Cooling a mains transformer

[iamdarkyoshi]

So I built a 350w dust collector and I have been powering it from my variac and a bridge rectifier so far. I want to make it run without my variac. So I found this transformer in my collection, and I have it in a rather odd config.

Anyway it gets hot. I could obviously just put it on the output of the giant fan, but that seems a little too derpy. The motor cage has a fair amount of airflow in it but there is not enough room.

 

Should I take the sheet metal cover off of it and put a bit heatsink on it? The issue is that the windings are not very well thermally coupled to the steel core...

 

Wat do?

 

[W-L]

9 minutes ago, iamdarkyoshi said:

-SNIP-

While transformers do get hot if it's overly hot you may be overloading it and it can ruin the windings, other than a fan to cool it as you mentioned the only other really effective way to cool a transformer is to have it immersed in a cooling fluid. Not exactly the most practical though for small stuff like this but effective. 

[iamdarkyoshi]

2 minutes ago, W-L said:

While transformers do get hot if it's overly hot you may be overloading it and it can ruin the windings, other than a fan to cool it as you mentioned the only other really effective way to cool a transformer is to have it immersed in a cooling fluid. Not exactly the most practical though for small stuff like this but effective. 

Its a good chance I am overloading it a bit but I have no other options. I haven't run it long enough to really test temps because I am already pushing 20% over my bridge rectifier's rating. It stays cold but I still don't want to exceed its ratings. This thing is scary... why did I make it out of flamable things...

[W-L]

3 minutes ago, iamdarkyoshi said:

Its a good chance I am overloading it a bit but I have no other options. I haven't run it long enough to really test temps because I am already pushing 20% over my bridge rectifier's rating. It stays cold but I still don't want to exceed its ratings. This thing is scary... why did I make it out of flamable things...

Haha well it won't be red hot, but yeah you might want to potentially tone down the load a little  

 

[iamdarkyoshi]

3 minutes ago, W-L said:

Haha well it won't be red hot, but yeah you might want to potentially tone down the load a little  

 

I just need a newer PSU to steal parts from. 4A rectifiers were all they needed back then

 

I think I might try putting it in front of the fan. This thing moves absurd amounts of air. Easily enough to cool an entire rack of linus-level servers...

[Enderman]

just stick a heatsink on it

the coils are close enough to the core to transfer heat alright

[iamdarkyoshi]

So I ran an experiment. I stuck the transformer in the air outlet of the blower and set my variac to 100v. Damn I love variacs

 

Anyway it got to about 55 degrees according to my flesh based 5 point temperature probe. Its hotter than I would like.

[Stefan1024]

16 hours ago, iamdarkyoshi said:

So I ran an experiment. I stuck the transformer in the air outlet of the blower and set my variac to 100v. Damn I love variacs

 

Anyway it got to about 55 degrees according to my flesh based 5 point temperature probe. Its hotter than I would like.

A transformer can take well over 100°C unless you have extremly cheap and crapy isolation on the windings that melts at a low temperature.

 

Adding a heat sink will help, but the best way to do it is definitely oil submersion. This will give you optimal heat transfert from the windings to the coolant. I will have a oil submerged cooled transformer in my PC

 

EDIT: rigth on top it says 130°C, so you are fine. Unless the wired you attached to it can only widestand 80°C.

[iamdarkyoshi]

13 minutes ago, Stefan1024 said:

A transformer can take well over 100°C unless you have extremly cheap and crapy isolation on the windings that melts at a low temperature.

 

Adding a heat sink will help, but the best way to do it is definitely oil submersion. This will give you optimal heat transfert from the windings to the coolant. I will have a oil submerged cooled transformer in my PC

 

EDIT: rigth on top it says 130°C, so you are fine. Unless the wired you attached to it can only widestand 80°C.

It came out of a rackmount UPS inverter, so its probably of half decent quality. Also not sure how I failed to notice the temp rating

 

I will add some heatsinks to its side and keep it in the fan's exhaust airflow path. Should keep it cool enough.

[iamdarkyoshi]

2 hours ago, Stefan1024 said:

A transformer can take well over 100°C unless you have extremly cheap and crapy isolation on the windings that melts at a low temperature.

 

Adding a heat sink will help, but the best way to do it is definitely oil submersion. This will give you optimal heat transfert from the windings to the coolant. I will have a oil submerged cooled transformer in my PC

 

EDIT: rigth on top it says 130°C, so you are fine. Unless the wired you attached to it can only widestand 80°C.

Well I sandwiched it between two heatsinks. It isnt pulling the heat away from the windings very well. 

 

The windings are too hot to touch. Probably about 60 degrees The core is "warm"

 

Its making hot smells though...

[Stefan1024]

19 hours ago, iamdarkyoshi said:

Well I sandwiched it between two heatsinks. It isnt pulling the heat away from the windings very well. 

 

The windings are too hot to touch. Probably about 60 degrees The core is "warm"

 

Its making hot smells though...

Sooooo... oil submersion?

[Hackentosher]

On 5/15/2016 at 10:52 AM, Stefan1024 said:

Sooooo... oil submersion?

What's the flash point of mineral oil? Pulling too much current could end in a very bad day and some very angry parents. 

[Stefan1024]

18 hours ago, Hackentosher said:

What's the flash point of mineral oil? Pulling too much current could end in a very bad day and some very angry parents. 

Depending on the viscosity 120°C to 350°C.

The one I use for my PC is 187°C and the temperture should not reach this value