Patent ID: 7528336

Claim:
A gas circuit breaker comprising: an interrupter for turning on and off electric power by opening and closing a contact between a fixed contact member and a movable contact member; a link mechanism comprising a first lever, a second lever rotatably linked to the movable contact member, and a rotational shaft for attaching the first and second levers, the first and second levers rotating together around the rotational shaft; an operation unit which comprises a third lever, a main shaft for rotating the third lever, and an opening spring attached to the main shaft through a main lever to rotate the main shaft and generate a driving force for driving the movable contact member; and a link for interconnecting the third lever of the operation unit and the first lever of the link mechanism: wherein an operation angle of the second lever with respect to a direction perpendicular to the motion direction of the movable contact member is almost the same between when the contact is open and when the contact is closed; and a first operation angle of the first lever with respect to a direction parallel to the motion direction of the movable contact member when the contact is open is larger than a second operation angle thereof when the contact is closed.