Temperature rise in power transformers atheistrical

[Carl Pugh]

The post "Temperature rise in power transformers was locked, however there may be a simple safe answer.

The post said the winding temperature was 73 deg C.
73 deg C is safe for winding temperature.

If it was winding temperature RISE of 73 deg C, then there may be problems.

So which was it?

 

[m.s.j]

The thermal capability of a transformer is defined in a slightly different way from the rated KVA. Thermal capability is the KVA load applied to the output of a transformer that causes the hottest area in the windings, called the winding hot spot, to reach some limiting temperature. The hot-spot temperature determines the rate of loss of life of the transformer as a whole, which is a cumulative effect. Therefore, the hot-spot temperature limit is usually based on a loss-of-life criterion. The KVA rating of a transformer is simply the steady-state KVA load applied to the output of the transformer at the voltage rating of the output winding that produces an average winding temperature rise (above the ambient temperature) equal to 65 (degree C.). Advances in insulating materials allowed a 10 (degree C.) increase in average temperature.



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