CPU heatsink on UPS transformer? - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: January 25, 2018, 06:52:52 am
content: So I would like to moddify my UPS by adding a heatsink to the transfomer as it gets hot under maximum load (60C+) on the outter metal surface and since there is a fan blowing heat away from it, I thought that increading the surface area for better heat transfer would be a good way to keep it cooler.My question is would it make sense to slap on a heatsink held by thermal adhesive? If so, should I scrape off the enamel like coating on the surface of the transformer first for better heat transfer?I like to tinker with things even though it doesn't really have to be done I do it just for fun.

author: Someone
author_rank: Super Contributor
timestamp: January 25, 2018, 08:10:45 am
content: Also losses from iron cores drop with increasing temperature so its not always best to cool magnetics (applies to ferrite and other cores too).

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: January 25, 2018, 08:47:46 am
content: In that case are you saying I should not slap a heatsink on that beast?How hot can it get? I can smell a nasty odor coming from it. I am afraid it will burn out eventually...

author: happy_mosfet
author_rank: Newbie
timestamp: January 25, 2018, 11:57:04 am
content: I've seen UPS transformers go up to 80°C and they kept working fine for many years, so don't worry too muchSome transformers also have oil inside them to cool them down, as well as a thermal cutoff (this is usually not resettable, but at least it prevents the transformer from catching fire).What kind of UPS do you have? Maybe someone has a datasheet for the transformer inside, which should tell you the maximum recommended temperature.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: January 25, 2018, 12:01:10 pm
content: Quote from: happy_mosfet on January 25, 2018, 11:57:04 amThere is a thermocouple inside the transformer the model is cyberpower cps1000e.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 25, 2018, 12:12:58 pm
content: Attaching a heatsink to the outside of the transformer won't do much for the heat of the winding. If it was we'd be making them with heatsink.Get a better transformer.

author: 2N3055
author_rank: Super Contributor
timestamp: January 25, 2018, 12:15:29 pm
content: Core temp is not a problem.. Winding temp is, because of enamel on wire... 60°C is pedestrian temp, although I doubt temp inside is that low....Basically, transformers that are supposed to be cooled are designed that way from begining.All you can do as an afterthought is to put it in airflow of cool air...UPS transformers are not usually designed for continuous duty...Propper, different transformer might be needed..Regards,Sinisa

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: January 25, 2018, 01:44:52 pm
content: Quote from: 2N3055 on January 25, 2018, 12:15:29 pmAssuming an emissivity of 0.95 I measured the core to be around 115C.Not sure if this acceptable or not since I have no datasheet for this specific transformer.

author: 2N3055
author_rank: Super Contributor
timestamp: January 25, 2018, 02:38:47 pm
content: It really depends on the insulation type..Please find attached short overview...

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 25, 2018, 02:57:58 pm
content: Industrial transformers should have temperature ratings on the label. They are designed for maximum working temperatures. Probably not the case for transformers in consumer gear like domestic UPS, etc.If the transformer is getting so hot that it is emitting odors, It seems likely that you are overloading it. At best, it will likely reduce its expected life-cycle, and at worst, it may be a fire hazard.Many people connect things to UPS that don't really need it. The only things that should be operating on UPS are the things necessary for orderly shutdown in case of power failure. That doesn't include things like printers, scanners, lamps, etc.

author: uski
author_rank: Frequent Contributor
timestamp: January 25, 2018, 04:16:55 pm
content: I agree with Richard above.I suggest you replace your UPS with a higher power unit, or get another unit and split your load across the two UPSs.The enamel is TOXIC when heated. Look at the MSDS of enameled wires. If it starts smoking, it is a health hazard, and I'm not getting into the fire hazard and decreased insulation resistance if the enamel has overheated.I also agree with the replies saying you can't really cool a transformer. You may get the illusion it' s colder but there may be dangerously hot spots in the windings.

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2018, 08:29:31 pm
content: How about just adding a fan? Circulating air can result in a large temperature drop. It's rare that you'd need a heatsink on the transformer.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: January 26, 2018, 03:36:11 pm
content: submerse transformer in the oil , then small car radiator.