A Hybrid DC Vacuum Circuit Breaker for Medium Voltage: Principle and First Measurements

A novel concept of hybrid dc vacuum circuit breakers (VCBs), based on the combination of zero-voltage switching (ZVS) and zero current switching principle, was developed to meet the needs of the dc zonal distribution system on shipboard rated for a current of several kiloamperes and a voltage of several kilovolts. In normal operation, the VCB handles the continuous flow of dc current, minimizing the onstate losses. When protection against the fault is requested, the current is first divided between the VCB and the static branch before being quickly interrupted under a forced commutation principle. Laboratory tests have been dedicated to characterize the reliability of the high-current commutation from the VCB to the static branch and the turnoff characteristic of the silicon-controlled rectifier under high-current conditions. Finally, the critical design of the high-speed VCB is discussed.