A rotary switch assembly, including a rotary contact and a stationary contact, and a rotary actuator for rotating the rotary contact such as to connect with and disconnect from the stationary contact. The rotary actuator includes a shield for shielding the rotary contact from a side that faces the stationary contact when the rotary contact and the stationary contacted are being disconnected from each other.

A power supply system includes a control unit, a switch, a direct current source, and a power change unit. The switch includes a switch unit and an operation mechanism. The operation mechanism is configured to receive a switch-off signal and control the switch unit to be turned on or off. The switch unit includes a first static contact, a movable contact, and a first arc extinguishing structure. When the switch unit is turned off, the movable contact rotates about a rotation center relative to the first static contact by a first included angle to be separated from the first static contact, to generate a first arc. The first arc extinguishing structure includes a first arc extinguishing end part and a second arc extinguishing end part. A connection line between the first arc extinguishing end part and the rotation center of the movable contact is a first line.