Design of a Polysil DC Insulator

Under an EPRI sponsored contract, two designs of suspension insulators using Polysil as the dielectric are being developed for use on HVDC overhead transmission lines. These insulators resemble standard porcelain or glass suspension units; however, they are designed to exhibit unique operating characteristics that will make them more desirable for use on HVDC lines. One design is based on the theory that by properly shaping the electric field, a higher percentage of the total contamination will be deposited on the upper surfaces of the insulator. If this can be accomplished, the insulator should have better flashover performance as top surface contamination is more easily removed by wind and rain. A second design is an effort to produce a mechanically fail-safe insulator. This design uses chain-like links that are cast within and separated by the Polysil dielectric. This insulator will prevent a conductor from dropping even if all the dielectric material is destroyed.