The electric power transformer is the main element of modern power systems that ensures a regular and reliable supply of electricity to the final consumer. And the operational condition of such equipment largely depends on the quality of transformer oil and the preventive maintenance program employed by the transformer operator. Special attention should be paid to the restoration of the operating characteristics of the transformer’s insulation system since the majority of transformers have exceeded their expected service life.
Transformer oil purification consists of removing mechanical impurities, moisture and gases. The components listed above can be removed either separately or as a part of a combined technological process.
Very often, adsorption or thermal vacuum treatment is applied to remove moisture. Mechanical impurities may be also be removed by circulating transformer oil through fine and coarse filters.
Thermal vacuum treatment consists of the removal of water vapor by a pump in a special vacuum chamber. Adsorption purification removes moisture by utilizing both natural or synthetic sorbents. As a rule, synthetic sorbents include zeolites. A zeolite unit will consume more energy compared with thermal vacuum equipment. Additionally, oil does not make contact with an adsorbent during thermal vacuum drying thereby extending the service life of filter elements.
It is recommended to use two methods to reactivate sorbent materials:
- heating by hot air and cooling by dry air; and
- thermal vacuum.
In this case, regeneration is performed at low temperatures that make it possible to reduce the risk of overheating the sorbent and preserving its structure.
units are recommended to be used for transformer oil drying (dehydration).