Page 261 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Methods for cooling transformers: Following are the methods of cooling employed in transformers. Any one or
more methods could be adopted depending upon the size, application and location of the transformer.
• Natural air method
• Air blast method (Fig 1)

• Natural oil cooled method (Fig 2)
• Oil blast method
• Forced circulation of oil
• Oil and water cooled (Fig 3) and

• Forced oil and water cooled
Natural air cooling method is generally adopted for low capacity distribution transformer upto 100KVA. The
natural circulation of the surrounding air is used to carry away the heat from the transformer winding.
In air blast method, the fans are used to blow the air on the surface of the transformer thereby the heat generated
is carried away by the air blast.
Transformer of 200KVA above capacity are cooled by using an insulating oil. The winding and core are immersed
in oil. The area of the tank is increased by using cooling tubes. (Radiator tubes)
In oil and water cooled system, the low pressure water tubes through the heated oil used to remove the heat from
the transformer.

Fig 1 Fig 2

Fig 3

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CITS : Power - Electrician & Wireman - Lesson 41-49