Ultra high-speed solid-state circuit breakers for AC and DC power lines

Half cycle solid state circuit breakers, which can cut off fault current in a half cycle, have been put into use. These circuit breakers seem uneconomical because a large number of thyristors are required to be connected in parallel to withstand large fault current. Recently, the authors developed two new economical types of current limiting solid state circuit breakers (CLSCB) for AC three-phase 440 V and DC 750 V industrial power lines. These CLSCB´s operate at a fault current limit of 5000 A, AC or DC, where total performance time to circuit interruption is less than 250μsec. This paper deals with the CLSCB´s which have fault current interruption and load power control functions.