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
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.

Thank you for the quick response.

t

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.

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.

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.