Transformer oil is a substance produced by refining of crude oil and is intended for power and measurement transformers, reactors and oil switches.
The use of transformer oil in these systems is due to its good insulation and heat dissipation properties, as well as the ability to protect solid insulation from moisture.
Among the electrophysical properties of the oil, the more important ones are the high dielectric strength and low dissipation factor.
At the same time, transformer oil must comply with some requirements:
- solve water well (to protect solid insulation from moisture);
- have minimal thermal expansion ratio to allow small expansion tank size;
- density less than the density of ice at low temperature;
- inert to the electrical equipment construction materials;
- no separation or sediment;
- vapors must be non-inflammable and explosive safe;
- heat dissipation.
Such oils are produced using certain processes. First, crude oil is distilled at atmospheric pressure and the temperature of 300-400ºС. This results in a product referred to as the distillate. Then the product is purified from the undesirable substances to make it suitable for electrical insulation, add oxidation tability and decrease viscosity. These results can be obtained through one of the four main processing methods:
- acid and alkali purification;
- selective purification;
- hydro purification;
- adsorption purification.
Then dewaxing is performed and addities, such as depressants, passivating and inhibiting agents, are added to the product.