Patent Publication Number: US-7723634-B2

Title: Contactor assembly with arc steering system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional application and claims priority to U.S. patent application Ser. No. 11/856,326 filed on Sep. 17, 2007 which is a continuation-in-part of U.S. patent application Ser. No. 11/526,040 filed on Sep. 22, 2006, now U.S. Pat. No. 7,551,050 both being titled “Contactor Assembly with Arc Steering System” and the disclosures of which are incorporated herein. 

   BACKGROUND OF THE INVENTION 
   The present invention is directed to electrical contactors and, more particularly, to an arc steering system for such contactors. 
   A contactor or circuit breaker is a type of current interrupting switch or severable electrical connection that is capable of substantially limiting the duration and the intensity of current flowing in a circuit experiencing a short circuit fault. Other severable electrical connections are commonly referred to as relays, disconnects, circuit breakers, switches, safety switches, enclosed circuit breakers, power circuit breakers, current-limiting circuit breakers, ground fault circuit breakers (GFCI&#39;s), and arc fault circuit interrupters (AFCI&#39;s). Understandably, these are but a few of the devices commonly referred to as switches or current switches or breakers. It is further appreciated that a severable electrical connection according to the present invention be provided as a manual or automatically operable switch. The switches defined by the present claims include all such switching configurations. 
   As one example of an implementation of the present invention, to limit the duration and the intensity of short-circuit currents, a circuit breaker quickly separates the contacts of the circuit breaker. The separation of the contacts while electrical current is flowing through the contactor results in an arc being formed between the contacts of the contactor. Prolonged arcing between the contacts can damage the mating surfaces of the contacts, can damage structures adjacent the contactor, and/or can result in the welding together of the contacts. 
   Arc damage to the mating surfaces of the contacts detrimentally affects the life of the contactor as well as the continued operability of the contactor. Irregularities in the surface of the contacts caused by arc damage results in contacts that do not fully close in a coplanar manner and in separations between the current carrying surfaces of the contacts when the contacts are closed. These irregularities mean that current that is communicated through the contactor is carried over a smaller surface area thereby generating localized current concentrations and thermal gradients in the contacts of the contactor assembly. Arcing can also cause irregularities that protrude above the preferably planar mating surfaces of the contacts. These irregularities tend to attract subsequent circuit termination arcs that further degrade the mating surface of the contact. Accordingly, during a short circuit condition, it is desirable to not only quickly separate the contacts but also to quickly transfer any resultant arc away from the contacts. 
   Among the devices for achieving desired quenching of the arc, the most typical is an arc arrestor which has an arc chute generally aligned along a given number of superimposed ferromagnetic plates. The plates are generally separated from one another and provided with projections or horns that extend toward the path of the arc drawn between the contacts. The plate configuration draws the arc into the arc chute where it is cooled and split up into a plurality of individual smaller arcs, or arclets. However, such a configuration allows the arc to maintain engagement with the contacts until the contacts are sufficiently separated that the resistance between the contacts is greater than the resistance between one contact and a plate of the arc arrestor. Accordingly, although such an arc arrestor aims to quickly quench a circuit termination arc, such arc arrestors inadequately address expedient transfer of the arc away from the contacts. 
   Still others have attempted to improve the transfer of the arc from the contacts to the arc arrestor through implementation of a slot motor magnet or a magnetic intensifier positioned proximate one of the contacts of the contactor assembly. As current flows through the contacts, a slot motor magnet generates a magnetic force on the arc that is directed toward the arc arrestor. Thus, during separation of the contacts, the magnetic field generated by the slot motor magnet directs the resultant arc toward the arc arrestor. 
   Such magnetic intensifiers occasionally result in the arc being attracted to the conductive material of the slot motor magnet damaging the slot motor assembly and possibly delaying movement of the arc away from the contacts. Others have attempted to prevent arcing to the slot motor magnet by encasing the magnet material of the slot motor magnet in a non-conductive material. Unfortunately, such modification increases the distance between the slot motor magnetic material and the contactor thereby reducing the magnitude of the magnetic force associated with the slot motor magnet. Accordingly, although such a modification minimizes the potential of arc attraction with the conductive material of the slot motor magnet, such modification also detrimentally affects the desired magnetic effect of the slot motor magnet. 
