transformer coil type

[Jay Pai]

I am specifying a non-ventilated transformer (750KVA, 480-208Y/120V, 3ph, 3W) due to "harsh" environments.

Transformer to be floor mounted in a process area with dust, mist, and process stuff floating about.

Do I still need to specify cast coils or is dry type going to get me in trouble? I am thinking dry type is acceptable since the transformer will be totally enclosed (NEMA 12).

 

[templdl]

Re: transformer coil type

Have you considered a nonflammable liquid cooled?
It may be smaller and less expensive. Liguid cooled coolants have come a long way over the years. Totally enclosed dry types can a bit pricey.

 

[Jay Pai]

Re: transformer coil type

Originally posted by templdl:
Have you considered a nonflammable liquid cooled?
It may be smaller and less expensive. Liguid cooled coolants have come a long way over the years. Totally enclosed dry types can a bit pricey.

No liquid allowed, means containment.

 

[templdl]

Re: transformer coil type

I'll have to kick this one around a bit. Nema12=totaly enclosed=cooling issue. With cast coils or standard coils air is circulated into the enclosure and out with convection and fans can assist in cooling if required. Sealing the enclosure created a problem now with the ability to exchange heat. A simple enclosure relies on the surface area to give up heat but is that surface area enough?
The manufacturer has to now design an enclosure that will be able to dissipate the heat.
I know ABB used to make a completly sealed dry type that has its own atmosphere of non-flammable inert gas.
It has a PRD, VPG, DTT, NLTC, with HV and LV ATC similar to a liquid filled.