Applicability of a Vacuum Interrupter as the Basic Switch Element in HVDC Breakers

High voltage, high current vacuum interrupters were experimentally tested in a simulated HVDC breaker circuit. Fault currents which rose to ~10 kA in 5 mS were commutated to zero by a charged capacitor in 5-10 μS. Negative recovery voltage across the interrupter developed to 150 kV in 1-2 XIS and positive recovery voltage to 110 kV in 50-60 μS. Either a saturable or linear reactor was placed in series with the interrupter. Results indicate that a linear reactor sufficies for reliable interruption of 8 KA dc against >100 kV.