Silicone Transformer Liquid: Use, Maintenance, and Safety

Silicone transformer liquid has been in use in over 10 000 small and medium power transformers in the United States since 1972. In this time, the reliability and performance of silicone liquid has been proven. Silicone liquid is chemically inert and thermally stable. These characteristics will allow for a long and useful life and ease of reclaiming contaminated liquid. Similar procedures are used to process and test silicone liquid and mineral oil. Transformer designs have been modified in only minor ways to accommodate the differences between silicone, mineral oil, and askarel. The coefficient of expansion, the heat transfer characteristics, and the dielectric properties have all been thoroughly investigated. Silicone fluid has been used in new and retrofilled transformers without any unusual or premium design features. In a monitoring program, no water contamination, leaking, overheating or any other operational problem were experienced in over three million documented hours of service in all kinds of environments. The safety of silicone liquid has been established through thorough testing and field experience. The very low heat release rates and unique burning characteristics combine to make silicone a very safe material for use in power transformers. In addition, silicone liquids are among the least toxic of all commercial chemicals. This, and their ecological compatibility, make silicone a safe environmental choice in replacing askarel.