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Time：2025-06-16 11:28:16 Reading volume：
Transformer oil serves as the primary insulating and cooling medium for oil-immersed transformers. The quality of its electrical strength and chemical composition directly affects the transformer's performance. If the oil contains a small amount of moisture and impurities, the insulation strength will decrease; and the oil is in contact with oxygen and is easily oxidized and deteriorated at high temperatures.
Therefore, transformer oil should be filtered when the transformer is installed.
To prevent the safe operation from being affected by the deterioration of oil quality, oil samples should be regularly collected for chemical analysis of the normal distribution of power distribution, and the oil should be treated according to the results of the analysis. The inspection cycle for chemical supervision of the distribution operation of oil is stipulated to be at least once every 3 years.
Acid value indicates the amount of acidic substances contained in the oil. The number of milligrams of potassium hydroxide required to neutralize the acidic substances in 1g of oil is called the acid value. Acid value includes organic acids and inorganic acids contained in the oil, but in most cases, the oil does not contain inorganic acids. Therefore, the oil acid value represents the content of organic acids in the oil.
The organic acids contained in the new oil are mainly cyclohexane acids. During storage and use, the organic acids generated by the oxidation of oil are fatty acids. The acid value is a sign of the degree of refining for new oil and a sign of the degree of oil aging for running oil. It is one of the important indicators for determining whether the oil can continue to be used.
Its over-limit value is less than 4.2. There are two possible reasons for exceeding the limit value: oil aging; oil contamination. The following countermeasures can be taken for water-soluble acid exceeding the limit value: increase the number of tests and compare with the acid value to find out the reason. Regenerate the oil, and if it is economical and reasonable, change the oil.
Its over-limit value is less than 20kV. There are two possible reasons for exceeding the limit value: excessive water content in the oil; impurity particle contamination in the oil. The following countermeasures can be taken for the breakdown voltage exceeding the limit value: find out the reason, perform vacuum oil filtration, plate and frame pressure oil filter, or ｒｅｐｌａｃｅ new oil. Generally, the breakdown voltage of the oil after ZJB vacuum oil filtration is required to be greater than 50 kV.
Its over-limit value is less than 130℃. Or it is 5℃ lower than the previous test value. There are two possible reasons for exceeding the limit value: there is a local overheating fault in the equipment, or the wrong oil is added. The following countermeasures can be taken for the flash point exceeding the limit value: find out the cause and eliminate the fault; degas the vacuum oil filter, or change the oil.
If the oil is opaque and there are visible impurities or suspended matter. Or the oil color is too dark, and the oil appearance is abnormal. Possible reasons for abnormal appearance are: the oil contains water, fiber, carbon black and other solids. The following countermeasures should be taken for oil with abnormal appearance: If the oil is unclear, turbid and white, it indicates that the oil contains water, and the water content should be checked.
If carbon particles are found in the oil, the oil color is black, or even has a burnt smell, it may be that there is an arc or partial discharge fault inside. It should be combined with other tests to investigate the cause and eliminate the fault.
If the oil color is dark and the color of the oil has changed significantly, attention should be paid to whether the aging of the oil is accelerated. It can be combined with the acid value test analysis of the oil, or the monitoring of the operating temperature of the oil should be strengthened.
