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Why Transformer Oil Deteriorates

Why Transformer Oil Deteriorates

how to regeneration degraded transformer oil, by thermal vacuum and regeneration technology

Transformer oil is an important mineral insulating medium widely applied in power systems. It is currently mainly used in various transformers to insulate, dissipate heat, cool and extinguish arcs. Due to the influence of temperature, voltage, oxygen, etc. during operation, oil will continue to age during operation. Insulation aging products can damage the equipment and endanger the safe operation of the equipment, and in severe cases, it will cause the equipment to fail.

  • Why Transformer Oil Deteriorates ?

Transformer oil is a mixture of various hydrocarbons. Under the action of physical and chemical factors such as light, heat, oxygen, electric arc, electric field, magnetic field, and radiation, the physical properties such as color, odor, kinematic viscosity and dielectric loss change, and the electrical performance gradually changes. Decrease, lose the original physical and chemical properties, this is a more complicated chemical change. There are several reasons for the deterioration of transformer oil, namely: oxidation, electrical ageing, transformer fault ageing (overheating, discharge fault), and poor technical supervision and lax management in the process of transformer manufacturing, installation, and maintenance.

The main factor of transformer oil deterioration is the result of oxygen, which mainly comes from the air in the transformer oil. When new oil is injected into the equipment, even if the high vacuum degassing method is used to inject the oil, all the oxygen in the oil cannot be removed, and there is still a small amount of oxygen in the transformer oil injected into the equipment. Transformer oil has a strong affinity for oxygen. No matter how good the sealing performance of the transformer is, there is still a certain amount of oxygen in the transformer oil. At the same time, the insulation material paper fiber in the equipment also has a source of oxygen during the degradation reaction process that occurs under the action of heat. Moisture is the main catalyst of oil oxidation. It can penetrate into the oil from the outside of the equipment through the moisture in the atmosphere. At the same time, the moisture absorbed by the fiber is immersed in the oil, or the moisture formed by the aging of cellulose. Many chemical reactions will accelerate the oxidation process in the presence of copper and iron. When the operating temperature of the transformer oil increases, the vibration of the transformer due to magnetostriction and electric machinery will also accelerate the oxidation rate of the oil.

  • Necessity of Deteriorated Transformer Oil Treatment

In the process of using transformer oil, due to long-term contact with oxygen in the air, it will gradually oxidize and deteriorate, forming a series of oxidation products, making its original excellent physical and chemical properties and electrical properties deteriorate, so that it can not be used and becomes Waste oil, oxidation products in waste oil only account for a small part, generally 1% to 25% of the total, and the remaining 75% to 9% are ideal components. If this part of the oxidation products can be used simply The process method is to remove the oil from the oil and restore the original excellent performance of the oil. The waste oil will become good oil and can be reused.

Power system transformer oil consumption is large, and international oil prices have risen steadily in recent years. If the waste oil that is replaced every year can be reprocessed and reused, it will not only improve the economic efficiency of the enterprise, but also save energy.

  • How to treat Degraded Transformer Oil ?

Reasonable regeneration of dereriorated transformer oil is the basic principle for selecting the regeneration method. According to the degradation degree of the waste oil, the impurity content and the quality requirements of the regenerated oil, choose a method that is simple to operate, consumes less materials, and has high regeneration quality to improve it. Economic benefits.

Mainly include the following three processing methods:

  1. Physical purification method. This method mainly includes sedimentation, filtration, centrifugal separation and water washing. The specific regeneration time can be selected according to the degree of deterioration of the oil, equipment conditions, etc., and one or several unit operations can be selected as the purification treatment of the oil.
  2. Physical-chemical methods to purify oil. This method mainly includes operation units such as condensation and adsorption.
  3. Chemical regeneration method. This method mainly includes sulfuric acid treatment, sulfuric acid-clay treatment and sulfuric acid-alkali-clay treatment and so on.
Among the above three methods, the first physical filtration method can remove sludge and impurities in the oil, but cannot alleviate the aging problem of the oil; the third chemical method usually uses sulfuric acid and clay to regenerate the degraded transformer oil, but This method has extremely high requirements on the operation, and the amount of sulfuric acid and clay is also very high. The amount needs to be adjusted according to different oil conditions. It is difficult for ordinary electrical engineers to accurately grasp this regeneration method.
The degraded Transformer Oil Regeneration method developed by PURETECH OIL FILTRATION adopts the second method. This method uses the characteristics of the adsorbent which has a large active surface area and has a strong adsorption capacity for oxidation products and water in the waste oil. The oil is fully contacted to remove the harmful products in the oil and achieve the purpose of purification. It is especially suitable for when the deterioration of oil is not too serious, the oilification is not deep, the acid value is below 0.1mg KOH/g, the water-soluble acid appears in the oil or the tga is significantly increased. Its advantage is also that it can be used to treat transformer oil in operation. When the equipment is not powered off, the charged filtration and adsorption treatment has obvious effect on the treatment of mildly degraded oil.

PURETECH OIL FILTRATION designs and manufactures two types of degraded Transformer Oil Regeneration plants.

- With vacuum degassing. It is capable of processing transformer oil by removing water, gases, impurities, oxides, as well as regeneration.

- Without vacuum degassing. Only for oil filtration and regeneration,cannot remove water and gases.

  • Standards of Regenerated Transformer Oil

The regenerated insulating oil shall be subjected to a full analysis test of the regenerated oil in accordance with relevant regulations. The quality standards should be the new insulating oil quality standards in the oil quality standards. After the waste oil is processed, the antioxidant content in the oil will be consumed to a certain extent, and the content will be reduced. It is required to determine the content of the regenerated oil "T501" (the name code of the antioxidant added to the T501 oil), and the general new oil The content of "T501" is 0.3~0.5%. If it is lower than this content, it should be supplemented to improve the anti-oxidation stability of the oil and prolong the service life of the oil.

More information about transformer oil filtration/transformer oil regeneration, welcome to contact us.


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