The present invention is a meter socket. In particular, the present invention relates to a meter socket that has a reduced number of components so that it can be easily assembled and disassembled.
In the electric utility industry, plug-in, socket-type watthour meters are commonly used to measure electric power consumption at residential or commercial sites. The most common type is more properly known as a kilowatt hour meter or a joule meter. When used in electricity retailing, the utilities record the values measured by these meters to generate an invoice for the electricity. These meters may also record other variables including the time when the electricity was used.
The socket for the watthour meter is usually installed in a housing that is mounted on a wall of the residence or commercial building. Typically, the housing is transparent or has a window so that the meter can be read without opening the housing. The meter socket contains pairs of line and load terminals which are respectively connected to electric line and load conductors. The terminals receive the blade contacts of a plug-in watthour meter to complete an electric circuit through the meter between the line and load terminals.
Meter sockets having locking jaws for receiving the bayonet or blade contacts of a watt-hour meter are well known. The meter jaws allow a meter to be quickly and easily installed and removed without the use of screws or other fastening devices. The meter opposing sides of the meter jaws are biased towards each other compressively engage the blade contacts of the meter.
Meter sockets are generally located on a panel or in an enclosure having openings in the side and/or end walls for receiving the line cables and the load cables. When the meter socket is mounted in an enclosure, it is typically mounted to a panel attached to the back wall of the enclosure. The enclosure has a removable front cover or door with an opening for receiving the dome portion of the meter, which extends therethrough when installed in the meter socket.
The meter socket generally includes four or six jaw-type terminals for receiving the blade contacts of the meter. As discussed in U.S. Pat. No. 3,281,550 to Waldrop, some meter sockets can also include bypass conductor members that are used to short the line and load contact of the same phase by operation of a lever. In this particular instance, the bypass conductor members are moved to an open position by placing an insulative material against the bypass member to move the cantilevered bypass member out of electrical contact with the load side jaw-type terminals.
A meter for measuring the usage of electricity is coupled to a plurality of bus members or lines at a meter socket. The meter socket includes a non-conductive base formed by one or more members, a plurality of lugs for connecting the bus lines, a plurality of pincer-like jaw assemblies (also referred to herein as a “meter jaw”), and a base bracket. Typically, the base bracket is attached to a grounding/support structure and the non-conductive base is attached to the base bracket. The lugs are attached to the non-conductive base member(s) and each of the jaw assemblies is connected to a lug. Thus, each jaw assembly is in electrical communication with either the line or the load bus. The jaw assembly openings face away from the front of the meter socket to allow easy insertion of the bayonet connectors (also referred to herein as blade connectors) of the meter. The meter typically includes a cylindrically-shaped enclosure containing a metering device with the meter display on the front side and a plurality of bayonet connectors extending from the back side. The bayonet connectors are adapted to be received by the jaw assemblies to electrically connect the line and load buses through the meter. The metering device collects data relating to electrical usage based on the amount of electricity passing through the meter.
The meter sockets that are currently in use (“the old types” or “prior art”)) are generally assemblies that include two mounting blocks attached to a steel support bridge, two stand-alone support blocks, a plurality of jaw assemblies and connectors and a plurality of screws, connectors and/or fasteners. Typically, these meter socket assemblies use two different types of connectors (45-degrees or 90-degrees depending of construction type) for the line and load connections. Moreover, these prior art designs with their numerous components and fasteners require a considerable amount of assembly time.
The old types of meter sockets typically have rectangular spacers that receive the meter jaw assemblies. These spacers fit into rectangular holes in the block and tend to slide from side-to-side. When a cable is installed in the cable receiving port and torque is applied to the retaining screw, a force is transferred to the body of the connector that causes the connector to move away from the block wall and can damage the block.
In addition, the two “old types” of connectors typically require three holes through the planar portion; one hole for receiving the jaws assembly and two holes that corresponded to dimples on the block. These additional two holes reduce the cross-section of the connector (i.e., the amount of material in the connector), which is carrying electrical current. The reduced cross-section means that the same amount of electricity must be carried by less conductive material, which is less efficient and increases the temperature of the connector.
