Interrupter and air circuit breaker comprising same

An air circuit breaker, comprising:

• a cover;
• an arc extinguishing unit disposed within the cover and comprising a plurality of side plates and a grid coupled between the plurality of side plates;
• and
• a circuit breaking unit disposed adjacent to the arc extinguishing unit, wherein the circuit breaking unit comprises:
• a fixed contact terminal having a fixed contact disposed at a first end and extending in a first direction away from the fixed contact toward a second end;
• a movable contact terminal comprising a movable contact and configured such that the movable contact is formed to move in a direction toward the fixed contact or in a direction away from the fixed contact;
• a runner disposed extending in the first direction from the fixed contact, wherein a first end of the runner is coupled to the fixed contact terminal, and a second end of the runner, opposite to the first end, is spaced apart from the fixed contact terminal;
• and
• wherein:
• the movable contact includes a protrusion extending from the movable contact in the first direction, energized when in contact with the runner, and spaced apart from the runner when the movable contact is tripped,
• the movable contact terminal is provided as one of a plurality of movable contact terminals,
• one of the plurality of the movable contact terminals which is centrally disposed among the plurality of movable contact terminals is formed to have a length longer than that of other movable contact terminals of the plurality of movable contact terminals by including an extension portion extending in a direction toward the runner, and
• the protrusion is disposed on the extension portion so as to be located closer to the runner than ends of the other movable contact terminals.