To improve current-limiting cut-off performance by constraining and holding a movable contact, which is opened as it received an electromagnetic repulsive force generated by a short-circuit current, in an open electrode position in linkage with an electromagnet mechanism of an electromagnetic tripping device.
A circuit breaker comprises a movable contact 5 located as opposing a fixed contact 4, a contact holder 6 that holds the movable contact 5 and is linked to an opening/closing mechanism, a contact spring 7, and an electromagnet mechanism 13 of an electromagnetic tripping device, which is composed of an electromagnetic yoke 13a, an armature 13b, and a return spring 13c. When a short-circuit current flows, the circuit breaker causes the movable contact 5 to open to an open electrode position as the movable contact 5 receives an electromagnetic repulsive force before a tripping action of the opening/closing mechanism. A slide-type lock member 15 that emerges in linkage with the armature 13b is disposed on an electrode-opening path of the movable contact 5 as opposing the rear end of the movable contact 5, so that the movable contact 5, which is opened as it received the electromagnetic repulsive force immediately after the start of current cut-off, is constrained and held in the open electrode position with the lock member 15 so as not to return to a closed electrode position in the middle of current-limiting cut-off.
SATO SUKETAKA
ONCHI TOSHIYUKI
ISOZAKI MASARU
| JP2005353336A | 2005-12-22 | |||
| JP2003217424A | 2003-07-31 |