Patent Publication Number: US-6337447-B1

Title: Electrical disconnect switch assembly

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to electrical disconnects. More specifically, the present invention relates to an electrical disconnect switch assembly. 
     U.S. Pat. No. 4,851,963 entitled “Weatherproof Air Conditioning Disconnect Switch” describes a simple switch enclosed within a metal enclosure that includes a pull-out handle that carries the movable contacts in and out of connection with the fixed contacts arranged within the switch housing. To prevent inadvertent replacement of the handle when the air conditioning equipment is being installed or repaired, the operator may retain the handle until such repair or installation is completed. 
     U.S. Pat. No. 5,272,297 entitled “Streamlined Air Conditioning Disconnect Switch” describes a switch contained within a metal enclosure wherein the switch utilizes a ramped movable contact arrangement for slidably opening and closing the switch contacts without the requirement of a removable pull-out handle. A plastic faceplate covering the switch terminals allows the use of a metallic enclosure of reduced depth. 
     Non-automatic (manual) electrical disconnects are located near electrical equipment such as motors, compressors, motor controls or other electrically driven machinery. Electrical disconnects allow maintenance personnel to manually isolate the machinery from electrical power when maintenance or replacement of the machinery is necessary, thus protecting the personnel from electric shock. 
     Industrial air conditioning and refrigeration equipment, and the disconnects that service this equipment, are often located on roof tops or other outdoor locations. Consequently, the electrical disconnects must not only protect personnel from the potential hazards of electric shock, but must also be water-resistant and tamper-proof. 
     Electrical disconnects generally comprise a disconnect switch assembly (switch) and related connecting equipment, e.g., lugs and ground terminals, housed within a disconnect enclosure (enclosure). When the disconnect is installed, the switch is electrically connected to both the power supply (line) wiring and the equipment (load) wiring via the lugs. Thus, the switch forms part of the electrical circuit providing electrical power to the electrically driven machinery. The electric disconnect switch may operate within a metal enclosure without the requirement of circuit breakers to turn the associated electric equipment on and off. 
     The switches come in a variety of configurations, e.g., toggle type and pull type. The disconnects must meet accepted industry standards, e.g., Underwriters&#39; Laboratory (UL) standards or National Electric Code standards, depending on their use. The disconnects for air-conditioning (AC) disconnects must meet Article 430 of the National Electric Code, one such industry standard. 
     The enclosure is generally shaped as an elongated parallelepiped, with a top wall, a bottom wall, a back wall, two side walls, and a cover. 
     The cover allows access to the switch and related connecting equipment housed within the enclosure. The enclosure is generally constructed of plastic or metal, and it must meet a variety of accepted industry standards, including UL standards or National Electric Code standards, depending on their use. One such standard is UL 50, entitled “Standard for Safety for Enclosures for Electrical Equipment.” 
     The interior components of the electric disconnect, such as the handle assembly, are generally constructed of plastic materials and must comply with UL standards for strength and temperature. During production, prior art disconnects are assembled by mounting the base section of the handle assembly within the interior compartment of the enclosures with a plurality of mounting screws. Further, the line and load blades are secured to the handle assembly with a plurality of mounting screws. This method of assembly requires that an inventory of screws be maintained and controlled for this operation. Additionally, proper production tooling, e.g. screw guns, must be used. For these reasons the use of screws adds significant cost and labor to the production process. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, an electric disconnect switch assembly is mounted within a disconnect enclosure for manually disconnecting electrical equipment from a source of supply power. The electric disconnect switch assembly includes a receptacle and a handle assembly. The receptacle is attached to a bottom wall of the enclosure. The receptacle includes a load stab arranged in a first pocket and in contact with a load terminal lug and a line stab arranged in a second pocket and in contact with a line terminal lug. The handle assembly includes a handle grip projecting from one end and a line blade and a load blade extending from an opposite end thereof. The handle assembly is slidably arranged within the receptacle and the line blade and the load blade are moved into and out of contact with the line and load stabs by manual operation of the handle grip. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a fully assembled disconnect embodying the present invention; 
     FIG. 2 is an isometric view of the receptacle of FIG. 1; 
     FIG. 3 is a cross-sectional view of the handle assembly of FIG. 1; 
     FIG. 4 is an enlarged cross sectional of a portion of the handle base of the handle assembly; 
     FIG. 5 is a cross sectional view of the portion of the handle base of FIG. 4; 
     FIG. 6 is a cross-sectional front view of the electric disconnect switch assembly of FIG. 1; and 
     FIG. 7 is a cross-sectional end view of the electric disconnect switch assembly of FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1 a perspective view of an exemplary embodiment of a fully assembled disconnect, such as used for air-conditioning or refrigeration equipment, is shown generally at  10 . The disconnect  10  comprises an upstanding, pull-type handle assembly (handle assembly)  12  mounted within an insulative plastic receptacle (receptacle)  34 . Receptacle  34  is fixedly attached to a disconnect enclosure  14 . Handle assembly  12  forms part of a circuit (not shown) for providing electric current to electrically powered equipment (not shown). Handle assembly  12  serves to isolate the electrically powered equipment from a source of supply power, by enabling a user to manually break the circuit conducting the supply power to the equipment. The disconnect enclosure  14  comprises a base  16  hingedly attached to a separate cover  18 . An oval recess  27  is integrally-formed within the cover  18  to provide clearance for an upstanding grip  76  of the handle assembly  12 . An electric disconnect switch assembly is generally shown at  152  in the “ON” position and comprises the handle assembly  12  and receptacle  34 . 
