Abstract:
The invention provides a meter socket assembly for a watt-hour meter with removable and changeable meter jaws. The meter socket assembly comprises a meter base, at least one meter jaw assembly with two optional 5 th  terminal provisions. The assemblies are snapped on to the meter base and locked into the meter base. Any meter jaw assembly in the meter socket device is able to be removed or changed by simply loosening a connection nut and then releasing the meter jaw assembly by pressing a cross locking tab. The meter base, mounted to enclosure of a meter socket device or a meter socket module, is also changeable. The meter socket device is suitable for a meter socket with line and load busing connections, especially modular metering devices.

Description:
FIELD 
     This invention relates to a watt-hour meter socket device or modular (group) metering devices. In particular, this invention relates to a meter socket assembly having an interchangeable meter jaw assembly for use with a watt-hour meter. 
     BACKGROUND 
     Socket type electrical watt-hour meters are used to measure and indicate the amount of electrical power consumption in a residence, industry or business. Typically, a socket type watt-hour meter plugs into a meter socket using a blade-like stab or meter blade connector located on the watt-hour meter. The meter socket itself is mounted inside a meter base or a panel. A meter socket commonly has a spring loaded receptacle-like jaw to receive and contact the watt-hour meter blade insertion. The meter jaw and spring provide enough force to press meter blade and conduct electricity while maintaining a certain current load and a heat rise. 
     The line side of a meter socket is connected to the utility electrical power source, while the load side of a meter socket is connected to the tenant. A watt-hour meter is inserted onto the meter jaws on a meter socket to bridge the line and load making the electrical connection between the utility power source and the tenant. In the industry, spring tempered copper meter jaws are mounted on meter sockets to receive plug-in watt-hour meters. Due to limited spacing and special application, the meter jaws carry high current density and have less contact surface area. Therefore, the contact surface may be weak for electrical connection between a meter jaw and a watt-hour meter blade, a meter jaw and its mount connector, and a meter jaw itself. This is evident in modular metering devices, which have heavier line and load buses and stronger bounding bus connections. Such weak positions with electrical connection make the components of meter jaw assemblies prone to damage during a power surge or electrical interruption. From a time saving perspective, it would be more beneficial to be able to change an individual front removable and replaceable meter jaw assembly on a meter socket or even replace a whole meter socket in modular metering devices whenever a meter jaw assembly or a meter socket is damaged, rather than replacing the whole meter box device. 
     Meter jaw alignment is another factor that affects meter socket performance conducting electricity. Meter jaw misalignment is caused by tolerance built-up in multiple components in fabrication and during the assembly process. In the field, meter jaw misalignment may cause service and reliability issues. A meter socket with misaligned meter jaws or meter jaw assemblies make installing a watt-hour meter more difficult. There will be connection issues for conduction of electricity. For example, a twisted, deformed or even damaged meter jaw may cause extensive heat on meter jaws. 
     Therefore there is a need for improvement in meter sockets and in particular meter jaw assemblies. 
     There is also a need to provide a robust meter socket base to assist precise meter jaw alignment with their mounting plates. 
     OBJECT 
     In accordance with this invention, a meter socket device for an electrical meter box comprising: a meter socket base; and at least one interchangeable meter jaw assembly wherein the meter jaw assembly locks into the meter socket base fastenerless. 
     In accordance with another aspect of this invention, an interchangeable meter jaw assembly for an electrical meter box comprising: a mounting plate; a meter jaw for contacting a meter blade of a watt hour meter fastened to the mounting plate; and an insulating guide attached to the meter jaw for protection from contact. In accordance with another aspect of this invention, A method of retaining at least one interchangeable meter jaw assembly on a meter socket base in an electrical meter box, the steps comprising: providing an interchangeable meter jaw assembly; providing a meter socket base with at least one receiving slot wherein the receiving slot includes means for receiving and locking the interchangeable meter jaw assembly fastenerless; sliding the interchangeable meter jaw assembly to stop position; and fastening the mounting plate to an electric connect. 
     In accordance with another aspect of this invention, a method of interchanging meter jaws, the steps comprising: loosening a fastener of a mounting plate; pressing a cross locking tab; and sliding a meter jaw assembly out. In accordance with another aspect of this invention, A method of meter jaw alignment in an electrical meter box, the steps comprising: providing a meter jaw; providing a meter jaw mounting plate; affixing meter jaw to meter jaw mounting plate; affixing meter jaw mounting plate to a meter socket base; providing a mounting plate wherein the mounting plate is shaped to be locked in position for supported meter jaw and keeping jaw alignment; and providing mounting plate with means for centering. One objects of this invention is to provide a robust meter socket with individually front removable and replaceable meter jaw assemblies and 5 th  terminal provision. Another of the objects is to provide a meter socket base on which meter jaw assemblies are able to be easily replaced and retained. 