The prior art meter socket described above, as well as other well known meter sockets, suffers a variety of disadvantages. Accordingly, there is a need for a meter socket with unitary construction (i.e., a “mono-block” or a “uni-block”) that doesn't use a steel bridge to connect the two mounting blocks and doesn't require fasteners or screws to attach the stand-alone support blocks. There is also a need for a meter socket that is designed to receive a jaws assembly so that it does not slide when the retaining screws are torqued to secure the line and load cables.
There is also a need for a meter socket that can use connectors for the line and load connections that only require one hole so that they will more efficiently conduct electricity and operate at a lower temperature. There is also a need for a meter socket that can use a single connector to make connections of 45° or 90° with respect to the centerline of the meter socket.
The present invention is directed to overcoming each of the disadvantages set forth above as well as other disadvantages not specifically described herein but which will become readily apparent to those of ordinary skill in the art in view of the detailed description of the present invention.
Thus, it would be desirable to provide a watthour meter socket that has a simplified construction, uses fewer components and requires fewer manufacturing steps. It would also be desirable to provide a watthour meter socket adapter with stand-alone support blocks that can be attached without screws or fasteners. It would also be desirable to provide a watthour meter socket adapter designed to fixedly receive a jaws assembly so that it stayed in position when the connector retaining screws are tightened. It would also be desirable to provide a watthour meter socket adapter having a connector that has only one hole for increased efficiency and that can be mounted to the meter socket mounting block at different angles.
In accordance with the present invention, a meter socket base assembly is provided. The meter socket base assembly includes a mounting block, one or more connectors, one or more meter jaws and, optionally, at least one support block. The mounting block includes a base, first and second walls, a channel and, optionally, first and second coupling mechanisms. Preferably, the mounting block and the support blocks are formed from electrically non-conductive material. The meter socket base assembly can also include a connector for connecting a neutral conductor.
The base has first and second ends, first and second sides, a top, a bottom and a longitudinal axis between the first and second ends. The first and second walls extend from the top of the base on the first and second sides and are substantially parallel. Each wall has a top surface, a pair of opposing ends and interior and exterior sides. The top surface at each opposing end has a recessed portion with one or more indentations and at least one substantially round opening (also referred to herein as an aperture) extending through the top surface. The one or more indentations in the recessed portion of the block can be slots. Preferably, there are at least a first slot extending substantially perpendicular to the longitudinal axis of the base and a second slot extending at about a 45-degree angle to the longitudinal axis. Preferably, at least the opposing ends of the first and second walls of the mounting block are hollow.
The channel has a bottom formed by the top surface of the base that is disposed between the interior sides of the first and second walls and extends between the first and second ends of the base. The channel can be adapted to receive an insulated neutral conductor. The channel can also include one or more apertures in the bottom. These apertures are adapted for receiving a screw to attach the mounting block to a surface.
The optional first and second coupling mechanisms of the mounting block are formed in or on the exterior side of the first and second walls, respectively. The coupling mechanisms can include one or more slots and/or apertures in the side wall or one or more rails and/or members extending from the exterior side of the wall.
Each of the one or more connectors is constructed of electrically conductive material and has a substantially planar body with a first end, a mid-portion and a second end. The first end has a cable receiving port and retaining screw for connecting a cable, the mid-portion has an aperture and the second end has a member that extends substantially perpendicular to the body. The member is adapted to be received by one of the indentations in one of the recessed portions. Preferably, the member is a lip that extends along the second end of the connector and the indentation is a slot. For most applications, the meter socket base assembly requires two or four connectors.
Each of the one or more meter jaws is constructed of electrically conductive material and has a first end adapted to receive a blade contact of a meter (preferably a watthour meter) and a second end with an aperture adapted for attachment of the meter jaw to one of the connectors and the mounting block. A fastening device, preferably a threaded member such as a screw or bolt and a nut, can be attached to the second end of one of the meter jaws through one of the hollow ends of one of the mounting block walls to secure the meter jaw to the mounting block.
