To reduce parts cost by forming a punching hole in the main body portion of a fixed contact, forming a folded piece portion so as to extend from the tip portion side toward the base end portion side of the main body portion, and further bending the tip portion of the folded piece portion at an arc- distinguishing portion.
When a heavy-current flows in a current carrying part 22 on the occurrence of a short-circuit accident or the like, the heavy current of respectively reverse directions flows in the folded piece portion 44 and the bent piece portion 45 of a fixed contact 23 and a moving contact 26. A large electromagnetic repulsion force occurs between the piece portion 44 and the piece portion 45 of the contact 23 and the contact 26, the same becomes larger than the energizing force of a torsion coil spring 27. The contact 26 turns against the energizing force taking a pin 25 as a turning fulcrum so as to part from a contact 23. The arc generated between a moving contact 29 and a fixed contact 28 is extinguished by an arc-extinguishing device 30. Then a trip gear detects an overcurrent and operates, the lower link 38 of a switch mechanism 31 moves upward, and a cross bar 24 and the contact 26 turn and move to a trip position.
YONEZU HIDEKAZU
SOMEKAWA YUKINORI
