt trip main with a 24 volt coil fed from a small class-2 transformer, way less for the money:? and labor wise also, I have never seen a shunt trip that required power to maintain but if one is made then you could have the best of both worlds, I do see your point and I understand that fail safe is better, but some of those deep fryers are 30-40 amps and contactors would be expensive.

Of course you could feed a sub panel from a contactor and have the fail safe also.

It is also easy enough to to use the NC contacts of a small Ice cube relay that would do the samething as it would fail safe to shunt trip the breaker and still use the NC contacts in the Ansel system to turn off the relay.

Amp for amp, contactors are cheaper that shunt trip breakers, certainly in 3-pole. And yes, if you have a ton of electric junk under the hood, by all means, use a sub-panel fed through a suitable contactor, which will still be cheaper than a main shunt trip breaker or a collection of half a dozen shunt trip panel breakers.

 

[kwired]

Contactors are not guaranteed fail safe either. Contacts weld together, coils overheat and melted plastic ends up holding armature in closed position.

Power for the shunt trip is best to be derived from the shunt trip breaker itself if possible then you have no worry about loss of control power, if it is lost the controlled item doesn't work and you know there is a problem.

Next best option is to get power from shunt trip from something common like the exhaust fan in the kitchen hood install. If the exhaust fan goes down there is a problem and it will be noticed.

 

[iwire]

Amp for amp, contactors are cheaper that shunt trip breakers, certainly in 3-pole.

This assumes you already have the regular breaker.

Without question a shunt trip breaker is less than a regular breaker and contactor, the labor is less as well.

 

[gadfly56]

This assumes you already have the regular breaker.

Without question a shunt trip breaker is less than a regular breaker and contactor, the labor is less as well.

For new construction or gut-and-rehab, the economics will swing that way. We usually see a situation where someone managed to get the electric appliances installed without the shutdown and it's a retrofit. And overall, I still prefer the contactor for a more-likely fail safe operation.

 

[gadfly56]

Contactors are not guaranteed fail safe either. Contacts weld together, coils overheat and melted plastic ends up holding armature in closed position.

Power for the shunt trip is best to be derived from the shunt trip breaker itself if possible then you have no worry about loss of control power, if it is lost the controlled item doesn't work and you know there is a problem.

Next best option is to get power from shunt trip from something common like the exhaust fan in the kitchen hood install. If the exhaust fan goes down there is a problem and it will be noticed.

I know that we've done this in the past, but I couldn't find anything in the NEC that allowed me to do a tap at the breaker inside the panel to get this done, so I told my techs to stop doing that. I know that I'm certainly not a code weenie as far as NFPA 70 is concerned, so maybe someone here can help out.

Still, if the wire were disloged or removed by someone who didn't know what it was for (Murphy's Law and all), you'd be back at square one for shunt coil power.

 

[kwired]

I know that we've done this in the past, but I couldn't find anything in the NEC that allowed me to do a tap at the breaker inside the panel to get this done, so I told my techs to stop doing that. I know that I'm certainly not a code weenie as far as NFPA 70 is concerned, so maybe someone here can help out.

Still, if the wire were disloged or removed by someone who didn't know what it was for (Murphy's Law and all), you'd be back at square one for shunt coil power.

Why does it need to be tapped at the breaker?

Overcurrent protection can be an issue, that is why the exhaust fan works well most of the time.

 

[KSAcontractor]

Shunt Trip Breaker issue

Shunt Trip Breaker issue

I would check the coil voltage on the shunt trip breaker to confirm the operating voltage then check the contacts across the Ansul system to make sure they are working and connected to the correct voltage.
In a fire alarm system, most if not all operate "energize to trip" so a normally open (NO) set of contact should be used so that when the Ansul system is activated in an alarm condition the contacts change state to the closed position completing the circuit and activating the shunt trip coil on the circuit breaker. Make sure the Ansul system is in the test or safe position so you do not accidently discharge while working on it. I would contact the local equipment service provider to assist you before starting any work.