     Base  16  includes a bottom wall  20 , with a first side wall  22  and a second side wall  24 . First side wall  22  and second side wall  24  extend substantially perpendicular from opposing side boundaries of the bottom wall  20 . Additionally, base  16  includes a front wall  26  and a rear wall  28 , which extend substantially perpendicular from front and rear boundaries of the rear wall  20 , respectively. The bottom wall  20 , first side wall  22 , second side wall  24 , front wall  26  and rear wall  28  define an interior compartment  30  of the base  16  for mounting the handle assembly  12  therein. 
     Also attached to the bottom wall  20  of the enclosure  14 , is the neutral terminal assembly  142  which includes a pair of neutral terminal screws  146 . The neutral terminal assembly  142  is mechanically attached and electrically bonded to the disconnect enclosure  14  by means of a machine screw  148 . 
     A plurality of knockouts  150  are cut within the front wall  26 , first side wall  22  and second side wall  24 . These knockouts allow for wiring access to the line terminal lugs  112 ,  114  and load terminal lugs  108 ,  110  contained within the electric disconnect switch assembly  152 . 
     Referring to FIG. 2, receptacle  34  is shown having a base section  36 , a first side  37 , a second side  41 , a third side  38 , and a fourth side  40 , and a rear side  42 . First side  37  extends generally perpendicularly outward from an end of rear side  42 . Second side  41  extends generally perpendicularly outward from an opposing end of rear side  42 . A first partition wall  50  having a first outer edge  83  and a second outer edge  85  extends longitudinally between the first and second sides  37 ,  41 . A second partition wall  44  is generally parallel to first and second sides  37 ,  41 . Second partition wall  44  includes an elongated slot  172  located at a top end  55 , preferably centrally located at the top end  55 . First side  37 , rear side  42 , second partition wall  44  and first partition wall  50  define a first compartment  52 . Second side  41 , rear side  42 , second partition wall  44  and first partition wall  50  define a second compartment  54  adjacent to first four-sided compartment  52 . Preferably, first and second compartments  52 ,  54  are four-sided and similar in size and shape. 
     Third side  38  extends outward from first partition wall  50  a distance designated by “d 1 ” from first outer edge  83 . Third side  38  is parallel to first side  37 . Fourth side  40  extends from first partition wall  50  a distance designated by “d 2 ” from second outer edge  85 . Fourth side  40  is parallel to second side  41 . Preferably, “d 2 ” is equal to “d 1 ”. 
     A double partition wall  134  extends generally perpendicularly outward from first partition wall  50  over base section  36  and parallel to second and third sides  38 ,  40 . Double partition wall  134 , third side  38  and first partition wall  50  define a third compartment  46 . Double partition wall  134 , fourth side  40  and first partition wall  50  define a fourth compartment  48 . Double partition  134  is proximate the load terminal lugs  108 ,  110  (FIG. 1) and serve as insulative barriers. Third side  38  and fourth side  40  are proximate the line terminal lugs  112 ,  114 , (FIG. 1) respectively and serve as insulative barriers. 
     Base section  36  extends through the first, second, third and fourth compartments  52 ,  54 ,  46 ,  48 . Base section  36  extending through third and fourth compartments  46 ,  48  includes a top surface  60 , preferably planar, facing in the direction of the interior of the cover  18  (FIG. 1) when the cover  18  is in the closed position (not shown). 
