UPGRADE ONAN TO ONAF

[Dhia33]

HI
How do I choose fans ( power in kw )to upgrade a 2000 kVA ONAN transformer to ONAF cooling, and what is the optimal position and number of fans .
thank you for any help or reference.

 

[RedSnake]

Well I assume that the oil cooling system on the ONAN is dimensioned to take care of the rated power of the transformer.
This will of course only work up to a specific surrounding air temperature.
The fans should be placed blowing at the existing oil radiators.

How many fans you need depends on how much you want to lower the oil temperature in the transformer, the dissipating surface and the temperature of the surrounding air.

Best Regards A



“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[waross]

If the transformer has an ONAF rating, spend the money and follow manufacturer's specs.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Kiribanda]

Any oil immersed ANSI/IEEE transformer is designed to overload for sometime to a certain percentage specified by
IEEE Loading guide. Therefore, are you looking for 2.66MVA which is the standard ONAF rating for 2MVA ONAN base rating?

 

[RRaghunath]

Dhia 33,
Every transformer (ONAN) can be upgraded to some extent by installing cooling fans (ONAF rating). But, it is a specialised task for Transformer designer to decide optimum location, size and no. of fans and corresponding uprating that can be achieved. As a consumer or utility, don't try to experiment. You may not like the end result.
In the utility that I worked earlier, the purchase specifications used to ask for transformers ready for fitting fans at a later date for uprating by 20%. The transformers used to come with fan support structures installed and the ONAF rating indicated in the Transformer name plate but no fans actually installed.
Hope you appreciate!

 

[Dhia33]

Thank you everybody for your time and answers.
I will try and contact the manufacturer for information, but the transformer didn't came with any ONAF ratings.
If they didn't provide any answers, I will test some fans myself. Concerning the ratings I m looking for , I am just looking to improve the cooling as much as possible.