This application is related to commonly assigned, concurrently filed:
U.S. patent application Ser. No. 11/549,316, filed Oct. 13, 2006, entitled “ELECTRICAL SWITCHING APPARATUS, AND CARRIER ASSEMBLY AND INDEPENDENT PIVOT ASSEMBLY THEREFOR”;
U.S. patent application Ser. No. 11/549,309, filed Oct. 13, 2006, entitled “ELECTRICAL SWITCHING APPARATUS, AND MOVABLE CONTACT ASSEMBLY AND CONTACT SPRING ASSEMBLY THEREFOR”; and
U.S. patent application Ser. No. 11/549,294, filed Oct. 13, 2006, entitled “ELECTRICAL SWITCHING APPARATUS, AND HOUSING AND INTEGRAL POLE SHAFT BEARING ASSEMBLY THEREFOR”, all of which are hereby incorporated herein by reference.
1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to conductor assemblies for electrical switching apparatus, such as circuit breakers. The invention also relates to flexible conductive elements for circuit breaker conductor assemblies.
2. Background Information
Electrical switching apparatus, such as circuit breakers, provide protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include an operating mechanism which opens electrical contact assemblies to interrupt the flow of current through the conductors of an electrical system in response to such fault conditions.
Many low-voltage circuit breakers, for example, employ a molded housing having two parts, a first half or front part (e.g., a molded cover), and a second half or rear part (e.g., a molded base). The operating mechanism for such circuit breakers is often mounted to the front part of the housing, and typically includes an operating handle and/or button(s) which, at one end, is (are) accessible from the exterior of the molded housing and, at the other end, is (are) coupled to a pivotable pole shaft. Electrical contact assemblies, which are also disposed within the molded housing, generally comprise a conductor assembly including a movable contact assembly having a plurality of movable contacts, and a stationary contact assembly having a plurality of corresponding stationary contacts. The movable contact assembly is electrically connected to a generally rigid conductor of the conductor assembly by flexible conductors, commonly referred to as shunts. The movable contact assembly includes a plurality of movable contact arms or fingers, each carrying one of the movable contacts and being pivotably coupled to a contact arm carrier. The contact arm carrier is pivoted by a protrusion or arm on the pole shaft of the circuit breaker operating mechanism to move the movable contacts into and out of electrical contact with the corresponding stationary contacts of the stationary contact assembly. The contact arm carrier includes a contact spring assembly structured to bias the fingers of the movable contact assembly against the stationary contacts of the stationary contact assembly in order to provide and maintain contact pressure when the circuit breaker is closed, and to accommodate wear.
The shunts typically comprise either copper wire ropes or layered copper ribbons, and are solidified at their ends using heat and pressure and then brazed to the rigid conductor at one end, and to the fingers of the movable contact assembly at the opposite end. One of the disadvantages associated with known wire rope or braided-type shunts is that they do not fit well within the limited spacing which is available between the adjacent fingers of the movable contact assembly. Specifically, the body of such shunts tends to expand outward and occupy more than the width of the finger, thus interfering with adjacent structures. The wire ropes also tend to bunch together during short circuit events, thus inhibiting the flexibility of the assembly. This is problematic in view of the compound motion which the fingers experience as a result of the well known “heel-toe” and/or “blow-on” arcing schemes which are commonly employed by low-voltage circuit breakers. See, e.g., U.S. Pat. No. 6,005,206, which is hereby incorporated herein by reference. Layered ribbon-type shunts also suffer from a number of unique disadvantages. Among them is the fact that they are typically V-shaped, thus having a single relatively sharp bend which undesirably creates an area of stress concentration. This V shape also consumes a substantial amount of valuable space within the molded housing of the circuit breaker.
There is a need, therefore, for elements (e.g., shunts) which have a high degree of flexibility, yet which are compact in their design and configuration and are rugged in order to accommodate and withstand the full range of movement (e.g., compound motion) of the movable contact assembly of the circuit breaker, while occupying minimal space within the molded housing of the circuit breaker.