   SUMMARY OF THE INVENTION 
   The present invention provides a contactor having a magnetic field intensifier that, rather that encasing the slot motor magnet in an insulator and moving it away from the arc, moves the magnetic field intensifying structure closer to the arc by extending a magnetically reactive arm along a side of the contact. The arm is designed to attract the arc and to promote movement of the arc toward the suppressor. A combination of the shape of the arm to promote arc movement and the increased strength of the magnetic field provided by the arm, serves to minimize arc damage to the contact. 
   Specifically then, the present invention provides a switch assembly that includes a stationary contact, an arc contact, an arc arrestor, and a magnetic intensifier. The magnetic intensifier is constructed to be positioned in generally close proximity to one of the contacts of the switch assembly. During communication of power through the contactor assembly, the magnetic intensifier accentuates a magnetic field generated by a current passed through a turnback of one of the contacts and increases the magnitude of a magnetic force directed toward the arc arrestor. In one embodiment, the magnetic intensifier is formed as a pair of arms that extend from the turnback in close proximity to contact. Preferably, the intensifier and turnback are formed from a continuous piece of copper clad steel. 
   Therefore, in accordance with one aspect of the present invention, a magnetic intensifier for use in a switch for severing an electrical circuit is disclosed. The switch includes a pair of electrical contacts that separate along an axis and produce an arc along the axis between front surfaces of the contacts. At least one of the contacts provides a turnback wherein current to the contact passes along at least a partial loop passing in part behind the contact. The magnetic intensifier includes a magnetically responsive body that forms at least a portion of the turnback proximate the one contact. An arm extends from the magnetically responsive body beyond a side of one contact and proximate the one contact to manipulate magnetic flux formed by the current passing through the partial loop. Such a construction provides an intensifier assembly that can be formed integrally with the electrical components of the switch. 
   Another aspect of the invention disclosed a circuit interrupter assembly that has a first contact and a second contact that is movable between a first position and a second position. The first contact and second contact are electrically connected when the second contact is located in the first position and the first contact and the second contact are electrically separated when the second contact is located in the second position. A turnback is constructed to support one of the first contact or the second contact. An intensifier extends beyond a side of the turnback proximate the one contact and is configured to concentrate magnetic flux generated by current passing through the turnback. 
   A further aspect of the invention discloses a method of manufacturing a switch assembly. The method includes cutting a body from a metallic material. A turnback is formed by folding the body along a first fold line such that a first portion of the body overlies a second portion of the body. The body is folded along second and third fold lines that are oriented in crossing directions with the first fold line such that the turnback is flanked by a pair of arc rails which extend in a direction away from an area bound by the first and second portions of the body. The arc rails intensify the magnetic field associated with a current passing through the turnback. Such a construction simplifies the construction and assembly of the switch. 
   These and various other features, aspects, and advantages of the present invention will be made apparent from the following description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention. In the drawings: 
       FIG. 1  is perspective view of a three-phase contactor assembly equipped with a magnetic field intensifier according to one embodiment of the present invention. 
       FIG. 2  is a top perspective view of the contactor assembly shown in  FIG. 1  with a cover removed therefrom. 
       FIG. 3  is a perspective view of a stationary contact of the contactor assembly shown in  FIG. 2 . 
       FIG. 4  is a top plan view of the stationary contact shown in  FIG. 3 . 
       FIG. 5  is a perspective view of the stationary contact shown in  FIG. 3  with the magnetic field intensifier removed therefrom. 
       FIG. 6  is a plan view of the magnetic field intensifier shown in  FIG. 5 . 
       FIG. 7  is a cross-sectional elevational view of the contactor assembly taken along line  6 - 6  shown in  FIG. 1 . 
       FIG. 8  is an elevational view of one side of the contactor assembly shown in  FIG. 7  with the carry contacts and the arc contacts positioned to communicate current through the contactor assembly. 
       FIG. 9  is a view similar to that shown in  FIG. 8  with the carry contacts separated so that current is only communicated through the arc contacts. 
       FIG. 10  is a view similar to that shown in  FIG. 9  with the movable arc and carry contacts moved away from the stationary arc and carry contacts to prevent the communication of current through the contactor assembly. 
       FIG. 11  is an elevational view of the stationary contact and magnetic field intensifier positioned proximate the arc arrestor of the contactor assembly shown in  FIG. 10 . 
