Seismic retrofitting of an HV circuit breaker using base isolation with steel cable dampers. Part I: Preliminary tests and analyses

This paper briefly describes the design and characterization of a new base isolation system that protects HV ceramic circuit breakers during seismic events to allow their qualification according to the European standard CEI EN 62271-207. The solution is based on steel cable dampers, which are also known as 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 the simplicity to upgrade the equipment for seismic protection.