Transformer Cooling

[Zerodefects]

My client has a 7.5/10MVA ONAN/ONAF 69kV/25kV station transformer operating at 10.1MVA. They want to add load of 0.6MVA. I am considering auxiliary cooling. Does anyone have experience with portable style oil coolers and are they effective?

Thanks

 

[davidbeach]

10.1 is greater than 10, 10.7 is even more than 10. You'd need a full rerating from someone who is capable of doing that. Questions over the internet probably aren't your best solution in this case.

 

[QBplanner]

In the company I work, for distribution Trx, if the additional loads is not constant loads but peak load type not 24 hours a day. the Trx can be loaded up to 118.5% of the nameplate rating based on IEEE and CSA standard.
Your Trx 10MVA is based on what oil Temp.55/65?
You may want to ask equipment specialist to do a real time rating study of the Trx to see the maximum rating the Trx can get before you decide to install additional cooling fan.

 

[ScottyUK]

Ratings are based on temperatures within the tank and assume certain ambient conditions from which the temperature rise is calculated or measured. The temperature limits are determined by insulation operating limits. If your ambient conditions are cooler than those assumed by the rating then you can operate the transformer at a higher load without exceeding the design temperature limit. You really need help from the OEM if possible as they will have the thermal design data for the transformer.


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If we learn from our mistakes I'm getting a great education!

 

[controlsdude]

recommended fan packages

http://www.electricservice.com/

http://www.sunbeltusa.com/

If they do not know, then its a bigger xfmr