How to improve the cooling of 2000 kVA ONAN transformer

[dhia33]

I have a transformer with ONAN cooling (natural ventilation like figure) and 2000 kVA that works always near full capacity, in summer it over heats above the limit. to improve the cooling and prevent reaching the oil temperature limit. I decided to place an exhaust fan and an inlet fan like exactly the figure. the exhaust fans are usually used but I want to know if it is ok to place a fun under the transformer to blow air directly to the radiator knowing that it was originally designed as ONAN and not ONAF.

 

[dhia33]

Are there pockets on the Tx to mount the PT100? If so are they for winding or oil temps or both?

there is one , but I m not sure for which. I think it is for oil temp it has a depth of 12 cm. There is no direct contact with oil.

 

[plugsandsparks]

Did not appreciate this was an indoor installation. Don't suppose you can move significant air into the room and out say with some wall plate fans exhausting with some inlet grills to let fresh air in ?

That would be my first choice for cooling if the room temp is significantly above outside ambient. You can create a room temp alarm pretty easy to link to your manned control room or something similar.

 

[R-fur]

I would agree that cooling the room should help. Is it possible to fit high and low level vents and let the heat from the transformer circulate the air via convection? If you go down the route of fans you can either use a room stat or a better solution would be to fit an oil stat. The oil stat would be fitted in the pocket you have on top of the tank. Fill the pocket with oil and insert the stat, heat from the transformer oil will conduct through to the oil in the pocket which will then indicate the temperature of the transformer oil albeit with a slight delay.

 

[dhia33]

Did not appreciate this was an indoor installation. Don't suppose you can move significant air into the room and out say with some wall plate fans exhausting with some inlet grills to let fresh air in ?

That would be my first choice for cooling if the room temp is significantly above outside ambient. You can create a room temp alarm pretty easy to link to your manned control room or something similar.

Hi plugsandsparks
I followed a guide to chose the correct exhaust fans ( power and flow for the amount of heat generated)
and I will place an other fan in the inlet under the transformer or somewhere else to help)

 

[dhia33]

I would agree that cooling the room should help. Is it possible to fit high and low level vents and let the heat from the transformer circulate the air via convection? If you go down the route of fans you can either use a room stat or a better solution would be to fit an oil stat. The oil stat would be fitted in the pocket you have on top of the tank. Fill the pocket with oil and insert the stat, heat from the transformer oil will conduct through to the oil in the pocket which will then indicate the temperature of the transformer oil albeit with a slight delay.

Hi R-fur
I will follow your idea to measure the oil temp and room temp and I'm using a fan in the inlets under the transformer and an exhaust on the top of the wall.
I will post about the results when I finish .

 

[Pete999]

Are there pockets on the Tx to mount the PT100? If so are they for winding or oil temps or both?

 

[Pete999]

Hi Pete I will check and search for anords.

To add I would discuss with the AE authorising Engineer about the problems before you start adding cooling fans etc, after all he /she will have the final say on any alterations to the Switch gear etc, the AE will have the final responsibility on the site

 

[dhia33]

To add I would discuss with the AE authorising Engineer about the problems before you start adding cooling fans etc, after all he /she will have the final say on any alterations to the Switch gear etc, the AE will have the final responsibility on the site

Yes of course pete, and thank you and everybody for your time.