Oil purification methods
Transformer oil serves to insulate the energized parts and components of electric power transformers and also acts as a heat transfer medium. Additionally, it protects the solid insulation from damaging moisture. Besides transformers, insulting oil is used in switches, high voltage capacitors and power cables. In switches, the oil acts as an arc extinguisher preventing fires and possible explosions.
Over the course of the transformer’s service life, that may span many years of operation, the insulting oil will accumulate various contaminants that adversely affect the oil’s performance characteristics. Once the insulating oil’s performance characteristics have been diminished, the transformer’s solid insulation will be in greater risk of failure. In order to restore them, the oil must be purified of foreign substances and contaminates (water, gases and solid particles). Today, we’d like to look into the methods of transformer oil purification. Different methods of purification can be used depending on the substance(s) that need to be removed from the oil.
Centrifugal purification is a method for water removal. It separates unwanted materials, including water and moisture, under centrifugal force. The main advantage of this method is the relatively high rate of water removal. There are however, several drawbacks to this method that include; (1) a low degree of overall purification of the oil; and (2) complexity and the necessity for constant presence of service personnel supervising the process.
Another method for water removal is adsorption purification. The biggest advantage of this method is its simplicity. The drawbacks are: (1) the dependency of the purification rate on the type of sorbent used; (2) the need to dispose of used sorbent and the potential environmental risks; and (3) the high quality requirement to input oil and the low rate of processing capacity.
The difference between he boiling point of water and oil is the essence of thermovacuum drying. The oil to be purified goes into a special chamber with low pressure. In such conditions water evaporates at room temperatures. The method allows for high efficiency purification. It is very reliable and requires no complex adjustments. The main drawback is the relatively low rate of water removal.
The above methods may also be used for removal of gases, solids and acids from transformer insulating oil, e.g. thermovacuum purification is also a good method for removing unwanted gasses. Centrifugal purification can also remove solid particles. Single and multiple use filters with a high degree of purification are also used for the same purpose. Such filters must be replaced from time to time. Acidity of the oil is decreased by the adsorption method and has become a highly desirable process for a more complete maintenance service for your electric power transformers.
The most modern and cost effective method for performing transformer maintenance is the industry leading GlobeCore Process which uses a Fuller’s Earth sorbent filtering system. The GlobeCore Process uses the adsorption method to not only purify the transformer insulating oil, but to completely “regenerate” the oil by removing the contaminates and moisture from the entire transformer and not just the oil.
Unlike the older adsorption methods, the GlobeCore Process has eliminated the need to dispose of spent sorbent materials through the development and use of an automatic sorbent reactivation system. This technological breakthrough has now made the GlobeCore Process of transforemer oil purification and regeneration the most efficient and cost effective transformer maintenance system in the world.