Abstract:
An electrical plug is provided including a plug housing having a hollow interior surrounded by an outer wall, a first plurality of electrical connectors positioned within the hollow interior that are adapted to mate with a second plurality of electrical connectors positioned on a plug housing, a first aperture extending through the outer wall, a locking member extending from within the hollow interior through the first aperture in the outer wall, wherein the locking member includes a retainer that abuts a surface of the outer wall, wherein the locking member includes one a more holes positioned outside of an outer surface of the outer wall, a locking element secured through the one or more holes on the locking member, and wherein the locking member prevents the plug receptacle from being fully engaged with the plug housing.

Description:
RELATED APPLICATIONS 
     This application claims priority to Indian Application Serial No. IN201721007973 entitled “Safety Lockout Feature for Plug,” filed on Mar. 7, 2017. 
     FIELD 
     This patent application is directed generally to electrical plug assemblies that may be used to connect power for industrial equipment. More particularly, the patent application is directed to an electrical plug having a plug housing adapted to mate with an electrical plug receptacle, where the plug housing includes a lockout mechanism to prevent insertion of the plug housing into the plug receptacle when it is desired to prevent electrical contact between the electrical connectors in the plug receptacle and the plug housing. 
     BACKGROUND 
     Electrical plugs and electrical plug receptacles are used to connect a power source to energize electronic equipment, often in industrial applications. In such industrial applications, there are times when the equipment undergoes maintenance, service, or repair, in which case the power or electricity to the equipment needs to be disconnected. To disconnect the power or electricity from reaching the equipment, the electrical plug may be unplugged from the electrical plug receptacle to stop the power or electricity from reaching the electrical equipment being maintained, serviced, or repaired. 
     In industrial applications, often high voltage and/or high amperage is involved such that in the event that the electrical plug is inadvertently or accidently inserted into the electrical plug receptacle, a dangerous situation may result for the individuals involved in the maintenance, service, or repair of the electrical equipment. As a result, it would be desirable to provide a mechanism to prevent an electrical plug from being inserted into an electrical plug receptacle during such maintenance, service, or repair such that the electrical plug is “locked out” or prevented from coming into electrical engagement with the electrical plug receptacle. 
     SUMMARY 
     An electrical plug assembly is provided which advantageously provides for locking out an electrical plug from electrical engagement with an electrical plug receptacle when electronic equipment is undergoing maintenance, service, or repair. An electrical plug is provided with a plug housing having a hollow interior surrounded by an outer wall and a plurality of electrical connectors positioned within the hollow interior that are adapted to mate with a plurality of electrical connectors positioned on a plug receptacle. In order to provide the locking out functionality, an aperture extends through the outer wall of the plug housing, and a locking member extends from within the hollow interior of the plug housing through the aperture in the outer wall of the plug housing. To retain the locking member in place, the locking member includes a retainer that abuts either an inner surface of the outer wall of the electrical plug housing adjacent a first aperture in the outer wall, or abuts an outer surface of the outer wall of the electrical plug housing adjacent a second aperture in the outer wall. Further, the locking member includes one a more holes positioned outside of an outer surface of the outer wall of the plug housing where a locking element, such as a padlock, may be secured through the one or more holes on the locking member. The use of the locking member prevents the plug from being fully engaged with the plug receptacle, and prevents the plurality of electrical connectors on the electrical plug housing and the electrical plug receptacle from coming into electrical contact; thereby locking out the electrical plug from engagement with the electrical plug receptacle and preventing the energization of the electronic equipment during maintenance, service, or repair. 
     In one embodiment, an electrical plug is provided including a plug housing having a hollow interior surrounded at least partially by an outer wall, a first plurality of electrical connectors positioned within the hollow interior of the plug housing that are adapted to mate with a second plurality of electrical connectors positioned on a plug receptacle, a first aperture extending through the outer wall of the plug housing, a locking member positionable through the first aperture in the outer wall of the plug housing, wherein the locking member includes a retainer that abuts a surface of the outer wall of the plug housing when the locking member is extended through the aperture of the outer wall from within the hollow interior of the plug housing, wherein the locking member includes one or more holes adapted to receive a locking element or lockout tag, and wherein when the locking member is positioned through the first aperture in the outer wall of the plug housing and the locking element or lockout tag is secured through the one or more holes of the locking member, the plug receptacle cannot be fully engaged with the plug housing. 
