TransformersQuestion 1142 of 1506

Why are large power transformers filled with oil?

To add winding resistance and limit the load current
To move heat away, muffle noise, and keep out moisture
To keep the magnetic flux inside the core and the case
To raise the operating frequency of the unit

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Correct answer: To move heat away, muffle noise, and keep out moisture

The oil moves heat to the radiator tubes, damps the hum, and displaces moisture that would harm the insulation.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.8: Practical Considerations - Transformers

Questions last reviewed: 18 October 2026

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