Abstract:
A fuse status indicator assembly ( 40, 41, 42 ) for insertion in an opening ( 31 ) in a side wall of the fuse cartridge ( 20   a,    20   b,    20   c ) including a fuse ( 35 ) has a snap-in removable carrier ( 41 ) in the event that the bulb ( 42 ) has burned out and must be replaced. Labels ( 22 ) are attached to the fuse cartridges ( 20   a,    20   b,    20   c ) to identify the circuits and ratings of the fuses ( 35 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable  
         [0002]     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
         [0003]     Not Applicable  
       TECHNICAL FIELD  
       [0004]     The field of the invention is fuse cartridges for fused disconnect switches of the type used in enclosures for electrical control equipment.  
       BACKGROUND ART  
       [0005]     In factory automation and other commercial applications requiring control of motors and other electrical equipment, it is typical to mount electrical controls in a cabinet-styled enclosure. Power to the electrical devices in the cabinet is supplied through a fused or non-fused disconnect switch. Fuses are often included in a cartridge which can be inserted and removed from a switch body to replace the fuse. It is beneficial to include fuse status indicators to indicate the condition of the fuse.  
       SUMMARY OF THE INVENTION  
       [0006]     The invention relates to a fuse status indicator assembly for insertion in a removable fuse cartridge, which is used, for example, in a power disconnect switch. The indicator enables a service person to quickly identify a blown fuse condition before removing a fuse cartridge. The fuse status indicator is provided on a removable carrier in the event that the indicator itself has burned out and must be replaced.  
         [0007]     It is one object of the invention to provide a modular fuse status indicator assembly that is compact and easy to install and remove on a fuse cartridge for a disconnect switch assembly. This enhances the serviceability of the equipment.  
         [0008]     As an additional aid, labeling can be placed on the fuse cartridge to provide additional information about the fuse being serviced, so that a proper replacement part is readily available.  
         [0009]     These and other objects and advantages of the invention will be apparent from the description that follows and from the drawings which illustrate embodiments of the invention, and which are incorporated herein by reference. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective, partially exploded view of a disconnect switch assembly with a fuse status indicator of the present invention;  
         [0011]      FIG. 2  is an exploded, perspective view of one of the cartridges seen in  FIG. 1 ;  
         [0012]      FIG. 3  is a detail perspective view of an interior of the fuse cartridge of  FIG. 2 ;  
         [0013]      FIG. 4  is section view taken in the plane indicated by line  4 - 4  in  FIG. 1 ; and  
         [0014]      FIG. 5  is section view taken in the plane indicated by line  5 - 5  in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0015]      FIG. 1  illustrates a disconnect switch  10  which is mounted in the interior of an enclosure of the type disclosed in our co-pending U.S. Pat. Application, entitled “Rotary Service Switch for the Interior of Electrical Enclosures having a Disconnect Switch,” filed on even date herewith, the disclosure of which is hereby incorporated by reference.  
         [0016]     The disconnect switch  10  includes a switch body  11 . Electrical power is received through one set of input terminals (not shown) connecting to input terminals along the top of the disconnect switch body  11 . From there, power is routed through fuse cartridges  20   a ,  20   b  and  20   c . Output terminals  14   a ,  14   b  and  14   c  ( FIG. 1 ) are provided along the bottom of the switch body  11 , to conduct power to the other equipment in the cabinet (not shown). The electrical power is typically three-phase power and the disconnect switch  10  has at least three identical cartridges  20   a ,  20   b ,  20   c  ( FIG. 12 ) corresponding to switch poles or sub-circuits and is rated for three-phase operation, although single-phase operation is also possible.  
         [0017]     The disconnect switch  10  of the present invention is provided in sizes with ratings of 60 amps, 30 amps and smaller. The fuses  35 , one of which is seen in  FIG. 3 , are provided with suitable ratings for handling current overloads or faults. The size, type and ratings of the fuses are provided on labels  23  attached to the outside the cartridges  20   a ,  20   b ,  20   c  as exemplified in  FIGS. 1 and 2 . The labels  23  do not cover the full face of each cartridge, so as to allow room for vents  21  and an indicator window  39 .  
         [0018]     Referring again to  FIG. 1 , the disconnect switch  10  has a rotary actuating mechanism  13  with three positions, “ON”, “OFF” and “TEST”, as shown in  FIG. 1 . In the “OFF” position (shown in  FIG. 1  with the “OFF” legend opposite the arrow indicator  17 ) , the switch contacts in the disconnect switch are open and power is disconnected. When the mechanism  13  is rotated so that the “ON” legend is opposite indicator  17 , the rotational action is translated to another rotational member (not shown) extending transversely through the switch body  11  and when this member is moved, the switch contacts are closed with a snap action. This mechanism  13  is known from prior disconnect switches and is not part of the present invention.  