The meter socket base assembly can also include at least one threaded member, at least one spacer and at least one nut. The spacer is preferably cylindrically-shaped and about equal in length to the thickness of recessed portion of the mounting block. The spacer is inserted the opening in one of the recessed portions and then the threaded member is sequentially inserted through the spacer, the aperture in one of the connectors and the aperture in one of the meter jaws. The nut is then threaded onto the threaded member to secure the connector and the meter jaw to the mounting block. Each of the connectors can also include a retaining screw adapted to secure a cable in the cable receiving port. When the retaining screw is tightened to retain a cable in the port, the spacer is adapted to transfer the force created by tightening the retaining screw from the first end of the body to the member on the second end. The member then transfers the force to the indentations or slot in the recessed portion.
Each of the support blocks includes an electrical terminal and has a top, a bottom, a pair of sides, a pair of ends and a coupling mechanism. The electrical terminal on the support block is connected to one of the meter jaws on the mounting block by an electrical conductor, preferably an electrical strap or buss. The support blocks can also include one or more apertures that are adapted for receiving a screw to attach the support block to a surface. The coupling mechanism is adapted to be coupled with one of the coupling mechanisms on the mounting block to attach the support block to the mounting block. The coupling mechanism can include one or more slots and/or apertures in the sides or one or more rails and/or members extending from one of the sides.
The coupling mechanisms on the walls of the mounting block and on the side of the support block are correspondingly located so that the one or more rails on one of the blocks engages the one or more slots on the other block or the one or more members on one of the blocks engages the one or more apertures on the other block. Other types of coupling mechanisms can be used and are within the scope of the invention, including coupling mechanism that slide and/or snap together to couple the support block to the mounting block.
The preferred embodiments of the meter socket assembly of the present invention, as well as other objects, features and advantages of this invention, will be apparent from the accompanying drawings wherein:
The present invention is a meter socket base assembly that can be used with meters, preferably watthour meters, in applications of up to 200 amps. The mounting block portion of the assembly is constructed from a single block, i.e., a “mono-block” that replaces the prior art designs that had two separate mounting blocks connected by a metal bridge. The “mono-block” design requires fewer components, is faster to assemble, and performs better. The “mono-block” and connectors are designed so that the connectors can be installed in two different orientations (45-degrees or 90-degrees) and provide better resistance to the forces applied when the connectors are tightened. In addition, the “mono-block” is constructed from non-electrically conductive materials, preferably a plastic or nylon material, which improves the dielectric insulation.
The mono-block construction can be used for meter socket assemblies designed for applications up to about 200 amps. By constructing the support block of the meter socket assembly as a unitary structure, the mono-block design reduces the number of components and eliminates the need for a steel mounting bridge. As a result, the meter socket assembly has one mounting block instead of two and two screw fasteners instead of eight (for attaching the mounting block(s) and support blocks to a surface). This reduces assembly time. In addition, the connections for the mono-block design are configured so that the line and load connectors are separated by a greater distance from grounded metal parts, which results in a higher dielectric insulation performance.
The mono-block has recessed portions of the surface (also referred to as pockets) that are adapted for receiving the line and load connectors at the four corners on the top surface. These recessed portions (i.e., pockets) have at least one aperture through which a fastening device is inserted for securing the connector and a meter jaw to the mono-block. The dimensions of the pockets are designed so that the connectors can be oriented and installed at angles of either 45- or 90-degrees from the longitudinal axis of the support block. In previous designs, two different types of connectors were required, one for the 45-degree position, and the other for the 90-degree position. The pockets are defined in the top surface of the mono-block by a wall having a plurality of sections. Indentations or slots in the pockets extend along at least two of these wall sections for receiving the lip of a connector, as explained in more detail below.
The meter socket assembly is designed so that the mounting block can be used without support blocks. However, the mono-block design enables the user to easily attach support blocks to the mounting block at any time, even after the mounting block is installed in an enclosure. The user simply loosens the three screws that secure the mounting block to the back wall of an enclosure and slide the support block and mounting block together using the coupling mechanisms. The three screws on the mounting block and a fourth screw on the support block are then tightened to complete the installation. The coupling mechanisms on the mounting block and the support blocks are not attached using screws and, thus, up to four screw fasteners are eliminated from the final assembly.
If an insulated neutral is required for the meter socket assembly, it needs to be mounted in a position not far from the line and load connectors. The mono-block design allows the neutral termination to be installed in the center of the mono-block, in between the line and load connectors. This is the position of the neutral preferred by most end-users. In previous designs, an insulated neutral had to be installed on the side or the top of the block assembly, further away from the line/load connectors.
