Remote automatic meter reading apparatus

Instantaneous current and voltage values are digitized at each of a plurality of electrical utility customer sites and integrated by a processor to calculate electrical power consumed at each customer site. A communication interface couples the processor at each customer site to a central processor in a central utility site to communicate the power consumed values of each customer site to the central utility site. In a preferred embodiment, the automatic meter reader apparatus is mounted in an electrical watthour meter socket adapter which plugs into a watthour meter socket at each customer site. Telephone modem circuitry mounted in the socket adapter connects to telephone lines to communicate calculated power values from each customer site to the central utility site.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates, in general, to automatic watthour meter 
reading apparatus and, specifically, to remote automatic watthour meter 
reading apparatus. 
2. Description of the Art 
The advantages of automatic reading of electrical watthour meters and other 
utility meters have long been recognized. Such advantages accrue from the 
elimination of the high costs associated with manually reading meters 
located a long distance from a central utility office, inside of a 
customer's premises, at dangerous locations, and at the remote ends of a 
distribution network. Further, in rural utility networks, long distances 
are typically encountered between each meter location. Thus, more 
employees are required to manually read each meter on a predetermined time 
schedule for accurate billing. 
However, such advantages have not been fully attained by previously devised 
automatic meter reading apparatus for several reasons. Most automatic 
meter reading apparatus require a specially designed watthour meter 
containing the telephone communications circuit, the power measuring 
circuitry and the data accumulation circuitry. In a typical electrical 
utility having tens to hundreds of thousands of electrical meters, the 
capital cost of replacing all watthour meters with specially designed 
automatic reading watthour meters is extremely high. Further, a single 
utility system typically uses several different types of watthour meters. 
Converting such meters in all locations to automatic reading meters is 
impractical since it would require several different types of automatic 
meter reading apparatus thereby increasing inventory and complicating 
ordering, installation and service of the meters. Previously devised 
automatic meter reading apparatus have also had a high cost compared to 
conventional, single phase, mechanical rotating ring-type counter meters 
and have other disadvantages which have limited their widespread 
application. 
In the context of providing an economical, easily installed, widely usable 
automatic meter reading apparatus for watthour meters, another factor 
which must be addressed is accuracy in measuring power usage. The accuracy 
standard for automatic meter reading apparatus is the .+-.2% accuracy of 
conventional mechanical watthour meters. Some automatic meter reading 
devices sense rotation of the mechanical rotating ring in a conventional 
watthour meter and convert the sensed rotations to digital signals 
corresponding to indicated power usage. Thus, such automatic meter reading 
devices are limited to the accuracy of the mechanical watthour meter. 
Electronic sensing of current and voltage for the calculation of power has 
also been proposed for electronic watthour meterrs. Such sensing circuits 
have been specifically designed for use in a specially designed electronic 
watthour meter. However, little attention has been paid in such single 
phase watthour meters for accurately measuring power consumption. 
Another disadvantage of previously devised automatic meter reading devices 
utilizing conventional telephone lines has been the inclusion of complex 
telephone dialing, call-back and reporting circuits to coordinate the flow 
of power usage information between each remote watthour meter site and the 
central utility office. This has increased the cost of automatic meter 
reading devices beyond the point of widespread economical implementation. 
Further, the use of dedicated telephone lines which do not interfere with 
a customer's telephone usage has also been proposed along with the 
attendant cost of running additional telephone lines to each customer 
site. 
Another factor which has not been fully addressed by previously devised 
automatic meter reading devices is the desirability of having time of day 
and demand power control by the utility company at residential locations. 
The increased cost of generating electricity has required other billing 
approaches by utilities including time of day billing where varying rates 
are applied to electrical usage at different periods during each 24 hour 
day. Another billing approach is demand or peak billing where the amount 
of power consumed is billed at a higher rate for power usage exceeding a 
predetermined amount. In order to implement such alternate billing 
approaches, it is necessary for the utility company to have accurate power 
consumption data, such as having the ability to determine the peak load of 
any customer and the power usage during any time period during the day. 
