Abstract: A current limiting circuit breaker is provided which has a stationary contact assembly and a movable contact bridge. A contact carrier is connected to the contact bridge and biases the contact bridge toward the closed position. The downward biasing force on the contact bridge is mechanically reduced in response to a preselected amount of opening movement of the contact bridge.

Abstract: A stationary contact assembly is provided for a current limiting circuit breaker. The contact assembly includes a curved input arm which has a contact fastened thereon and a generally straight output arm which also has a contact fastened thereon and which has an opening for receiving the contact end of the input arm. The contacts are encapsulated in an insulating material which separates the contact arms from each other. A magnetic element is also embedded in the encapsulation material between the input and output contact arms. As current flows through the contact arms, a field is developed about the magnetic element which draws in an armature which reduces the opening force of the contacts.

Abstract: A so-called blow-off type current limiting circuit breaker includes a stationary contact strap that is divided into three elongated closely spaced coplanar parallel arms that are connected to each other at one end of the strap. The stationary contact is mounted to the interior one of the parallel arms at the end thereof remote from the one end of the strap. A terminal portion of the strap connects exterior ones of the parallel arms to one another at the ends thereof remote from the one end of the strap. A movable contact engageable with and disengageable from the stationary contact is mounted to one end of a movable contact arm that is pivoted at its opposite end in the region of the one end of the strap, extending parallel to the arms of the strap and being aligned with the interior arm. Current in the interior arm flows in a direction opposite to the direction of current flow in the exterior arms and the movable contact arm.

Abstract: A so-called blow-off type current limiting circuit breaker is constructed with a contact pressure spring that also holds the contact arm in open contact position when the contacts are blown open by electrodynamic forces. A multi-section cam means transmits contact opening and closing forces produced by a spring powered overcenter toggle type operating mechanism to the movable contact arm. A follower on the latter is biased into engagement with the cam means by the contact pressure spring. The cam means is so constructed that during contact blow-off the movable contact arm requires relatively little motion to move overcenter in the opening direction. One section of the cam means is constructed so that when the contact arm moves overcenter in the opening direction during contact blowoff, speed of the contact arm is controlled to an extent that contact rebound does not become a problem.

Abstract: A so-called blow-off type current limiting circuit breaker is provided with an elongated movable contact arm that is pivotally mounted at one end thereof on a pin that projects from opposite sides of a support. The contact arm is constructed of parallel sections that are biased toward one another, by spring means disposed remote from the support, with the support being resiliently clamped between the sections to provide a good electrical connection between the support and contact arm. The pivot pin extends through aligned enlarged pivot apertures in the parallel sections to facilitate weld breaking. A wall of each pivot aperture is disposed to cooperate with the pivot pin to achieve a camming action that moves the contact arm slightly lengthwise after initial butting engagement of the circuit breaker main contacts to wipe the engaged contacts with respect to one another.