Abstract:
A barrier member is for an arc chute assembly of an electrical switching apparatus. The arc chute assembly comprises a first sidewall and a second sidewall opposite and spaced apart from said first sidewall. The barrier member comprises a body portion structured to be disposed between said first sidewall and said second sidewall, said body portion comprising a first support portion, a second support portion, and a cover portion connecting said first support portion to said second support portion; a first containment portion extending from said first support portion, said first containment portion being structured to be disposed proximate said first sidewall; and a second containment portion extending from said second support portion toward said first containment portion, said second containment portion being structured to be disposed proximate said second sidewall, wherein said second containment portion is spaced from said first containment portion.

Description:
BACKGROUND 
     1. Field 
     The disclosed concept pertains generally to electrical switching apparatus. The disclosed concept also pertains to arc chute assemblies for electrical switching apparatus. The disclosed concept further relates to barrier members for arc chute 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, and abnormal level voltage conditions. 
     Circuit breakers, for example, typically include a set of stationary electrical contacts and a set of movable electrical contacts. The stationary and movable electrical contacts are in physical and electrical contact with one another when it is desired that the circuit breaker energize a power circuit. When it is desired to interrupt the power circuit, the movable contacts and stationary contacts are separated. Upon initial separation of the movable contacts away from the stationary contacts, an electrical arc is formed in the space between the contacts. The arc provides a means for smoothly transitioning from a closed circuit to an open circuit, but produces a number of challenges to the circuit breaker designer. Among them is the fact that the arc results in the undesirable flow of electrical current through the circuit breaker to the load. Additionally, the arc, which extends between the contacts, often results in vaporization or sublimation of the contact material itself. Therefore, it is desirable to extinguish any such arcs as soon as possible upon their propagation. 
     To facilitate this process, circuit breakers typically include arc chute assemblies which are structured to attract and break-up the arcs. Specifically, the movable contacts of the circuit breaker are mounted on arms that are contained in a pivoting assembly which pivots the movable contacts past or through arc chutes as they move into and out of electrical contact with the stationary contacts. Each arc chute includes a plurality of spaced apart arc plates mounted in a wrapper. As the movable contact is moved away from the stationary contact, the movable contact moves past the ends of the arc plates, with the arc being magnetically drawn toward and between the arc plates. The arc plates are electrically insulated from one another such that the arc is broken-up and extinguished by the arc plates. 
     Additionally, along with the generation of the arc itself, ionized gases, which can cause excessive heat and additional arcing and, therefore, harm to electrical components, are formed as a byproduct of the arcing event. The ionized gases can undesirably cause the arc to bypass a number of intermediate arc plates as it moves through the arc chute. This reduces the number of arc voltage drops and the effectiveness of the arc chute. It also creates current and gas flow patterns that tend to collapse groups of arc plates together, further reducing the voltage divisions in the arc chute and its cooling effectiveness. Additionally, debris, such as, for example, molten metal particles, are created during the arcing event and can collect in the gaps between arc plates, causing an electrical short, and high current levels during current interruption generate high magnetic forces, which attract the arc plates together. 
     There is thus room for improvement in electrical switching apparatus, and in arc chute assemblies and barrier members therefor. 
     SUMMARY 
     These needs and others are met by embodiments of the disclosed concept wherein a barrier member is provided which among other benefits, controls the flow of ionized gases in an arc chute assembly of an electrical switching apparatus. 
     In accordance with one aspect of the disclosed concept, a barrier member for an arc chute assembly of an electrical switching apparatus is provided. The arc chute assembly comprises a first sidewall, a second sidewall opposite and spaced apart from the first sidewall, and a plurality of arc plates disposed between the first sidewall and the second sidewall. The arc chute assembly is structured to be disposed in the electrical switching apparatus. The electrical switching apparatus comprises a housing and a pair of separable contacts enclosed by the housing. The contacts are structured to trip open. An arc and ionized gases are generated in response to the contacts tripping open. The barrier member comprises a body portion structured to be disposed between the first sidewall and the second sidewall, the body portion comprising a first support portion, a second support portion, and a cover portion connecting the first support portion to the second support portion; a first containment portion extending from the first support portion, the first containment portion being structured to be disposed proximate the first sidewall; and a second containment portion extending from the second support portion toward the first containment portion, the second containment portion being structured to be disposed proximate the second sidewall. The second containment portion is spaced from the first containment portion. 
