VD9-12 indoor permanent magnet high-voltage vacuum circuit breaker (hereinafter referred to as circuit breaker) is an indoor switchgear used in 12KV power systems, serving as a protection and control unit for power grid equipment and industrial and mining enterprise power equipment. Due to the use of patented CDY permanent magnet mechanism and direct transmission structure design, the circuit breaker has excellent performance, making it particularly suitable for frequent operation or multiple short-circuit current breaking places. The circuit breaker is equipped with a dedicated propulsion mechanism to form a handcart unit.