       FIG. 12  is a perspective view similar to  FIG. 5  of another embodiment of a magnetic intensifier according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows an exemplary circuit interrupter or contactor assembly  10  according to the present invention. Contactor assembly  10  includes a housing  12  having a plurality of connections  14 ,  14 ′,  16 ,  16 ′,  18 , and  18 ′ passing therethrough. Understandably, it is appreciated that, as shown, contactor assembly  10  is configured as a three-phase contactor assembly and that other contactor assembly configurations, such as single phase, are envisioned and within the scope of the claims. It is recognized that the present invention is applicable for contactor assemblies having one contactor to a plurality of contactors, including more than three. 
   Cover  20  is constructed to engage housing  12  and generally encloses the electrical componentry disposed therebehind. As shown in  FIG. 2 , removing cover  20  from housing  12  exposes a fixed portion  22  of a plurality of severable electrical circuits  24 ,  26 ,  28  between connectors  14 ,  14 ′;  16 ,  16 ′ and  18 ,  18 ′. Housing  12  includes a plurality of upstanding walls  30 ,  32  configured to isolate the conductive components of adjacent circuits  24 ,  26 ,  28 . Each circuit  24 ,  26 ,  28  includes at least one stationary contact  34  electrically connected to at least one of connectors  14 ,  14 ′,  16 ,  16 ′,  18 ,  18 ′. Each stationary contact  34  includes a stationary arc contact or arc contact  36  and a stationary carry contact or carry contact  38 . An arc arrestor  40  is positioned proximate each of the arc contacts  36  and is constructed to quench a circuit termination arc that is established at arc contact  36 . 
   As shown in  FIG. 3 , arc arrestor  40  includes a plurality of plates  42  that are constructed to be positioned in relatively close proximity to stationary contact  34 . A gap  44  is formed between adjacent plates  42  such that, during quenching of a current termination arc, the current termination arc is divided into a plurality of arclets which are formed across gaps  44  between adjacent plates  42 . The division of the current termination arc into a plurality of arclets reduces the temperature associated with the circuit termination arc and thereby encourages the collapse of the circuit termination arc. 
   A pair of channels  46  extends a length, indicated by arrow  48 , of arc arrestor  40  and is configured to further enhance cooling of the arc arrestor. A plurality of optional arms  50  extends from a selected number of plates  42  and is configured to generally flank an upstanding portion  55  of stationary contact  34 . 
   Contact  36  is positioned on top of a turnback  56  which provides a looping path of current from base  58  communicating and supporting the carry contact  36  to a cantilevered horizontal portion  64  supporting the contact  36 . A vertical portion  66  of turnback  56  offsets horizontal portion  64  of turnback  56  from base  58 . 
   A magnetic intensifier  54  is positioned between a turnback  56  and the base  58  of stationary contact  34 . Passage of current through turnback  56  and base  58  of stationary contact  52  generates a magnetic force on an arc having a magnitude oriented generally in the direction indicated by arrow  60 . Magnetic intensifier  54  is preferably a ferromagnetic material and serves to concentrate the magnetic field generated by current flow through the turnback  56  and thereby increases the magnitude of magnetic force  60  and maintains the same direction thereof. Alternatively, intensifier  54  could be constructed of the nonconductive ferromagnetic material such as a ceramic magnetic. A rivet  62  secures magnetic intensifier  54  to a horizontal portion  64  of turnback  56 . An arm  68  extends from magnetic intensifier  54  toward base  58  and ensures snug engagement of magnetic intensifier  54  within an underside  70  of horizontal portion  64  of turnback  56 . 
   A pair of projections, arms, ramps, or wings  72 ,  74  extend upward from magnetic intensifier  54  flanking horizontal portion  64  of turnback  56  to be positioned about opposite sides of arc contact  36 . The wings  72 ,  74  extend between a first end  76  and a second end  78  of magnetic intensifier  54  providing a continuous magnetic path. The upper surface of each wing  72  and  74  provides a ramp with sharpened edges sloping upward as one moves away from the arm  68 . A notch  80  is formed in wings  72 ,  74  proximate first ends  76  nearest the arc arrestor  40 . As will be described further below with respect to  FIGS. 8-10 , wings  72 ,  74  ensure the repeatable transfer of a circuit termination arc away from arc contact  36 . 
