运行中的变压器油因受氧气、温度、电场、电弧、及水分、杂质和金属催化剂等的作用，发生氧化、裂解等化学反应，不断变质。

Due to the effects of oxygen, temperature, electric field, electric arc, moisture, impurities and metal catalyst, the transformer oil in operation is subject to oxidation, cracking and other chemical reactions, which leads to continuous deterioration.

变质后的变压器油，其油务化学监督各个项目的测试结果将会有或多或少项超出油的质量指标的极限。

After the deterioration of transformer oil, the test results of each item of oil chemical supervision will more or less exceed the limit of oil quality index.

而判断变压器油油质好坏有哪几项主要指标?

What are the main indexes to judge the quality of transformer oil?
           

变压器油按其特性有物理和化学两类。

Transformer oil can be divided into physical and chemical types according to its characteristics.

物理特性包括外观色度、密度、粘度、闪点、凝固点、水分、杂质、绝缘电阻、电气绝缘强度、介质损失角、热膨胀系数、吸收比和析出气体等。

Physical properties include appearance chromaticity, density, viscosity, flash point, freezing point, moisture, impurities, insulation resistance, electrical insulation strength, dielectric loss angle, coefficient of thermal expansion, absorption ratio and gas release.

化学性质包括酸价、溶于水的酸碱含量、安定度、活性硫、苛性钠、灰分和机械杂质等。

Chemical properties include acid value, acid-base content in water, stability, active sulfur, caustic soda, ash and mechanical impurities.

通过检测上述指标，依据标准对运行中变压器油超出极限值的原因及应采取的对策一一分析。

Through the detection of the above indicators, according to the standard, the causes of transformer oil exceeding the limit value in operation and the countermeasures to be taken are analyzed one by one.