变压器油是天然石油中经过蒸馏、精炼而获得的一种矿物油，是石油中的润滑油馏份经酸碱精制处理得到纯净稳定、粘度小、绝缘性好、冷却性好的液体天然碳氢化合物的混合物。俗称方棚油，浅黄色透明液体，相对密度0.895。凝固点<-45℃，比热容约为0.5（卡/克*度）主要由三种烃类组成，主要成分为环烷烃（约占80%），其它的为芳香烃和烷烃。在我国，变压器油有石蜡基油、环烷基油。石蜡基油产于大庆，环烷基油产于新疆克拉玛依。
Transformer oil is a kind of mineral oil obtained by distillation and refining in natural oil. It is a mixture of pure and stable liquid natural hydrocarbons with low viscosity, good insulation and good cooling property obtained by acid-base refining of lubricating oil fraction in oil. Commonly known as Fangpeng oil, light yellow transparent liquid, relative density 0.895. Freezing point < - 45 ℃, specific heat capacity about 0.5 (cal / g * d) is mainly composed of three hydrocarbons, the main component is cycloalkanes (about 80%), others are aromatic hydrocarbons and alkanes. In China, there are paraffin base oil and naphthenic base oil in transformer oil. Paraffin base oil is produced in Daqing and naphthenic base oil is produced in Karamay, Xinjiang.
良好的变压器油应该是清洁而透明的液体，不得有沉淀物、机械杂质悬浮物及棉絮状物质。如果其受污染和氧化，并产生树脂和沉淀物，变压器油油质就会劣化，颜色会逐渐变为浅红色，直变为深褐色的液体。当变压器有故障时，也会使油的颜色发生改变一般情况下，变压器油呈浅褐色时就不宜再用了。另外，变压器油可表现为浑浊乳状、油色发黑、发暗。
Good transformer oil should be clean and transparent liquid, free of sediment, mechanical impurities, suspended solids and cotton flocculent substances. If it is polluted and oxidized, and resin and sediment are produced, the quality of transformer oil will deteriorate, and the color will gradually change to light red until it turns to dark brown liquid. When there is a fault in the transformer, the color of the oil will also change. Generally, when the transformer oil is light brown, it is not suitable to use it again. In addition, transformer oil can be shown as turbid emulsion, black and dark.
变压器油浑浊乳状，表明油中含有水分。油色发暗，表明变压器油绝缘老化。油色发黑，甚有焦臭味，表明变压器内部有故障。
The turbid emulsion of transformer oil indicates that there is moisture in the oil. The darkening of oil indicates that the oil insulation of transformer is aging. The oil turns black and even has a scorching smell, indicating that there is a fault inside the transformer.
为什么DL/T572-95《变压器运行规程》规定油浸式变压器上层油温不许超过95℃：
Why DL / t572-95 "transformer operation regulation" stipulates that the upper oil temperature of oil immersed transformer shall not exceed 95 ℃:
一般油浸式变压器的绝缘多采用A级绝缘材料，其耐油温度为105℃。在国标中规定变压器使用条件高气温为40℃，因此绕组的温升限值为105-40=65(℃)。非强油循环冷却，油温与绕组油温约差10℃，故油温升为65-10=55(℃)，油温度为55+40=95(℃)。强油循环油温升一般不超过40℃。
Generally, the insulation of oil immersed transformer is made of grade a insulation material, and its oil resistance temperature is 105 ℃. According to the national standard, the high temperature of transformer is 40 ℃, so the temperature rise limit of winding is 105-40 = 65 (℃). Non strong oil circulation cooling, top oil temperature and winding oil temperature difference is about 10 ℃, so the top oil temperature rise is 65-10 = 55 (℃), the top oil temperature is 55 + 40 = 95 (℃). The top oil temperature rise of strong oil circulation generally does not exceed 40 ℃.