Thus, it would be desirable to provide an automatic meter reading device 
for watthour meters which overcomes the problems of previously devised 
automatic meter reading devices. It would also be desirable to provide an 
automatic meter reading device which is usable with conventional watthour 
meters without requiring modifications to such watthour meters or the 
meter socket. It would also be desirable to provide an automatic meter 
reading device for watthour meters which utilizes data communication via 
conventional telephone lines with a central utility site. It would also be 
desirable to provide an automatic meter reading device for watthour meters 
which is usable with most of the many different types of watthour meters 
currently used by utility companies. 
SUMMARY OF THE INVENTION 
The present invention is a remote automatic meter reading apparatus which 
is capable of sensing, calculating and storing power consumption values at 
a plurality of electrical utility customer sites and communicating such 
power consumption values via a communication interface to a central 
utility site. 
Generally, the automatic meter reading apparatus of the present invention 
includes a central processing means, disposed at the central utility site, 
which executes a stored program to interrogate automatic meter reading 
equipment at each of a plurality of remotely located utility customer 
sites and to receive, process and store power consumption values 
communicated from each remote customer site. A communication interface 
means communicates data signals between the central utility site and each 
of the remote customer sites. The communication interface may comprise 
conventional telephone conductors with modems employed at the central 
utility site and each remote customer site. 
Current sense means are coupled to the electrical power conductors at each 
customer site for sensing the instantaneous current of the electrical load 
at each customer site. Voltage sense means are also coupled to the 
electrical power conductors at each customer site for sensing the 
instantaneous voltage at each customer site. The current and voltage 
values are digitized in an analog to digital converter in the remote 
automatic meter reader apparatus at each customer site under the control 
of a processor means which executes a stored program and integrates the 
sensed and digitized instantaneous current and voltage values over time to 
generate power consumption values in kilowatt hours and/or KVA which are 
stored in a memory in the remote automatic meter reader apparatus at each 
customer site. 
A communication protocol established by the control program executed by the 
central processor means at the central utility site interrogates the 
processor means at each customer site on a predetermined time basis to 
receive the calculated power consumption values therefrom for use in 
customer billing and for other purposes. Additionally, low voltage and 
high voltage limits can be programmed into the automatic meter reading 
apparatus at each customer site from the central utility to insure 
compliance with applicable regulatory rules. 
In a preferred embodiment, the remote automatic meter reading apparatus at 
each customer site is mounted in an electrical watthour meter socket 
adapter which plugs into the standard watthour meter socket at each 
customer site and which may receive a conventional watthour meter therein. 
In the preferred embodiment, the current sense means comprises coils 
disposed about the blade terminals in the socket adapter which are 
connected to the electrical power conductors when the socket adapter is 
plugged into the watthour meter socket. The voltage sense means comprises 
amplifiers connected to the electrical load terminals in the socket 
adapter which sense the instantaneous voltage at each customer site. The 
processor means, associated memory, communication interface, analog to 
digital conversion, and power supply are also mounted in the socket 
adapter. 
A power outage monitoring program is stored in memory in each remote 
automatic meter reading unit and senses, totals and stores information for 
monitoring the frequency and duration of power outages at the associated 
customer site. This power outage information is reportable to the central 
utility site on demand and/or along with the transmission of power 
consumption data to the central utility site. 
The automatic meter reading apparatus of the present invention enables 
remote automatic meter reading capabilities to be coupled with a 
conventional watthour meter without requiring any modification to the 
conventional watthour meter or watthour meter sockets. The automatic meter 
reading apparatus of the present invention is mountable in a watthour 
meter socket adapter so as to be easily employed at each remote customer 
site.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawing, there is depicted an automatic meter reader 
apparatus particularly suited for automatic reading of electrical watthour 
meters located remotely from a central utility site or office. 
