Abstract:
An arc runner assembly for use in a circuit interrupter provides a pair of arc runners that are situated at opposite sides of a stationary contact of the circuit interrupter. If used in a DC application, the arc runner assembly is configured to communicate a positive DC arc along one of the arc runners in a first direction away from the stationary contact and is further configured to communicate a negative DC arc along the other arc runner in another direction away from the stationary contact. The arc runner assembly additionally includes a support that is electrically engaged with a conductor of the circuit interrupter on a surface opposite that on which the stationary contact is disposed. The improved arc runner assembly advantageously facilitates extinction of electrical arc and extinguishes both positive and negative DC arcs in a DC application.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field 
         [0002]    The disclosed and claimed concept relates generally to circuit interrupters and, more particularly, to an arc runner assembly for use in a circuit interrupter, as well as to a circuit interrupter. 
         [0003]    2. Related Art 
         [0004]    Circuit interrupters are known for use in numerous applications. Circuit interrupters are employed, for example, to open a portion of a protected circuit in certain predefined circumstances, such as might include predefined overcurrent and under-voltage circumstances, as well as other circumstances. 
         [0005]    As is generally understood in the relevant art, a circuit interrupter typically includes a set of separable contacts that are electrically interposed between line and load conductors, and the separable contacts can be separated from one another in order to open the portion of the protected circuit to which the line and load conductors are connected. Since an electrical arc is typically formed between the contacts during their initial separation, and since such an electrical arc can be destructive to the circuit interrupter and to the protected circuit, such electrical arcs are desirably extinguished as soon as possible, and circuit interrupters typically employ some type of apparatus or system to extinguish such arcs. One type of arc extinction system includes an arc chute that includes a plurality of arc plates that are divergently oriented and which are configured to break up and extinguish an arc. An arc runner typically is employed adjacent a stationary contact of the set of separable contacts to direct the arc toward the arc chute. Any of a wide variety of devices can be employed to help move the arc in the direction of the arc chute, and these can include devices that generate magnetic fields which push the arc toward the arc chute, devices that generate gases in the presence of an arc that push the arc toward the arc chute, and the like. 
         [0006]    While such arc extinction systems have been generally effective for their intended purposes, they have not been without limitation. For example, many of the known arc extinction systems have been developed for use in AC applications wherein an arc often lasts for at most only one-half of a cycle. Such arc extinction systems are typically not directly applicable to DC applications since a DC arc can exist for longer period of time. Moreover, whereas the voltage in AC varies between positive and negative according to a known cycle, DC is typically either positive or negative and, depending upon the application, a protected DC circuit may at different times experience either positive voltage or negative voltage. A circuit interrupter that is intended to protect a DC circuit therefore desirably has the capability to interrupt both positive DC and negative DC at given current level in. Furthermore, certain applications such as photovoltaic applications have required successively greater and greater current interruption capabilities. It thus would be desirable to provide solutions that address such shortcomings in the art. 
       SUMMARY OF THE INVENTION 
       [0007]    An improved arc runner assembly for use in a circuit interrupter provides a pair of arc runners that are situated at opposite sides of a stationary contact of the circuit interrupter. If used in a DC application, the arc runner assembly is configured to communicate a positive DC arc along one of the arc runners in a first direction away from the stationary contact and is further configured to communicate a negative DC arc along the other arc runner in another direction away from the stationary contact. The arc runner assembly additionally includes a support that is electrically engaged with a conductor of the circuit interrupter on a surface opposite that on which the stationary contact is disposed. The improved arc runner assembly advantageously facilitates extinction of electrical arc and extinguishes both positive and negative DC arcs in a DC application. 
         [0008]    Accordingly, an aspect of the disclosed and claimed concept is to provide an improved arc runner assembly for use in a circuit interrupter to extinguish electrical arcs. 
         [0009]    Another aspect of the disclosed and claimed concept is to provide an improved arc runner assembly which, if used in a DC application, extinguishes both positive and negative DC arcs. 
