Patent Application
20100124856
The present application relates generally to receptacles for use with hazardous location plugs. Specifically, the receptacles include a sliding key portion that aids in preventing the use of standard plugs with the receptacles.
Hazardous location plugs and receptacles are typically used in hazardous areas where power is to be supplied to electrical equipment, such as compressors, motors, motor-generator sets, tools, lighting systems, and similar devices. The plugs and receptacles may be used, for example, in military applications, aerospace applications, damp or corrosive areas, armored applications, on board ships, or in other harsh or hazardous environments.
Conventional receptacles for use with hazardous location plugs typically include a rotatable locking plate adapted to receive the contact pins of the plug, contacts positioned behind the locking plate and within the receptacle, and a number of fixed key portions surrounding the locking plate. The hazardous location plug is inserted into the locking plate completely. The plug is then rotated in a clockwise direction to engage the internal contacts of the receptacle and to complete an electrical circuit.
Conventional hazardous location plugs also include grooves that fit over the fixed key portions of the receptacle. Once the plug is inserted into the locking plate and the locking plate is depressed and rotated, the plug is locked into place via a ledge on the fixed key portions positioned in the grooves. The locking of the plug in place helps prevent accidental disengagement (which could lead to sparking) of the plug from the receptacle.
To safely disengage the hazardous location plug from the hazardous location receptacle, the plug must be rotated in a counter-clockwise direction to disengage the plug's contact pins from the receptacle contacts and to break the electrical circuit. Any sparking that may occur from the break in the electrical circuit is confined within the receptacle. In addition, the fixed key portions do not lock the plug in place upon rotation in the counter-clockwise direction. The plug can then be removed from the locking plate of the receptacle.
One deficiency in the design of conventional hazardous location receptacles is that any standard plug may be inserted into the receptacle. Similar to the insertion of hazardous location plugs into the receptacle, standard plugs can be inserted into the locking plate, and the locking plate can be depressed and rotated to contact the contacts in the receptacle. The difference, however, is that standard plugs generally have a smaller diameter than hazardous location plugs and lack the grooves that fit over the fixed key portions to lock the plug in place. Therefore, standard plugs can easily be pulled out of the receptacle, which could lead to sparking and result in an explosion.
Therefore, a need exists in the art for a receptacle that can prevent the use of non-hazardous location plugs with a receptacle in hazardous areas.
The receptacles described herein can aid in preventing the use of standard plugs with a hazardous location receptacle, thus minimizing the possibility of sparking from using standard plugs.
In one aspect of the invention, the receptacles of the present invention include a housing having a cavity, a locking plate positioned within the cavity, and a sliding key portion movably coupled to the locking plate. In certain aspects, the sliding key portion may be coupled to the locking plate by a spring. The spring facilitates movement of the sliding key portion when a hazardous area plug is inserted into the receptacle. The sliding key portion includes a ledge that prevents the locking plate from rotating unless the sliding key portion is depressed, and thus prevents the use of standard plugs with the receptacle since the housing diameter of standard plugs is not large enough to depress the sliding key portion upon insertion into the receptacle housing. Upon insertion of the plug into the receptacle, the spring compresses and the ledge of the sliding key shifts into a groove in the receptacle housing and allows the locking plate to then rotate. Upon rotation of the locking plate, the pins of the plug contact internal pins of the receptacle and make an electrical connection.
In another aspect of the invention, the sliding key portion may be movably coupled to the interior wall of the receptacle housing.
In yet another aspect of the invention, systems of the present invention include a receptacle mated with a hazardous area plug.
These and other aspects, objects, and features of the invention will become apparent to those having ordinary skill in the art upon consideration of the following detailed description of exemplary embodiments exemplifying the best mode for carrying out the invention as presently perceived.
The application discloses receptacles having a sliding lockout key for preventing the use of standard plugs with the receptacles. The receptacles can be used for both general purposes and in hazardous areas.
The receptacle 100 also includes a rotatable locking plate 110 positioned in the cavity 104 of the housing 102. The locking plate 110 is coupled to three springs (not shown) and a contact body (not shown) that allows the locking plate 110 to move in a vertical direction upon compression of the three springs. The locking plate 110 is loosely fitted within the housing 102, and thus can also rotate axially within the housing 102. The locking plate 110 is circular to correspond with the cavity 104 of the housing 102 and includes two parallel rectangular slots 110a for receiving contact pins 210a (
The locking plate 110 also includes two notches 110c located at a perimeter of the locking plate 110 and positioned opposite each other. The notches 110c are configured to receive two fixed key portions 114. The fixed key portions 114 are fixed on the interior wall of the cylindrical housing 102. The fixed key portions 114 do not extend significantly below the locking plate 110. When the plug 200 is inserted into the locking plate 110, the locking plate is depressed below the fixed key portions 114 to allow the locking plate 110 to rotate at a position below the fixed key portions 114.
The locking plate 110 further includes a notch 110d located at a perimeter of the locking plate 110. The notch 110d can be positioned at any suitable location on the perimeter of the locking plate 110 to accommodate the plug 200 to be used in conjunction with the receptacle 100. The notch 110d is configured to receive a sliding key 120, which will be described in further detail hereinafter with respect to
Referring to
Referring to
When a hazardous area plug 200 (
The plug 200 also comprises a gasket 216 to seal the connection between the plug 200 and the receptacle 100 to protect the electrical connection. As a result, the gasket 216 provides ingress protection required by the National Electrical Code (NEC). The plug 200 further comprises a gland nut 218 opposite the contact pins 210a and the ground pin 210b. The gland nut 218 is used to connect wiring comprising two conductors and a ground conductor (not shown) to the pins 210a, 210b in the interior of the plug 200.
To disengage the receptacle 100 from the plug 200, the plug 200 and the locking plate 110 are rotated in a direction so as to disengage the extensions 110e from the grooves 102e and break the electrical circuit. At this stage, the locking plate 110 can move vertically within the receptacle 100. Also, the fixed key portions 114 shift within the grooves 212a to allow disconnection of the plug 200 from the receptacle 100. Any sparking resulting from the break in the electrical circuit is contained within the receptacle 100 and below the locking plate 110. After disengagement of the extensions 110e from the grooves 102e and the fixed key portions 114 from the grooves 212a, the plug 200 can be safely removed from the receptacle 100. The spring 124 also decompresses and shifts the sliding key 120 vertically so as the prevent the locking plate 110 from rotating.
The diameter of the cavity of the receptacles of the present invention has a diameter that is larger than the outer diameter of the housing of standard plugs, thereby making standard plugs unable to compress the sliding key. As a result, the locking plate of the receptacle cannot be rotated such that the pins of the standard plug contact the internal contacts of the receptacle. Thus, an improved receptacle is realized that prevents the use of standard plugs with the receptacle.
Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those having ordinary skill in the art and having the benefit of the teachings herein. Having described some exemplary embodiments of the present invention, that the use of alternate receptacle housing configurations and hazardous area plugs is within the purview of those having ordinary skill in the art. Additionally, while the present application generally illustrates cylindrical plugs and receptacles, it is understood that a number of other non-circular configurations may be used. Furthermore, while the sliding key is shown as being coupled to the locking plate, in alternative embodiments, the sliding key can be slidably coupled to the interior wall of the receptacle housing.
While numerous changes may be made by those having ordinary skill in the art, such changes are encompassed within the scope and spirit of the invention as defined by the appended claims. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and that all such variations are considered within the scope and spirit of the claimed invention. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.