Central Utility 
As shown in FIG. 1, a central utility company site is depicted generally by 
reference number 10. The central utility site 10 may be the central 
business office of the utility, a generating station, etc., where billing 
information is accumulated, tabulated and recorded. A central processing 
unit 12 is located at the site 10. The central processing unit 12 may be 
any suitable computer, such as a mainframe, a PC, a PC network, 
workstation, etc., having the capacity of handling all of the utility 
company customer billing transactions as well as the remote data 
communications, .as described hereafter. For example, a 386 based PC may 
be employed. The central processing unit 12 communicates with a memory 14 
which stores data specific to each utility customer, as well as other data 
regarding power usage of each customer. The memory 14 comprises both hard 
disc storage memory and on board volatile memory. Although high voltage, 
electrical power distribution lines denoted generally by reference number 
16 for a three-wire, single-phase electrical system, are shown as 
extending from the central utility site 10 to each utility customer 
denoted generally by reference number 18, it will be understood that the 
electrical power distribution lines 16 may extend from a separate 
electrical power generating site through electrical transmission lines 
with appropriate voltage transformations, and not directly from the 
central utility site 10. Further, it will be understood that the 
electrical power distribution lines 16 may provide three-phase power to 
each customer site 18. 
As shown in FIG. 1, various input and output devices, such a keyboard, 
printer(s) 13, display terminals or monitors 15, etc., may also be 
connected to the central processing unit 12 as is conventionally known. In 
addition, one or more modems 20 are connected to the central processing 
unit 12 at the central utility site 10 and to conventional telephone 
wiring circuits denoted generally by reference number 22 which extend to 
each utility customer site 18. The number of modems 20 matches the number 
of telephone lines between the central site 10 and all of the customer 
sites 18. Each modem is capable of handling a large number of remote 
customer units 18, such as, for example, 2880 remote customer units 18, 
based on the assumption that a telephone call to a remote unit 18 is made 
every five minutes during a twelve hour period each day and for only the 
approximate twenty days per monthly billing period. The telephone wiring 
circuits 22 may be conventional telephone wires, as well as fiber optics, 
satellite, microwave or cellular telephone communication systems. The 
modem 20, which may be any conventional modem, functions in a known manner 
to communicate data between the central processing unit 12 and each 
utility customer site 18, as described in greater detail hereafter. 
Also stored in the memory 14 are the various software control programs used 
by the central processing unit 12 to automatically communicate with the 
electrical watthour meter at each utility customer site 18 as described 
hereafter. The memory 14 also stores the power usage data for each utility 
customer as well as various billing routines utilized by a particular 
utility company. 
Generally, the software control program stored in the memory 14 is a menu 
driven database capable of handling multiple simultaneous calls to a 
number of remote automatic meter reader circuits. The control program 
stores each customer's power usage in accumulated KWH and KVA, and 
instantaneous voltage, current and power factor measurements. Also, the 
control program generates an end-of-day summary printout through a printer 
13. 
The control program also enables a utility employee to remotely program 
each automatic meter reading circuit at the central site 10. Such 
programmable features include time, date and year data, a multi-level 
security code for communication access, receive call and originate call 
modes, line voltage quality set points, start and end times for multiple 
demand billing period intervals, i.e., three intervals in each 24 hour 
period, the date, time and duration of a communication window for 
communication with the central site 10, and the date and on or off 
conditions of a relay at the remote site 18. 
FIG. 16 depicts the main system menu which appears on the monitor 15 at the 
central site 10. The main system menu provides various options which may 
be selected by the user to monitor incoming calls from the remote AMR 
units, to call a specific remote unit, to review the records of any remote 
unit, to review a remote unit setup, to utilize system maintenance or a 
general help selection. 
FIG. 17 depicts a menu screen which is generated when the first option in 
the main system menu entitled "monitor incoming calls" is selected. As 
shown in FIG. 17, two remote AMR units are currently calling or are about 
to call the central processing unit for the transmission of data to the 
central site. The telephone number and identification number of each 
remote AMR unit currently transmitting data to or about to transmit data 
to the central site are depicted on the screen shown in FIG. 17. 
