Seismic evaluation and analysis of high-voltage substation disconnect switches

Disconnect switches are one of the components of an electrical substation that are vulnerable to the effects of earthquake shaking. Three vertical-break and two horizontal-break 230 kV switches of porcelain and composite construction were tested on a triaxial earthquake simulator in various configurations. Three-pole switches were mounted on a stiff, low-profile frame and tested according to the industry standard IEEE-693-1997. The vulnerable components of the switches were the aluminum spacers at the base of the switch posts and the welded post-blade connections and the bolted connections at the base of the posts. Single-degree-of-freedom models of the switch insulator posts were developed using experimental data to establish the amplification of seismic demand on the switches when mounted on frames of different heights and stiffness.