Now this Thermogram got me thinking!! As you can clearly see, the entire cooling fin bank of this transformer is abnormally cool. Not only that, but the entire opposite cooling fin bank was also cold. And that's not all.... The winding area of the transformer was badly overheating. It was so hot that you could not even touch it with you hands.
My first conclusion was that the fins were blocked at the headers. But then again, what are the odds of this happening on both sides? After further investigations, it was found that the oil level was excessively low which prevented the oil from circulating and cooling.
After a few gallons of oil was poured into the transformer, the fins looked normal and warm and the windings returned back to a normal temperature.
