Transformer oil is a natural mineral oil oil obtained after distillation, refining, oil in lubricating oil distillates by acid-base refining processing a mixture of pure stability, low viscosity, good insulating liquid hydrocarbons, natural cooling of the. Commonly known as square shed oil, light yellow transparent liquid, relative density of 0.895. The freezing point is <-45 DEG C, and the specific heat capacity is about 0.5 (kcal / g *), which is mainly composed of three hydrocarbons, mainly composed of naphthenic hydrocarbons (about 80%), and others are aromatic hydrocarbons and alkanes. In our country, transformer oil has paraffin base oil and naphthenic base oil. Paraffinic base oil produced in Daqing and naphthenic based oil; produced in Xinjiang, Karamay.
Good transformer oil should be clean and transparent liquid, no mechanical impurities precipitate and suspended solids and cotton wool material. If it is contaminated and oxidized and produces resin and sediment, the oil in the transformer oil will deteriorate and the color will gradually change to pale red until it becomes dark brown liquid.
When the transformer is faulty, it will also change the color of the oil, under normal circumstances, when the transformer oil is light brown, it should not be used again. In addition, transformer oil showed turbid emulsion, color black, dark. The transformer oil is milky and milky, indicating that the oil contains moisture. Color dark, show that the transformer oil insulation aging. The color black, even burnt smell, that the transformer internal fault.
Why DL/T572-95 "transformer operation rules" stipulates that the upper oil temperature of oil immersed transformer is not allowed to exceed 95 degrees centigrade:
The insulation of general oil immersed transformer is mostly grade a insulating material, and its oil resistance temperature is 105 degrees centigrade. Specified in GB transformer operating conditions maximum temperature of 40 degrees, so the temperature rise value of the winding is 105-40=65 (C). Non oil circulation cooling, the top oil temperature and winding temperature about 10 DEG C, so the oil temperature is 65-10=55 (c), the top oil temperature is 55+40=95 (C). Oil temperature at the top of the strong oil circulation is generally not more than 40 degrees centigrade.
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