A switch, a power conversion apparatus, and a power supply system. The power supply system includes a control unit, a switch, a direct current source, and a power conversion unit. The switch is electrically connected between the direct current source and the power conversion unit, and the control unit is configured to send a switch-off signal to the switch when a fault occurs on the direct current source or the power conversion unit. The switch includes a contact component, a trip-free structure, and a knob that are sequentially disposed in a stacked manner in a first direction. A trip unit of the trip-free structure is configured to receive the switch-off signal, to unlock the trip unit from the cradle. The cradle drives the connecting rod structure to move, to separate the moving contact from the fixed contact.

The present application relates to a rotation shaft structure, a transmission system, an operation mechanism, and a switching device assembly. The rotation shaft structure includes a rotation shaft, being capable of rotating between a first rotation position and a second rotation position, and further configured to be capable of translating between a first translation position and a second translation position in a direction along a rotation axis of the rotation shaft; a blocking assembly, being capable of switching between a first posture and a second posture; and a cooperative blocking member, when the blocking assembly is in the first posture, the cooperative blocking member is out of a translation path of the rotation shaft from the first translation position to the second translation position, when the blocking assembly is in the second posture, the cooperative blocking member is in the translation path.