   As shown in  FIG. 4 , notches  80  of wings  72 ,  74  allow the relatively close engagement of stationary contact  34  with arc arrestor  40 . Wings  72 ,  74  include a number of corners  82  that are generally positioned between arc contact  36  and arc arrestor  40 . Corners  82 , the wrapping of wings  72  and  74 , and the amplification of magnetic force  60  cooperatively ensure the efficient and repeatable communication of a circuit termination arc away from arc contact  36  and toward arc arrestor  40 . Additionally, the relatively close positioning of wings  72 ,  74  between arc contact  36  and arc arrestor  40  provide assist in the expedient transfer of a circuit termination arc from arc contact  36 . 
   As shown in  FIG. 5 , horizontal portion  64  of turnback  56  of stationary contact  34  includes an opening or hole  84  formed therein. A hole or recess  86  is also formed in magnetic intensifier  54  and constructed to allow fastening of the magnetic intensifier to horizontal portion  64  of turnback  56  via rivet  62 . Understandably, other fastening or securing means such as crimping or screwing are envisioned and within the scope of the claims. It is further appreciated to simply friction secure magnetic intensifier  54  to turnback  56  through friction fitting such as with arm  68  or like structure. Wings  72 ,  74  are constructed to generally flank and extend above a pair of sides  88 ,  90  of horizontal portion  64  of turnback  56 . Upper surface  92  of magnetic intensifier  54  snuggly engages underside  70  of turnback  56 . Rivet  62 , arm  68 , and another arm  94  ensure the secure engagement of magnetic intensifier  54  within a space  96  between horizontal portion  64  of turnback  56  and base  58  of stationary contact  34 . As shown in  FIG. 5 , when magnetic intensifier  54  is disposed within space  96 , wings  72 ,  74  each form a ramp  98  which gradually extends above a face  100  of arc contact  36  between first end  76  and second end  78  of magnetic intensifier  54 . As described further below, the construction of ramps  98  provide quick and repeatable separation of a circuit termination arc from arc contact  36 . 
   Referring to  FIG. 6 , stationary contact  34  includes a generally regular trapezoidal body  102  wound to form wings  72 ,  74 . Body  102  is formed of a magnetic material, a ferromagnetic, or a rare earth material. The trapezoidal body is folded along fold lines  104 ,  106  that are generally perpendicular to one another. Wings  72 ,  74  form a pair of upstanding arc rails which generally flank a central portion  109  of base body  102 . Positioning upper surface  92  of magnetic intensifier  54  adjacent underside  70  of stationary contact  34  generates a magnetic field force that is directed in a common direction with a direction of reduced resistance of wings  72 ,  74  as determined by a comparison of the distance between the movable arc contact and the stationary arc contact and the movable arc contact and the wings  72 ,  74 . Optionally, a magnet  107  may be attached to the underside of magnetic intensifier  54  to further boost the magnetic field that serves to move the arc into the arc arrestor  40 . 
     FIG. 7  is an elevational cross-sectional view of circuit  24 ,  26 ,  28  of contactor assembly  10 .  FIGS. 7-11  depict an operational sequence of the movable elements of contactor assembly  10 . Understandably, it is appreciated that contactor assembly  10  is constructed to selectively close an electrical circuit as well as automatically sever the electrical circuit when a ground fault is detected or when a user desires to sever the electrical circuit. 
   Referring to  FIG. 7 , a moveable contact assembly  108  includes an arc contact bridge  110  and a carry contact bridge  112  that are moveably connected to contactor assembly  10 . Arc contact bridge  110  and carry contact bridge  112  are moveable in a direction, indicated by arrow  114  such that opposing ends  116 ,  118  of arc contact bridge  110  engage arc contacts  36  of stationary contacts  34  and opposing ends  120 ,  122  of carry contact bridge  112  engage adjacent carry contacts  38 . As shown in  FIG. 7 , moveable contact assembly  108  is an open or nonconducting position  121  wherein electrical current is not communicated through the contactor assembly. As shown in  FIG. 8 , when it is desired to communicate power through contactor assembly  10 , moveable contact assembly  108  is displaced in direction  114  such that arc contact  36  and carry contact  38  of stationary contact  34  electrically engage an arc contact  124  connected to arc contact bridge  110  and a carry contact  126  attached to carry contact bridge  112 . Comparing  FIGS. 7 and 8 , it is shown that moveable contact assembly  108  is movable between the open circuit position shown in  FIG. 7  and a closed or conducting position  134  shown in  FIG. 8 . As shown in  FIG. 8 , when desired or during normal power providing conditions, the movable arc contact  124  and movable carry contact  126  engage the stationary arc contact  36  and stationary carry contact  38 . Accordingly, electrical power is communicated through both carry contact bridge  112  and arc contact bridge  110  of contactor assembly  10  when the contactor assembly is closed. 
