Siemens Energy & Automation, Inc.

Robert E Black

Bernard DiMarco

James Edward Ferree

Stephen D Cella

Neal B Reeves

John M Brown, Jr

David P McClellan

A circuit breaker (10) has a housing (12). A crossbar (114) is pivotally connected to the housing to pivot about an axis (117) between open and closed positions. A load contact arm (110) is pivotally connected to the crossbar (114). The load contact arm (110) is capable of pivoting about the axis (117). A cam mechanism (140) is mechanically coupled to the load contact arm (110). The cam mechanism (140) is slideably mounted within the crossbar (114) for movement between first and second positions. In the first position of the cam mechanism (140), the load contact arm (110) pivots through an angle (.beta.) about the axis, relative to the crossbar (114) between the 'touch' and closed positions, and the load contact arm (110) pivots together with the crossbar (114) through an angle (.alpha.) about the axis (117) between the open and 'touch' positions. (2) In the second position of the cam mechanism (140), the load contact arm (110) is free to pivot about the axis (117) through the angle .alpha. to the open position while the crossbar (114) is in the closed position. A biasing spring (160) applies a biasing force to bias the cam mechanism (140) towards the first position.

Movable contact structure for a circuit breaker, including crossbar and

A molded case circuit breaker includes a generally 'Z' shaped intermediate latch structure which has upper and lower substantially planar sections that are each bent at an angle with respect to a center pivot section. The upper portion of the intermediate latch includes one or two latch surfaces. One of these latch surfaces engages the cradle of the operating mechanism of the circuit breaker, to latch the operating mechanism when the circuit breaker is closed. The other latch surface engages a trip bar or an intermediate latch bar, which is rotated by the trip unit when an overcurrent condition occurs. The lower portion of the intermediate latch structure also includes a latch surface which may engage a trip bar. This latch surface is sloped such that when the latch surface of the trip bar is moved along this sloped latch surface, the trip bar rotates. This rotation of the trip bar adjusts the spacing between the trip bar and a bimetallic strip or magnetic armature of a thermal and magnetic trip unit to allow the rating of the circuit breaker to be changed in the field. The pivot portion of the intermediate latch structure includes two mounting tabs, one on either side of the latch. The mounting tabs have a generally rectangular cross-section and, due to the angled relationship between the pivot portion and the upper and lower portions of the intermediate latch, the latch pivots on an edge of the mounting tabs. This edge is aligned with an angular opening in the mechanical frame to mount the intermediate latch. The mounting tabs also retain a biasing spring which biases the intermediate latch toward the cradle and biases the trip bar or latch bar toward the intermediate latch.

Intermediate latch for a molded case circuit breaker

A thermal and magnetic trip unit for a multi-pole circuit breaker includes a thermal structure having a bimetallic element and one or more heater elements. Each of the heater elements and a portion of the bimetallic element is generally 'U' shaped defining a conductive path which extends from one leg of the U to the other leg. The heater elements and bimetallic element may be configured in parallel to reduce the level of current flowing through the bimetallic element and thus increase the current level at which the bimetallic element will trip the breaker. Alternatively, the heater elements may be configured in series with the bimetallic element, by inserting electrical insulators between the bimetallic element and each of the heater elements and connecting the various 'U' shaped elements using a connecting bus which connects the second leg of one element to the first leg of the next element. In this configuration, the thermal structure defines a coil having one turns for each heater element and the bimetallic element. This coil may be used to implement a magnetic trip structure by inserting one or two magnetically permeable yokes, each yoke surrounding one leg of the combined thermal structure. An armature is positioned to be separated from the yoke by a gap such that, when the armature is pulled toward the yoke, it will engage the trip unit. In addition, the trip unit includes a calibration and adjustment bar that allows the gap to be adjusted as well as the force exerted on the armature by a biasing spring. The calibration and adjustment bar also allows each pole of the circuit breaker to be independently calibrated.

Variable thermal and magnetic structure for a circuitbreaker trip unit

A pivoting lower contact arm arrangement and a circuit breaker including the arrangement. The pivoting lower contact arm arrangement includes a pivoting lower contact arm and a biasing arrangement. The biasing arrangement maintains the contact arm in an operating position with a first force, and biases the arm from a blown-open position toward the operating position with a second force. The first force is greater than the second force to provide increased separating speed when the pivoting lower contact arm blows apart from a pivoting upper contact arm of the circuit breaker and moves from its operating position. The biasing arrangement also variously provides magnetic shielding and coupling between the pivoting lower contact arm and other current carrying components of the circuit breaker. The magnetic shielding enhances the blow-apart forces between the pivoting upper contact arm and the pivoting lower contact arm.

Circuit breaker with magnetic shield

A pivoting lower contact arm arrangement and a circuit breaker including the arrangement. The pivoting lower contact arm arrangement includes a pivoting lower contact arm and a biasing arrangement. The biasing arrangement maintains the contact arm in an operating position with a first force and biases the arm from a blown-open position toward the operating position with a second force. The first force is greater than the second force to provide increased separating speed when the pivoting lower contact arm blows apart from a pivoting upper contact arm of the circuit breaker and moves from its operating position. The biasing arrangement also variously provides magnetic shielding and coupling between the pivoting lower contact arm and other current carrying components of the circuit breaker. The magnetic shielding enhances the blow-apart forces between the pivoting upper contact arm and the pivoting lower contact arm.

Circuit breaker with dual movable contacts

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.

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Snellville, GA, United States of America

Robert E Black