     In another embodiment, an electrical plug is provided including a plug housing having a hollow interior surrounded at least partially by an outer wall, a first plurality of electrical connectors positioned within the hollow interior of the plug housing that are adapted to mate with a second plurality of electrical connectors positioned on a plug receptacle, a first aperture extending through the outer wall of the plug housing, a locking member extending from within the hollow interior of the plug housing through the first aperture in the outer wall of the plug housing, wherein the locking member includes a retainer that abuts a surface of the outer wall of the plug housing, wherein the locking member includes one or more holes positioned outside of an outer surface of the outer wall of the plug housing, a locking element secured through the one or more holes on the locking member, and wherein the locking member prevents the plug receptacle from being fully engaged with the plug housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments are described herein with reference to the drawings wherein: 
         FIG. 1  is a perspective view of an electrical plug  100  with electrical connectors  110   a - d , that is part of an electrical plug assembly; 
         FIG. 2  is a perspective view of the electrical plug  100  shown in  FIG. 1  with the electrical connectors  110   a - d  removed, and showing an aperture  150  in outer wall  120  of electrical plug  100 ; 
         FIG. 3  is a perspective view of locking member  140  used in connection with electrical plug  100 ; 
         FIG. 4  is a close up perspective view of electrical plug  100  shown in  FIG. 1 , showing locking member  140  extending through outer wall  120  of electrical plug  100  with a locking element  130  secured to locking member  140  to lock out a plug receptacle from engagement with the electrical connectors  110   a - d  of electrical plug  100 ; 
         FIG. 5  is a perspective view of electrical plug  100 ′ with locking member  240 . 
         FIG. 6A  is a cross-sectional view of electrical plug  100  shown in  FIGS. 1 and 2 ; 
         FIG. 6B  is a cross-sectional view of electrical plug receptacle  200 ; and 
         FIG. 6C  is a cross-sectional view of electrical plug  100  engaged with electrical plug receptacle  200 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of an electrical plug  100  with electrical connectors  110   a - d  (one of which may be a ground pin). Electrical plug  100  is part of an electrical plug assembly that is adapted to electrically connect with an electrical plug receptacle to provide power or electricity to an electrically driven device, such as industrial equipment. When the electrical plug  100  is electrically engaged with an electrical plug receptacle (as shown in  FIG. 6C ), power or electricity is allowed to power the piece of industrial equipment. When the electrical plug  100  is electrically disengaged from the electrical plug receptacle, the power or electricity is no longer provided, allowing for the piece of industrial equipment to be maintained, serviced, or repaired. 
     Once the electrical plug receptacle is electrically disengaged from the electrical plug  100  (as shown in  FIGS. 6A and 6B , it is important that the electrical plug receptacle is unable to be inadvertently or accidentally electrically reengaged with electrical plug  100 . As shown in  FIG. 1 , a locking member  140  extends outwardly from outer wall  120  of electrical plug  100 . A locking element  130  (here shown as a padlock) is shown secured through a hole in the locking member  140  to provide a mechanism for locking out an electrical plug receptacle from engagement with the electrical plug  100 . The locking element  130  prevents an electrical plug receptacle from inadvertently or accidentally reengaging with the electrical plug  100  during maintenance, service, or repair. 
     In  FIG. 1 , outer wall  120  is shown surrounding the electrical connectors  110   a - d  in a continuous fashion. However, the outer wall  120  could also partially surround the electrical connectors  110   a - d , for example if one or more vertical slits were positioned in the outer wall  120  so that it was not continuous. 
     In  FIG. 1 , outer wall  120  is shown having circular inner and outer portions. However, in other embodiments the outer surface or inner surface of outer wall  120  could have a different geometry, such as oval, square, or hexagonal. In addition, in  FIG. 1 , the outer wall  120  is shown having a uniform wall thickness where both the inner and outer surfaces of outer wall  120  have a circular geometry. However, in other embodiments, the inner surface of the outer wall  120  could have a different geometry than the outer surface of the outer wall  120  such that outer wall  120  has a non-uniform wall thickness. For example, the outer surface of outer wall  120  could be circular or square and the inner surface of outer wall  120  could be hexagonal. 
       FIG. 2  is a perspective view of the electrical plug  100  shown in  FIG. 1  with the electrical connectors  110   a - d  removed, and showing an aperture  150  in outer wall  120  of electrical plug  100 . The aperture  150  allows for the locking member  140  shown in  FIG. 1  to extend therethrough to provide for a mechanism for locking out an electrical plug receptacle from electrically engaging with the electrical plug  100 , while a piece of industrial equipment has been de-energized to allow for maintenance, service, or repair. In this embodiment, aperture  150  is shown as a horizontal slit. However, in other embodiments, different geometries could be used for aperture  150 , such as a vertical or angled slit, circle, oval, hexagon, square, or other geometric shapes. 
