How Transformers are Cooled

Custom Search
Increasing the cooling rate of a transformer increases its capacity to handle more power requirements. Various methods exist for cooling oil immersed industrial transformers to guarantee efficient operation. Cooling methods must not only maintain a sufficiently low average temperature, but must prevent an excessive temperature rise in any portion of the transformer. It must prevent hot spots within the transformer. For this reason, working parts of large transformers are usually submerged in high-grade insulating oil. This oil must be kept as free as possible from moisture and oxygen, dissolved combustible gases, and particulates

Transformer Cooling Methods
The efficiency of the cooling is a crucial factor determining the operational safety and the life span of a transformer. Below are the four common cooling methods for industrial transformers. Each method is illustrated with a diagram:

(a) Natural air cooling with radiators (ONAN)
(b) Radiators additionally cooled by fans (ONAF)
(c) Cooling by separate radiator banks
(d) Water as cooling medium