Control Transformer Spacing

[iamintn]

I have a panel in our shop that has three SQD 9070T (1000 VA) transformers installed adjacent to one another. The cases of the transformers are getting very warm to the touch with no load. The only mfg recommendation that I can find is merely air spacing requirements. That being said, it looks like something is causing these things to heat up (eddy currents????). The coils however, are not warm, just the outside case. Anybody run into this before? Any ideas to the cause? Thanks!

 

[mxslick]

See it all the time.

The cause is normal no-load losses in the transformers.

How warm is "very warm?" Most motors and transformers can operate safely at temperatures that are too hot to touch with a bare hand but are well within normal operating temperatures.

You would need to get an accurate reading with an actual thermometer to determine if it's getting too hot.

Anything roughly under 40 degrees c (I don't remember what that translates to in degrees f) is normal.

 

[iamintn]

It is 'touchable', but very hot to the touch. I would not want to put my hand on it for long, but it's well under 40 degrees C. Thanks for the info!

 

[iamintn]

Actually, now that I think about it, 40 C is only 104 F. I think it is over that temp. I am going to get them to barrier the xfmr's with AL between them and see if that helps.

 

[LarryFine]

Anything roughly under 40 degrees c (I don't remember what that translates to in degrees f) is normal.

It's kinda easy to remember how to convert between F and C if you understand the difference. They're both based on freezing and boiling of water.

Freezing on the F scale is 32 degrees above that scale's zero, so you subtract 32 from both ends of the scale (32 and 212), which gives you 0 and 180.

Compare the two scales' freezing and boiling points, 180:100, or 9:5, the ratio of F degrees to C degrees. So, to convert between F degrees and C degrees:

deg. F, -32, /9, *5 = deg. C

deg. C, /5, *9, +32 = deg. F

Note: always add or subtract the 32 while in F degrees.

40C = (40/5 = 8, * 9 = 72, +32) 104F

 

[lakee911]

If you place two next to each other, would the air spacing requirements need to be doubled? Can they share the same space?

 

[mxslick]

See it all the time.

The cause is normal no-load losses in the transformers.

How warm is "very warm?" Most motors and transformers can operate safely at temperatures that are too hot to touch with a bare hand but are well within normal operating temperatures.

You would need to get an accurate reading with an actual thermometer to determine if it's getting too hot.

Anything roughly under 40 degrees c (I don't remember what that translates to in degrees f) is normal.

Actually, now that I think about it, 40 C is only 104 F. I think it is over that temp. I am going to get them to barrier the xfmr's with AL between them and see if that helps.

I have to correct my original response..the 40c I referred to was, in my mind, the allowable RISE above ambient. So theoretically if the surrounding air is at 80f , (thanks for the conversion formulas Larry) then the transformer can be as hot as 184f (80 + 104 = 184).

Here's the offical word on the subject from the application guide found HERE: (See page 4)

• Type T transformers are designed with various temperature classes:
— 25–150 VA with a 55? C temperature rise, 105? C insulation
— 200–350 VA with a 80? C temperature rise, 130? C insulation
— 500–5000 VA with a 115? C temperature rise, 180? C insulation

Looks like it can get quite hot safely. (115c = 239f)

I suggest you forget the barrier..first off I don't think it will help at all and you would void the panels' warranty.

 

[iamintn]

Thanks for the responses. I've been monitoring and it looks like we are good to go.