Seismic retrofitting of an HV circuit breaker using base isolation with wire ropes. Part 1: Preliminary tests and analyses

•An isolation system based on wire rope is proposed for the seismic protection of HV equipment.•A 380 kV circuit breaker installed in typical electrical substations was selected as case study.•A new model for the simulation of the cyclic response of wire rope isolators has been proposed.•A simplified numerical model was used to simulate the response of circuit breaker.•Time-history analyses demonstrated the effectiveness of the proposed isolation system.

This paper briefly describes the design and characterisation 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.