Molded case circuit breaker with an improved operating mechanism having a pivot-transfer trip-free linkage

摘要

A molded case circuit breaker includes a highly integrated operating mechanism having an over-center, trip-free, pivot transfer toggle mechanism for opening and closing a pair of electrical contacts in response to overload and short circuit or fault current conditions. The toggle mechanism includes a pair of stationary, spaced apart links and a pair of movable, spaced apart toggle links. Each of the movable links includes an integrally formed, first or initial pivot point formed along its surface for engagement with a surface of one of the stationary links. Each of the stationary links includes a second pivot point formed along its surface for engagement by a surface of one of the movable links. The movable links are sequentially pivotably movable during a trip operation of the circuit breaker initially about the first pivot points and subsequently about the second pivot points. The movement of the movable links about the first pivot points effect a rapid separation of the electrical contacts at the beginning of the trip operation. The movement of the movable links about the second pivot points effect a rapid acceleration of a movable electrical contact during a subsequent portion of the trip operation to increase the arc voltage and thus rapidly extinguish any electrical arc between the electrical contacts.