         [0019]     The fuse cartridges  20   a ,  20   b  and  20   c  are attached and detached from the switch body  11 , the fuse cartridges having housings that are received in snap-in seats  15  ( FIG. 1 ) formed on the switch body  11 . Each cartridge also has electrical stab connectors  24  and  25  which are received in mating electrical sockets (not shown) which are electrically connected to the input and output terminals to form circuit paths through the fused cartridges.  
         [0020]     Referring to  FIG. 2 , each cartridge, represented by cartridge  20   a , has a housing with front wall  28 , two side walls  29  and two end walls  30 . On the front wall  28  is a recess  22  for receiving an adhesively attached label  23  along the left half portion. The label  23  provides information about the electrical parameters and circuit in which the fuse is situated, so that it can be expeditiously replaced when necessary. The right half portion of the front wall  28  is formed with elongated vents  21  and a relatively shorter, transversely oriented aperture  39  for viewing a blown fuse indicator bulb  42 . In the right side wall as seen in  FIG. 2 , there is an opening  31  for receiving a fuse status indicator assembly  40  that includes the bulb  42 .  
         [0021]     The fuse status indicator assembly  40  ( FIG. 2 ) has a base  41  with a generally planar back portion having a shape for keyed insertion into an opening  31  in the fuse cartridge side wall  29 . The base is preferably made of a molded plastic material with integrally formed, resilient, barbed retaining fingers  48 ,  49 ,  50  for insertion into apertures  32 ,  33 ,  34 , seen in  FIGS. 2, 3 ,  4  and  5 . A planar retainer member  60  ( FIG. 3 ) which may be integrally formed with the wall  29  forms the apertures  32 ,  33 ,  34  for receiving the fingers  48 ,  49  and  50 . The barbed fingers  48 ,  49  and  50  will release in response to a withdrawal force coupled with a lifting action.  
         [0022]     The fuse indicator assembly  40  also has a first trough-shaped support  43  ( FIGS. 3 and 4 ) projecting into the fuse cartridge  20   a  from the base  41  for supporting the fuse status indicator  42  in position so as to be seen from a front of the fuse cartridge  20   a  through aperture  39  ( FIG. 4 ). The fuse status indicator  42  is preferably a neon bulb, but other types of illumination devices may be used.  
         [0023]     In this embodiment, a resistor  44  is connected in series with the bulb  42  using leads  46  and  47 , to limit current through the bulb, which is much less than through the fuse  35 . The resistor  44  is contained side-to-side between ribs  62 ,  63  ( FIGS. 2 and 5 ) formed just interior of the side wall  29  and front-to-back between the back member  41  and the retaining member  60 . These ribs  62 ,  63 , provide the apertures  33 ,  34  seen in  FIG. 2  for receiving the barbed fingers  49 ,  50 . Cross member  65  ( FIGS. 2 and 4 ) extends across the top of opening  32  for receiving barbed finger  48  and also helps retain and route lead  46  as seen in  FIG. 4 . An additional rib  61  ( FIGS. 2, 5 ) is formed on the back portion of base  41  to locate the resistor  43 , which is comparable in size to the bulb  42 .  
         [0024]     As seen in the interior of the cartridge in  FIG. 3 , the stab connectors  24 ,  25  are connected to fuse clips  26 ,  27 , which receive fuse terminals  36  on opposing ends of the fuse  35 , when the fuse  35  is installed, thus forming a circuit. The stab connectors  24 ,  25  also have contact portions  24   a ,  25   a  which extend laterally under the edges of retaining member  60  are seen in  FIG. 2  through the opening  31 . The fuse indicator circuit has leads  38 ,  47  seen in  FIG. 4  which are wired in series with the fuse  35 , so that when the fuse blows, the indicator  42  will lose its illumination, indicating a blown fuse. When a fuse is blown, a fuse link in the fuse is interrupted. The stripped ends of wires  38 ,  47  are pressed against the contact portions  24   a ,  25   a  by ribs  64  on the carrier base  41  seen in  FIG. 2 , when the assembly  40  is inserted in the cartridge  20   a  to complete the fuse indicator circuit.  
         [0025]     This has been a description of several preferred embodiments of the invention. It will be apparent that various modifications and details can be varied without departing from the scope and spirit of the invention, and these are intended to come within the scope of the following claims.