Seismic retrofitting of a HV circuit breaker through base isolation with steel cable dampers. Part 1: Preliminary tests and analyses

This paper briefly describes the design and characterization of a base isolation system that protects HV ceramic circuit breakers during seismic events. This qualifies them to the European standard CEI EN 62271-207. The solution is based on an innovative application of wire rope isolators. Preliminary numerical analyses and tests were performed on a typical HV circuit breaker and demonstrated the effectiveness of the proposed isolation system in reducing seismic demand. The results were also validated using a shaking table, which is described in an accompanying paper. The on-site installation of this system in several Italian substations has finally proved simple enough to upgrade the equipment for seismic protection.