Bundled-Conduuctors for EHV Transmission Systems with Compressed -- SF6 Insulation

This report presents the results of a theoretical study to evaluate the practicability of bundled conductors in SF6-insulated transmission systems operating at EHV levels. The bundled conductors are evaluated according to their ability to maintain the electric-field intensity at the conductor surface below the corona-on-(or breakdown) level of the conductor, and are compared with practical coaxial-conductor systems. The results obtained show that the concept of bundled conductors can be adapted for use in SF6-insulated systems. The proposed bundle configuration consists of a central conductor surrounded by n small subconductors forming an electrostatically protective screen, the conductor bundle itself enclosed within an outer envelope. Compared with conventional coaxial configurations, it presents several advantages, namely, flexibility of design to meet the system's high-current, mechanical and insulation requirements separately, smaller electrode area exposed to high field intensities, and less stringent specifications for the supporting epoxy spacers.