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Dry-Type Dstribution Transformers

Dry-Type Dstribution Transformers

Dry-Type Dstribution Transformers


I have recently completed startup on several large air handlers. Each air handler has a service corridor maintaining room temperature.
There are four transformers in each corridor and they all have surface temperatures of 150F.
I expect high temperatures on transformers, but is this too high?

Should I track temperature over time?

Thank you,


RE: Dry-Type Dstribution Transformers

That would be around 65 C, which is a healthy surface temperature. Modern insulation materials can take much more - even if they are not run at maximum temperature. I wouldn't worry.

Gunnar Englund
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Dry-Type Dstribution Transformers

Thank you for the quick response.


RE: Dry-Type Dstribution Transformers

I thought most dry type transformers are 100 degree c rise if its wound with copper. There should be a temp sensor phenolic/glastic tube installed from manufacturer, probably located in the hi low barrier of the xfmr. This would be where the temp sensor would be installed. This would go back to your overtemp instrument or plc to alarm.

I think the only thing worry about dry type xfmr is dust buildup from all the ozone. dry type xfmr are dust magnets. Filter changing is critical on the enclosure.

RE: Dry-Type Dstribution Transformers

The XFMR nameplate should have temperature rise information on it. I would look there first. Also, if memory serves me, the nameplate temperature is the max safe "rise" temperature ABOVE ambient.

RE: Dry-Type Dstribution Transformers

What is safe for the transformer is not necessarily safe for human contact. A heavily loaded Class H dry-type transformer will be hot enough to cook on. If the transformer is in an accessible walkway where it presents a burn hazard then you may need to provide protection against contact even though the transformer is operating well within its capability.

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