Integral insulation for high voltage bus bar and switch gear components

As the trend continues for electrical equipment to be designed more compactly and with the accompanying rise in operating temperatures, more time is being spent to develop better insulating materials and equipment designs. In the case of switch gear, for example, the size has been reduced by approximately 1/3 over the past ten years. In earlier designs, air gap alone was used, in most instances, to provide the phase to phase separation; more recent equipment has been designed using insulated conductors in order that the distance between them can be reduced. In high voltage equipment, phenolic sleeves were probably the first materials used for insulating bus duct and current carrying members. Sometime after that, casting systems based on epoxy and polyester resins came into use. A newer process currently being investigated by the industry involves the application of epoxy powders to the bus duct and current carrying members using the fluidized bed coating process.