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.