Purpose of Oil in Transformer | Functions

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In an earlier article, we studied the basic parts of an electric transformer. The oil-conservative tank is one of the main parts of the transformer.

Here, I am describing what is the importance of transformer oil with its purposes and functions.

Purpose of Oil in Transformer

What is the importance of transformer oil?

1. Insulator (Insulation medium)

The oil in the transformer mostly works as an insulator. It has good dielectric strength. So, oil can easily protect from the high voltage and prevent to rise in temperature.

It has great electrical insulating properties (such as thermal conductivity, and chemical stability). Thus, this oil insulating medium ensures increased reliability at high temperatures.

2. Coolant (Cooling medium)

Basically, oil is used in transformers for two main purposes.

  • One is to reduce the temperature from generated high voltage.
  • And another is to prevent the transformer copper coils from burning.

For the large industrial (i.e. high rating such as MVA and KVA) transformers, the oil helps to dissipate large quantities of heat and to stable high temperatures due to iron losses in core and winding.

The dielectric mineral oil is widely used in transformers as insulators and coolants.

3. Better Lubrication

The oil provides good lubrication for the internal parts of the transformer. The on-load tap changer (OLTC) is one of the transformer’s parts where oil is very essential as a lubricant.

4. Arc Generation

If any fault condition occurs, then an arc is generated in transformer oil. Arc quenching is one of the best methods where the system is protected by using oil.

5. Damping

The transformer work on the electromagnetic principle that continuously generates magnetic pulses in the core field. Because of the vibration that occurs during the pulsating magnetic field, noise occurs. To reduce the sound and noise, oil is used in the transformer as damping.

Is there any alternative to the transformer oil?

There is also an alternative to the oil which is air. But, oil has greater advantages over the air medium in the transformer.

What are the types of oil used in the transformer?

Parafillin oil and Naptha oil are widely used in transformers.

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