There is, therefore, room for improvement of conductor assemblies for electrical switching apparatus such as, for example, low-voltage circuit breakers.
These needs and others are met by embodiments of the invention, which are directed to a conductor assembly for an electrical switching apparatus, such as, for example, a low-voltage circuit breaker, and independent flexible conductive elements (e.g., shunts) therefor.
As one aspect of the invention, a flexible conductive element is provided for a conductor assembly of an electrical switching apparatus. The electrical switching apparatus includes a stationary contact assembly having a number of stationary electrical contacts and the conductor assembly includes a load conductor and a movable contact assembly with a number of movable contact arms each having a movable electrical contact which is structured to move into and out of electrical contact with a corresponding one of the stationary electrical contacts of the stationary contact assembly. The flexible conductive element comprises: a first end structured to be electrically connected to the load conductor of the conductor assembly; a second end structured to be electrically connected to a corresponding one of the movable contact arms of the movable contact assembly; and a plurality of bends between the first end and the second end, wherein a first one of the bends is in a first direction and at least a second one of the bends is in a second direction, and wherein the second direction of the at least the second one of the bends is generally opposite the first direction of the first one of the bends.
The flexible conductive element may include as the plurality of bends, a first bend in the first direction and a second bend in the second direction, in order that the flexible conductive element is generally S-shaped. The flexible conductive element may further comprise a first portion, a second portion, and a third portion, wherein the first portion is disposed between the first end and the first bend, the second portion is disposed between the first bend and the second bend, and the third portion is disposed between the second bend and the second end of the flexible conductive element. An axis may extend between the first end of the flexible conductive element and the second end of the flexible conductive element, wherein the first portion of the flexible conductive element forms a first angle with respect to the axis and the third portion of the flexible conductive element forms a second angle with respect to the axis. The first angle between the first portion of the flexible conductive element and the axis may be greater than the second angle between the third portion of the flexible conductive element and the axis, for example, when the flexible conductive element is disposed in a first position corresponding to the movable contact of the movable contact assembly being in electrical contact with the corresponding stationary contact of the stationary contact assembly.
As another aspect of the invention, a conductor assembly is provided for an electrical switching apparatus including a stationary contact assembly having a number of stationary electrical contacts. The conductor assembly comprises: a load conductor; a movable contact assembly including a number of movable contact arms; a number of movable electrical contacts mounted on the movable contact arms of the movable contact assembly, the movable electrical contacts being structured to move into and out of electrical contact with the stationary electrical contacts of the stationary contact assembly; and a plurality of flexible conductive elements electrically connecting the load conductor and the movable contact assembly, each of the flexible conductive elements comprising: a first end electrically connected to the load conductor, a second end electrically connected to a corresponding one of the movable contact arms of the movable contact assembly, and a plurality of bends between the first end and the second end, wherein a first one of the bends is in a first direction and at least a second one of the bends is in a second direction, and wherein the second direction of the at least the second one of the bends is generally opposite the first direction of the first one of the bends.
The load conductor may comprise a solid conductor having a first portion and a second portion generally opposite the first portion, wherein the solid conductor includes a first aperture at or about the first portion of the solid conductor. The first aperture may comprise a single elongated recess which receives the first end of every one of the flexible conductors. The first aperture of the load conductor may further comprise an interior arcuate portion and a neck portion. The corresponding one of the movable contact arms may comprise a second aperture having an interior arcuate portion and a neck portion. The first end of the flexible conductive element may comprise a first generally round head disposed within the interior arcuate portion of the first aperture of the load conductor, and the second end of the flexible conductive element may comprise a second generally round head disposed within the interior arcuate portion of the second aperture of the corresponding one of the movable contact arms. When the first generally round head is disposed within the interior arcuate portion of the first aperture of the load conductor and the second generally round head is disposed within the interior arcuate portion of the second aperture of the corresponding one of the movable contact arms, the neck portion of at least one of the first aperture and the second aperture may be compressed against the flexible conductive element in order to retain a corresponding one of the first end of the flexible conductive element within the first aperture and the second end of the flexible conductive element within the second aperture. At least one of the first and second generally round heads may further comprise a pin, and the flexible conductive member may comprise a shunt having layers of conductive ribbon, wherein the layers of conductive ribbon wrap around the pin within at least one of the first and second apertures of the load conductor and the corresponding one of the movable contact arms, respectively.