     A first recess  56  is located on top surface  60  in third compartment  46  proximate to double partition wall  134 . A second recess  58  is located on top surface  60  in third compartment  46  proximate to third side  38 . A third recess  62  is located on top surface  60  in fourth compartment  48  proximate to double partition wall  134 . A fourth recess  64  is located on top surface  60  in fourth compartment  48  proximate to fourth side  40 . Proximate to both the first recess  56  and third recess  62  are two marks with the word “Load.” Proximate to both the second recess  58  and fourth recesses  64  are accordingly marked with the word “Line”. The “Line” and “Load” indicia are formed integral with the forming of the receptacle  34  and are permanently affixed therein. 
     A first pocket  66  is molded in first compartment  52  proximate to second partition wall  44  and in the same general plane as base section  36 . A second pocket  68  is similarly formed in first compartment  52  proximate to first side  37 . A third pocket  70  is similarly formed in second four-sided compartment  54  proximate to second partition wall  44 . A fourth pocket  72  is similarly formed in second compartment  54  proximate to second side  41 . Preferably, first, second, third and fourth pockets  66 ,  68 ,  70 ,  72  are similar in size and shape. 
     First partition wall  50  includes at least one, preferably four, fingers  73  extending inwardly and between first recess  56  and first pocket  66 , between second recess  58  and second pocket  68 , between third recess  62  and third pocket  70  and finally, between fourth recess  64  and fourth pocket  72 . 
     Base section  36  also includes a first opening  80  that is located in the first compartment  52  between first pocket  66  and rear side  42 . A second opening  82  is located in the first compartment  52  between the second pocket  68  and the rear side  42 . A third opening  84  is located in the second compartment  54  between the third pocket  70  and the rear side  42 . A fourth opening  86  is located in the second compartment  54  between the fourth pocket  72  and the rear side  42 . Preferably, first, second, third and fourth openings  80 ,  82 ,  84 ,  86  are rectangularly shaped and similar in size. 
     A first tab  188  extends outward from the top of the rear wall  42  proximate second partition wall  44 . A second tab  190  extends outward from the top of first partition wall  50  proximate to the double wall partition  134  and opposite to the first tab  188 . 
     Referring to FIG. 3, handle assembly  12  is shown having grip  76  and a handle base  132  with a bottom surface, preferably planar, generally indicated at  100  that faces in the direction of bottom wall  20  (FIG.  1 ). Handle base  132  also includes a first end  45  and a second end  47 . Grip  76  includes an aperture  78 , preferably two apertures  78 , which an operator can utilize to manually position the handle assembly  12  within the plastic receptacle  34  (FIG.  1 ). Handle assembly  12  also includes two protruding fins  102  separated by a fin  170  extending perpendicularly between. Fins  102  extend from a central point within the grip and partition the bottom surface  100 . Fins  102  partition the bottom surface  100  into a first bottom surface  104 , preferably planar, and a second bottom surface  106 , preferably planar. 
     Referring to FIG. 3, the handle base  132  section of the handle assembly  12  will be discussed. 
     First cavity  88  is positioned in first bottom surface  104  of the handle base  132  proximate the fin  102 . A second cavity  90  is positioned in first bottom surface  104  proximate to the end of the first bottom surface  104 . A third cavity  92  is positioned in second bottom surface  106  proximate fin  102 . A fourth cavity  94  is positioned in second bottom surface  106  proximate to the end of the second bottom surface  106 . First, second, third and fourth cavities  88 ,  90 ,  92 ,  94  each having opposing sidewalls  196 ,  198  with a planar wall  200  partially connecting the opposing sidewalls  196 ,  198  and facing base  20  (FIG.  1 ). Preferably, first, second, third and fourth cavities  88 ,  90 ,  92 ,  94  are rectangular in shape. 
     Referring to FIGS. 3,  4  and  5 , the features of the first, second, third and fourth cavities  88 ,  90 ,  92 ,  94  will be discussed in further detail in relation to the second cavity  90  of the handle base  132 . FIG. 4 is an enlarged view of a second cavity  90  located within the handle base  132 . FIG. 5 is a cross-section of the second cavity  90 . Although the discussion below details the configuration of the second cavity, it is understood that the first, third and fourth cavities  88 ,  92 ,  94  are similar. 
