An Experimental Study on the Current Interruption of the Sub-Millisecond Ultra-Fast Vacuum Interrupter

The rapid development of power systems led to an increase in the short-circuit current level of the system. Ultra-fast vacuum interrupters (VIs) are promising equipment for the fast interrupting short-circuit current. In this paper, the 40.5 kV sub-millisecond ultra-fast VI is developed based on the electromagnetic repulsion mechanism and the 40.5 kV lightweight VI. The average velocity of the 40.5 kV sub-millisecond ultra-fast VI is significantly improved, which is 9.83 m/s within 4 mm of contact separation. Then, a voltage-source converter (VSC) assisted resonant current (VARC) direct current circuit breaker (DCCB) based on 40.5 kV sub-millisecond ultra-fast VI was constructed, and current interruption experiments were carried out. The results show that the inherent opening time for 40.5 kV sub-millisecond ultra-fast VI is 0.57 ms, and it takes 0.98 ms for VARC DCCB to interrupt 11 kA from contact separation, significantly improving the capability of fault fast clearance after receiving a trip signal.