Extremely hot transformer

[Flex]

Recently installed a 480v - 120/240 transformer panel combo. Output voltage was good when 1st energized. Bout 3 days later went to put a label on and transformer was unbelievably hot. Didnt have any tools on me to troubleshoot. When i go back tomorrow what should i look at 1st?

 

[don_resqcapt19]

Did you actually measure the temperature of the surface? Many transformers have a 150?C rise over a 40?C ambient. That would permit the winding temperature to be 190?C (374?F). That can result in an exterior surface temperature that is too hot to touch without getting burned.
That being said, you need to check the wiring and the load as well as the spacing from walls or other things that could block the flow of air.

 

[charlie k.]

Flex, is this like a SqD mini power zone? If so I have installed many of these and the transformers do get hot.
They are not the typical open design. They are potted in an epoxy type material and they do get hot. Look at the temperture rating on the nameplate.

Charlie

 

[chris kennedy]

When i go back tomorrow what should i look at 1st?

The fire extinguisher?

What is the tranny kva and the load? 1??

 

[brian john]

Encapsulated or air cooled

Size?

Primary/secondary amps measured?

Actual temperatures?

 

[hurk27]

X/0 bonded on primary side if primary is a Y

 

[spikes2020]

Flex, is this like a SqD mini power zone? If so I have installed many of these and the transformers do get hot.
They are not the typical open design. They are potted in an epoxy type material and they do get hot. Look at the temperture rating on the nameplate.

Charlie

If it is one of the Mini Power Zones, we use those also, and yes they are extremely heavy and they do get quite warm. They are not CSA rated i believe for one of those reasons.

 

[petersonra]

I would not get real excited about it. Some transformers get really warm in operation. Check the rating. I have been near some that would have scalded me if I touched the surface but had been running that way for years.

 

[Electric-Light]

What is it powering? If it's predominantly computer or other non-linear loads, you may need to use a K-rated transformer

 

[templdl]

I found this reference:

Transformers with a standard 150? C winding
temperature rise operate at full load with a maximum
50? C / 122? F temperature rise on the surface areas of
the enclosure. As an example, with a 40? C ambient,
the maximum measured enclosure surface temperature
would be 90? C / 194? F.

 

[Besoeker]

They are potted in an epoxy type material and they do get hot. Look at the temperture rating on the nameplate.
Charlie

Cast resin type.
I've come across a few of these, mostly at medium voltage.
On one site I went to, there was a suite of eight fairly big variable speed drives with them. They were under rated for the duty and got very hot. Too hot to touch even after having been de-energised for several hours.

 

[templdl]

It would seem to me that the allowed 194deg F serface temperature qualifies as being very hot wouldn't you think?