Abstract:
A meter adapter in the form of a collar interposed between meter and associated socket, provides a smooth curved jaw configuration for meter terminal blades, and branch fuse safety features.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to adapters to meters that, among other capabilities, measure common resources, especially electrical energy. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are meters that, among other capabilities, measure common resources (herein, meant to include consumption of commodities like electrical energy, water, and gas). Standard meters, as understood in the electrical utilities business in the United States, Canada and herein, are those that conform to ANSI standard C12.10. This standard and others (and counterparts in jurisdictions around .the world) dictate a host of restrictions, including the physical envelope or form factor, the dimensions, locations and materials for power pins, the permissible types of electrical connections with the meter, and similar items, for a one or multi-phase electricity measuring meter. These standards try to maximize safety and inter-compatibility of meters from different manufacturers. This ANSI standard in effect, prohibits or strongly discourages any electrical connection between the meter and anything else except for the power pins and grounds. 
         [0003]    To make a standard meter a useful part of a network, it is desirable to provide it with extra functionality and ideally, to so provide by means of an easily releasably attachable adapter, and in particular herein, a collar with superior (mechanical and electrical) interconnection and safety (e.g. fuse) capabilities. It is also desirable to minimize the overall physical “footprint” of the collar (while still conforming to safety standards) and yet be large enough to house the desired extra functionality. The present invention addresses those objectives. And although the embodiment of the present invention described below is with reference to a standard electrical meter, certain aspects of it are not thereby restricted thereto, and are applicable to meters that measure other resources (such as water and gas). 
         [0004]    The current art has complexities and associated disadvantages. Typical is U.S. Pat. No. 5,762,522 that shows a fuse and mechanical contact clip which is complex (in requiring a plurality of parts, including rivets and several angled portions). The present invention addresses the complexities with a simpler approach. 
         [0005]    For a metered premise (house or commercial/industrial venue), the branch circuits and associated safety management (e.g. fuses) are conventionally on the load side of the meter (i.e. the part of the meter that is associated with the load side terminals, and which the utility uses to measure consumption or other attribute of electricity by the load side circuit, and is governed by a utilities regulatory regime, as distinct from a safety standards regime). Thus, for example, fuse/circuit breaker panels (and associated branch circuits to various in-house loads) are found typically inside the house and are (at least) electrically downstream from the line side of the meter, i.e. they tap the load side terminals. 
         [0006]    For evolving applications and needs (e.g. for “smart grid” meters, as exemplified in U.S. Pat. No. 7,019,666), there are advantages to create and supply “branch circuits” on the line side of the meter (i.e. the part of the meter that is associated with the line side terminals, and that is not measured by the utility for consumption of electricity, and is governed by a safety and related regulatory regime (like the National Electric Code or equivalent), as distinct from a utilities regulatory regime). 
         [0007]    Previous attempts (for examples, U.S. Pat. Nos. 7,182,632 and 7,040,920) promised added functionality to the meter collar using the line side of the meter without address the consequent issues. For such extra functionality, the present invention addresses such issues, including those related to safety. 
       SUMMARY OF THE INVENTION 
       [0008]    There is provided a collar adapter for a utility meter and its associated meter socket, which has terminals for the line side and terminals for the load side, comprising: (a) a first power pin for receiving first terminal blade of the meter; (b) said first power pin is connectable to first line side terminal of the meter socket; (c) a first branch fuse, attached to said line side power pin, that is in electrical parallel relationship thereto and that runs to a branch load circuit. 
         [0009]    There is also provided a collar adapter for a utility meter and its associated meter socket, which has terminals for the line side and terminals for the load side, comprising: (a) a power pin that has two opposed jaws for receiving one terminal blade of the meter; and (b) a C-shaped ring spring that biases said jaws towards each other. 
