Shunt Trip

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hillbilly1

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..and what happens to the individual shunt trip circuits? How do you monitor an open wire on a passive circuit?

Hint: check out the Genius I/O system from GE.
As I said before, monitoring shunt trips is rare, they do not have the requirements that Fire alarm systems and such. Even switchgear manufactures do not monitor the shunt trip connected to the ground fault relay. In a super critical application, the Genius I/O system would be ideal though.:smile:
I would not use shunt trips for critical application anyway, electrically held contactors would be a better choice, if any part of the circuit fails, power is disconnected. There are pros and cons for either system.
 
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As I said before, monitoring shunt trips is rare, they do not have the requirements that Fire alarm systems and such. Even switchgear manufactures do not monitor the shunt trip connected to the ground fault relay. In a super critical application, the Genius I/O system would be ideal though.:smile:
I would not use shunt trips for critical application anyway, electrically held contactors would be a better choice, if any part of the circuit fails, power is disconnected. There are pros and cons for either system.
Electrically held contactors are a good solution. However, I have seen contactors weld shut or not to open after being held close for a long time. (It was a freak manufacturing defect though; some laminate coating residue getting between the core's polished surfaces and effectively 'gluing' the surfaces together as the heat polymerized the material.) Positively driven safety contactor, such as AB's Guardian series could eliviate at elast some of the concerns. None offers the integrity monitoring capability of the Genius though.
 
Are you getting a commission on sales of the Genius I/O system or are you just trying to help GE's Stock through the recession or what ? :grin:
Nope, despise GE in the electrical business, they let the industry down, ower and ower.

It's a simple shunt trip, hit the pushbutton they shunt out... :wink:
Except when they don't. Been there done that. Couldn't shut down a 3500HP motor without shutting the whole substation down. So if it absolutely, positively had to be shut down think of some alternatives to the shunt trip.
 

hillbilly1

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Atlanta,Ga
Occupation
Field coordinator/ technical support
Unfortunately anything can fail, no matter how well designed and implemented. Their is a previous post about a shunt trip breaker in a generator that failed, coil could not overcome the mechanical failure of the trip mechanism. Only regular testing and maintaince would reduce, but not eliminate, the chance of failure. :smile:
 
Unfortunately anything can fail, no matter how well designed and implemented. Their is a previous post about a shunt trip breaker in a generator that failed, coil could not overcome the mechanical failure of the trip mechanism. Only regular testing and maintaince would reduce, but not eliminate, the chance of failure. :smile:
Neither regular testing nor maintenance will detect a passive failure mode of 'fail to operate'. Both would DISCOEER that the device had already failed. What I was suggesting is a continous, on-line monitoring that WOULD discover any changes in the characteristic of the trip circuit that may be indicative of failure and a WILL definitely detect an open circuit. So you will have a way to detect that the shunt trip may not be available or it is definetly unavailable BEFORE it is called to trip.

Again, in many cases shunt trips are used as a last resort measure when all the normal shutdown functions did not work and it MUST ABSOLUTELY and POSITIVELY HAS TO TRIP, yet an ordinary shunt trip assures neither of these.

As mentioned before an electrically held contactor would execute the same function with a much higher reliability, especially with the caviats I added.
 
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hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Neither regular testing nor maintenance will detect a passive failure mode of 'fail to operate'. Both would DISCOEER that the device had already failed. What I was suggesting is a continous, on-line monitoring that WOULD discover any changes in the characteristic of the trip circuit that may be indicative of failure and a WILL definitely detect an open circuit. So you will have a way to detect that the shunt trip may not be available or it is definetly unavailable BEFORE it is called to trip.

Again, in many cases shunt trips are used as a last resort measure when all the normal shutdown functions did not work and it MUST ABSOLUTELY and POSITIVELY HAS TO TRIP, yet an ordinary shunt trip assures neither of these.

As mentioned before an electrically held contactor would execute the same function with a much higher reliability, especially with the caviats I added.
I understand where your coming from, but the on-line monitoring would not be able to detect a mechanical failure, only electrical. As with the generator shunt trip, the coil was good until activated, then self destructed once it was unable to move the mechanical linkage. So there is nothing that is absolutely foolproof, only a combination of things can reasonably assure that it will function when it counts.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
We are really getting down to minor details here, but I would:

1. Keep the hot wires going to the shunt trip coils shown on top, and the neutrals on the bottom. That seems to be the convention most people use.

2. I prefer to use "L" for line (instead of "H" for hot) because the "H" and "N" look so similar. (More important for those of us over 40)>

Steve
 
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