The connectors and meter jaws are attached to the mono-block using a fastener, preferably a threaded member such as a screw or a bolt and a nut. Prior to installing the fastener, a substantially round spacer is inserted into the aperture in the recessed portion of the mono-block. The spacer is preferably made from a metal such as steel and can be shaped like a washer, a cylinder or a tube with an outer diameter sized to snugly fit into the aperture and an inner diameter sized to snugly receive the fastener. The spacer is designed so that it can freely rotate in the aperture and the fastener can freely rotate inside the spacer. In another embodiment, the spacer can have a cylindrical body with a flanged end. The cylindrical body snugly fits in the aperture and the flanged end has a diameter larger than the diameter of the aperture, which prevents the spacer from passing through the aperture. When a spacer with a flanged end is used, it is installed in the aperture from the back side or bottom of the mono-block. After the spacer is installed, the screw or bolt is inserted through the spacer from the bottom and then through an aperture in the connector and an aperture in the base of the meter jaw. A nut is then threaded onto the screw or bolt and tightened to secure the connector and the meter jaw to the mono-block.
When the retaining screw of the connector is tightened to hold a wire or cable in the connector, the torque applied to tighten the retaining screw is transferred to the body of the connector. As used herein, the term torque refers to the rotational force created along the longitudinal axis of the retaining screw when the screw is tighten to secure a cable in the cable receiving port of a connector. This rotational force is transferred to the body of the connector as a planar force. The design of the spacer permits only axial movement so that the connector pivots on the spacer and threaded member securing the connector to the block and transfers the force to the other end of the connector, which abuts against the side wall and is secured in the indentation or slot in the pocket. The connector for the meter socket assembly also has an extending member, such as a tab, a prong or a lip, which fits into an indentation, preferably a slot, in the mono-block. This provides an increased resistance and absorbs the torque applied to the connectors when the retaining screw is tightened. This design eliminates the need for dimples on the mono-block and holes on the connector so that the connector has a full cross-section, which reduces the increase in the temperature of the connector when it is in operation.
Turning now to the drawings,
The openings 28, 30 at the ends 20, 22 of the side walls 14, 16 are used to secure two pairs of meter jaws 32, 34 to the mounting block 10. The meter jaws 32, 34 are adapted to receive the blade contacts of a meter (not shown). For one pair of meter jaws 32, each meter jaw 32 is connected to a connector 36, which receives a wire or cable (not shown) in a port 38 and then secures the wire or cable in the connector 36 by tightening a retaining screw 40. Each of the other pair of meter jaws 34 is connected to a terminal 42 by an electrical conductor 44.
The side walls 14, 16 have coupling mechanisms 46, 48 formed by a plurality of slots 50, 52, respectively, that extend upwardly from the base 12. As described in more detail below, the coupling mechanisms 46, 48 are used to connect support blocks 54 (
The meter socket assembly 8 also includes a connector 66 for a neutral conductor (not shown). The connector 66 has a terminal 68 for securing a lug or spade-type connector and an aperture 70 for receiving a wire or cable (not shown) and a retaining screw 72 for securing the wire or cable in the connector 66. The neutral conductor is typically used in a 3-wire service.
When a cable is installed in the port of the connector and the retaining screw is tightened, torque resulting from the tightening is transferred to the body of the connector and then to the rectangular spacer 25′ causing it to move in the rectangular hole of the block. The torque created when the retaining screw is tightened is transferred to the body of the connector as a planar force. The planar force F′ on the connector can eventually result in the rectangular spacer shearing the connector from the block. The design shown in
Thus, while there have been described the preferred embodiments of the present invention, those skilled in the art will realize that other embodiments can be made without departing from the spirit of the invention, and it is intended to include all such further modifications and changes as come within the true scope of the claims set forth herein.
Number | Name | Date | Kind |
---|---|---|---|
3764956 | Norden | Oct 1973 | A |
5657200 | Leach et al. | Aug 1997 | A |
7106576 | Schoonover et al. | Sep 2006 | B2 |
7142412 | Witherbee et al. | Nov 2006 | B2 |
7291042 | Johnson | Nov 2007 | B2 |