     A further object is to provide a meter socket with built in features for precise meter jaw alignment. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a meter socket device with front removable meter jaw assemblies. 
         FIG. 2  is a perspective view of an alternative configuration of the meter socket device with front removable jaw assemblies and horn by-pass. 
         FIG. 3  is a front view of a modular metering device with the meter socket device installed. 
         FIG. 4   a ) is an enlarged view of an insulating meter jaw guide. 
         FIG. 4   b ) is an enlarged view of a detached meter jaw assembly with mounting plate. 
         FIG. 5  is a perspective view of the meter jaw mounting plate. 
         FIG. 6  is a perspective view of the meter socket base. 
         FIG. 7  is a perspective view of the receiving slot on the meter socket base. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a meter socket device  10  as described in this invention. The meter socket device  10  comprises a meter socket base  100 , a pair of line meter jaw assemblies  200  and  200 ′, a pair of load meter jaw assemblies  300  and  300 ′, and an optional 5 th  terminal assembly  500 . The line meter jaw assemblies  200  and  200 ′ and the load meter jaw assemblies  300  and  300 ′ are collectively called the meter jaw assemblies  400 . The meter jaw assemblies  400  are installed and removed from the meter socket base  100  by simply releasing the cross locking tab  600  shown in  FIG. 7  located on the meter socket base  100 . The cross locking tab  600  fastens and holds the end of the meter jaw mounting plate  800  of the meter jaw assemblies  400 . This will be described further in  FIG. 6 . 
       FIG. 2  shows an alternative embodiment of meter socket assembly  10  with a horn by-pass installed. The horn by-passes are installed on load meter jaw assemblies  300 H and  300 H′, while the horn by-passes are installed separately on the meter jaw mounting plates  800  of the line jaw assemblies  200  and  200 ′ of the meter socket assembly. The line and load horn by-passes, optional for ringless type metering devices, are connect to a manual by-pass cable which wilt by-pass a watt-hour meter. A horn by pass is used in cases where electrical power has to be supplied continuously when the watt-hour meter is to be removed for maintenances or upgrades, for example, an emergency room or a situation where medical conditions demand continuous electrical power. 
       FIG. 3  shows a ring type modular metering device  1000  that has the meter socket assemblies  10  installed. The meter socket assemblies  10  are mounted inside the enclosure  1020  and covered by meter covers  1010 , while the center of the meter cover align with the center of the meter socket device  10  so that a watt-hour meter (not shown but standard in the art) may be installed onto the meter socket assembly  10  through a meter cover opening. The meter cover  1010  and protective cardboard cover  1100  were blanked in order to see the interior components. The meter socket assembly  10  is mounted to the enclosure  1020  on a pair of mounting brackets  1030  with fasteners  1040 . The line meter jaw assembly  200  and  200 ′ is connected to a riser bus  1200  and  1200 ′. The riser bus  1200  and  1200 ′ links to the line electrical power, through the line strap  1300  and  1300 ″ joined with a fastener  1400 . The load meter jaw assembly  300  and  300 ′ is connected to load strap (not shown but standard in the art), which leads to load tenant, by a fastener  1400 . Therefore, whenever a line meter jaw assembly  200  and  200 ′ or a load meter jaw assembly  300  and  300 ′ needs to be replaced, only one fastener  1400  needs to be loosened to retrieve the line meter jaw assembly  200  and  200 ′ or the load meter jaw assembly  300  and  300 ′. Once a new line meter jaw assembly  200  and  200 ′ or a load meter jaw assembly  300  and  300 ′ has been installed, the appropriate fastener  1400  must be tightened to a specified torque to complete installation. 
       FIG. 4   a ) is an enlarged view of an insulating meter jaw guide  1600  that may be fastened onto either the line meter jaw assembly  200  and  200 ′ or the load meter jaw assembly  300  and  300 ′ to provide protection from accidental contact. 
       FIG. 4   b ) shows an enlarged view of a line meter jaw assembly  200  and  200 ′ or a load meter jaw assembly  300  and  300 ′. The meter jaw  1700 , the metal meter jaw spring guide  700  and the meter jaw mounting plate  800  are assembled together with a fastener from the bottom of the meter jaw mounting plate  800  (not shown due to the orientation of the view). The special shape of the meter jaw mounting plate  800  is designed to fit in the meter socket base  100  and to be locked in position for supporting meter jaw  1700  and keeping jaw alignment. 
