| 摘要 |
<p>Disclosed is a withdrawable device of main circuit for a circuit breaker. A ring-shaped guide recess is formed at a central part of a transfer nut screw-coupled to a lead screw, and supporting surfaces are formed on side surfaces of the guide recess. And, rotation prevention pins are elastically supported by springs in a moving direction of the transfer nut, and are selectively locked, thereby allowing the transfer nut to perform an idle operation. Accordingly, a structure for an idle operation of the transfer nut is simplified, and the number of components is reduced. An axial load is attenuated to a plane-contact distributed load, not a point-contact concentrated load, thereby preventing damage of the components. Also, a vacuum circuit breaker has enhanced reliability of the idle operation at a run position and a test position.</p> |
