Transformer oil is a kind of petroleum fractionation product. The standard of China is GB 2536. The demarcation of transformer oil brand is defined according to the level of oil freezing point, which is divided into three categories: 10 × 10, 25 × 45 × 45. 10 × transformer oil is produced by paraffin based oil, 25 × transformer oil is produced by intermediate based oil or naphthenic based oil, 45 × transformer oil is produced by Naphthenic based oil# Transformer oil is produced with naphthenic base oil.

　　一、变压器油的主要作用：

　　1、 Main functions of transformer oil:

　　（1）绝缘作用：变压器油具有比空气高得多的绝缘强度。绝缘材料浸在油中，不仅可提高绝缘强度，而且还可免受潮气的侵蚀。

　　(1) Insulation function: transformer oil has much higher insulation strength than air. The insulating material soaked in oil can not only improve the insulation strength, but also avoid the erosion of moisture.

　　（2）散热作用：变压器油的比热大，常用作冷却剂。变压器运行时产生的热量使靠近铁芯和绕组的油受热膨胀上升，通过油的上下对流，热量通过散热器散出，保证变压器正常运行。

　　(2) Heat dissipation: the specific heat of transformer oil is large, and it is often used as coolant. The heat generated during the operation of the transformer makes the oil close to the iron core and winding expand and rise by heating. Through the convection of the oil up and down, the heat is released through the radiator to ensure the normal operation of the transformer.

　　(3)消弧作用：在断路器和变压器的有载调压开关上，触头切换时会产生电弧。而变压器油具有较好的导热性，在触头切换产生电弧的高温影响下，变压器油可以分化大量气体，形成比较大的压力，增强介质的灭弧作用，从而促使电弧迅速熄灭。

　　(3) Arc suppression: on the on load voltage regulating switch of the circuit breaker and transformer, the arc will be generated when the contact is switched. The transformer oil has good thermal conductivity. Under the influence of high temperature of arc generated by contact switching, the transformer oil can differentiate a large number of gases, form a relatively large pressure, enhance the arc extinguishing effect of the medium, so as to promote the rapid extinction of the arc.

　　二、对变压器油的性能通常有以下要求：

　　2、 The performance of transformer oil usually has the following requirements:

　　（1） 变压器油密度尽量小，以便于油中水分和杂质沉淀。

　　(1) The density of transformer oil shall be as small as possible to facilitate the precipitation of moisture and impurities in the oil.

　　（2）粘度要适中，太大会影响对流散热，太小又会降低闪点。

　　(2) Viscosity should be moderate, too much influence convection heat dissipation, too small will reduce flash point.

　　（3） 闪点应尽量高，一般不应低于136℃。

　　(3) The flash point shall be as high as possible, generally not lower than 136 ℃.

　　（4）凝固点应尽量低。

　　(4) The freezing point shall be as low as possible.

　　（5） 酸、碱、硫、灰分等杂质含量越低越好，以尽量避免它们对绝缘材料、导线、油箱等的腐蚀。

　　(5) The lower the content of acid, alkali, sulfur, ash and other impurities, the better, so as to avoid their corrosion to insulating materials, wires, oil tanks, etc.

　　（6） 氧化程度不能太高。氧化程度通常用酸价表示，它指吸收1克油中的游离酸所需的氢氧化钾量（毫克）。

　　(6) The degree of oxidation should not be too high. The degree of oxidation is usually expressed in terms of acid value, which refers to the amount of potassium hydroxide (mg) needed to absorb the free acid in 1g oil.

　　（7） 安定度不应太低，安定度通常用酸价试验的沉淀物表示，它代表油抗老化的能力

　　(7) the stability should not be too low. The stability is usually indicated by the acid value test sediment. It represents the ability of oil to resist aging.

　　三、如何防止变压器油劣化

　　3、 How to prevent transformer oil from deterioration

　　防止油劣化变压器油在运行中会逐渐氧化变质，缩短其使用寿命，而且对充油电器设备的安全运行 构成威胁。为防止油的老化、延长油的使用寿命，应对运行油采取有效的防劣化措施。 GB/T 14542—2005《运行变压器油维护管理导则》规定》电力变压器必须采取下述一项防 劣措施，lOOOkVA及以上设备应装净油器，8000kVA及以上的设备应装密封式储油柜。

　　In order to prevent oil deterioration, transformer oil will gradually oxidize and deteriorate in operation, shorten its service life, and pose a threat to the safe operation of oil filled electrical equipment. In order to prevent the oil from aging and extend its service life, effective anti deterioration measures should be taken for the operating oil. According to GB / T 14542-2005 guide for maintenance and management of operating transformer oil, power transformer must take one of the following measures to prevent deterioration. Oil purifier shall be installed for ookva and above equipment, and sealed oil conservator shall be installed for 8000kVA and above equipment.

　　1.添加抗氧化剂

　　1. Add antioxidant

　　能减缓油品抗轼化安定性的少量物质称为油品的抗氧化添加剂，油中添加抗氧化剂是减 缓油质劣化的有效方法。在国内的变压器油中普遍使用的是T501抗氧化剂（2, 6 —二叔丁 基对甲酚)。抗氧化剂的作用机理是：从油品烃类氧化的连锁反应解释，抗氧化剂之所以能减缓油品 的氧化，关键是抑制剂能“吃掉”活性自由基，分解剂能终止氧化的链反应。T501为第三类抗氧化剂，它能与油在氧化过程中产生的R 和R02 作用生成非活性 自由基或稳定化合物，从而抑制油分子的氧化过程。

　　A small amount of substance which can slow down the anti-oxidation stability of oil is called the anti-oxidation additive of oil. Adding antioxidant in oil is an effective way to slow down the deterioration of oil quality. T501 antioxidant (2,6-di-tert-butyl-p-cresol) is widely used in transformer oil in China. The mechanism of antioxidants is: from the chain reaction of hydrocarbon oxidation of oil, the key to the antioxidants slowing down the oxidation of oil is that the inhibitors can "eat" the active free radicals, and the decomposers can stop the chain reaction of oxidation. T501 is the third kind of antioxidant. It can react with R and R02 produced in the oxidation process of oil to form inactive radicals or stable compounds, thus inhibiting the oxidation process of oil molecules.

　　2. 安装净油器

　　2. Install oil purifier

　　净油器是一种渗滤过滤装罝，具有结构简单、维护工作量小、对油的防劣效果好等特 点，是电力系统防止变压器油劣化的有效防劣措施之一。净油器按循环方式分为热虹吸净油器和强制循环净油器两类。热虹吸净油器使用的是一 种吸附净油法，也称连续再生法，它是利用变压器油的自然循环进行油的净化。

　　Oil purifier is a kind of filtration device, which has the characteristics of simple structure, small maintenance work and good anti deterioration effect on oil. It is one of the effective anti deterioration measures to prevent transformer oil deterioration in power system. The oil purifier can be divided into two types according to the circulation mode: thermosiphon oil purifier and forced circulation oil purifier. The thermosiphon oil purifier uses an adsorption oil purification method, also known as continuous regeneration method, which uses the natural circulation of transformer oil for oil purification.