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cooling 3 phase distribution box

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gabeNC

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A friend has a 3 phase large metal milling machine and the wiring box seems to get quite hot (i know that's a relative statement). I thought maybe a 80mm fan could be installed in the door and some holes drilled into the bottom of the case. Currently he runs the machine with the door open and a large fan pointed at the box. I'm not sure of the age of the machine nor the components but their doesn't seem to be any discoloration or burning smell indicating something obviously wrong. Where most of the heat is coming from is to the left of the transformer.

So the easiest solution would be tie the fan(s) into a 12v wall wart (making sure the current doesn't exceed the fan spec) but it would be nice to tap into the box itself ensuring the fans come on automatically.

Any thoughts/suggestions?

(sorry about the bad picture... came from my phone. If neccessary I can take a better pic and get component ID's.)


thanks!
 

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Pommie

Well-Known Member
Most Helpful Member
If it's working correctly then there is no advantage cooling it.

If you want it to run cooler then fit bigger cables.

Mike.
 

tcmtech

Banned
Most Helpful Member
I've seen this problem before when someone buys a used commercial machine that was set up for 480 volt and then changes it over to 240 volt. The amps load doubles and the wiring runs hot. Actual 'hot' on one of those commercial boxes is when you cant put your hand on it for more than a few seconds.

I am rather sure that is a weather or basic explosion proof box so putting a fan on it will defeat its original design. Not that it matters much. But you will get dust and junk building up in it if you try cooling it with a fan.

And insurance company's love finding electrical boxes with fans attached to them that should not need cooling when the building burns down! No money for you!
 

Chippie

Member
Looks like a plain ordinary box to me...

I dont think its a good idea leaving the door open while he is using the mill....Swarf could get in there and cause untold damage..Heck it may catch fire and burn the place down like tcmtech suggests :) No money for you...:(

Best thing is find out why all the heat is being generated...is something in the box under rated? cant make out what is to the left of the transfo.....
 

stevez

Active Member
Some comments:

A. All of the equipment within the box may be designed and rated to run at the temperatures that concern you. They also may not be. You could measure the temp (properly closed) the inspect the major components to see if the operating temp is within the design of the components. The wire might be included.

B. While everything with current flowing thru it gives up some heat, you might find the significant contributor by examination or measurement - measurement with IR or similar meter. Replacement of an item, the wire, whatever, might keep things a little cooler.

C. As already suggested, the cabinet is there for a reason and is likely a code requirement. Operating with the door open increases risks of injury or failure (dirt, dust, metal chips, etc). It probably should be closed.

D. A fan with a filter could be provided which helps ease the contamination concern however it may create a non-compliance issue in that the cabinet or enclosure may no longer meet the requirements for the application.

I (and I know others feel the same way) feel like I over-emphasize compliance with rules or I get picky with modifications but in many situations it is of critical importance. I've spent the last zillion years inside industry and it does matter.
 

tcmtech

Banned
Most Helpful Member
I see the door interlock switch is jumpered out. No money for you!
Someone sticks their fingers in there while its live, Lots of money for his layer and some money for him!
No money and insurance for you for a long time!
 

Chippie

Member
Some comments:


I've spent the last zillion years inside industry and it does matter.

Wow....how old does that make you?......I thought I'd been around for a long time but you've bettered my existance... :)


Some good points you make there ;)

My respect to ya!
 

stevez

Active Member
Chippie - my engineering career officially began 40 years ago because I am allowed (education department standards) to count my engineering apprenticeship time (yes, they used to have boot camp for engineers). That was listed in the local newspaper recently as a new assignment was announced. That resulted in many people asking - "Just how OLD are you?" .......I just turned 58. 58 doesnt' seem so old - 40 years in a career - that's a long time.
 

Chippie

Member
Chippie - my engineering career officially began 40 years ago because I am allowed (education department standards) to count my engineering apprenticeship time (yes, they used to have boot camp for engineers). That was listed in the local newspaper recently as a new assignment was announced. That resulted in many people asking - "Just how OLD are you?" .......I just turned 58. 58 doesnt' seem so old - 40 years in a career - that's a long time.
My response was tongue in cheek...Didnt mean to dis you( as the young of today would say...)

I'm 51...(...oh dear I let slip how old I am) did my apprenticeship as an Instrument Artificer when I left school..had various career paths since but maintained an interest in electrical/electronic stuff ever since

I like to think of this place as somewhere where we can learn and have some light hearted banter but at the same time teach the young whippersnappers who think they know better because they are doing degrees in electrical/electronic engineering....
Theory isnt the be all and end of things.....
 
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gabeNC

Member
Thanks for the input gents, I'll pass it along.

I've seen this problem before when someone buys a used commercial machine that was set up for 480 volt and then changes it over to 240 volt. The amps load doubles and the wiring runs hot.
@TCM: That's probably what has happened. I'll find out more later.


graci.
 

timsvb

New Member
Could be wrong,but are those cables in the foreground,red white blue & black, be your supply? If so, they look a bit on the small side to me.The other cables look like 4mm, and the supply looks like 2.5mm.Don't see an incoming earth either.If this is your supply, you could probably do a lot worse than revise your cable calculations to include de-rating and volt drop.I'm just an electrical apprentice,but have seen a lot of gear heating up with with people looking everywhere else but the supply source.IR losses cause heat. Like I said,could be wrong.
Regards Tim from oz.
 

tcmtech

Banned
Most Helpful Member
I dont think your wrong. Its what I made my assumptions on.
I have seen the same thing you are talking about a number of times myself. People get high voltage gear and set it up to run on lower voltage feeds and then have all sorts of odd power problems and cant figure out why.
 
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