As yet another aspect of the invention, a conductor assembly is provided for an electrical switching apparatus. The conductor assembly comprises: a load conductor; a movable contact assembly including a number of movable contact arms; a plurality of flexible conductive elements, each of the flexible conductive elements including a first end electrically connected to the load conductor and a second end electrically connected to a corresponding one of the movable contact arms of the movable contact assembly; and at least one pin, wherein the load conductor is a single solid load conductor including a single elongated recess, wherein the single elongated recess receives the first end of every one of the flexible conductive elements, and wherein at least one pin is inserted through the first end of every one of the flexible conductive elements within the single elongated recess of the single solid load conductor.
As another aspect of the invention, an electrical switching apparatus comprises: a housing; a first electrical conductor and a second electrical conductor housed by the housing; a stationary contact assembly including a number of stationary electrical contacts, the stationary contact assembly being electrically connected to one of the first electrical conductor and the second electrical conductor; and a conductor assembly electrically connected to the other of the first electrical conductor and the second electrical conductor, the conductor assembly comprising: a load conductor, a movable contact assembly including a number of movable contact arms; a number of movable electrical contacts mounted on the movable contact arms of the movable contact assembly, the movable electrical contacts being operable between a closed position in which the movable electrical contacts are in electrical contact with the stationary electrical contacts of the stationary contact assembly, and an open position in which the movable electrical contacts are out of electrical contact with the stationary electrical contacts, and a plurality of flexible conductive elements electrically connecting the load conductor and the movable contact assembly, each of the flexible conductive elements comprising: a first end electrically connected to the load conductor, a second end electrically connected to a corresponding one of the movable contact arms of the movable contact assembly, and a plurality of bends between the first end and the second end, wherein a first one of the bends is in a first direction and at least a second one of the bends is in a second direction, and wherein the second direction of the second one of the bends is generally opposite the first direction of the first one of the bends.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
For purposes of illustration, embodiments of the invention will be described as applied to low-voltage circuit breakers, although it will become apparent that they could also be applied to the contact assemblies of any known or suitable electrical switching apparatus (e.g., without limitation, circuit switching devices and circuit interrupters such as circuit breakers other than low-voltage circuit breakers, network protectors, contactors, motor starters, motor controllers and other load controllers).
Directional phrases used herein, such as, for example, left, right, clockwise, counterclockwise and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.
As employed herein, the statement that two or more parts are “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts.
As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality).
As shown in
When the conductor assembly 50 is assembled within the circuit breaker housing 3 (
Referring to
An axis 220 extends between the first end 202 of the shunt 200 and the second end 204 of the shunt 200. The first portion 210 of the shunt 200 forms a first angle 222 with respect to axis 220 on one side of the axis, and the third portion 214 of the shunt 200 forms a second angle 224 with respect to the axis 220, on the opposite side of the axis 220. Preferably the first and second angles 222,224 of the first and third portions 210,214 of shunt 200, are different. For example, the first angle 222 of the shunt 200 of
Continuing to refer to
For each of the example shunts 200, the first and second generally rounds heads 226,228 of the first and second ends 202,204 further include first and second pins 232,234 disposed through the center of the heads 226,228 within the first and second apertures 54,116, respectively. More specifically, the layers of conductive ribbon 230 of the shunt 200 wrap around the first and second pins 232,234 within the first and second apertures 54,116, respectively, of the load conductor 52 and the corresponding movable contact arm 110, respectively, as shown in
In
As best shown in
Accordingly, the conductor assembly 50 includes generally S-shaped flexible conductive elements 200 (e.g., shunts) which enable it to accommodate the compound motion (e.g., movement in more than one direction at the same time, such as, for example and without limitation, pivoting of the conductor assembly 50 about first pivot pin 160 and/or pivot pin 132 of
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
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