The final degree to which the temperature rises after continuous working for some hours, depends on the total losses in iron and copper, on the total radiating surface, and on the facilities afforded for cooling.
There are various methods of cooling transformers, the cooling mediums employed being
- 1. Air;
- 2. Oil;
- 3. Water.
The means adopted for getting rid of the heat which is inevitably developed in a transformer by the waste energy is one of the important considerations with respect to its design.
Ques. What is the behaviour of a transformer with respect to heating when operated continuously at full load?
Ans. The temperature gradually rises until at the end of some hours it becomes constant.
The difference between the constant temperature and that of the secondary atmosphere is called the temperature rise at full load. Its amount constitutes a most important feature in the commercial value of the transformer.
Figs. 1,957 to 1,960.—Porcelain bushing for Westinghouse transformers.