       FIG. 5  shows the detail of the meter jaw mounting plate  800 . In the line meter jaw assembly  200  and  200 ′ or the load meter jaw assembly  300  and  300 ′, a meter jaw  1700  stands on the top surface  810  of the meter jaw mounting plate  800  and is mounted through the aperture  820 . The halfshear (or emboss)  830  on the top surface  810  fits into a slot at the bottom of a meter jaw  1700  to guide the center line of the meter jaw  1700  aligning it with the center line of the meter jaw mounting plate  800 . The first side slots  840  and  840 ′ and the second side slots  850  and  850 ′ are precisely fabricated to fit in the holding pads  2200  shown in  FIG. 7  and mate with the side guide features  2400  in order to control the alignment of either the line meter jaw assembly  200  and  200 ′ or the load meter jaw assembly  300  and  300 ′. The first extended fins  860  and  860 ′ and the second extended fins  870  and  870 ′ inserted into the holding slots  2500  in  FIG. 7  of a meter jaw pocket  2100  (see  FIG. 6 ). The first end surfaces  880  and  880 ′ and second end surfaces  890  and  890 ′ of the first and second extended fins  860  and  860 ′;  870  and  870 ′ respectively are directly against the close ends  2600  of the meter jaw assembly holding slots  2500  (shown in  FIG. 7 ) when one of meter jaw assemblies  400  is installed. The cross locking tab  600  in  FIG. 7  will lock the end surface  900  of the meter jaw mounting plate  800 . The open “U” shaped slot  910  is to receive a fastener  1400  as shown in  FIG. 3  from the connection bus to build electrical connection, and allows one of the meter jaw assemblies  400  to slide off from the opening end of the slot  910  by loosening the fastener  1400  whenever one of meter jaw assemblies  400  needs to be replaced. 
       FIG. 6  shows the meter socket base  100 . The mounting area  1800  surrounded by barreling wall  1900  mount to enclosure  1020  and ring type meter covers  1010  in  FIG. 3  or ringless meter support bracket (not shown). Four mounting holes  2000  are provided for robust and firm joint to withstand the force of the insertion and extraction of a watt-hour meter. There are four receiving slots  2100  for receiving line meter jaw assemblies  200  and  200 ′ or load meter jaw assemblies  300  and  300 ′ in a meter socket assembly  10 . Six o&#39;clock position 5 th  terminal  2100  and nine o&#39;clock position 5 th  terminal  2200  provisions are provided for alternative 5 th  terminal connection. 
       FIG. 7  shows a detailed view of receiving slot  2100  for one of meter jaw assemblies  400 . When installing one of meter jaw assemblies  400  to the meter socket base  100 , one of meter jaw assemblies  400  is fitted in between the holding pads  2200  and laid on the sliding platform  2300  and  2300 ′ with the guiding features  2400  directly against the first and second slots  840  and  840 ′;  850  and  850 ′ on the meter jaw mounting plate  800 . The tolerance between the guiding features  2400  is tight so that the clearances between the guiding features  2400  and the first and second slots  840  and  840 ′;  850  and  850 ′ on the meter jaw mounting plate  800  are precisely controlled. This enables one of the meter jaw assemblies  400  to slide by and prevents a meter jaw assembly  400  from rattling. While the cross locking tab  600  is pressed down, a meter jaw assembly  400  may slide in under the holding pads  2200  and against the close end  2600 . The end surface  900  of the meter law mounting plate  800  passes the cross locking tab  600 , then the cross locking tab  600  rebounds back and blocks on the end surface  900  of a meter jaw assembly  400  from moving back. The cross locking tab  600  includes three portions: the flex link  610 , the locking pad  620 , and the extension  640 . The flex link  610 , rooted on the back side of the sliding platform  112  and  112 ′, is a thin strip of a diagonal bridge  630  and  2300  that extends to the middle of the receiving slot  2100 . The top surface of the locking pad  620  is above the surface of the sliding platform  2300  and  2300 ′ to block the end surface  900  of the meter jaw mounting plate  800  when a meter jaw assembly  400  is installed. The slot  630  on the locking pad  620  allows a screw driver or the like to press down on the cross locking tab  600  for releasing an assembled meter jaw assembly  400 . The extension  640  paired with stop tab  2900  is a protection feature that prevents the cross locking tab  600  from over travel and damage when the locking pad  620  is pressed to release an installed meter jaw assembly  400 . Between the end walls  2700  and the top of the supporting link  2800 , the open receiving slot is to clear the sliding path for installing and removing a meter jaw assembly  400 . The supporting link  2800  also links the opening end of the open receiving slot to strengthen the meter socket base  100 . 
     While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the true spirit and scope of the present invention.