         [0010]    Within the physical frame of a meter collar, the present invention provides the operator of the meter (for example, the utility) the opportunity to conveniently and safely use the line side terminals to power new functionality of a branch load. Because the use is located within the collar, advantages and conveniences are provided, including the fact that the customer will not be billed for any use of electricity for that new functionality. Although current safety regulations are not yet formalized on the line side, the present invention satisfies load side regulations as if notionally transposed to the line side. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which: 
           [0012]      FIG. 1  is a perspective view of the collar in relationship with the meter and meter socket; 
           [0013]      FIG. 2  is a detailed perspective view of the collar; 
           [0014]      FIG. 3  is a partially broken back perspective view of the branch fuse in the collar; 
           [0015]      FIG. 4  is a partially broken front perspective view of the branch fuse in the collar; 
           [0016]      FIG. 5  is a back perspective view of the power pin and branch fuse; 
           [0017]      FIG. 6  is a more detailed side of the jaw portion of  FIG. 5 ; 
           [0018]      FIG. 7  is a perspective view of the ring spring; 
           [0019]      FIG. 8  is a diagram of the forces on the jaw finger on installation; and 
           [0020]      FIG. 9  is a graph of a model curve for the jaw finger. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    As shown in  FIGS. 1-5 , collar  105  is interposed (mechanically and electrically) between utility meter  10  and its associated meter socket  20 . 
         [0022]    The mechanical interposition is achieved partially by conventional mechanisms (including fastening mechanisms and mating of respective perimeter profiles and mounting surfaces) and partially by improved mechanisms (described below). The electrical agency between meter  10  and meter socket  20  is provided by the use of four identical power pins  109 , snugly fitted into collar mounting slots  121  and  122  (for the meter load line terminals) and into collar mounting slots  123  and  124  (for the meter line side terminals). 
         [0023]    As shown in  FIG. 5 , attached to power pin  109  (for a line side terminal), is branch fuse holder  400  that fixedly holds fuse  410 . Holder  400  has conductive friction grips  401  to attach (electrically and mechanically) holder  400  to power pin  109  associated with a line side terminal; first and second fuse holder brackets  402  and  403  that releasably hold fuse  410  by conventional snap spring mechanisms; and electric terminal  404  depending from second bracket  403  and intended for electric connection to a load circuit (being a branch load or circuit on the meter line side, not shown). Fuse  410  is in electrical parallel relationship with power pin  109  (for a line side terminal). 
         [0024]    In  FIG. 4 , collar mounting slot  123  has been partially broken away to show branch fuse holder  400  and grips  401  partially inserted therein. The walls of slot  124  are profiled to receive grips  401  in a removably insertable relationship while providing a snug fit therewith. 
         [0025]    As shown in  FIGS. 5-7 , power pin  109  has jaw  110  and blade terminal  111 . Jaw  110  includes two, opposed clips or fingers  1091  and  1092 , and ring spring  112  to keep those fingers in opposition and resistant to their separation. Ring spring  112  is shown only in  FIGS. 6-7  for simplicity of illustration in other drawings. Power pin fingers  1091  and  1092  are identical and are orientated in opposition as shown and are further described below. 
         [0026]    Ring spring  112 , as shown in  FIGS. 6-7 , has two opposed, identical protruding tabs  1131  and  1132 . Jaw fingers  1091  and  1092  have respectively apertures  1141  and  1142  that respectively accepts insertion of ring spring tabs  1131  and  1132 . 
         [0027]    Once tabs  1131  and  1132  are inserted in their respective associated apertures  1141  and  1142 , they remain there, and ring spring  112  then biases opposed fingers  1091  and  1092  toward each other to resist separation in the “installed state” of meter  10 . (i.e. when meter  10 , and in particular its meter blades  11 ,  12 ,  13  and  14 , are inserted into collar  105 , and in particular, its power pins  109 ). 
         [0028]    In “installed state”, jaw  110  of each power pin  109  (and in particular, fingers  1091  and  1092  thereof) releasably or removably receives therebetween a meter power blade (one of blades  11 ,  12  associated with meter line side terminals, or one of blades  13  and  14  associated with meter load side terminals); and blade terminal  111  of each power pin  109  is inserted into the corresponding socket of meter socket  20 ; thereby creating electrical agency between meter  10  and meter socket  20 . In “installed state”, ring spring  112  force fingers  1091  and  1092  towards each other to enhance the sandwich grip thereby on meter power blades  11 ,  12 ,  13  or  14 . 
         [0029]    When meter  10  is not inserted into collar  105  (the “uninstalled state”), although ring spring  112  contacts fingers  1091  and  1092  at tabs  1131  in apertures  1141  and  1142 , they apply no or very little force on fingers  1091  and  1092 . 
