Transitional motion three-position isolating switch over-position protection device

The invention relates to power transmission and distribution equipment, and in particular relates to a transitional motion three-position isolating switch over-position protection device. An electric operation mechanism and a screw rod mechanism driven by the electric operation mechanism are arranged on a frame; the end part of the screw rod shaft of the screw rod mechanism is used for driving an auxiliary screw rod through a gear transmission mechanism; a transitional motion nut is arranged on the auxiliary screw rod in a matching manner; a section of limiting rod is connected with one side of the transitional motion nut; an outer bracket is arranged on the outer side of the frame; a guide groove parallel to the auxiliary screw rod is formed in the outer bracket; the limiting rod is inserted into the guide groove and is limited by the guide groove, so that the limiting rod can only move forwards and backwards and cannot rotate; travel switches which can be triggered by the transitional motion rod are respectively arranged in the front and rear limiting positions where the limiting rod moves; the travel switches are connected with the control circuit of the electric operation mechanism. The device is simple in structure and convenient to manufacture and mount, the rotation travel of the screw rod is limited through the travel switches, a moving contact is effectively prevented from over-position in action, and the operation reliability of the switches is improved.