We have shunt trip breakers on all our commercial kitchen equipment, obviously set to trip when fire suppression is triggered. We have 2 generators that run a weekly cycle, when they transfer over, the breakers trip. Any input on why? We havent had this issue in the past. After recent renovation and addition of new equipment, it does it every week. A new hood sytem was installed and tied into the existing hoods we have now. Thanks
shunt trip breakers tripping when generators run weekly cycle
- Thread starter pipersdad
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Since you gave me no clue as to what the ST is and what type of breaker is it and the ST data should be included on the breaker also. There are numerous ways that breasker's can be tripped remotely and are often referred to a ST. There is the common ST, the flux transfer ST, and even an under voltage release mechanism UVR.
Also, it appears that you are blaming it on the breakers and not focusing your attention to the control that sends the signal o the tbreaker to trip.
My guess is that this will be the start of a long series of posts all guessing at what you may have.
The control may be set up to trip the breakers upon a loss of power during a transfer from the normal to the emergency source.
kwired
Electron manager
- Location
- NE Nebraska
Have you double checked the control circuit? Is something in that circuit changing state upon power loss/restoration and as a result sending a signal to the shunt trip coils?
One such thing could be a aux contact on the exhaust fan controller - if it drops out for any reason or at least when it isn't properly shut down, it powers the trip coils and shuts down all the cooking equipment. Never seen this scheme but makes sense that some may do that.
One such thing could be a aux contact on the exhaust fan controller - if it drops out for any reason or at least when it isn't properly shut down, it powers the trip coils and shuts down all the cooking equipment. Never seen this scheme but makes sense that some may do that.
kaichosan
Member
- Location
- San Francisco, CA
As kwired mentioned...possibly check the circuit from the ATS. It could be opening the shunt prior to transfer of power.
- Location
- Massachusetts
Your control circuit must have a relay that is dropping out during transfer.
kwired
Electron manager
- Location
- NE Nebraska
much simpler explanation then mine was :thumbsup:
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Are you sure it's a shunt trip and not a contactor?
kwired
Electron manager
- Location
- NE Nebraska
Contactor may drop out when transfer occurs, but likely pulls back in after transfer is done, unless there was a holding circuit keeping it held, then it needs restarted, it would drop out on any power failure if done that way.
Shunt trip once activated needs manual reset, so if any relay/contactor is in the control circuit and is held open, loss of power closes the shunt trip circuit or there is an undervoltage type of trip mechanism with this shunt trip.
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
All reasonable comments as to the root cause. But one area that was not focused on was triggered by the comments in bold type. If the control circuits (ST in particular) to all the breakers have not been changed since the renovation then one has to ask the question: Has the added load (and I assume additional load has been added to the existing breakers) raised the inrush currents beyond the instantaneous pickup threshold of the breakers causing them to trip?
If this is the case then in our business this is a very common problem of added loads changing the dynamics during load transfer between two power sources(Well this never happened before!?!?) High inrush currents produced by transformers and loads are possible on transfer of ATS's.
Without knowing more specifics of the system and the type of transfer switches involved:
>standard transition?
>closed transition?
>delayed transition?
> inphase monitor enabled?
Has a load study been performed to account for the added load of the new equipment?
And as Templdl has mentioned one cannot draw any intelligent conclusion as to the root case without answers to these questions and knowing more about the system.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The troubleshooting comes down to starting by determining whether the breaker trip was really a shunt trip or instead a mag or thermal trip.
One step would be to disconnect the shunt trip just before cycling the generator.
One step would be to disconnect the shunt trip just before cycling the generator.
That would make way too much sense.
Probably not a thermal trip but could be magnetic due to an out of phase tràñsfer. Not very likely but never the less should be a consideration.
Remember that we still don't really know for sure if he is dealing with a shunt trip or a flux transfer ST or UVR which the OP still didn't respond to my earlier post which is not all that unusual. Just because a breaker can be tripped remotely doesn't necessarily me it is tripped by a shunt trip. We could be chasing our tail again.
mgookin
Senior Member
- Location
- Fort Myers, FL
That would make way too much sense.
Probably not a thermal trip but could be magnetic due to an out of phase tràñsfer. Not very likely but never the less should be a consideration.
Remember that we still don't really know for sure if he is dealing with a shunt trip or a flux transfer ST or UVR which the OP still didn't respond to my earlier post which is not all that unusual. Just because a breaker can be tripped remotely doesn't necessarily me it is tripped by a shunt trip. We could be chasing our tail again.
So put a logger on the shunt circuit and re-create the event?
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
Or just disconnect it as Goldigger mentioned
Personally, if I were the OP I would fucus my attention of the control rwhich has all but been ignored thus far. First, how is the breaker labeled? What option allows the breaker to trip remotely? At shunt trip, flux transfer shunt trip, or maybe even an under voltage release. Then, how is the trippinhg device being signaled. As previously suggest simply remove the leads to a shunt trip would prevent the breaker from being tripped.
We are starting the beat an extremely simple trouble shooting procedure to death.
Sorry for no replies or comments. Have been away from computer. Read all responses yesterday. The split second power loss during the transfer is causing it. We installed a UPS on the control circuit, as the entire facility is on generator backup, it has taken care of the issue. You will have to forgive any lack of intelligence I may seem to have on this issue. As a couple reponses seem to clearly point out. Thanks for all the help, i will be more careful next time i post a question. Have a wonderful holiday season!
- Location
- Massachusetts
- Location
- Massachusetts
Great. Then this makes it three. But personally I do think it's a control issue though.
Maybe there is still time for you to complain more about the information provided in the question.
kwired
Electron manager
- Location
- NE Nebraska
Not saying you have lack of intelligence, there is just something in that control circuit that you either didn't take the time to figure out or you just don't have experience with the type of condition that is going on here. There about has to be a contact somewhere in that control circuit that operates when there is a loss of power sending a signal to trip the breaker in question. You have remedied the problem by making sure power is not lost. May not have been the only option but works.
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