A novel hybrid current-limiting circuit breaker for medium voltage: principle and test results

Although many attempts have been made to design a fault-current limiting (FCL) circuit breaker (FCLCB) for medium voltage electric power systems, no economically attractive solution has been achieved so far. In this paper, a novel concept for a FCLCB is introduced based on a hybrid arrangement of semiconductors, temperature-dependent resistors, and a newly developed fast-opening mechanical switch. The latter utilizes one part of an electrodynamic repulsion drive, which is concurrent with the moving double-contact system. Laboratory tests as well as computer simulations of the complete FCLCB verify, as an example, the feasibility for the goal ratings 12 kV and 2/20 kA (single phase). A cost analysis shows the FCLCB to be more expensive than a conventional generator CB, but to be in the price range of the Is-limiter and below the costs of superconducting FCL principles. It is concluded that the presented method provides the basis for further commercial product development.