To improve assembling workability by improving the structure of an overcurrent tripping unit to be assembled in a breaker body case.
In the circuit breaker such as an automatic breaker, a thermal overload tripping gear 7 and an electromagnetic overcurrent tripping gear 8 to be assembled in the body case are mounted on an insulating holder 9 to form a tripping unit and a box terminal fitting 10 is combined with a terminal plate 11 of a main circuit terminal drawn from the rear end of the unit and connected with an electric wire of an external wiring. A terminal fitting receiving portion 9a is provided at the rear end of the insulating holder for receiving the lower end of the box terminal fitting 10 fitted through the terminal plate 11 to temporarily lock and hold it at an assembly position, thus preventing the falling of the terminal fitting. In assembling processes for the circuit breaker, work can be done for transporting the unit and assembling it into the body case without any trouble, as a fastening screw 10a for the box terminal fitting 10 remains loosened.
KUBOYAMA KATSUNORI
TAKAHASHI TATSUNORI
KAWADA HISAO
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