The mineral oil which is used in the tank of a transformer is called transformer oil. The main aim of this oil is to provide a better insulation and a better medium for heat conduction and finally dissipation. The transformer oil should have the following properties:
- It should have good dielectric strength at least 35 kV/mm, or as per the maker’s instructions specified for the particular transformer.
- It should be cleaned and free from the dust.
- It should not have any moisture.
- The flashpoint should not be less than 160C and freezing point 1OC.
- It should have the property to quench the spark if any.
- It should have good thermal conductivity.
- In brief the uses of the transformer oil, are
- It provides a very good insulation.
- It quenches the spark if any.
- It helps in conducting dissipating the heat.
Exhaust pipe. Many large transformers are provided with the exhaust pipe made of steel. It is connected to the tank and covered from the top by a glass disc. It protects the tank from the large expansion of the accidental gas formation in large quantity and abrupt rise in pressure in case of short circuit etc. It operates at a certain pressure when the formation of gases comes to that limit.