Class H transformerette tests on new barrier insulation

Class H insulating materials have gone thru a very rapid development period in the past ten or fifteen years, with the introduction of many new and versatile materials in varied forms. They are mainly based on a combination of heat stable fibrous materials, such as asbestos and glass fibers, with silicone resins and rubbers used to fill the spaces between and around the fibers. This marriage of mechanical strength, dielectric strength, and heat stability has gone thru a steady improvement in quality and dependability along with cost reductions brought about by greater volume and improved manufacturing techniques. At the same time, engineers and designers have learned to utilize the best qualities while minimizing the short comings of these materials. This paper describes the development of improved barriers achieved by the introduction of another heat stable material of extraordinary qualities.