On 2018-08-08 14:48:54
How to improve the insulation strength of transformer oil
In order to improve the insulation strength, dielectric loss coefficient and other indicators of transformer oil, transformer oil must be treated before being injected into the oil tank to remove moisture, gas and impurities in the oil. In practical application, we treat different types of transformer oil and the effect is better.
1. For transformer oil generally polluted by impurities such as water and dust, the plate-frame pressure filter can be used, which can usually meet the requirements after repeated filtration. Its principle is to use oil filter paper to absorb water, filter impurities. Because of its simple structure and easy to carry, it is also widely used. The disadvantage is that the filtration is not complete, the effect of fine impurities removal is not good, and the cost is relatively high, when the water is large, oil filter paper needs to be replaced frequently.
2, now commonly used is the vacuum oil filter, it can not only thoroughly remove water and gas in the oil, but also can effectively remove small impurities. The technological process is as follows: transformer oil to be treated → coarse filtration → fine filtration → heating oil vacuum degassing → clean oil. Coarse filtration adopts metal screen and strong magnet, fine filtration usually filters 1 ~ m 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 core of filter paper with special structure.
Transformer oil heating vacuum dewatering degassing. The principle is to vacuum the tank and spray the heated transformer oil to form an oil mist, so that the gas and water in the oil escape. Oil temperature is generally around 65℃, not too high, so as not to make the oil aging. This method has good degassing effect and is widely used at present. However, if the oil is sprayed into a very fine mist, it can easily be removed by vacuum pumps.
If the oil is sprayed into oil beads with a certain diameter, the high interfacial tension of the oil beads makes it difficult for the moisture and gas in the oil beads to give full play. To this end, the diameter of the nozzle hole should be chosen appropriately, and it is generally necessary to set up several baffles at the suction mouth of the tank to prevent the transformer oil from being evacuated by the vacuum pump.
At present, a relatively advanced film degassing method has been adopted both at home and abroad, that is, the oil entering the tank is formed into a very thin oil film after passing through some degassing elements, and the whole process of degassing is always completed in an oil film state, so that the water and gas in the oil can be easily removed.