         [0010]    Another aspect of the disclosed and claimed concept is to provide an improved circuit interrupter that employs such an arc runner assembly. 
         [0011]    These and other aspects of the disclosed and claimed concept are provided by an improved arc runner assembly that is structured for use in a circuit interrupter having a first conductor, a second conductor, and a set of separable contacts electrically interposed between the first conductor and the second conductor. The set of separable contacts include a stationary contact situated on one of the first conductor and the second conductor. The arc runner assembly can be generally stated as including a first arc runner and a second arc runner, with the first and second arc runners are spaced apart from one another. The first arc runner is structured to be situated adjacent a first side of the stationary contact and to communicate an electrical arc away from the stationary contact in a first direction. The second arc runner is structured to be situated adjacent a second side of the stationary contact opposite the first side and to communicate an electrical arc away from the stationary contact in a second direction different than the first direction 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A further understanding of the disclosed and claimed concept can be gained from the following Description when read in conjunction with the accompanying drawings in which: 
           [0013]      FIG. 1  is a perspective view of an improved arc runner assembly in accordance with the disclosed and claimed concept; 
           [0014]      FIG. 2  is a side elevational view of the arc runner assembly of  FIG. 1 ; 
           [0015]      FIG. 3  is a perspective view, partially cut away, of an improved circuit interrupter in accordance with the disclosed and claimed concept that employs the arc runner assembly of  FIG. 1 ; 
           [0016]      FIG. 4  is a perspective view of a portion of the circuit interrupter of  FIG. 3 ; and 
           [0017]      FIG. 5  is a sectional view as taken along line  5 - 5  of  FIG. 3 . Similar numerals refer to similar parts throughout the specification. 
       
    
    
     DESCRIPTION 
       [0018]    An improved arc runner assembly  2  is depicted generally in  FIGS. 1 and 2 . The arc runner assembly  2  can be employed in a circuit interrupter  4  in accordance with the disclosed and claimed concept, as is depicted generally in  FIG. 3  and is depicted in part in  FIG. 4 . The improved arc runner assembly  2  advantageously enables the circuit interrupter  4  to rapidly extinguish an electrical arc. Arc runner assembly  2  and circuit interrupter  4  are particularly advantageously employed in DC applications but are employable in AC applications without departing from the present concept. 
         [0019]    The circuit interrupter  4  can be said to include a first conductor  6 , a second conductor  8 , and a set of separable contacts  10  that are electrically interposed between the first and second conductors  6  and  8 . One of the first conductor  6  and the second conductor  8  will typically be considered a line conductor, and the other of the first and second conductors  6  and  8  will typically be considered a load conductor, although the specific designation is not important herein. The set of separable contacts  10  in the depicted exemplary embodiment include a stationary contact  12  that is depicted as being situated on the first conductor  6 . The set of separable contacts  10  further include a movable contact  14  that is situated on a movable contact arm  18  and that is electrically engageable with an engagement surface  16  of the stationary contact  12 . 
         [0020]    The circuit interrupter  4  further includes an arc extinction apparatus  20  that includes a set of arc plates (collectively indicated at the numeral  22 ), a first magnet  24 , a second magnet  26 , and a brace  28 . The first and second magnets  24  and  26  are rare earth permanent magnets having their south poles facing toward one another and are held in place by the steel brace  28 . The first and second magnets  24  and  26  could alternatively have their north poles facing toward one another without departing from the present concept. It is also expressly noted that the first and second magnets  24  and  26  could be of any form, i.e., whether or not permanent magnets, whether or not formed of rare earth materials or other materials, etc., without departing from the present concept. The arc extinction apparatus  20  further includes an intermediate element  30  that extends midway through the set of arc plates  22  and that includes a steel guide element  32  ( FIG. 5 ) that is covered by a sheath  34  which, in the depicted exemplary embodiment, is formed of a polymer material. As is understood in the relevant art, the circuit interrupter  4  additionally includes an operating mechanism that pivots the contact arm  18  to move the movable contact  14  between positions electrically connected with and electrically disconnected from the stationary contact  12 . 
