US 3714615 A
Description (OCR text may contain errors)
D United States Patent 11 1 [111 3,714,615 Coley A 1 1 Jan. 30, 1973 54 DETACHABLE METER MOUNTING R25,184 6/1962 McAdam .339 112 R x  Inventor: Kenneth R. Coley, Fairfield, Conn. 2: 2" i  Assignee: Westinghouse Electric Corporation, 2,704,838 3/1955 Macha et al ..339/259 F Pittsburgh, Pa. Primary Examiner-Richard E. Moore 22 Fl d. F b. 1,197] l 1 e 1 e Attorney-A. T. Stratton and C. L. Freedman  Appl. No.: 111,546
 ABSTRACT  U.S. Cl. ..339/112 R, 339/259 F A meter mounting is provided with Contact jaws which  Illt. Cl. .1101! 13/12 are mounted on a tharmallrconductive terminal  Flam of Search "339/111 272 UC bracket. The contact jaws are electrically insulated from the terminal bracket by means of a sheet of insu-  References cued lation which has good thermally-conductive proper- UNITED STATES PATENTS ties- 2,935,666 5/1960 VanNamen, Jr ..339/112 R X 9 Claims, 4 Drawing Figures r1 I5 I Y I 0 13 was 3| j .l l 29b 36 l I \37 Patented Jan. 30, 1973 2 Sheets-Sheet l FIG.|.
WITNESSES M V Re 0 O T C mR V Nh t DETACI-IABLE METER MOUNTING BACKGROUND OF THE INVENTION l Field of the Invention:
The invention relates to releasable electrical connection assemblies and it has particular relation to mountings for detachable electric meters.
The invention is applicable to electrical connections wherein contact blades are received in contact jaws. The invention is particularly suitable for detachable electric meters which have contact blades releasably received in contact jaws of a meter mounting and will be described as applied to a meter mounting for a detachable watthour meter.
2. DESCRIPTION OF THE PRIOR ART A detachable watthour meter has terminals in the form of short rigid copper contact blades extending outward from the back of the meter. The connection of the contact blades to line and load wires is effected through a mounting device in the form of a meter socket. The socket has contact jaws for detachably receiving contact blades of the meter and connectors for line and load conductors.
Watthour meters and mounting devices capable of carrying large currents such as 200 amperes are available. Apparatus of this type is described in the Electrical Metermens Handbook, 7th Edition published 1965 by the Edison Electric Institute, New York City.
' Difficulties have been encountered in providing adequate dissipation of heat generated in mounting devices, particularly those designed for large currents. This is recognized in the following excerpt from page 378 of the aforesaid Handbook:
With the growth of domestic loads and the development of self-contained Class 200 meters, the heavyduty socket also rated at 200 amp has been introduced. There are two types of such heavy-duty sockets. In one the jaws are made of massive material and sometimes have only one flexible member. This may be spring loaded but will still depend on jaw resiliency for good contacts. In the other type the jaws are made of nonflexible heavy material and the jaws are wrench tightened or lever tightened after the meter is in place. Either type of jaw can carry 200 amp continuously without excessive heating.
The first type of heavy-duty socket is illustrated in U.S. Pat. No. 2,709,793 which issued May 31, 1955. This patent discusses the provision of jaws of massive construction having large cross sections. The second type is illustrated in U.S. Pat. No. 2,782,387 which issued Feb. 19, I957. The latter patent also discussed the removal of heat from the inside of the meter by head conduction through the terminal blade and through the aws.
As previously pointed out the dissipation of heat from the meter and the meter connection creates a problem which is particularly acute for large capacity meters. The problem is even more acute for apparatus which is subjected to high ambient temperatures such as those encountered in the southwestern portion of the United States.
The provision of meter mountings having heavy bus bars, socket jaws and lugs mounted on heavy bases constructed of a phenolic resin or porcelain represents an attempt to solve the problem by a heavy, bulky and costly construction.
I SUMMARY OF THE INVENTION In accordance with the invention a meter mounting is provided with contact jaws which are held insulated from a supporting thermally-conductive bracket by insulating material having adequate electrical insulation properties and having good thermal or heat conductivity. This permits a bracket to assist in conducting and dissipating heat from the contacts jaws. Furthermore, if the bracket is secured directly to thermally-conductive portions of a mounting enclosure the mounting enclosure itself assists in the dissipation of the heat. This construction permits a material reduction in size, weight and cost of meter mounting components.
BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention reference may be had to the preferred embodiment exemplary of the invention shown in the accompanying drawings in which:
FIG. 1 is a view in front elevation with parts broken away of a meter mounting embodying the invention;
FIG. 2 is a view in side elevation with parts broken away of the meter mounting shown in FIG. 1;
FIG. 3 is a view in side elevation ofa contactjaw subassembly employed in the meter mounting of FIGS. 1 and 2 and FIG. 4 is a view in end elevation of the subassembly shown in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, FIGS. 1 and 2 show a meter-mounting assembly 1 which may be in the form ofa customary box or trough. The assembly includes an enclosure defined by walls such as a rear wall 3, side walls 5 and a cover 7 which are generally constructed of a material which is a good thermal or heat conductor such as sheet steel. The cover generally is readily removable from the remainder of the enclosure for the purpose of providing access to components located within the enclosure.
The meter-mounting assembly may be of the ring or ringless'type. For illustrative purposes it will be assumed that the meter-mounting assembly is of the ring type. To this end the cover 7 is provided with a circular opening surrounded by a flange or rim 9 which is designed to abut a base rim of a watthour meter 11 of the detachable type. A sealing ring 13 is shown for sealing the meter 11 to a metermounting assembly in a conventionalmanner.
Terminals in the form of conventional contact blades 15 project rearwardly from the meter 11. The number of contact blades depends upon the type of meter. For present purposes it will be assumed that the meter 11 has four planar contact blades 15. Four contact jaws 17, 19, 21 and 23 are provided in the meter mounting assembly for releasably receiving the four contact blades 15. The contact jaws l7 and 19 form parts of a subassembly 25. The contact jaws 21 and 23 form parts of a similarsubassembly 27. Inasmuch as these subassemblies are similar in construction a discussion of the subassembly 25 will suffice forboth subassemblies.
The contact jaw 19 includes a contact terminal 29 which may be constructed of a suitable electroconductive material such as copper, bronze or beryllium copper. The contact terminal 29 has a planar part 29a positioned to engage a contact blade when the meter is in mounted position. The contact terminal has a portion29b projecting at right angles from the plane of the portion 29a. The portion 29b has one or more threaded openings 290 for threaded reception of machine screws which are employed for electroconductively connecting straps such as the straps 30a and 30b shown in FIGS. 1 and 2 to the contact terminal.
The contact jaw 19 also has a contact plate 31 which may be constructed of material similar to that employed for the contact terminal 29. This contact plate has its upper portion as viewed in FIG. 4 spaced from the contact terminal 29 to complete a jaw for reception of the associated contact blade 15. The upper ends of the contact terminal 29 and the contact plate 31 may be flared away from the contact blade 15 for the purpose of facilitating entry of the contact blade 15 into the contact jaw.
The contact jaw 19 is mounted on a terminal bracket 33 which is constructed of a thermally-conductive material such as sheet steel. The terminal bracket has an upper portion 33a as viewed in FIG. 4 which extends parallel to the plane of th e portion 29a of the contact terminal 29. These two portions are spaced from each other by an insulation shield 35. This shield provides adequate electric insulation between the two portions but is designed to provide good thermal or heat conductivity between the two portions. Desirably the shield may be constructed of a sheet of phenolic resin material having a thickness less than one-sixteenth of an inch. Excellent results have been obtained from a sheet having a thickness of 0.032 inch.
As pointed out in the AEIC-EEI-NEMA standards for Watthour- Meter Sockets, EEI Pub. No. MSJ-7 1968, a report. of three sponsors including the Edison Electric Institute of New York City, meter sockets are conventionally designed for nominal voltages in the range 120 to 600 volts. Insulation tests are specified in Section 4.05 of Pub. No. MSJ-7.
The contact terminal 29 is secured to the contact plate 31 by two rivets 36 which pass snugly through openings provided in the terminal and plate. The rivets also pass snugly through openings provided in the shield 35 and areinsulated from the terminal bracket 33 by means of an insulator 37.