FIG. 18 depicts a screen on the monitor 15 at the central site when option 
2 in the main menu is selected to call a specific remote AMR unit. This 
screen is preceded by another screen, not shown, which requires the user 
to enter his or her pass code and then the specific identification number 
of the remote AMR unit to be called. When the correct information is 
entered, the screen shown in FIG. 18 will be displayed on the monitor 15 
at the central site. If three erroneous pass codes are entered by the 
user, the control program of the central processing unit 12 will prevent 
further access to the system. 
FIG. 19 depicts the screen for option 3 in the main menu which enables a 
user at the central site 10 to view the records or data from a particular 
remote AMR unit. The instantaneous voltage and current readings on each of 
the incoming power line conductors at the time of the call to the selected 
remote AMR unit are displayed on the screen. Also, the maximum and minimum 
voltage on the line conductors, the number and duration of outages as well 
as accumulated KWH, KVAR and power factor (PF) since the last reading are 
depicted. Total KWH, KVAR and power factor readings to date are also shown 
as well as total power outages and power outage durations. 
Finally, FIG. 20 depicts a screen when option 4 on the main system menu is 
selected to view a remote AMR unit setup. All of the programmable 
information of a particular selected remote AMR is displayed in the screen 
shown in FIG. 20. This information includes the day, time in hours, 
minutes and seconds and the window duration of the primary data 
communication window to the selected AMR unit. The first and second 
alternate data communication windows and their duration are also shown. 
Power demand settings for a particular unit, if employed, are also 
depicted on the screen. Any of these values may be programmed into a 
specific remote AMR unit from the central site. 
At appropriate times, as determined by the utility company, the power 
consumption data from each remote AMR unit can be input to a suitable 
billing software program to generate bills for each customer. By way of 
example only, the power consumption values transmitted from each AMR unit 
to the central site, as described above, can be stored in a hard disk 
which can then be transferred to a separate billing computer system at the 
utility company to generate customer bills. 
Remote Utility Customer 
As shown in FIGS. 1 and 2, a plurality, such as tens or even hundreds or 
thousands of utility customer sites 18 are connected to the electrical 
power distribution network 16 at remote locations of varying distances 
from the central utility company site 10. 
As is conventional, each utility customer site 18, as shown in FIG. 1, 
includes a utility meter socket 30 having a plurality of internally 
mounted jaw terminals 32 which are connected to the single-phase 
three-wire line conductors of the electrical distribution network 16. 
Although not shown in FIG. 1, separate jaw terminals are provided in the 
socket 30 and connected to the individual service or load conductors at 
each utility customer site 18. In a conventional usage, the socket 30 is 
mounted at a suitable location at the utility customer site 18, such as on 
an exterior wall, with the load conductors extending from the socket 30 to 
the building wiring circuits. 
A conventional electrical watthour meter 34 for recording electrical power 
usage at a particular customer site 18 has a plurality of outwardly 
extending blade-type electrical terminals 36 which electrically engage the 
jaw contacts or terminals 32 in the socket 30. A sealing ring, depicted in 
FIG. 2 and described in detail hereafter, is provided for sealingly 
attaching the watthour meter 34 to a peripheral mounting flange 33 
surrounding an opening in the front cover of the socket 30 to lockingly 
attach the watthour meter 34 to the socket 30 and to prevent unauthorized 
removal or tampering therewith. 
AMR Socket Adapt 
As shown in FIGS. 1 and 2, and in greater detail in FIGS. 3 and 4, the 
automatic meter reader apparatus of the present invention, in a preferred 
embodiment, includes a socket adapter denoted generally by reference 
number 40. The socket adapter 40 is interconnected between the watthour 
meter 34 and the socket 30 in a known manner. However, according to the 
present invention, the socket adapter 40 includes internally mounted 
automatic meter reading and telephone communication circuits as described 
in greater detail hereafter. The use of the socket adapter 40 to house the 
automatic meter reading circuitry is a preferred embodiment of the present 
invention. It will be understood that such automatic meter reading 
circuitry, as described hereafter, can also be mounted at each customer 
site 18 by other means, such as in an enclosure separate from the watthour 
meter and meter socket. 