     Planar wall  200  includes a first end  214  and a second end  216 . Opposing sidewalls  196 ,  198  include a top end  218  and a bottom end  220 . First, second, third and fourth cavities  88 ,  90 ,  92 ,  94  each include a member  96 , preferably cantilevered, with a boss  98 . Preferably, member  96  is an integrally formed extension of planar wall  200 . Boss  98  is located at the second end (free end)  216  of the member  96 . The opposing sides of the first, second, third and fourth cavities  88 ,  90 ,  92 ,  94  also each include a first and second pair of ribs  97 ,  202 . First pair of ribs  97  includes a first rib  206  and a second rib  208 . First rib  206  and second rib  208  are integrally formed along the opposing sidewalls  96 ,  98  and generally extend in a cross-wise direction. First and second ribs  206 ,  208  are located proximate to the bottom ends  220  of the opposing sidewalls  96 ,  98 . Preferably, first rib  206  is parallel to and opposite second rib  208  and first and second ribs  206 ,  208  extend from first end  214  of the second cavity  90  but not all the way through to the second end  216 . Second pair of ribs  202  includes a third rib  210  and a fourth rib  212 . Third and fourth ribs  210 ,  212  are integrally formed along the opposing sidewalls  96 ,  98  and extend in a generally cross-wise direction. Preferably, third and fourth ribs  210 ,  212  are parallel to first and second ribs  206 ,  208  and are located proximate the top ends  218  of the opposing sidewalls  96 ,  98 . Most preferably, third and fourth ribs  210 ,  212  are the same general length as the member  96 . 
     Referring to FIGS. 1 and 6, the operation and assembly of the electric disconnect switch assembly  152  within the disconnect enclosure will be detailed. 
     The receptacle  34  is mounted within disconnect enclosure  14  by the use of at least one, preferably two or four dimples  136  that extend inward. Dimples  136  are punched into the first side wall  22  and second side wall  24  of the disconnect enclosure  14 , generally towards the rear wall  28 . Two ledges  140  are integrally formed and located along the bottom of first side  37  and second side  41  and serve to anchor the receptacle by sliding the ledges  140  under the dimples  136 . 
     An insulative plastic dead-front or shield  17 , preferably planar, is arranged over the electrical components on the electric disconnect switch assembly  152  by positioning the corners of the shield  17 , under a corresponding pair of tabs  154  formed on the first partition wall  50  of the receptacle  34  and overlaying the shield  17  onto the top portion of double partition  134 . The opposite end of the shield  17  rests on an inwardly extending horizontal tab  158  which is formed within the front wall  26  of the disconnect enclosure  14 . 
     The pair of load terminal lugs  108 ,  110  is positioned within first recess  56  and third recess  62 , respectively. The pair of line terminal lugs  112 ,  114  is positioned within second recess  58  and fourth recess  64 , respectively. The load terminal lugs  108 ,  110  are mechanically and electrically connected to a corresponding pair of load stabs  116 ,  120 . The line terminal lugs  112 ,  114  are mechanically and electrically connected to a corresponding pair of line stabs  118 ,  122 . 
     A first blade (first load blade)  124  is slidably and releasably engaged (snap-fit) between the first and second pair of ribs  97 ,  202  located on first sidewall  196  and second sidewall  198 . The first blade  124  is additionally supported by boss  98  (FIG.  3 ). Similarly, a second blade (first line blade)  126  is slidably and releasably engaged into second cavity  90 , a third blade (second load blade)  128  is slidably and releasably engaged into third cavity  92  and a fourth blade (second line blade)  130  is slidably and releasably engaged into fourth cavity  94 . First, second, third and fourth blades  124 ,  126 ,  128 ,  130  each having an elongated slotted section  151  formed on one side. Preferably, first, second, third and fourth blades,  124 ,  126 ,  128 ,  130  also have a top section  153 , preferably U-shaped, slidably mounted between the first and second pair of ribs  97 ,  202 . 
     A first fuse  180  snap-fits between the first blade  124  and the second blade  126 . A second fuse  182  snap-fits between the third blade  128  and the fourth blade  130 . First fuse  180  and second fuse  182  are thus positioned in a horizontal arrangement and end to end along the bottom surface  100  of the handle assembly  12 . 
     Handle base  132  of the operator handle  14  with the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  attached thereto fit within first compartment  52  and second compartment  54 . Fins  102  serve as a guide for positioning the operator handle  14  within the receptacle  34 . Fins  102  are spaced sufficiently apart so as to be positioned proximate to second partition wall  44  (FIG.  2 ). The fin  170  will rest on the bottom edge of slot  172  to ensure that the grip  76  extends outward from the first and second compartments  52 ,  54  to facilitate operating the operator handle  14 . Thus, when assembled, the base section  132  mounts flush with the interior surfaces of first side  37 , second side  41 , rear side  42  and first partition wall  50 . 
