Long Shot

[mshields]

This is a long shot gentlemen but if anyone has any insight I would certainly appreciate it.

been asked by a client to look at why they are having problems with 4, 208, 3ph, N and Ground, L21-30R circuits each of which is feeding a TSE Climatic Chamber in a vivarium. These Chambers among other things are temperature controlled and may be set to anything between 22 deg C and 30 deg C.

am trying to get a wiring diagram but so far not getting a lot of corporation from the vendor.

So we've put a meter on these things, and the amp values are all over the map. As it is heating or cooling (which ought to represent the worst case current draw), first of all phase A will go to maybe 12amps but it keeps bouncing from near zero then back up to the 12 amps. Phase B goes up to around 7Amps and also bounces and then phase C has nothing.

What's even stranger is that the brand new square D panelboard is arcing on the line side of each of these 4 breakers seemingly on phase B. I guess it could be a problem with the panelboard but I can't help but to think it's somehow related to these damn chambers.

Has anyone ever run into something like this?

Thanks,

Mike

 

[Jraef]

It's far more plausible that the arcing and sparking in your panelboard is what's causing the current to appear erratic at the chambers than the other way around. There should NEVER be any arcing and sparking in a panelboard! I'd suspect a bad connection somewhere, either a breaker to the bus or the bus to fingers, depending on the design.

 

[ptonsparky]

It's far more plausible that the arcing and sparking in your panelboard is what's causing the current to appear erratic at the chambers than the other way around. There should NEVER be any arcing and sparking in a panelboard! I'd suspect a bad connection somewhere, either a breaker to the bus or the bus to fingers, depending on the design.

Not that you need backup, but if it sounds like a duck, looks like a duck and walks like a duck, it most likely is. That sparking arcing is a pretty good clue.

 

[ActionDave]

..What's even stranger is that the brand new square D panelboard is arcing on the line side of each of these 4 breakers seemingly on phase B. I guess it could be a problem with the panelboard but I can't help but to think it's somehow related to these damn chambers.

Has anyone ever run into something like this?

Thanks,

Mike

Yes. What Jraef and pton said, it's a bad connection. Just because it's a new panel does not mean it immune.

 

[steve66]

I'd check the panel first too. Disconnect the load, pull the breakers and take a good look for anything wrong in the panel. Maybe even connect some steady 30 amp loads to the panel and see if that works.

does the load have some large inductances or generate any higher voltages. It's just possible that could cause some arcing at the panel if that's the only place where you have uninsulated terminals really close together.

 

[Jraef]

I'd check the panel first too. Disconnect the load, pull the breakers and take a good look for anything wrong in the panel. Maybe even connect some steady 30 amp loads to the panel and see if that works.

does the load have some large inductances or generate any higher voltages. It's just possible that could cause some arcing at the panel if that's the only place where you have uninsulated terminals really close together.

Meh, still shouldn't be happening in the panelboard. A contactor switching it, yes. The breaker when you flip it off, sure. But a connection to bus should NEVER be arcing and sparking.

 

[mshields]

thanks

thanks

appreciate the feeback

 

[templdl]

This is a long shot gentlemen but if anyone has any insight I would certainly appreciate it.

been asked by a client to look at why they are having problems with 4, 208, 3ph, N and Ground, L21-30R circuits each of which is feeding a TSE Climatic Chamber in a vivarium. These Chambers among other things are temperature controlled and may be set to anything between 22 deg C and 30 deg C.

am trying to get a wiring diagram but so far not getting a lot of corporation from the vendor.

So we've put a meter on these things, and the amp values are all over the map. As it is heating or cooling (which ought to represent the worst case current draw), first of all phase A will go to maybe 12amps but it keeps bouncing from near zero then back up to the 12 amps. Phase B goes up to around 7Amps and also bounces and then phase C has nothing.

What's even stranger is that the brand new square D panelboard is arcing on the line side of each of these 4 breakers seemingly on phase B. I guess it could be a problem with the panelboard but I can't help but to think it's somehow related to these damn chambers.

Has anyone ever run into something like this?

Thanks,

Mike

May it be that there are actually (3) L-N loads which are being switch in and out as demand dictates? And each L-N load may be different which would result in the various readings. The demand for the 3rd L-N load may not be required showing no load if the first 2 are adequate.
Each L-N loading may be designed not be equal to one another and stepped for regulation since the range is so narrow to prevent overshooting the parameters.
Yes, a schematic may help to understand what is happening as the load my not actually be a balanced 3 phase load.