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.
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.
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:
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.
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
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
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
Referring to
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 (
As seen in
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
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
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 (
As seen in
Referring again to
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.