       FIG. 3  is a perspective view of locking member  140  used in connection with electrical plug  100 . In this embodiment, the locking member  140  is shown having a horizontal flange  146  that extends through aperture  150 . A circular hole  147  and an oval hole  148  are positioned on horizontal flange  146  that may be used to allow a locking element, such as a padlock to “lock out” the electrical plug  100  to prevent an electrical plug receptacle from being inadvertently or accidentally electrically engaged with the electrical plug  100 . Although in this embodiment the locking member  140  includes a horizontal flange  146 , other geometries could be used as well. For example, the flange could have a round, oval, square, or rectangular cross-section, extend vertically or at an angle, or have other geometric configurations. In  FIG. 3 , locking member  140  includes a retainer  142  shown as an upwardly extending vertical flange that is attached to horizontal flange  146 . Retainer  142  abuts an inner surface of outer wall  120  (shown in  FIG. 4 ) when in use. In the embodiment of  FIG. 3 , retainer  142  is shown as an upwardly extending vertical flange. However, in other embodiments, retainer  142  could extend downwardly, to the side, or in a non-vertical manner. In addition, retainer  142  could also have other geometric configurations such as round, oval, square, etc. 
     In addition, retainer  140  includes a hole  144  extending therethrough to which a lanyard  170  could be attached. In this manner, the locking member  140  may remain attached to the electrical plug  100  via a lanyard  170  when it is not being used. As a result, when it comes time to “lock out” the electrical plug receptacle, the locking member  140  will be readily available. 
       FIG. 4  is a close up perspective view of electrical plug  100  shown in  FIG. 1 , showing locking member  140  extending through outer wall  120  of electrical plug  100  with a locking element  130  secured to locking member  140  to lock out an electrical plug receptacle from engagement with the electrical connectors  110   a - d  of electrical plug  100 . A vertical slot  160  is also shown which is used to align an electrical plug receptacle in an appropriate orientation. In  FIG. 4 , retainer  142  of locking member  140  can be seen abutting an inner surface of outer wall  120  to prevent the locking member  140  from exiting the outer wall  120 . Horizontal flange  142  is shown extending through the aperture in outer wall  120  and locking member  130  (in this case a padlock) is secured through a hole in the horizontal flange. In particular, padlock arm  132  of padlock  130  extends through a hole in horizontal flange  146 . In addition, a tag  160  is secured to padlock arm  132  of padlock  130  that may provide information explaining that the electrical plug is locked out, who is authorized to unlock, and where the key to unlock may be located. 
     In the configuration shown in  FIG. 4 , the electrical plug  100  is locked out, meaning that the locking member  140  serves to prevent an electrical plug receptacle from being inadvertently or accidentally electrically engaged with the electrical plug. A number of styles of plug assemblies may exist. For example, a plug housing can be used for style  1 , style  2 , or style  1  &amp;  2 . The position of the lockout slot  150  relative to the polarizing slot (vertical slot feature  160 ) may change for different plug styles. Preferably, the location of the lockout slot  150  is positioned further away from the ground pin (one of electrical connectors  110   a - d ) than any of the reminder of the plurality of pins (electrical connectors  110   a - d ). 
       FIG. 5  is a perspective view of electrical plug  100 ′ with locking member  240 . In  FIG. 5 , the electrical plug  100 ′ and locking member  240  are slightly different than locking element  140  shown in  FIGS. 1-4 . In particular, electrical plug  100 ′ includes two apertures in the outer wall, through which locking member  240  extends. Electrical plug  100 ′ operates in a similar fashion to electrical plug  100  to lock out an electrical plug receptacle from engaging the electrical connectors  110   a - c  shown in  FIG. 5 . In the embodiment of  FIG. 5 , locking member  240  extends through opposite sides of outer wall  120  and extends over the electrical connectors  110   a - c  and horizontal flange  246  extends outwardly from an outer surface of outer wall  120 . Horizontal flange  246  includes a plurality of holes  248   a - c  through which a locking element, such as a padlock, may be secured to. Locking member  240  includes a retainer  242  that abuts an outer surface of outer wall  120  to secure the locking member in place with electrical plug  100 ′. 
     As with the locking member  140  shown in  FIGS. 1-4 , locking member  240  is shown as a horizontal flange. However, locking member  240  could also be oriented vertically or at an angle. In addition, locking member  240  could also have other geometric cross-sectional configurations such as round, oval, square, hexagonal, etc. 
       FIG. 6A  is a cross-sectional view of electrical plug  100  having outer wall  120  and aperture  150  disengaged from the electrical plug receptacle  200  shown in  FIG. 6B . When engaged, electrical plug  100  may be inserted into cavity  210  of electrical receptacle  200 . 
       FIG. 6C  is a cross-sectional view of electrical plug  100  engaged with electrical plug receptacle  200 . In this view, the locking member has been removed from aperture  150  and the outer wall  120  of electrical plug  100  is shown inserted into cavity  210  of electrical plug receptacle  200  to provide for an electrical engagement. 
     Example embodiments of the present invention have been described above. Those skilled in the art will understand that changes and modifications may be made to the described embodiments without departing from the true scope of the present invention, which is defined by the claims.