Abstract: An improved tripping mechanism for use in a circuit breaker wherein magnetic tripping is responsive to low levels of overcurrent by limiting the depth of engagement of a trip lever of a cradle with respect to the latch engagement tab of the armature. Responsiveness of the magnetic tripping is enhanced by positioning of the magnetic yoke adjacent to the bimetallic member while at the same time being movable with respect to the bimetallic member. Positioning the magnetic member independently of the position of the bimetallic member facilitates having magnetic tripping responsive to low overcurrent conditions while at the same time allowing thermal tripping by movement of the bimetallic member to be fully maintained.

Abstract: Discloses a method of non-destructively testing an aluminum-to-copper butt weld in a bar comprising an aluminum section and a copper section joined together by said weld. Forces are applied to the bar in such a manner that the weld is subjected to total stresses that are at least 80 percent, and preferably at least 90 percent, shear stresses. An acoustic emission signal is produced by the stresses at the weld, and this signal is sensed by a suitable transducer to provide an indication of weld quality.