         [0021]    As is depicted generally in  FIGS. 1 and 2 , the arc runner assembly  2  can be said to include a first arc runner  36 , a second arc runner  38 , a support  40 , and a base  42 . The arc runner assembly  2  is formed from a plate of stainless steel that is electrically conductive but that does not affect the magnetic fields within the arc extinction apparatus  20  or the other components of the circuit interrupter  4 . In the depicted exemplary embodiment, the first and second arc runners  36  and  38  and the support  40  are formed in the arc runner assembly  2  via cutting and bending. In the embodiment depicted herein, the first and second arc runners  36  and  38  and the support  40  each extend from the same end of the base  42 . The base itself has a mounting hole  44  formed therein which, in the depicted exemplary embodiment, is threaded to receive therein a threaded fastener  46  (as is depicted generally in  FIG. 3 ) which extends through a molded case component of the circuit interrupter  4  to secure the arc runner assembly  2 , the first conductor  6 , and other structures within the circuit interrupter  4 . 
         [0022]    It is noted, however, that in other embodiments of the arc runner assembly  2 , the mounting hole  44  can accommodate other types of fasteners without departing from the present concept. 
         [0023]    The first arc runner  36  can be said to include a first arc runner element  48  situated on a first leg  50 . The first leg  50  supports the first arc runner element  48  in a position spaced from the base  42 . The second arc runner  38  likewise can be said to include a second arc runner element  52  situated on a second leg  54 , with the second leg  54  supporting the second arc runner element  52  in a position spaced from the base  42 . The support  40  can be said to include a support element  56  situated on a strut  58 , with the strut  58  supporting the support element  56  at a position spaced from the base  42 . The first and second arc runners  36  and  38  can be said to be situated on opposite sides of the support  40 , and the support  40  can alternatively be said to be situated generally between the first and second arc runners  36  and  38 . 
         [0024]    The first arc runner element  48  includes a generally planar first arc runner surface  60 , and the second arc runner element  52  likewise has a generally planar second arc runner surface  60 . The first and second arc runner surfaces  60  and  62  are generally coplanar with one another and with the engagement surface  16  of the stationary contact  12 . The support element  56  has a generally planar support surface  64  that is oriented parallel with and offset from the first and second arc runner surfaces  60  and  62 , as can be understood from  FIGS. 1 and 2 . The support surface  64  is structured to be electrically engaged with a surface of the first conductor  60  opposite that upon which the stationary contact  12  is situated. The support  40  engaged with the aforementioned surface of the first conductor  6  supports the first conductor  6  when the contact arm  18  compressively engages the movable contact  14  with the engagement surface  16  of the stationary contact  12 . Such supporting engagement also provides the aforementioned electrical engagement between the first conductor  6  and the arc runner assembly  2  which enables an electrical arc that may be formed between the stationary and movable contacts  12  and  14  to be communicated along the first arc runner surface  60  or the second arc runner surface  62  which, in a DC application, depends upon the polarity of the DC that is being interrupted. 
         [0025]    As has been suggested elsewhere herein, arc runner assembly  2  is formed by cutting and bending a piece of stainless steel or other appropriate conductive material. 