     As another aspect of the disclosed concept, an arc chute assembly for an electrical switching apparatus is provided. The electrical switching apparatus includes a housing and a pair of separable contacts enclosed by the housing. The separable contacts are structured to trip open. An arc and ionized gases are generated in response to the separable contacts tripping open. The arc chute assembly comprises a plurality of retaining components comprising a first sidewall and a second sidewall opposite and spaced apart from the first sidewall; a plurality of arc plates disposed between the first sidewall and the second sidewall; and a barrier member comprising: a body portion disposed between the first sidewall and the second sidewall, the body portion comprising a first support portion, a second support portion, and a cover portion connecting the first support portion to the second support portion; a first containment portion extending from the first support portion, the first containment portion being disposed proximate the first sidewall; and a second containment portion extending from the second support portion toward the first containment portion, the second containment portion being disposed proximate the second sidewall. The second containment portion is spaced from the first containment portion. 
     As another aspect of the disclosed concept, an electrical switching apparatus comprises a housing; separable contacts enclosed by the housing; an operating mechanism structured to open and close the separable contacts and to trip open the separable contacts in response to an electrical fault; and at least one arc chute assembly disposed at or about the separable contacts in order to attract and dissipate an arc and ionized gases which are generated by the separable contacts tripping open in response to the electrical fault, the at least one arc chute assembly comprising: a plurality of retaining components comprising a first sidewall and a second sidewall opposite and spaced apart from the first sidewall; a plurality of arc plates disposed between the first sidewall and the second sidewall; and a barrier member comprising: a body portion disposed between the first sidewall and the second sidewall, the body portion comprising a first support portion, a second support portion, and a cover portion connecting the first support portion to the second support portion; a first containment portion extending from the first support portion, the first containment portion being disposed proximate the first sidewall; and a second containment portion extending from the second support portion toward the first containment portion, the second containment portion being disposed proximate the second sidewall. The second containment portion is spaced from the first containment portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1A  is an isometric view of an electrical switching apparatus, and arc chute assembly and barrier member therefor, in accordance with an embodiment of the disclosed concept, shown in the closed position with a portion of the housing cutaway to show hidden structures; 
         FIG. 1B  is an enlarged isometric view of a portion of the electrical switching, and arc chute assembly and barrier member therefor of  FIG. 1A ; 
         FIG. 2A  is an isometric view of the electrical switching apparatus, and arc chute assembly and barrier member therefor of  FIG. 1A , modified to show the electrical switching apparatus in the open position; 
         FIG. 2B  is an enlarged isometric view of a portion of the electrical switching apparatus, and arc chute assembly and barrier member therefor of  FIG. 2A ; 
         FIG. 3A  is an isometric view of the arc chute assembly of  FIG. 2B ; 
         FIG. 3B  is an exploded isometric view of the arc chute assembly of  FIG. 3A ; 
         FIGS. 4A and 4B  are isometric views of the barrier member for the arc chute assembly of  FIG. 3B ; and 
         FIG. 5  is an isometric view of a pair of barrier members for the arc chute assembly of  FIG. 3B , each shown prior to being completely formed. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For purposes of the description hereinafter, directional phrases used herein such as, for example, “top”, “bottom”, “front”, “back”, “behind”, “side”, “right”, “left”, “upper”, “lower”, and derivatives thereof shall relate to the disclosed concept, as it is oriented in the drawings. It is to be understood that the specific elements illustrated in the drawings and described in the following specification are simply exemplary embodiments of the disclosed concept. Therefore, specific orientations and other physical characteristics related to the embodiments disclosed herein are not to be considered limiting with respect to the scope of the disclosed concept. 
