in a power feed path switching circuit via which first , second and third stations are coupled to each other in a normal state , a first unit senses a first current flowing in a first path connecting the first and second stations via a branching node and disconnects a second path connecting the third station and the branching node from the branching node when the first current is sensed . a second unit senses a second current flowing in the first path and gradually discharges the second path when the second current is sensed . a third unit senses a third current flowing in the first path and grounds the second path when the third current is sensed .