New Concept for VFTO Attenuation in GIS with Modified Disconnector Contact System

This paper investigates on a new concept for very-fast transient overvoltages (VFTOs) attenuation in gas-insulated switchgear (GIS). The concept, first introduced by the authors in this paper, involves modification of the GIS disconnector contact system in order to dissipate the VFTO energy in damping elements placed inside the GIS busbar conductor. The concept is an alternative to the state-of-the-art method where magnetic rings are placed in the space between the GIS conductor and the enclosure. The proposed arrangement has no impact on the damping element on the dielectric design of the GIS busbar, and it highly reduces the impact on the GIS thermal design. This paper presents analyses which show feasibility of the concept, through 1) principles which govern voltage conditions inside the GIS busbar and 2) full-Maxwell finite-element method electromagnetic simulations of VFTO attenuated with the use of the proposed concept.