Power supply circuit cut-off device and method of controlling power supply

A power supply circuit cut-off device capable of opening and closing a power supply circuit, comprising:

• a housing;
• a cover that is connectable to and separable from the housing, the cover having at least one restricting wall;
• a lever mounted to the cover and movable from a partial locking position to a full locking position for connecting the cover to the housing and being movable from the full locking position to the partial locking position for separating the cover from the housing;
• a stopper mounted to the lever and being slidable on the lever between an initial position and a final position;
• at least one power supply terminal that opens the power supply circuit by being disconnected from the power supply circuit when separating the cover from the housing;
• and
• at least one detection terminal that is switched from an ON-state to an OFF-state when separating the cover from the housing;
• wherein
• the stopper contacts the at least one restricting wall at the final position of the stopper on the lever to restrict a movement of the lever from the fully connected position toward the partially connected position until the stopper is slid to the initial position on the lever, the sliding of the stopper from the final position to the initial position causing a delay during separation of the cover from the housing sufficient to prevent a spark when the power supply terminal is disconnected from the power supply circuit after the detection terminal is switched from the ON-state to the OFF-state while separating the cover.