IEEE Standards PC37.122.4\u2122/DG Draft Guide for Application and User Guide for Gas-insulated Transmission Lines (GIL), Rated 72.5 kV and Above

The purpose of this guide is to provide technical assistance for the selection, application and project management for a Gas Insulated Line (GIL) transmission project from initial planning through decommissioning and retirement. It is not within the scope of this guide to address contractual or commercial questions related to GIL projects. The document included tables, flowcharts and other aids that maybe of use in a typical GIL project. While not required, a certain minimum knowledge of GIL is advantageous in order to utilize the benefits of this technology. The relevant information for accurate system planning using GIL is also included in this document along with operations and maintenance information. This guide includes equipment with the following specifications or characteristics: rated voltage 72.5 kV and above, alternating current, single-phase, rigid (solid aluminum) enclosure, installed above ground, in a trench, directly buried or in tunnel, laid horizontally, vertically at any angle and using pure SF6 or a mixture of SF6 with nitrogen as the insulating medium