The insulator 37 has holes through which the rivets .36 snugly extend. The insulator 37 also has a generally rectangular neck 39 which extends snugly through a generally rectangular opening in the terminal bracket 33 and which has holes through which the rivets 36 snugly extend. The neck 39 has a length which is slightly larger'than the thickness of the terminal bracket 33 to assure firm engagement between the end of the neck 39 and the shield 35. Consequently when assembly 1. In the illustrated embodiment, the foot is secured to a metal, heat-conductive pedestal 42 which is mounted on the rear wall 3.
It will be noted that the contact jaw 17 is similarly constructed and mounted on the same terminal bracket 33. The shield 35 is common to the two contact jaws.
As shown in FIG. 3 the terminal bracket 33 is shorter than the shield 35 except for a central section 33d which projects flush with-the upper edge of the shield 35. The shield guards the corners of the terminal bracket 33. The terminal bracket provides a large body for transmitting and dissipating heat from the two contact jaws.
Each of the contact jaws may be provided with a back-up spring for increasing the contact pressure.
in the contact plate31 to prevent rotation of the spring 41 about the axis of the screw 43.
When the meter is in mounted position and in operation the flow of current through the meter components and through the contact jaws generate substantial heat. A substantial portion of this heat is transmitted through the shields 35 to the associated terminal brackets 33. Heat is radiated from these brackets andis also transmitted through the brackets to the rear wall 3 of the enclosure for the meter mounting assembly. Thus the enclosure itself serves as a heat conducting and radiating element.
Because of the excellent heat dissipation characte'ristics of the resultant assembly the jaw assemblies can be constructed of smaller, lighter and less costly parts.
Mechanical forces applied to the contact jaws or terminal connections subject the insulation essentially to compressive forces, the type which insulation is best able to withstand.
1. In an electric connector assembly for releasably receiving a contact blade, a contact unit having a pair of spaced electroconductive members each having portions substantially parallel to each other so as to define a contact jaw for receiving a contact blade, one of said members having a substantial first surface parallel with the portion thereof defining said contact jaw, a thermally-conductive support element for mounting said contact jaw and having a substantial second surface parallel and spaced immediately adjacent to said first surface, a thermally-conductive electric-insulation sheet positioned between said first and second surfaces, and an insulated fastener securing the one member, said support element and said sheet together so that said contact jaw is' electrically insulated from the support element and heat is transmissible between the contact jaw and the support element.
2. An assembly as claimed in claim 1 wherein said sheet comprises a sheet of phenolic resin having a thickness which does not exceed one-sixteenth of an inch.
3. An assembly as claimed in claim 1 with said fastener including a headed part of electric insulating material having a neck extending through the support element into engagement with the sheet, and means securing the fastener to at least the last-named member with the sheet secured between such member and the neck of the fastener.
4. An assembly as claimed in claim 3 wherein said surfaces and sheet are of planar configuration, said support element having a foot extending in a plane substantially transverse to the plane of said planar surfaces.
5. A connector assembly as claimed in claim 1 wherein said contact unit has a second pair of spaced electroconductive members defining a second contact jaw for receiving a contact blade, said second pair being similar to the first-named pair and being associated in a similar manner with the sheet.
6. An assembly as claimed in claim 5 wherein said surfaces and sheet are of planar configuration in combination with an enclosure for the assembly having a circular opening extending transverse to the planar-surface electroconductive members exposing the contacts jaws for reception of the contact blades of a detachable watthour meter, said enclosure having a thermally-conductive wall coupled to said support element in thermally-conductive relationship.
does not exceed one-sixteenth of an inch in thickness and wherein said planar sheet projects substantially beyond a substantial portion of the support element towards the jaw-entry edges of the members having the first surfaces.
9. An assembly as claimed in claim 4 wherein said support element has a foot extending in a plane substantially transverse to the plane of the planar surfaces, in combination with an enclosure for the assembly having a circular opening extending transversely relative to the planar surfaces and exposing the contact jaw for reception of the contact blade of a detachable watthour meter, said enclosure having a thermally-conductive wall coupled to said foot in thermally-conductive relationship.