     When the operator handle  14  is fully positioned within the receptacle  34  in the “ON” position, the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  provide continuity between the line terminal lugs  112 ,  114  and the load terminal lugs  108 ,  110 . More specifically, the elongated slotted section  151  of first, second, third and fourth blades  124 ,  126 ,  128 ,  130  is positioned proximate to the pair of line stabs  118 ,  122  and load stabs  116 ,  120  within first, second, third and fourth pockets  66 ,  68 ,  70 ,  72 , respectively. 
     Fingers  73  provide an insulative barrier for the first, second, third and fourth blades  124 ,  126 ,  128 ,  130 . Electrical continuity is provided when the elongated slotted section  151  of the first and second blades  124 ,  126  are inserted into first and second pockets  66 ,  68  and third and fourth blades  128 ,  130  are inserted into third and fourth pockets  70 ,  72 . 
     When the operator handle is removed from the receptacle  34 , turned 180 degrees and reinserted into the receptacle  34  (the “off” position), again using fins  102  as a guide, continuity between the line terminal lugs  112 ,  114  and the load terminal lugs  108 ,  110  is interrupted. First, second, third, and fourth openings  80 ,  82 ,  84 ,  86  now contain third, fourth, first and second blades  128 ,  130 ,  124 ,  126 , respectively. 
     Referring to FIG. 7, a side view of the electric disconnect switch assembly  152  is shown. Line stab  118  is shown having a bent section  184  and a flat section  186 . Bent section  184 , preferably U-shaped, is inserted into second pocket  68  and flat section  186  is inserted through line terminal lug  112 . 
     Referring again to FIGS. 1 and 6, load stabs  116 ,  120  and line stab  122  are similarly constructed with the flat section  186  and bent section  184 . Bent section  184  of line stab  122  is inserted into fourth pocket  72  and flat section  186  of line stab  122  is inserted through line terminal lug  114 . Bent section  184  of load stab  116  is inserted into first pocket  66  and flat section  186  of load stab  116  is inserted through line terminal lug  108 . Bent section  184  of load stab  120  is inserted into third pocket  70  and flat section  186  of load stab  120  is inserted through line terminal lug  110 . 
     Referring to FIGS. 2 and 6, corresponding “OFF” indicia is integrally-formed within first tab  188  and “ON” indicia is formed within the opposing second tab  190 , as indicated in FIG.  2 . To provide a clear indication of the position of the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  with respect to the corresponding line and load stabs  116 ,  118 ,  120 ,  122 , an indicating tab  192  centrally located on the grip  76  of the handle assembly  12  is employed. Indicating tab  192  interacts with the first and second tabs  188 ,  190  in the following manner. When the electric switch assembly  152  is in its “ON” condition, the elongated slotted sections  151  of each of the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  are inserted within the first, second, third and fourth pockets  66 ,  68 ,  70 ,  72 , respectively, and electrical connection is made between the adjacent load and line stabs  116 ,  118 ,  120 ,  122 . The indicating tab  192  overlaps and covers the first tab  188  thereby concealing the “OFF” indicia contained thereon. The “ON” indicia located on the opposing second tab  190  is readily visible. 
     In like manner, when the electric switch assembly  152  is in its “OFF” condition such that the elongated slotted sections  151  of each of the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  are inserted within the fourth, third, second and first four-sided rectangular openings  86 ,  84 ,  82 ,  80 , respectively, the indicating tab  192  conceals the “ON” indicia located on the second tab  190  such that the “OFF” indicia located on first tab  188  is readily visible. Thus, without removing the handle assembly  12  from the electric switch assembly  152 , the operator can quickly determine by visual inspection whether the electric switch assembly  152  is in the “ON” or “OFF” position. 
     As described herein, the electric switch assembly  152  reduces parts since the base and guide sections of the receptacle  34  are integrally molded to form one piece. Further, the need for mechanical fasteners to connect the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  to the handle assembly  12  is eliminated. Thus, assembly time and material costs are reduced. The first and second fuses  180 ,  182  snap-fit within the first, second, third and fourth blades  124 ,  126 ,  128 ,  130  and are arranged horizontally and end to end along the bottom surface  100  of the handle assembly  12 . The efficient placement of the first and second fuses  180 ,  182  reduces the size requirement of the disconnect enclosure  14 . A reduction in the overall size of the disconnect enclosure  14  permits a wider use of the product in the field. Finally, the electric disconnect switch assembly  152  also reduces the amount of copper and plastic used. This reduction in raw material, while maintaining the necessary strength and temperature characteristics to meet UL requirements, results in material cost savings. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the overall inventive concepts described herein.