Seismic Rehabilitation of a Capacitor Bank Structure through Base Isolation

Abstract

It is well known that electrical substation oil circuit breakers, switches, current transformers and capacitor banks are highly susceptible to earthquake damage because of their brittle ceramic elements used for insulation as well as for the support of static loads and the lateral earthquake forces. Gaining special attention with the failure of important substation equipment during the 1971 San Fernando earthquake (Iwan, 1971), the seismic safety of the substation equipment and, in particular, the capacitor banks, utilized in interconnected electrical power distribution networks, became an important design consideration. Prior to 1971 event it was a common design practice to base the seismic design of almost all substation apparatus to a seismic coefficient of 0.2 in high earthquake risk areas ( Fallgren, et al., 1974). After the inadequacy of this design procedure is exhibited, several rational design procedures are suggested, which, in one case, have increased the seismic coefficient by %250 to 0.5 (Conway et al.,1978).