Medium-voltage rapid mechanical switch and opening and closing method

The invention relates to a medium-voltage rapid mechanical switch and a switching-on and switching-off method. The medium-voltage rapid mechanical switch structurally comprises a vacuum arc-extinguishing chamber, an insulating pull rod, an electromagnetic repulsion operating mechanism, a switching-on state/switching-off state maintaining device based on a semi-permanent magnet material and a hydraulic variable-diameter buffer device. The electromagnetic repulsion operating mechanism can enable the switch to be switched on and off rapidly, the switching-on state/switching-off state maintaining device based on the semi-permanent magnet material can provide stable maintaining force at the switching-on and switching-off position of the switch, and the hydraulic variable-diameter buffering device provides effective buffering for switching-off of the switch. During opening, the electromagnetic repulsion operating mechanism and the closing state/opening state maintaining device based on the semi-permanent magnet mat