Electrical connectors – Power measuring meter coupling part
Reexamination Certificate
2003-04-02
2004-06-22
Bradley, P. Austin (Department: 2833)
Electrical connectors
Power measuring meter coupling part
Reexamination Certificate
active
06752652
ABSTRACT:
BACKGROUND
The present invention relates, in general, to watthour meters and meter sockets and, more specifically, to watthour socket adapters or extender adapters for mounting, recording and other instrumentation equipment on ringless style watthour meter sockets.
In the electric utility industry, plug-in, socket-type watthour meters are commonly employed to measure electric power consumption at a residential or commercial building establishment. A socket is mounted on a wall of the residence or building and contains terminals which are connected to electric line and electric load conductors. The terminals are also connected to internal conductors within the socket which extend to jaw contacts positioned to receive the blade terminals of a plug-on watthour meter to complete an electric circuit through the watthour meter between the line and load terminals and the conductors.
One type of meter socket has a ring-type cover which includes an outwardly projecting, annular mounting flange surrounding an opening in the cover through which the blade terminals of a watthour meter extend. The mounting flange is sized to mate with a complementary formed mounting flange on the base of the watthour meter. The two mating mounting flanges are held together by a sealing ring.
Another type of meter socket has a ringless style cover which has only a slightly raised boss surrounding an aperture in the cover. The meter and/or socket adapter is connected to the jaw contacts in the socket and has an end portion which extends through the aperture.
While a socket adapter can be easily attached to either meter socket cover style for receving a plug-in watthour meter, it is necessary sometimes to connect load survey equipment or recording equipment to the meter socket for various study and reporting surveys. Since such equipment is frequently contained in a housing which is too large to pass through the aperture in the socket cover or to be connected to the mounting flange in a ring style cover for connection to the socket jaw contacts, latch base socket adapters have been devises which include the standard jaw blades for receiving blade terminals in the survey equipment in a plug-in connection, with ends of the jaw blades passing through the latch base for plug-in connection to the socket jaw contacts. Such a latch base includes lock members which are engagable exteriorly of the socket cover to move latch fingers behind the latch cover to securely mount the latch base to the socket cover on a meter socket.
One prior art approach to providing a latch base socket extender adapter is shown in
FIGS. 1A and 1B
. This extender adapter is modeled after Ekstrom Industries, Inc., 38 series extender adapter and is formed of a two-part base and shell. The base, shown in
FIG. 1A
, has a circular cross section formed of a bottom wall, a radially outward extending mounting flange and a short length side wall. A plurality of apertures extend through raised bosses on the base wall and the base wall for receiving the blade end of jaw blades shown in
FIG. 1B
mounted through the shell and base for interconnection with the socket jaw contacts.
A plurality of mounting screw bosses are disposed internally of an annular ring concentric within the mounting flange and extending from the base wall. The bosses receive mounting screws to which an L-shaped, steel latch flange is attached. The bosses guide movement of the L-shaped latch flange as the screws are threaded in and out relative to the base. Such movement of the screws bidirectionally extends a lower leg of the latch flange mounted around each screw underneath the adjoining raised boss on the ringless socket cover to fixedly attach the base to the metal surrounding the opening in the cover. Since the heads of the screws are disposed externally of the side wall of the base as part of a cast metal ring mounted around the side wall of the base on one side of the mounting flange, the base end of the extender adapter can be mounted through the opening in the ringless socket cover after the cover has been installed on the meter socket.
Bore are cross drilled in the screw heads for receiving a meter seal which extends through an adjacent aperture in an ear formed on the metal ring after the screws have been threaded to their fully latched position.
The shell has a bottom wall and a side wall extending therefrom to an external mounting flange mateable with complimentary mounting flanges on load survey recording equipment or other metering instrumentation. Bosses in the shell support the jaw blades which pass through the bottom wall of the shell and the bottom wall of the base for connection at a blade end with the socket jaw contacts. The shell is fixedly attached to the base by screws which extend through apertures in the bottom wall of the shell into bores formed in mounting bosses in the base as shown in
FIGS. 1A and 1B
.
While such an extender adapter proves an effective means to install load survey recorders and other types of meter recording equipment or instrumentation on ringless style sockets, it is difficult to reliably seal the shell to the base which can lead to corrosion. Further, as shown in
FIG. 1A
, the interior ends of the screws are disposed in close proximity to the jaw blades extending between the bottom wall of the shell and the bottom wall of the base. This creates an arcing potential. Further, there is no capability for accommodating a watthour meter having an external accessory box or an external wire which needs to be routed through the socket adapter into the meter socket.
A different approach to a latch base type socket adapter is one sold by Marwell Corporation as Model No. E/Z 1800. In this socket extender adapter, the cast ring and screw head seal ears are integrally molded as part of the short side wall of the base which has a double thickness compared to the latch base socket extender adapter shown in
FIGS. 1A and 1B
. The inside pocket surrounding the inner end of each screw has one higher length wall at a radially inner end. However, the other two side walls remain short exposing the metal screw and the latch flange to arcing potential from adjacent jaw blades.
This design also presents difficulties inadequately sealing the shell to the base which can lead to corrosion. Further, the close proximity of the screw seal ears and the screw heads prevents the use of the popular Plastic Padlock Seal sold by E.J. Brooks Company, Livingston, N.J.
In both latch base adapters shown in
FIGS. 1A
,
1
B and
2
, the mounting screws are retained in the base by means of roll pins inserted through holes drilled in the enlarged bosses on the ring and into an annular recess formed in each screw. Such roll pin captures a screw relative to the ring while allowing the screw to rotate to move the attached latch member between the latched and unlatched positions. However, the drilling of the holes in the ring for each roll pin and the mounting of the roll pins in the holes requires additional assembly steps and time which increase the cost of these prior latch base adapters.
Another deficiency of the prior art latch base adapters shown in
FIGS. 1A
,
1
B and
2
is that only, wire tamper indicating seals can be mounted through the screw heads and the ears for flanges on the ring to indicate that screws are in their final, latch engaged position without tampering or attempts to remove the latch base from the socket cover.
Thus, it would be desirable to provide a latch base watthour meter socket extender adapter which overcomes the problems associated with previously devised latch base socket extender adapters. It would also be desirable to provide a latch base socket extender adapter which has the mounting ring, base wall screws and latches formed as a one-piece assembly, which can accommodate different diameter shells so as to eliminate the need for a shell to base seal, which fully encapsulates the interior end of the mounting screws for high arc resistance, which accommodates seals for the mounting screws, which can easily accommodate a conventional watt
Bradley P. Austin
Ekstrom Industries, Inc.
Nguyen Phuongchi
Young & Basile PC
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