# VFD cabinet ventilation



## uconduit (Jun 6, 2012)

does it really need _ventilation_ as opposed to _heat removal_?

I've seen split system air conditioners used where air cooled transformers were installed in buildings (~1000kva+). 

They have these for enclosures too.

http://news.thomasnet.com/fullstory...ronic-Enclosures-offer-heater-option-20000194


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## uconduit (Jun 6, 2012)

....


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## erics37 (May 7, 2009)

uconduit said:


> does it really need _ventilation_ as opposed to _heat removal_?
> 
> I've seen split system air conditioners used where air cooled transformers were installed in buildings (~1000kva+).
> 
> ...


I suppose a small cabinet A/C unit wouldn't be out of the question. I'll look into that.


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## uconduit (Jun 6, 2012)

Yeah like a "Rittal"- [enclosure]-wall-mounted A/C or something

You may also want to consider these LEDs
http://www.electriciantalk.com/f8/led-100-efficient-cools-its-environment-50353/


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## stuiec (Sep 25, 2010)

Could you mount a giant "sacrificial" heat sink outside the enclosure, and let the draft do the work?


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## Handasee (Dec 18, 2009)

How about an air vortex cooling system.
http://www.exair.com/en-US/Primary ...binet Coolers/Pages/Cabinet Coolers Home.aspx


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## JRaef (Mar 23, 2009)

I've had lots of experience with drives near the ocean, the choices suck no matter what, it's just a matter of going with the least amount of suckage.

Money is the best cure. Hoffman and others makes NEMA4X air conditioners that are mostly stainless steel components on the outside exposed parts, that is the only thing that will last. The suckage in that solution is that the ACs usually will cost as much or more than the VFDs. When sizing the AC, use the free thermal management software or websites available from the mfrs, and assume your worst case heat rejection is 3% of the VFDs max HP rating, convertered to watts (1HP =746W). It will be less, but size for the worst.

If you exchange air, even the tiniest amount of salt spray in the air will kill the VFDs in short order. If you can get ones with conformally coated boards, they may last 5 or 6 years, but that's the most you can hope for. However the suckage there is that other things inside will corrode faster anyway.

I like using drives that offer a "Fins out" flanged heat sink option where you can cut a big hole in the back of the enclosure to put the heat sinks outside, but maintain a sealed enclosure rating. The salt still attacks the aluminum, but it takes a long time to do any serious damage. The only suckage here is that this option is usually only available on mid size frames, so you sometimes have to buy a frame size for a 20HP drive even if it is a 3HP motor.

Last resort, look up the mfrs enclosure size for a NEMA 1 drive, calculate the volume (L x W x H), and quadruple it. Do that for each drive, add up the volumes and use a sealed enclosure at least that size, backing out each dimension you can live with or is a standard maximum. Coastal areas are usually never too hot, this has worked for me in the Pacific NW. But fair warning, the suckage here is that the box can get HUGE!

Vortex coolers imply that you have clean, dried, oil free air, and if not, you have to buy a compressor. But it takes about a 7-1/2HP compressor to run one big enough to cool a single small VFD. The vortex cooler people dance around that issue so you don't find out until AFTER you have instailled it.


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## erics37 (May 7, 2009)

JRaef said:


> I've had lots of experience with drives near the ocean, the choices suck no matter what, it's just a matter of going with the least amount of suckage.
> 
> Money is the best cure. Hoffman and others makes NEMA4X air conditioners that are mostly stainless steel components on the outside exposed parts, that is the only thing that will last. The suckage in that solution is that the ACs usually will cost as much or more than the VFDs. When sizing the AC, use the free thermal management software or websites available from the mfrs, and assume your worst case heat rejection is 3% of the VFDs max HP rating, convertered to watts (1HP =746W). It will be less, but size for the worst.
> 
> ...


Good ideas, thanks.

The box is already installed, they put it in like 3 years ago and have been running it ever since. They have been leaving the panel door slightly ajar for ventilation.



Sounds like the stainless A/C unit is probably the best bet - I don't think it will be a difficult sell.


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## JRaef (Mar 23, 2009)

I recently used these guys, good prices, so far the product seems good. 

http://www.thermal-edge.com/aircon/CS011.aspx


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## John Valdes (May 17, 2007)

I also agree that installing heat sinks sticking out the back do help. But I have worked in extrusion plants and even that was not enough. 
We used individual AC units as discussed above. But the maintenance and constant break downs were not acceptable. We contracted the repair and minimal maintenance on these Hoffman AC units.
There was always one that was not working. Always.
There was a time I had at least one (1) panel with the door wide open and a fan blowing into the enclosure. At least one panel every day.

We had several large enclosures like this. Nine (9) to be exact.
We eventually hired a contractor to install AC units on the roof, install duct work to each panel and have it set up to pull ambient air if it was cold enough out side.

This corrected the problem, kept cold air moving and created a positive pressure in each cabinet. They stayed cleaner longer. And over temp trips stopped.


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## Jlarson (Jun 28, 2009)

I hate cabinet cooling and venting with a passion. I've fixed more cabinet AC units then I care to think about. 

The only solutions I hate the least is thermoelectric units but don't like the price tag.


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## bennysecond (Jan 18, 2013)

Don't forget to check cooling limitations of the outdoor unit in low outdoor temperatures


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## erics37 (May 7, 2009)

-sigh-

Too much info to process on a Friday night


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## gnuuser (Jan 13, 2013)

you want heat exchanging equipment and internal air circulation to isolate the vfd's from salt air


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## Flattop (Jan 24, 2013)

I have good luck with Pfanningberg Air Conditioners. http://www.pfannenbergusa.com/


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## Cow (Jan 16, 2008)

I know one of our farm customers painted his gray hoffman enclosures white to help with heat. He said it's made a difference. Looks good for a farm, I probably won't be doing that anywhere else though!:laughing:


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