   As shown in  FIG. 9 , when a non-conducting or open configuration of contactor assembly  10  is desired or a ground fault condition occurs, carry contact bridge  112  disengages or separates from carry contact  38  of stationary contact  34  thereby forming a gap  136  between stationary carry contact  38  and each of the moveable carry contacts  138 . Current is still communicated through contactor assembly  10  via the engagement of arc contact  36  of stationary contact  34  and moveable arc contact  124  attached to arc contact bridge  110 . Such a construction ensures that, during opening, or severing of the electrical connection, current is allowed to flow through arc contact bridge  110  after isolation of the carry contact bridge thereby ensuring any resultant circuit termination arc is formed between arc contacts  36 ,  124 . Such operation maintains the mechanical and electrical integrity and operability of carry contacts  38 ,  138 . 
   As shown in  FIG. 10 , opening of the circuit  24 ,  26 ,  28  is achieved with the translation of moveable arc contact  124  out of engagement with stationary arc contact  36 . Separation of stationary carry contact  38  and moveable carry contact  138  prior to disengagement of stationary arc contact  36  and moveable arc contact  124  ensures that any circuit termination resultant arc is generated proximate arc contacts  36 ,  124 . The shape of turnback  56  of stationary contact  34  generates electromagnetic magnetic force  60  directed toward arc arrestor such that the arc is broken up into a plurality of arclets between adjacent plates  42  of arc arrestor  40 . Magnetic intensifier  54  increases the magnitude of force  60  toward arrestor  40  and ensures expedient transfer of the arc from stationary arc contact  36  to the plates  42  of arc arrestor  40 . 
   Referring to  FIG. 11 , wings  72 ,  74  of magnetic intensifier  54  extend above contact face  100  of stationary arc contact  36  and are constructed to attract a circuit termination arc away from the stationary arc contact  36 . Accordingly, magnetic intensifier  54  is constructed to accentuate or intensify the magnitude of magnetic force  60  associated with turnback  56  in addition to providing an arc guiding or steering function for any resultant circuit termination arc away from contact face  100  of arc contact  36  toward arrestor  40 . As such, regardless of whether a circuit termination arc propagates to wing  72 ,  74  or rivet  62 , magnetic intensifier  54 , in amplifying magnetic force  60 , assists in the expedient transfer of a circuit termination arc from contact face  100  thereby maintaining the mechanical and electrical integrity of the stationary arc contact  36 . Optional magnet  107  further enhances the arc directing ability of contactor assembly  10 . Understandably, intensifier  54  and magnet  107  could be constructed of magnetically reactive materials, current magnetically reactive materials, simple magnetic materials such as natural or rare earth magnetic materials, ceramic based magnetic materials. 
     FIG. 12  shows a magnetic intensifier  150  according to another embodiment of the invention. As shown in  FIG. 12 , a turnback  152  includes a first portion  154  and a second portion  156 . First portion  154  and second portion  156  of turnback  152  are constructed to overlay one another relative to a turn axis or fold line  158 . An opening or hole  160  is formed in turnback  152  and receives a fastener  162  therethrough. A nut  164  and a washer  166  cooperate to provide a secure electrical connection of turnback  152  with a supporting structure. Understandably, it is envisioned that other conductive connectors, such as spring clips or the like provide means for electrically connecting turnback  152  to the circuitry of a switch assembly. 
