In the lifeline of modern cities and industry—the power system—a seemingly ordinary transparent liquid is silently safeguarding the safety of core equipment. This is dimethyl silicone oil (Polydimethylsiloxane, PDMS), which, thanks to its outstanding comprehensive performance, has become the preferred choice as an insulating and cooling fluid for high-end power transformers, earning it the title of "Liquid Guardian" for grid security.
Traditional mineral oil, used as a transformer insulating medium for a century, has low cost as its biggest advantage. However, under conditions of high temperature, high voltage, and prolonged electric fields, mineral oil is highly prone to oxidation, cracking, and polymerization reactions. Not only does this generate acidic substances that corrode internal metal components, but it also produces flammable gases like hydrogen and methane, which can lead to explosion accidents in severe cases. Furthermore, its poor biodegradability, flammability, and narrow operating temperature range (typically not exceeding 100°C) make it increasingly difficult to meet the stringent demands of modern smart grids for high reliability, long life, and environmental friendliness.
Against this backdrop, dimethyl silicone oil stands out with its unique molecular structure. Its backbone consists of alternating silicon (Si) and oxygen (O) atoms, with stable methyl groups (-CH₃) as side chains. The Si-O bond energy is far higher than that of carbon-carbon bonds, endowing the material with extraordinary thermal stability and chemical inertness. Dimethyl silicone oil has an extremely wide operating temperature range; from the severe cold of -50°C to the intense heat of 200°C, its key properties like viscosity and dielectric strength barely degrade. More importantly, its dielectric strength exceeds 20kV/mm, and its volume resistivity is as high as 10¹⁵Ω·cm, effectively isolating current and preventing internal short circuits and dangerous arc discharges. Even under extreme overload conditions, its performance fluctuation is controlled within 3%, providing a solid guarantee for the stable operation of the power grid.
Beyond its excellent insulating properties, efficient heat dissipation is equally critical. During operation, the transformer coils generate a large amount of Joule heat due to resistance. If this heat cannot be dissipated promptly, it will cause the insulating materials to age rapidly or even burn out. Dimethyl silicone oil possesses superior thermal conductivity and an extremely low viscosity-temperature coefficient. This means that regardless of ambient temperature, it maintains good fluidity, efficiently transferring the heat generated by the coils to the transformer casing via natural convection or forced circulation, and then dissipating it into the air, thereby keeping the equipment operating within its optimal temperature range.
