Tripping device for breaker knife switch

The utility model relates to a breaking tripping device for a breaker knife switch, which is used for breaking and unlocking for the breaker. The device adds one small detent (5) limiting a detent (11) on the detent (11) which limits a main shaft crank arm (8) in an old tripping device; the arc-shaped surface of the lower end of the small detent (5) abuts against a roller (6) of the detent (11); a small roller (1) of the upper end abuts against a bending plate contacted with a breaking driving element (a manual button or an electromagnet). when the switch is opened, the bending plate, the small detent and the detent orderly acts and are unlocked; the main shaft of the switch can rotate under the condition of breaking; a mechanism is driven to realise the breaking. After the small detent is added, the manual operation or the electrodynamic force for unlocking of the mechanism is reduced; the breaking is increased; especially, the reliability for breaking under the condition of low-voltage is increased.