     As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality). 
     As employed herein, the statement that two or more parts are “connected” or “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. 
     As employed herein, the statement that two or more parts or components “engage” one another shall mean that the parts touch and/or exert a force against one another either directly or through one or more intermediate parts or components. 
       FIG. 1A  shows an electrical switching apparatus (e.g., without limitation, mining circuit breaker  2 ) in a closed position. The circuit breaker  2  includes a housing  4 , an operating mechanism  6  (shown in simplified form), a stationary contact  8 , a contact arm  9 , and a movable contact  10  connected to the contact arm  9 . The housing  4  encloses the operating mechanism  6 , the contacts  8 , 10 , and the contact arm  9 . In operation, the operating mechanism  6  trips the contact arm  9  in response to an electrical fault condition, thus moving the movable contact  10  from the closed position, in which it engages the stationary contact  8 , to an open position ( FIG. 2A  and  FIG. 2B ), in which the movable contact  10  is spaced from the stationary contact  8 . As the movable contact  10  moves from the closed position to the open position, an arc flash event occurs due to the separation between the movable contact  10  and the stationary contact  8 . Additionally, ionized gases are formed as a byproduct of the arcing event. In order to attract and dissipate the arc and ionized gases generated by the tripping of the contacts  8 , 10 , and control the arc flash flow direction of the ionized gases, the circuit breaker  2  includes an arc chute assembly  100  near the contacts  8 , 10 . 
     The example circuit breaker  2  shown and described herein is a multiple pole circuit breaker  2 . It will be appreciated that the circuit breaker  2  may employ any number of arc chute assemblies for each of the poles of the circuit breaker  2 . Additionally, although the disclosed concept is being described in association with the multiple pole circuit breaker  2 , it will be appreciated that a single pole circuit breaker (not shown) may employ an arc chute assembly (not shown) in accordance with the disclosed concept in a similar manner as described herein, to control the arc flash flow direction of ionized gases given off during an arcing event. 
     Referring to  FIG. 3A  and  FIG. 3B , the arc chute assembly  100  includes a plurality of retaining components (e.g., without limitation, opposing and spaced apart sidewalls  102 ,  104 , and base  106  extending between the sidewalls  102 , 104 ). The arc chute assembly  100  further includes a plurality of arc plates (two arc plates  108 , 112  are indicated) and a barrier member  150 , each being located between the sidewalls  102 , 104 . The barrier member  150  is preferably press fit between the sidewalls  102 , 104 , advantageously allowing for a secure connection with the sidewalls  102 , 104 , without requiring an additional separate fastening mechanism, means or method. 
     It is, however, also within the scope of the disclosed concept for the barrier member  150  to engage the sidewalls  102 , 104  in a manner other than being press fit. For example, and without limitation, the barrier member  150  may be slot connected with the first sidewall  102  and/or slot connected with the second sidewall  104  (see, e.g., slot  103  schematically shown in simplified form extending along the top of the first sidewall  102  in  FIG. 3B ). It is within the scope of the disclosed concept for the barrier member  150  to have a protrusion (not shown) that extends into the slot  103 , thereby allowing for a relatively strong connection. In operation, as ionized gases given off from the tripping of the contacts  8 , 10  engage the barrier member  150 , such a strong connection between the barrier member  150  and the sidewalls  102 , 104 , be it by a press fit connection, by a slot connection or any other suitable secure engagement, advantageously enables the barrier member  150  to remain secure within the arc chute assembly  100 . 
