Power-off device and power system

The embodiment of the invention provides a power-off device and a power system. The power-off device comprises an on-off conducting bar, a breaking piston and an initiating explosive device, the on-off conducting bar comprises a moving contact and a static contact, the moving contact is in electric contact with the static contact, and at least part of the moving contact can move relative to the static contact so as to be separated from the static contact; the initiating explosive device comprises a first contact pin and a second contact pin, the first contact pin is electrically connected with the moving contact, and the second contact pin is electrically connected with the static contact; the breaking piston is used for cutting off the static contact under the driving of explosion pressure generated when the initiating explosive device explodes; when the current of the on-off conducting bar is larger than or equal to a first current threshold value, electrodynamic force generated between the moving contact a