In order to improve the insulation strength, trace water content, gas content, medium loss coefficient and other indicators of transformer oil and insulating oil, transformer oil must be treated strictly before it is injected into the tank to effectively remove water, gas and impurities in the oil. In practical operation, different types of transformer oil and insulation oil are treated by different types of Transformer Oil Purification Plant, and the effect is better.

1. For general transformer oil polluted by water and dust and other impurities, plate and frame pressure type Transformer Oil Filter Machine can be used. After repeated filtration, it can usually meet the requirements. Its principle is the use of oil filter paper to absorb moisture, filtering impurities. The advantages are that the removal effect of fine impurities is good, its structure is simple, convenient maintenance, reliable operation, convenient handling, so it is widely used. The disadvantage is that the water filtration is not thorough, so it is only suitable for low voltage grade transformer oil purification processing.

2. The vacuum Transformer Oil Filter Machine is widely used at present. It can not only completely remove water and gas in the oil, but also effectively remove small impurities. The process flow: transformer oil to be treated → coarse filtration → fine filtration → heating oil vacuum dehydration degassing → net oil. Coarse filter adopts metal filter screen and strong magnet, fine filter usually removes 1 micron small impurities. At present, there are many kinds of fine filters, such as metal powder sintered material, metal microporous material, ceramic filter material and filter paper with special structure.

Transformer oil is heated, filtration, dehydrated and degassed. The principle is to vacuum the tank, the heating transformer oil with spray method to form oil mist, and the gas and water in the oil escape. The oil temperature is generally about 50℃, not too high, so as not to make the transformer oil aging. This method of transformer oil purification processing has good dewatering and degassing effect and is widely used at present.

If the oil is sprayed into a certain diameter of the oil bead, the oil bead has a high interfacial tension, so that the water and gas in the oil bead is not easy to fully play. Therefore, the diameter of the injection hole should be selected appropriately, and several baffles should be set at the suction port of the tank in general to prevent the transformer oil from being pumped away by the vacuum pump.

At present, a relatively advanced film dehydration degassing method is also used at home and abroad, which is to make the oil entering the tank form a very thin oil film after some degassing elements, and always complete the whole process of dehydration and degassing in the oil film state, so that the water and gas in the oil are easy to remove.

3. the treatment of contaminated transformer oil. The polluted transformer oil (commonly known as dirty oil) refers to the colloid pollution of the transformer oil formed by the combination of extremely small impurities and oil molecules, and the transformer oil used for many years, generally released by the repair product (the pH value of the oil is very low). This kind of dirty oil must be treated by adsorption method to improve the index of oil. Silica gel (SiO2) or activated alumina (A1203) is generally used as adsorbent. In the Oil Purification Processing, in order to ensure full contact between silica gel and transformer oil, and facilitate the replacement of silica gel, a number of partitions are set in the silica gel tank, and the silica gel is rotated in a small cloth bag, not in bulk. After heating, the transformer oil is sent into the silica gel tank, which is circulated for a certain period of time to give full play to the adsorption effect, and then injected into the net oil tank by the oil filter. In the process of treatment should be regularly monitored to determine the adsorption effect, when the adsorption effect is not obvious, it should be considered to replace silica gel. Generally, the amount of silica gel accounts for about 3%~5% of the oil by weight.