         [0026]    The first arc runner  36  can be said to include a proximate bend  66  that is proximate the base  42  and to further include a distal bend  68  that is distal from the base  42 . The second arc runner  38  likewise includes proximate bend  70  and further includes a distal bend  72 . Support  40  includes proximate bend  74 , a distal bend  76 , and an intermediate bend  78  situated between the proximate and distal bends  74  and  76 . As can be understood from  FIGS. 1 and 2 , some of the various bends in the first and second arc runners  36  and  38  and the support  40  are generally in the same direction whereas other bend are in opposite directions. For instance, the proximate bends  66 ,  70 , and  74  are all in the same direction as one another, i.e., facing generally toward base  42 . However, while the distal bends  68  and  72  are generally in the same direction as one another, i.e., generally away from the base  42 , the distal bend  76  is in a direction opposite thereto, i.e., generally toward the base  42 . The intermediate bend  78  is in generally the same direction as the distal bend  76 . It is noted, however, that the arc runner assembly  2  can be formed in any of a variety of fashions and can have any of a variety of configurations without departing from the present concept. 
         [0027]    As can be understood from the foregoing, therefore, the first arc runner surface  60  is situated coplanar with the engagement surface  16  of the stationary contact  12  and is situated at a first side thereof Likewise, the second arc runner surface  62  is oriented coplanar with the engagement surface  16  and is situated at a second, opposite side of the stationary contact  12 . Since the arc runner assembly  2  is electrically connected with the first conductor  6 , any arc that is formed between the stationary and movable contacts  12  and  14  could potentially be communicated along either the first arc runner element  48  or the second arc runner element  52  at the first and second arc runner surfaces  60  and  62 , respectively, depending upon various factors. 
         [0028]    In the depicted exemplary embodiment, as is indicated generally in  FIG. 5 , the first and second magnets  24  and  26  are oriented and held in place by brace  28  such that the same magnetic poles face one another. In the depicted exemplary embodiment, the south poles of the first and second magnets  24  and  26  face toward one another, but in other embodiments the north poles could face one another without departing from the present concept. 
         [0029]    As is further depicted in  FIG. 5 , the guide element  32  is electrically connected with the brace  28 . The sheath  34  is of a relatively small thickness in comparison with the overall dimensions of the guide element  32  such that the guide element  32  extends expansively within intermediate element  30 . Since the south poles of the first and second magnets  24  and  26  face toward one another, and due to the presence of the ferrous and thus magnetic field directing guide element  32  therebetween, the magnetic field lines that exist between the first and second magnets  24  and  26  are represented generally at the numerals  80 A and  80 B in  FIG. 5 . Some of the field lines, such as those indicated generally at  80 A, extend from the guide element  32  directly toward either the first magnet  24  or the second magnet  26 . Other field lines, such as those indicated generally at the numeral  80 B, and which emanate from a free end of the guide element  32  opposite its connection with the brace  28 , can be said to extend generally outward from the free end of the guide element  32 , generally across the first or second arc runner elements  48  and  52 , and toward a different location on the first and second magnets  24  and  26 , respectively. 
         [0030]    According to the well understood Right Hand Rule, the magnetic fields indicated by the field lines  80 A and  80 B will direct a DC arc along either a first movement direction  82  or a second movement direction  84  depending upon the polarity of the DC arc being interrupted. More particularly, DC current going into the plane of the page of  FIG. 5 , i.e., from the movable contact  14  toward the stationary contact  12 , will be pushed generally along the first movement direction  82 , meaning that the DC arc will be communicated along the first arc runner surface  60  of the first arc runner element  48  and then toward the set of arc plates  22 . On the other hand, DC current coming out of the plane of the page of  FIG. 5 , i.e., going from the stationary contact  12  toward the movable contact  14 , will be pushed by the magnetic fields in the arc extinction apparatus  20  generally along the second movement direction  84 , which means that the arc will be communicated along the second arc runner surface  62  of the second arc runner element  52  and then toward the set of arc plates  22 . 
         [0031]    It is reiterated that the arc runner assembly  2  and circuit interrupter  4  can be employed in an AC application without departing from the present concept and will achieve similarly beneficial results. However, the first and second arc runner elements  48  and  52  that are situated at opposite sides of the stationary contact  12  very advantageously communicate DC arcs of either polarity along their surfaces toward the arc plates  22  for interruption of such arcs, which is highly advantageous. 
         [0032]    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 invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.