| 摘要 |
A mechanical time delay mechanism is shown which provides a predetermined time delay between the movement of the moving contact blade on a circuit breaker and the activation of a switch. The control circuit design of the circuit breaker provides for tripping at one level when the breaker is in the closed position and at a second lower fault level when the circuit breaker is closing and for a predetermined number of cycles thereafter. The subject time delay mechanism activates a switch to change the tripping level from the second level to the first level at the appropriate time. The mechanism includes a pivot link assembly connected directly to the moving contact arm, a ratchet assembly, and a pivot link connecting the two. The pivot link assembly includes a set of springs to delay the movement of the link with respect to the movement of the pivot link in response to an opposing pull on the link. The pull on the link comes from the ratchet wheel which is slowed by a weighted rocker which rocks over several ratchet teeth. The switch is activated by a pin mounted on the ratchet wheel after the ratchet wheel has rotated through a predetermined angle.
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