         [0030]    Conventional jaws are completely planar or have a hard angle that becomes the edge of contact with the installed meter blade. In contrast, power pin jaw finger  1091  is smoothly curved. The curve is modeled on the behaviour of three locations thereof,  1091   a ,  1091   b  and  1091   c , in response to the installation of meter  10  into collar  105  (i.e. the insertion of a meter blade into power pin jaw  110 ), as explained below. 
         [0031]      FIG. 8  shows (but not to scale) the approximate forces acting on a collar jaw as a meter blade is inserted therein.  FIG. 8  has a frame of reference for a typical application (e.g. meter  10 -collar  105 -meter socket  20  combination is horizontally orientated relative to the vertical outside wall of a house), where meter blade  11  is inserted horizontally from the right, leftwardly into jaw  110 , and thereby creating a vertically upward displacement of jaw finger  1091  (i.e. vertical separation between jaw fingers  1091  and  1092 ) because the resulting force F is vertically upwards. Because of the symmetries, only finger  1091  is shown and explained below (because the force diagram for opposed finger  1092  is identical to that of finger  1091  and merely orientated vertically downward instead). 
         [0032]    As seen in  FIG. 8 , location  1091   a  is approximately where jaw finger  1091  begins to curve and where ring spring tab  1131  is in jaw finger aperture  1141  (as explained below), i.e. is about where ring spring  112  directly acts on jaw finger  1091 . Edge  1091   b  is the edge of contact between the leading, terminal edge of meter blade  11  and jaw finger  1091 . Crest  1091   c  is the location representing the effective end of the curve (for modeling purposes). The curvature of finger  1091  is set by requiring a force F (created by the insertion of meter blade  11  into jaw finger  1091 ) to be maximum and uniform across the contact surface, acting vertically on jaw finger  1091 , as seen at these three locations of jaw finger  1091 , i.e. “spring location”  1091   a,  “leading edge”  1091   b  and “jaw crest”  1091   c.  The vertical displacement of a point on the (jaw finger model) curve (represented by “x” on the horizontal axis being the axis of insertion of meter blade  11 ) is modelled by force factors and vertical displacements at these three locations. Such a force F creates advantageous (mechanical and electrical) interaction between meter  10  and collar  105 . 
         [0033]    First, the vertical displacement of “spring location”  1091   a  (employing a rigid beam model of jaw finger  1091 ), is approximated by: 
         [0000]      Δ a =( F ·(Lac−x)/Lac)/Ka
 
         [0034]    where x=0 corresponds to spring location  1091   a;  Ka=approximated effect of the (inward) remainder of jaw at  1091   a  represented by a spring stiffness thereat; and Lac=horizontal distance between “spring location”  1091   a  and “jaw crest”  1091   c.    
         [0035]    Next, the vertical displacement of “jaw crest” position  1091   c  is due to the force felt at that position (assuming a rigid beam model), and is approximated as: 
         [0000]    Δ c =( F ·x/Lac)/Kc where Kc=approximated effect of the (outward) remainder of jaw at  1091   c  represented by a spring stiffness thereat; E=modulus of elasticity of copper; and I=the area moment of the cross-section of the meter blade profile=w·t 3 /12, where w=width of meter blade and t=half of the thickness of the meter blade (as applicable to interaction with jaw finger  1091 ). 
         [0036]    Due to these above factors, the total vertical displacement of “leading edge” position  1091   b  (employing a rigid beam model of jaw finger  1091 ), is approximated by: 
         [0000]      Δ b (rigid)=Δ c ·(x/Lac)+Δa·(L-x)/Lac
 
         [0037]    Next, employing an elastic beam model of jaw finger  1091  with fixed ends at  1091   a  and  1091   c,  the vertical displacement of “leading edge”  1091   b  is approximated as; 
         [0000]      Δ b (elastic)=( F·x   2 ·(Lac- x ) 2 )/(3 ·l·Lac)  
 
         [0038]    Thus the total vertical displacement of “leading edge”  1091   b  at position (x) is 
         [0000]        L ( x )=Δ b (rigid)+Δ Ab (elastic).