     The barrier member  150  includes a body portion  152  and a pair of containment portions (e.g., without limitation, elongated flaps  154 , 156 ). The body portion  152  includes a pair of support portions  158 , 160  and a cover portion  162  connecting the first support portion  158  to the second support portion  160 . The first elongated flap  154  extends from the first support portion  158  and is located near the first sidewall  102 . The second elongated flap  156  extends from the second support portion  160  and is located near the second sidewall  104 . Furthermore, the second elongated flap  156  extends toward the first elongated flap  154  and is spaced from the first elongated flap  154 . In operation, as ionized gases given off during an arc flash event flow throughout the arc chute assembly  100 , the elongated flaps  154 , 156  create a self-sealing effect. In other words, and with reference to  FIG. 2B , after the ionized gases reach the sidewalls  102 , 104 , the elongated flaps  154 , 156  block the ionized gases, thus preventing them from re-striking the contact arm  9 . This minimizes contact degradation and prevents dielectric breakdown, advantageously allowing for higher interruption capability of the circuit breaker  2 . 
     Referring to  FIG. 3B , the arc plate  108  includes an edge  109  that engages the sidewall  102 , and an edge  110  extending therefrom toward the base  106  in a direction  110 ′. The arc plate  112  similarly includes an edge (not shown) that engages the sidewall  104  and an edge  114  extending therefrom toward the base  106  in a direction  114 ′. The directions  110 ′, 114 ′ are each preferably at an angle with respect to the corresponding sidewall  102 , 104  of between 30 degrees and 60 degrees, and more preferably between 40 degrees and 50 degrees. Additionally, the first elongated flap  154  of the barrier member  150  extends from the first support portion  158  in a direction  154 ′ substantially parallel to the direction  110 ′. Likewise, the second elongated flap  156  extends from the second support portion  160  in a direction  156 ′ substantially parallel to the direction  114 ′. As seen in  FIG. 3A , the edge  110  of the arc plate  108  is substantially located between the first elongated flap  154  and the first sidewall  102 . Similarly, the edge  114  of the arc plate  112  is substantially located between the second elongated flap  156  and the second sidewall  104 . 
     In operation, this configuration of the arc plates  108 , 112  and the elongated flaps  154 , 156  further creates the self-sealing effect. More specifically, ionized gases given off by the tripping of the contacts  8 , 10  ( FIG. 1A  through  FIG. 2B ) located near the edge  110  of the arc plate  108  will advantageously be contained between the first elongated flap  154  and the first sidewall  102 , thereby avoiding re-striking to the contact arm  9 . For example, the first elongated flap  154  may engage the edge  110  of the arc plate  108 , thereby completely sealing a potential pathway for ionized gases, which would otherwise re-strike the contact arm  9 . Similarly, ionized gases located near the arc plate  112  will advantageously be contained between the second elongated flap  156  and the second sidewall  104 , thereby avoiding re-striking the contact arm  9 . 
     As seen in  FIG. 3A , the first sidewall  102  is located in a plane  102 ′ and the second sidewall  104  is located in a plane  104 ′. Additionally, the cover portion  162  is located in a plane  162 ′ and the support portions  158 , 160  are located in a plane  159  (e.g., the first support portion  158  is coplanar with the second support portion  160 ). The planes  159 , 162 ′ are each normal to the planes  102 ′, 104 ′ of the sidewalls  102 , 104 . Such a configuration advantageously allows for a relatively secure connection between the barrier member  150  and the sidewalls  102 , 104 . 
     Additionally, the cover portion  162  includes a number of elongated portions  166 , 168 , 170 . The first elongated portion  166  extends from the first support portion  158  and the second elongated portion  168  extends from the second support portion  160 . The third elongated portion  170  connects the first elongated portion  166  to the second elongated portion  168  and is normal to each of the first elongated portion  166  and the second elongated portion  168 . Furthermore, the third elongated portion  170  is elongated in a direction normal to the planes  102 ′, 104 ′. By having generally parallel opposing sides (e.g., the first support portion  158  and the first elongated portion  166  are generally parallel with respect to the second support portion  160  and the second elongated portion  168 ), and by having the elongated flaps  154 , 156 , the support portions  158 ,  160 , and the cover portion  162  be planar, manufacturing of the barrier member  150  is advantageously simplified. For example and without limitation, a flat unitary piece of metal (not shown) can be die cut and simply bent into the desired shape, as shown for example and without limitation, in  FIGS. 4A-5 . 
     Furthermore, although the disclosed concept has been described in association with the cover portion  162  including the elongated portions  166 , 168 , 170 , it is within the scope of the disclosed concept for the cover portion  162  to include other configurations (e.g., without limitation, a generally continuous square shaped cover portion (not shown)). Additionally, although the disclosed concept has been described in association with the planar elongated flaps  154 , 156 , it is within the scope of the disclosed concept to employ alternative flaps (not shown). For example and without limitation, it is within the scope of the disclosed concept to employ flaps (not shown) in an arc chute assembly (not shown) that are concave towards the sidewalls  102 , 104 . Moreover, it is within the scope of the disclosed concept to employ elongated flaps (not shown) in an arc chute assembly (not shown) with roughened or corrugated surfaces. 
     Referring to  FIG. 4A , there is an angle  155  between the first support portion  158  and the first elongated flap  154 . Likewise, there is an angle  157  between the second support portion  160  and the second elongated flap  156 . The angles  155 , 157  are preferably between 120 degrees and 150 degrees, and more preferably being between 130 degrees and 140 degrees. The self-sealing effect of the ionized gases is optimized by orienting the elongated flaps  154 , 156  as such with respect to the support portions  158 , 160 . 
     Furthermore, the first elongated portion  166  includes an end surface  172  that extends from the first support portion  158  at an angle  172 ′. Likewise, the second elongated portion  168  includes an end surface  174  that extends from the second support portion  160  at an angle  174 ′. The angles  172 ′, 174 ′, like the angles  155 , 157 , are preferably between 120 degrees and 150 degrees, and more preferably being between 130 degrees and 140 degrees. In this manner, the elongated flaps  154 , 156  are advantageously able to extend inwardly toward the base  106  ( FIG. 3A  and  FIG. 3B ) all the way to the end surfaces  172 , 174  of the cover portion  162 . This further improves the self-sealing effect, as the ionized gases will be prevented from traveling from the sidewalls  102 , 104  to the contact arm  9  by way of an opening proximate the end surfaces  172 , 174 . 
     As seen in  FIG. 4A , the cover portion  162  is at an angle  164  with respect to plane  159  of the support portions  158 , 160 . The angle  164  is preferably between 75 degrees and 105 degrees. As a result, the cover portion  162  substantially extends over and covers the arc plates  108 , 112  ( FIG. 3A  and  FIG. 3B ), advantageously aiding in preventing ionized gases given off from tripping of the contacts  8 , 10  ( FIGS. 1A through 2B ) from exiting the top of the arc chute assembly  100  and into the circuit breaker  2 . 
       FIG. 5  shows an isometric view of a barrier member  250 , shown prior to being fully formed. As seen, the barrier member  250  includes a pair of support portions  258 , 260  and a cover portion  262 . During manufacturing, the cover portion  262  is bent toward the support portions  258 , 260  to be brought into final shape (see, e.g., barrier member  150  of  FIGS. 3B, 4A and 4B ).  FIG. 5  also shows another barrier member  250 ′ that has not been fully formed. In this state, the barrier members  250 , 250 ′ are able to be nested with one another. Thus, shipping is advantageously simplified and costs saved as the barrier members  250 , 250 ′ are able to be more efficiently stacked with one another. 
     Referring again to  FIG. 1B , the first elongated flap  154  is elongated in a direction  154 ″ and the second elongated flap  156  is elongated in a direction  156 ″. As the movable contact  10  moves from the closed position ( FIG. 1B ) to the open position ( FIG. 2B ), the movable contact  10  moves toward the cover portion  162  in a direction  12  ( FIG. 2B ) parallel to the directions  154 ″, 156 ″. As the movable contact  10  moves from the open position to the closed position, the movable contact  10  moves away from the cover portion  162 . Additionally, each of the contacts  8 , 10  is located between the elongated flaps  154 , 156 . Accordingly, it will be appreciated that the disclosed concept advantageously results in a more controlled flow of ionized gases given off by the tripping of the contacts  8 , 10  throughout the arc chute assembly  100 . 
     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.