Dimethyl silicone oil is widely used as electrical insulation medium in the electromechanical industry. Although the electrical characteristics of dimethyl silicone oil is not stronger than general insulating oil, but its viscosity range is wide, good thermal stability, oxidation resistance, dielectric loss is small, freezing point and vapor low, flash point and ignition point is high, in a wide range of temperature and frequency to maintain good dielectric properties. And good compatibility with other insulating materials, so widely used in all kinds of transformers, capacitors, electronic equipment, components and components, cable connection parts of insulation, cooling, immersion, lubrication, damping, coating and heat carrier.

In the common transformer oil, mineral oil is the most used, its advantage is good dielectric property and low cost, fatal weakness is easy to burn, very unsafe.

For example: polychlorinated biphenyls (PCBS), although excellent fire resistance, have strong carcinogenicity, and have been banned in major countries; Although the fluorine chloride compound fire resistance is good, but the boiling point is too low, the seal is not strict that causes environmental pollution.

In contrast, dimethyl silicone oil has many advantages. So the transformer with dimethyl silicone oil as the cooling insulation medium develops rapidly with the development of society.

Since silicone oil was first used in transformers in 1972, not a single fault has been caused by silicone oil. On the contrary, during this period, the damage rate of non-silicone transformer is as high as 0.2%~0.4%. At present, the United States, Japan, Western Europe and even some countries in the Middle East have used silicone oil transformers in high-rise buildings, residential areas, schools, factories and key departments with special requirements. In the 1980s, China also developed silicon oil for transformers. Transformers made from it have been operating safely in Beijing subway and other departments for many years now. Since the 1970s, China began to use methyl phenyl silicone oil (250-30) instead of PCBS as maceration oil for power capacitors, which has received good results. Its advantages are small expansion coefficient, non-toxic and tasteless, chemical inertia, and easy to be compatible with other materials. It can extinguish the high voltage generated by partial discharge, and has strong hydrogen absorption in high voltage power plants. Compared with power capacitors using mineral oil, the capacity of a single capacitor can be increased by 2.75 to 5.00 times, and the power loss can be reduced by 50%. Under the same capacity condition, the volume of capacitor decreases and the capital construction cost decreases. High working temperature, large overload capacity, long - term safe operation.

Silicon oil, though, is more expensive than mineral oil. But with the compact design of transformers, can greatly reduce the amount of silicon oil loading, so as to greatly reduce the production of silicon oil transformers, now with dimethyl silicone oil instead of mineral oil for electrical insulation oil is becoming more and more.