 
         [0039]    Jaw finger  1091  is advantageously formed to have a curve in accordance with preceding formula. The preceding explanation applies identically to jaw finger  1092  and meter blades identical to meter blade  11 . 
         [0040]    An example of the model formula is show in  FIG. 9 , wherein t=50 mil; w=755 mil; Ka=5 Lbf/mil; Kc=3 Lbf/mil. 
         [0041]    In uninstalled state, the separation between fingers  1091  and  1092  is about  57  mils; and in installed state, the separation is in the order of 100 mils. 
         [0042]    Examples of details of the practising of the present invention, include the following. Ring spring  112  metal is  302  or  301  stainless steel with minimum yield strength of 150000 psi. Fuse  410  is a common, high interrupt amperage capability. Power pin  109  is made of hard copper with tin plating. Fuse holder  400  is made of phosphor bronze and can be made integrally by suitable bending of a single sheet of such metal. Collar  105  may be formed of polycarbonate plastic or any other material having similar physical properties, such as those related to robustness, rigidity, temperature sensitivity, and electrical insulation. Ring spring  112  can be made of a single metal sheet of appropriate tensile and other properties, that can be cut and bent cylindrically to create opposed tabs  1131  and  1132  that are alignably insertable into corresponding apertures  1141  and  1142  of fingers  1091  and  1092  respectively. 
         [0043]    Fingers  1091  and  1092  of power pin  109  are identical and are orientated in opposition as shown in the drawings. They may be made of a single sheet bent at the point corresponding to the jaw terminal  110  (to obviate the need of a fastener thereto). If fingers  1091  and  1092  are made discretely, they may be conventionally fastened rigidly (e.g. rivets). 
         [0044]    Although a cylindrical ring spring  112  is disclosed, other generally C-shaped shapes are possible, each with respective advantages and disadvantages. For example, a V-shaped spring is possible. 
         [0045]    The branch circuit may be within (entirely or partially) within collar  105  or connect to loads (i.e. devices) applicable in the factory, house or other venues. Examples of branch loads include those related to auxiliary power supply, data modem (for examples, for Internet Protocol based communications and Wide Area Networks and Local Area Networks (both wireless and wired embodiments), and external VOIP supervisory circuitry. Some branch loads may be manifested in compact form and be insertable (entirely or partially) within collar  105  and directly contact branch fuse terminal  404  (as shown). An example is the “adapter assembly” of U.S. Pat. No. 7,040,920, which may, for example, house an auxiliary backup battery pack. 
         [0046]    But also, some branch loads may be physically remote from collar  105  but electrically connected to branch fuse terminals  404 . 
         [0047]    Although branch fuse holder  400  has been shown and explained for a line side power pin, it can be used for a load line power pin, with fuse  410  appropriate for the applicable branch circuit load. 
         [0048]    Also, although two branch fuse holders  400  have been shown, one will suffice for some applications and this invention does not require two. However, depending on the particular application and risk management concerns, the advantages of redundancy of two branch fuses are justified—in addition to redundancy, fuse  410  for both line side terminals (as shown in  FIG. 2 ) will protect against electric faults in the power line occurring on both sides of meter  10 . 
         [0049]    Although fuse holder  400  has been shown with conductive friction grips  401  to attach (electrically and mechanically) holder  400  to power pin  109 , other fuse holders and conductive attachments are contemplated as physically residing within collar  105 , in particular, and electrically on the load line side of meter  10 , more generally. 
         [0050]    Although the embodiment described relates to a standard electrical power meter conforming to Form 2S, this invention is applicable to other standard meters (such as Form 3S and 4S) where only obvious modifications are necessary to accommodate a different socket/power pin arrangement. Also, it is understood by those in the art that this ANSI standard is unlikely to be modified substantially in the future but if it is modified slightly, it will be readily apparent to those in the art that this invention may be easily adjusted accordingly to fit the amended envelope or form factor. It would be a matter of simple design to accommodate different form factors (i.e. geometry of and number of sockets) and different types of meters (e.g. single-phase or multi-phase). 
         [0051]    Although the method and apparatus of the present invention has been described in connection with the preferred embodiment, it is not intended to be limited to the specific form set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as can be reasonably included within the spirit and scope of the invention as defined by the appended claims. All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood.