Evaluation of the Long-Term Thermal Capability of a High-Temperature Insulation System Using Silicone Liquid as a Dielectric Coolant

The functional thermal evaluation of test transformers insulated with silicon fluid is described. Studies have shown that polydimethylsiloxane fluids maintain good electrical properties at elevated temperatures, but system evaluation is required to determine their capability in a transformer. A transformer test facility meeting the requirements of IEEE Standard 262 is described and was used for the accelerated thermal testing of the transformer models. The test results are summarized and an indication is given of how silicone fluid can be used in the design of high-reliability industrial transformer systems.