Electrical cabinet cooling

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23 Oct 2021 10:36 #223980 by my1987toyota
Well I guess This could fall in the Show Your Stuff Section . However It is a bit off topic.
I have seen electrical cabinets that were either open loop cooling or closed loop cooling.
All my build to date have been open loop cooling with filter screens . Most Commercial
machines however are closed loop . That said has anyone built an electrical cabinets with
closed loop cooling? If so did it make it more maintenance free ? Or did it become more trouble
then it was worth?

  Also I am talking about any air to air or liquid to air type heat exchangers. I know that some
commercial types have used active refrigeration systems. That said I don't use my equipment
when it feels like 110 degrees F. in my garage.

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23 Oct 2021 12:23 #223983 by Aciera
Replied by Aciera on topic Electrical cabinet cooling
If I can get away without cutting vent holes into the enclosure I certainly prefer that. If only because the filters on those vents usually never get changed. This of course very much depends on what's in the enclosure and how big the enclosure can be since it basically becomes the heat exchanger. So a box made of aluminium would be preferable to plastic.
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23 Oct 2021 14:19 #223990 by tommylight
New electronics do not heat that much and can withstand much higher temperatures than the old ones, so in most cases i do not use cooling at all.
I do always check the temps in boxes on my machines and the highest i got during summer was 76C while the ambient temp was 39C in the shop.
My old Mazak has huge aluminium fins on the inside and outside of the cabinet and fans on both sides while the middle is fully closed.
On bigger boxes i have to use fans with filters, but i always mount them in the bottom of the box as intake and anywhere else as exhaust, this way the dust has less chance of going up and inside the box. Some are on for over 7 years and the inside of the box is still clean.
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23 Oct 2021 22:27 #224037 by my1987toyota

tommylight post=223990 userid=17274On bigger boxes i have to use fans with filters, but i always mount them in the bottom of the box as intake and anywhere else as exhaust, this way the dust has less chance of going up and inside the box. Some are on for over 7 years and the inside of the box is still clean.

That's good to know. The box I am going to use for the new Mill controller is a 24" X 20" x 8" and uses a Toroidal power supply
for the steppers. I doubt I can get away with no cooling. I was genuinely surprised when I took the cover off of the current controller
to see next to no dust in it. Although it hasn't been in service for 7 years. LOL
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27 Oct 2021 13:40 - 27 Oct 2021 13:42 #224515 by andypugh
Replied by andypugh on topic Electrical cabinet cooling
For monitoring...

linuxcnc.org/docs/2.8/html/man/man9/max31855.9.html

Might work. Don't bother with the thermocouple, just use the cold-junction temp that the chip returns....

(edit) The LinuxCNC driver does not output the cold junction, but I think that shorting the thermocouple inputs with a non-thermocouple bit of wire would work. 
Last edit: 27 Oct 2021 13:42 by andypugh.
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27 Oct 2021 20:24 #224535 by rodw
Replied by rodw on topic Electrical cabinet cooling
Andy's idea sounds cool and it made me remember a somewhat cruder approach.
Use a 50 deg C thermostat switch which can be had for about $5
People use them to switch on aftermarket intercooler fans etc on vehicles when she gets hot.
example: www.jaycar.com.au/normally-open-thermost...-50-degrees/p/ST3831
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27 Oct 2021 23:47 #224537 by my1987toyota
Thanks to both andypugh and rodw. Both those idea's sound good.
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29 Oct 2021 11:35 #224641 by my1987toyota
  So during work I had an idea. after seeing the prices of decent sized heat sinks I thought about using an air to air automotive
inter-cooler for turbocharging. I would need 2 holes in the cabinet one in the top of a side panel and one in the bottom of the same
side panel with a small fan to push the air through the cooler ducting. I also would need a fan to move air over the inter-cooler core.
Part of the reason I want a closed electrical cabinet is my mill is in my garage where humidity is usually pretty high.
Not the best environment for electronics. But I don't know, I usually over think things.

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29 Oct 2021 22:29 #224682 by rodw
Replied by rodw on topic Electrical cabinet cooling
That would work but perhaps consider a transmission cooler as they are a lot smaller. I used one on my air compressor as a precooler between the compressor and the storage tank. You can't touch the inlet, but the outlet is cool to the touch.

But you can get dedicated systems ready to pop in
www.1-act.com/enclosure-cooling/
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30 Oct 2021 01:59 #224688 by spumco
Replied by spumco on topic Electrical cabinet cooling

Part of the reason I want a closed electrical cabinet is my mill is in my garage where humidity is usually pretty high.
Not the best environment for electronics. But I don't know, I usually over think things.
 


I've helped my friend sort out his Fadals which are hyper-sensitive to humidity.  Any time it rains during the summer or the humidity climbs, both his mills start acting up.  Not good for production and he's been suffering with this for a number of years.

I got a couple of those small household dehumidifiers - not the peltier types, but actual compressors - and we riveted a kludgy duct and 4" hose to the intake vent of his main enclosure.  The dry air discharges in to his enclosure and the OEM fan is a pull-through type so it just pulls out the hot stuff.  I removed the enclosure vent filter since the dehumidifier has a filter on the intake already.

The compressors were less money (by 10x) than a dedicated enclosure cooler, and the condensate drins through a hose to his floor drain... no emptying the buckets.  They're left on all summer, but only cycle when the humidity climbs.

Part two was to put a pound of dessicant in a mesh sack stuffed in his operator panel.  That gets taken out when he remembers (or I remind him) and recharged in the house oven.  The operator panel doesn't have vents & fans, so it lasts quite a while before getting saturated.

In our case (Northern Ohio) heat isn't really a problem, but humidity is a pain.  The cobbled up 'environmental controls' have kept his mills running constantly this past year.

PS - Rod's spot-on about the transmission cooler on air compressors.  They work great, and adding an auto-drain before the tank keeps 90% of the water out of the tank.  But I don't think they'd be great for a low-pressure enclosure fan thing - not enough pressure to move air on the 'fluid' side of the exchanger.

-R
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