Patent Application
20140251773
1. Field
The disclosed concept relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus, such as circuit breakers. The disclosed concept also relates to link assemblies for electrical switching apparatus.
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. The electrical contact assemblies include stationary electrical contacts and corresponding movable electrical contacts that are typically mounted on movable (e.g., pivotable) arms. The stationary and movable contacts are in physical and electrical contact with one another when it is desired that the circuit breaker provide electrical current therethrough to a load. When it is desired to interrupt the power circuit, the movable contact arm is pivoted, thereby moving the movable contact away from the stationary contact creating a space therebetween. The opening distance (i.e., space) between the separable contacts can be undesirably limited by a number of factors, such as for example, size restrictions, and restrictions on the movement and mechanical interaction of assembly components.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in link assemblies therefore.
These needs and others are met by embodiments of the disclosed concept, which are directed to a link assembly for circuit breakers, which among other benefits, provides for increased break distance between separable contacts.
As one aspect of the disclosed concept a link assembly is provided for an electrical switching apparatus. The electrical switching apparatus includes a housing, separable contacts enclosed by the housing, and an operating mechanism for opening and closing the separable contacts. The operating mechanism includes a movable contact arm. The separable contacts comprise a stationary contact and a movable contact. The movable contact is disposed on the movable contact arm. The link assembly comprises: a pivot assembly structured to be pivotably coupled to the movable contact arm; a link element pivotably coupled to the pivot assembly; and a biasing element including a first end coupled to the link element and a second end structured to be coupled to the housing of the electrical switching apparatus.
The pivot assembly may comprise at least one pivot member having a first portion, a second portion, and a third portion disposed between the first portion and the second portion. The first portion may be structured to engage and cooperate with the housing, the second portion may be coupled to the link element, and the third portion may be structured to be pivotably coupled to the movable contact arm. The second portion may include a first movement element, wherein the link element comprises a number of second movement elements, and wherein the first movement element of the second portion cooperates with a corresponding one of the second movement elements of the link element. The first movement element may be an elongated slot, and the number second movement elements may be a number of protrusions, wherein a corresponding one of the protrusions is movably disposed in the elongated slot.
The link element may further comprise a first segment and a second segment disposed opposite and distal from the first segment. The number of protrusions may extend outwardly from the first segment, and the biasing element may be coupled to the second segment. The movable contact arm may further comprise a first side and a second side, and the at least one pivot member may be a first pivot member and a second pivot member. The first pivot member may be structured to be pivotably coupled to the first side of the movable contact arm, and the second pivot member may be structured to be pivotably coupled to the second side of the movable contact arm.
The first segment of the link element may include a first extension and a second extension disposed opposite and spaced from the first extension, wherein number of protrusions is a first protrusion extending inwardly from the first extension and a second protrusion extending inwardly from the second extension. The first protrusion may be movably disposed within the elongated slot of the first pivot member, and the second protrusion may be movably disposed within the elongated slot of the second pivot member.
An electrical switching apparatus employing the aforementioned link assembly is also disclosed.
A full understanding of the disclosed concept can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
Directional phrases used herein, such as, for example, clockwise, counterclockwise, left, right 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 terms “opening distance” and “break distance” are used substantially interchangeably to refer to the maximum available distance or space between separable contacts (i.e., a stationary contact and the corresponding movable contact).
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).
The opening distance or break distance between separable contacts (not shown) of conventional circuit breakers (not shown) is limited by a number of factors, such as for example and without limitation, size restrictions, and restrictions on the movement and mechanical interaction of assembly components. As will be described in greater detail herein, the disclosed link assembly 100 is designed to address and overcome these disadvantages by enabling an increase in the break distance.
Continuing to refer to
As best shown in
The third portions 124,126 include first pivot elements 128,130, and the movable contact arm 12 includes second pivot elements 14,16, which cooperate with the first pivot elements 128,130, respectively, to pivotably couple the pivot members 112,114 to the movable contact arm 12. In the non-limiting example shown herein, the first pivot elements 128,130 of the first and second pivot members 112,114 are holes 128,130 (best shown in
Similarly, it will be appreciated that the link element 104 could have any known or suitable alternative configuration other than the non-limiting embodiment shown and described herein. The example link element 104 includes a first segment 144 and a second segment 146 disposed opposite and distal from the first segment 144. The second portions 120,122 of the first and second pivot members 112,114 include first movement elements 136,138, and the first segment 144 of the link element 104 includes a number of second movement elements 140,142. The first movement elements 136,138 cooperate with the corresponding second movement elements 140,142 (all shown in
The first segment 144 of the example link element 104 further includes a first extension 148 and a second extension 150 disposed opposite and spaced from the first extension 148. The aforementioned first protrusion 140 extends inwardly from the first extension 148, and the aforementioned second protrusion 142 extends inwardly from the second extension 150. Thus, the first protrusion 140 is movably disposed within the elongated slot 136 of the first pivot member 112, and the second protrusion 142 is movably disposed within the elongated slot 138 of the second pivot member 114, as shown (in exploded form) in
In view of the foregoing, it will be appreciated that the disclosed link assembly 100 provides a multiple component design structured to facilitate movement of the movable contact arm 12, and ultimately increase separation of (i.e., distant between) the movable contact 8 from the separable contact 6 (both shown in
Specifically, in operation, when the movable contact arm 12 pivots or rotates from the ON position of
Accordingly, among other benefits, the disclosed link assembly 100 provides for greater break distance between the separable contacts 6,8 of the circuit breaker 2. This, in turn, advantageously increases the voltage the circuit breaker 2 can withstand before it dioelectrically breaks down.
While specific embodiments of the disclosed concept 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 disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.
