Design of Polymer Enclosures for High Voltage Equipment. Part II-Theory

The induced voltage on the surface of a polymer material used to construct an enclosure surrounding high voltage equipment must be at a sufficiently low level so that it does not present a hazard to personnel operating the equipment. A theoretical model, based on charge simulation techniques, is presented from which design parameters and dimensions of polymer enclosures can be obtained to construct substation enclosures. The dimensions of the enclosure are chosen to satisfy specific requirements of safety levels of a maximum touch voltage and a maximum short circuit current to a human body touching the enclosure. Good agreement is obtained between the theoretically predicted and the measured values of the induced voltage. Step by step design procedure and a typical calculation is included to aid the design process.