Transformer Inside Control Panel

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hutch75

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Detroit, MI
I opened a panel today(new installation), and found a 25kva 240x400volt three phase transformer inside a 36"x36"x12" deep control panel. The transformer is not enclosed(except by the closed interlocked door on the control panel), and the cabinet is not ventilated. My concern is that 450.8(b) calls for a case or enclosure, but does a control cabinet comply, and 450.9 calls for adequate ventilation so since I do not have any ventilation is the installation correct or not?

This panel is european made, and has power connectors that interconnect and power three pieces of equipment.

Any thoughts? My initial one is to purchase a new transformer, and mount it external to the cabinet, but short of calling out the xfmr company to determine adequate ventilation, I need some code cites or advice to make this happen.
 
Since this transformer is an integral part of the control panel, I would say it is not subject to NEC specs but rather a design issue from the manufacturer. I would assume the unit has been tested and found to be acceptable to deploy.
 
The code requires ventilation around the enclosed transformer, it does not require ventilation into the enclosure.
 
I believe it's permitted, but you might still want to look into the heat generation issue. We had a 75 kVA 34.5/480 transformer blow up last week from this exact problem. It was located in an arc-resistant switchgear enclosure that didn't have any ventilation.
 
If you are concerned about heat, just cut in a cooling fan kit. It will be a lot cheaper than a new enclosed transformer.
 
Laszlo, I guess you have never seen these kits, they come complete with

filter. FYI, in large industrial control cabinets they have mini a/c units for

cooling and they too have filters so all the outside #%^^%^ won't get in.
 
benaround said:
Laszlo, I guess you have never seen these kits, they come complete with

filter. FYI, in large industrial control cabinets they have mini a/c units for

cooling and they too have filters so all the outside #%^^%^ won't get in.
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Thank You.
 
weressl said:
..and carry the $%^#& in from the outside? Brilliant solution.....:rolleyes:
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I wouldn't call it brilliant, but it's a good solution, and most panel manufacturers carry them. (Hoffman, Weigman, etc...).:cool:
 
weressl said:
No, it is NOT necessarily a good solution as it may creates more problems than it solves. Would you do this in an outdoor environment? How about inside of a foundry? A carwash?
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Yes you can use them outdoors, and I have. Yes, I have used them and seen them many times inside a foundery. The only time I found dust in the enclosure was when maintenance took out the filter to move more air because a drive was kicking out. Without the filter you can have problems, but the application with a filter is made for those enviroments.
 
DAWGS said:
Yes you can use them outdoors, and I have..
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Nope, they are not directly suitable for outdoor use.

DAWGS said:
Yes, I have used them and seen them many times inside a foundery..
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It is a misapplication.


DAWGS said:
The only time I found dust in the enclosure was when maintenance took out the filter to move more air because a drive was kicking out. Without the filter you can have problems, but the application with a filter is made for those enviroments.
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As I said above it is a misapplication.
 
weressl said:
Nope, they are not directly suitable for outdoor use.



It is a misapplication.




As I said above it is a misapplication.
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I don't agree. The O.P. can look into them and make his own decision.
 
benaround said:
Laszlo, I guess you have never seen these kits, they come complete with

filter. FYI, in large industrial control cabinets they have mini a/c units for

cooling and they too have filters so all the outside #%^^%^ won't get in.
Click to expand...

Ever seen those filters after a few weeks in use? I have sen them where they are so clogged there is very little air passing though them.

Unless you have a very serious plant preventive maintenance program, I am not a fan of A/C as a means of cooling off a panel. A/C units only have a life span measured in years. The transformer can last decades.

However, its usually not that much of an issue. Transformers are typically rated for much higher temperature rises than you might think and it is very hard to keep that heat inside a metal box. Likely the heat will destroy the electronics inside the control panel long before the transformer itself would be damaged. thats why I try to mount transformers on the outside of control panels. Mostly I buy encapsulated units.
 
DAWGS said:
I don't agree. The O.P. can look into them and make his own decision.
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Nope, that would be a violation UNLESS the manufacturer/fabricator had specifically made that a field installable provision.

As the OP stated it is a fabricated panel from EU. EU laws specifically regulate the market that no panels without IEC compliance can be fabricated, unlike in the US where anybody can build anything if they have somebody to buy it, and definetly can not be exported. IEC would have taken care of the heat load issues.

Regardless, just to suggest to install a fan without knowing all the other parameters associated with the issue and appropriatels address those is a reckless fix, not a good solution.

The appropriate steps would be to review if the operating parameters listed with the panels do appropriatley cover the application or not, then going back to the fabricator and questioning the heat and ventilation issue and asking for a solution from them IF needed.

I would be FAR more concerned about panels coming out from Asia as we already seen it on another post.
 
benaround said:
Laszlo, Ever think of taking some classes at the local charm school ?
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The Prince and the Pea? Besides, they may not have a tutu in his color. :D
 
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