Hermetically sealed transformer calculation

[kucukerdem]

Hi,
I have a problem with the pressure&heat calculation of hermetically sealed oil xformers. Xformers are ONAN type and cooling is done with corrugated walls. Since design of hermetically sealed xformers are a bit different from pressure and cooling point of view. Is there anyone who can give any related standard number or calculation? Thanks for help

With Respect...

 

[CarlPugh]

Have worked at 3 companies that made oil cooled/insulated transformers. The policy at all three companies was to have 10% air space at 25 deg C. Transformers were 65 deg C rise. 10 PSI pressure relief valves were used. Mineral oil was used. There were never any problems.
If the inside height of the tank was 60", then there would be 6" air space and the oil level would be 54".

Yes you can calculate expansion of the oil, the tank expansion, how much air/gas is adsorbered in the oil at the higher temperature, copper or aluminum expansion, deformation of the tank, how much the air compresses, top oil and bottom oil tmperatures and probably some other things.

Are you checking someone else's design or designing a transformer.
Designing a large transformer without any design guide lines is a MAJOR task.