Transformer Oil Purification Processes And Methods

Transformers are an important asset in the power supply industry. To ensure continued efficiency in the performance of a transformer, the transformer oil must be purified at regular intervals. This has a few advantages such as the improvement in the insulation properties of the transformer oil. The improved insulation ensures that the transformer will have a longer life and fewer breakdowns, and fewer breakdowns contribute to a much more uninterrupted power supply. The higher efficiency of the transformer from regular cleaning will further bring down the costs of maintenance in the long run.

Transformer Oil Purification Procedure

The life of a transformer depends on the oil quality and quantity. The purification process of the transformer oil removes any sludge, dissolved moisture, and gases from the transformer oil.

Transformer Oil Purification is purified mainly in two ways: vacuum dehydration and centrifugal removal of gases.

  • The first step in the purification process is to increase the temperature of the oil up to about sixty-five degrees Celsius. This heat is essential in the removal of moisture and dissolved gases from the oil. Moreover, the viscosity of the oil drops with the heat, and this aids in the purification process.
  • The second step involves the removal of sludge and dirt from the oil. This is done by filtering the oil with a classic edge filter or a depth type filter. Both methods of filtration have their advantages and disadvantages. The edge filters are reusable at least three to four times after it is cleaned properly. However, this takes up a lot of time and effort.
  • An alternate method for the removal of sludge from the transformer oil is to use centrifugal force. This process does not necessarily require a power-driven centrifuge to be used to remove dirt from the oil but since this method can only remove dirt that is above 10 microns, the use of a power-driven centrifuge can sometimes become necessary. Power centrifuges can also remove undissolved water that may be present in the transformer oil and it drives down the cost by making it unnecessary to have the filter paper changed every time.
  • The third step in the purification of transformer oil is dehydration to remove dissolved moisture and degasification to remove dissolved gases. This process takes place in the degassing chamber where the transformer oil is separated from its dissolved impurities in an atmosphere of reduced pressure or vacuum. This is because each of the three components, the oil, the moisture, and the gases, have different boiling points and it can be separated this way.

Mineral oil can be used as transformer oil but it has some serious disadvantages. It can easily catch fire if there is even the smallest spark near it. Therefore, fire codes make it mandatory that the transformers inside or near buildings use non-flammable liquids as transformer oils. Another material that was used as transformer oil is polychlorinated biphenyls or PCBs. they are not flammable and have high electrical insulation but they are highly non-biodegradable, toxic, bioaccumulative, and cannot be safely disposed of.

The use of these two transformer oils being highly injurious to health and the environment, researchers are now experimenting with biodegradable oils and nanofluids to be used as transformer oils.

The transformer oil is a vital part of the functioning unit of a transformer because it works as an insulating layer in the transformer. This oil has to be stable at high temperatures and has excellent insulation abilities in electrical conditions. The transformer oil is found to be useful in oil-filled transformers, certain high powered transformers and other such applications. The purification of transformer oil is, therefore a necessary step in maintaining the strength and efficiency of a transformer.

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