Power Transformer Temp Setting

All this information will be available from the manufacturer. Follow their recommendations and then you won't be in trouble if things go wrong.

What are the designed limits for oil temperature rise & winding temperature rise over the maximum ambient temperature as specified in the ordering specification of the transformer ?

Don't listen to the manufacturer about cooling a transformer. They only know how to assemble a transformer. You will get a much higher efficiency and power handling capability from your transformer if you replace the oil with liquid nitrogen. Along with the added heat load your transformer can handle at these temperatures, the coils will tighten up around the core for a more efficient coupling.

Isn't this why you came here instead of contacting the manufacturer. You wanted to find out some hidden secret of transformer operations that the manufacturer won't tell you. Now if you can get some liquid helium instead, then you can get the conductors to super-conduct and further reduce your heat losses.

There is a thumbrule seting for temperature setting, you may follow it.

Winding temp trip- 95°C, Alarm-85°C

Oil temp trip- 85°C, Alarm- 75°C

Temp setting for fan auto start-70°C

Temp setting for fan auto stop- 65 or 60°C

Thanx