The SMS-PL column vacuum load switch and the SMS-PVl and SMS-PVh on-column vacuum circuit breakers are a new generation of on-column switches that have been fully developed by absorbing domestic and foreign advanced technology and mature experience. Excellent breaking performance, excellent The electrical characteristics, high reliability and long-term maintenance-free, suitable for three-phase AC 50Hz, 12kV or less power lines, as a protection control device for breaking, closing line load current, overload current and breaking short-circuit current.