Automatic transfer device for AC power supply circuit

The utility model relates to an automatic transfer device of a route of a power supply, which is used for controlling the switching of a mainly used power source in alternating current distribution (municipal power) and a spare power source (a self-spare oil machine or the other municipal power). The automatic transfer device can change the route of an AC power supply through changing the close direction of a knife switch, and is characterized in that the rotation or stop and the rotary direction thereof of a bidirectional motor are controlled by a control module. The wrenching of the knife switch is driven by the rotary torque of the motor through a transmission system of a worm gear and worm, and manpower wrenching is replaced by automatic wrenching. The utility model can be automatically transferred, has the safe and reliable advantages that the knife switch can be used for transferring the route of the power supply, and can be realized by that the existing alternating-current distribution panel is improved.