   A contact  168  is attached to turnback  152  proximate intensifier  150  and includes an upper face  170  constructed to engage a corresponding contact. Magnetic intensifier  150  includes a first arm  172  and a second arm  174  which extend from turnback  152  proximate contact  168 . Each arm includes a first portion  176  which extends away from a side of turnback  152  and a second portion  178  which extends upwardly from first portion  176 . Such a construction ensures that arms  172 ,  174  are located close enough to contact  168  to magnetically interfere with an arc that may establish without interfering with the electrical operation of contacts  168 . Arms  172 ,  174  extend from turnback  152  generally away from an area  180  between first and second portions  154 ,  156  of turnback  152 . Preferably, arms  172 ,  174  are formed by bending the portion of turnback  152  that forms the arms  172 ,  174  about fold lines  181  that are oriented in crossing directions with fold line  158 . It is appreciated that any of the height, length, thickness, and angle of extension of arms  172 ,  174  may vary depending on the construction of intensifier  150 , turnback  152 , contactor  168  or other structures adjacent or proximate arms  172 ,  174 . That is, it is appreciated that the shape and contour of arms  172 ,  174  can vary. 
   A terminal end  182  of each arm  172 ,  174  includes at least one sharp corner  184  configured to attract a contact separation resultant arc. It is further appreciated that terminal ends  182  may be tapered to direct an arc toward an arc suppressor constructed to be positioned proximate contact  168 . An area  186  of turnback  152  is constructed such that an arc arrestor generally similar to arc arrestor  40  may positioned operationally proximate contact  168 . It is further readily appreciated that although turnback  152  is shown as having a single contact  168 , turnback  152  could be constructed with more than one contact to provide separate arc and carry contacts. 
   Turnback  152  is constructed of a bimetal material such that the turnback is conductive and magnetically reactive. Preferably, turnback  152  is constructed of a first material that is more conductive than a second material and the second material is more magnetically responsive than the first material. More preferably, turnback  152  is constructed of a copper clad steel material. It is further envisioned that turnback  152  be cut or stamped from a common sheet of copper clad material and bent to form turnback  152  and magnetic intensifier  150 . Integration of intensifier  150  into turnback  152  simplifies the manufacture and assembly of a contact or switch assembly equipped with such a turnback and eliminates supplemental structure disposed between the respective portions  154 ,  156  of turnback  152 . 
   Magnetic operation of intensifier  150  may be further augmented with the inclusion of a supplemental intensifier, generally similar to intensifier  54 , disposed in area  186  between the respective portions  154 ,  156  of turnback  152 . Independent of such a configuration, turnback  152  provides quick and repeatable separation of a circuit termination arc from contact  168 . Accordingly, a contactor assembly constructed according to either of the embodiments of the present invention is constructed to withstand greater operating power and is less susceptible to arc termination and arc contact degradation. 
   Therefore, one embodiment of the invention includes a magnetic intensifier for use in a switch for severing an electrical circuit. The switch includes a pair of electrical contacts that separate along an axis and produce an arc along the axis between front surfaces of the contacts. At least one of the contacts provides a turnback wherein current to the contact passes along at least a partial loop passing in part behind the contact. The magnetic intensifier includes a magnetically responsive body that forms at least a portion of the turnback proximate the one contact. An arm extends from the magnetically responsive body beyond a side of one contact and proximate the one contact to manipulate magnetic flux formed by the current passing through the partial loop. 
   Another embodiment of the invention includes a circuit interrupter assembly that has a first contact and a second contact that is movable between a first position and a second position. The first contact and second contact are electrically connected when the second contact is located in the first position and the first contact and the second contact are electrically separated when the second contact is located in the second position. A turnback is constructed to support one of the first contact or the second contact. An intensifier extends beyond a side of the turnback proximate the one contact and is configured to concentrate magnetic flux generated by current passing through the turnback. 
   A further embodiment to the invention includes a method of manufacturing a switch assembly. The method includes cutting a body from a metallic material. A turnback is formed by folding the body along a first fold line such that a first portion of the body overlies a second portion of the body. The body is folded along second and third fold lines that are oriented in crossing directions with the first fold line such that the turnback is flanked by a pair of arc rails which extend in a direction away from an area bound by the first and second portions of the body. The arc rails intensify the magnetic field associated with a current passing through the turnback. 
   Understandably, the present invention has been described above in terms of the preferred embodiment. It is recognized that various alternatives and modifications may be made to these embodiments which are within the scope of the appending claims. It is further appreciated that the features of the multiple embodiments are no way limited solely thereto. That is, it is appreciated that one or more of the features of any one embodiment may be applicable to one or more of the other embodiments.