In general, the watthour meter socket adapter 40 includes a two-part 
housing formed of a base 42 and a shell 44 which are joined together by 
fasteners. As described hereafter, a plurality of electrical contacts 47 
are mounted in the socket adapter 40 and have a first end 46 extending 
outward from the base 42 for removable engagement with the jaw-type 
electrical contacts mounted in the watthour meter socket 30. The 
electrical contacts 47 are provided in the socket adapter 40 in any 
number, type and arrangement depending upon the electrical power 
requirements of a particular application. By way of example only, the 
electrical contacts 47 are arranged in the socket adapter 40 in a first 
line pair of contacts and a second load pair of contacts. Each of the 
contacts receives one of the blade-type electrical terminals 36 mounted on 
and extending outward from the watthour meter 34. Each of the contacts is 
preferably in the form of a pair of spring-biased fingers which are formed 
of an electrically conductive material. The jaws of each electrical 
contact in the socket adapter 40 are joined together to form a single 
blade-like terminal extending outward at a first end 46 from the base 42 
of the socket adapter 40. 
As is conventional, a peripheral flange 60 is formed on the base 42 of the 
socket adapter 40 which mates with a similarly formed flange 33 on the 
watthour meter socket or housing 30 for mounting of the watthour meter 
socket adapter 40 to the watthour meter socket 30. A conventional seal or 
clamp ring 62, such as a seal ring disclosed in U.S. Pat. No. 4,934,747, 
the contents of which are incorporated herein by reference, is mountable 
around the mating flanges 60 on the socket adapter 40 and the flange 33 on 
the socket 30 to lockingly attach the socket adapter 40 to the socket 30 
and to prevent unauthorized removal of or tampering with the socket 
adapter 40. 
It will also be understood that the socket adapter 40 and the socket 30 may 
be configured for a ringless connection. In this type of connection, not 
shown, the cover of the socket 30 is provided with an aperture which is 
disposable over the socket adapter housing and locked to the socket 30 
enclosure after the socket adapter 40 has been inserted into the socket 
30. 
As shown in FIG. 2, a second mounting flange 64 is formed at one end of the 
shell 44 of the socket adapter 40. The mounting flange 64 mates with a 
similarly configured mounting flange 66 formed on the watthour meter 34. A 
second sealing ring 68, which may be identical to the sealing ring 62, 
described above, is lockingly disposed about the mating flanges 64 and 66 
to lockingly attach the watthour meter 34 to the socket adapter 40. 
As shown in greater detail in FIGS. 4 and 15, the base 42 of the socket 
adapter 40 includes a central wall 70 which is integrally formed with and 
surrounded by an annular, peripheral side wall 72. The side wall 72 
extends outward from the central wall 70 for a predetermined distance to 
form an internal recess or cavity in the base 42. The outer portion of the 
side wall 72 is configured as the rim or mounting flange 60 for mating 
engagement with the mounting flange 33 on the socket 30. 
A plurality of mounting bosses 74 are integrally formed on the central wall 
70 and the side wall 72 at prescribed locations for connecting the base 42 
to the shell 44 by suitable fasteners, as described hereafter. In 
addition, a plurality of spaced bosses 76 are formed on and extend outward 
from the central wall 70. Each of the bosses 76 includes a central 
aperture 80. The aperture 80 is preferably in the form of a slot for 
receiving the blade terminals mounted in the shell 44 therethrough, with 
the exterior end 46 of the blade terminals extending outward from the back 
surface of the central wall 70 of the base 42 in the orientation shown in 
FIG. 4. 
Lastly, protective flanges 82 are formed on the back surface of the central 
wall 70 adjacent to each blade terminal to provide protection for the 
exterior end 46 of each blade terminal in a conventional manner. The base 
42 and its various described elements is preferably formed as a one-piece 
molded member from a suitable, electrically insulating, plastic material. 
Referring now to FIGS. 3, 4 and 15, the shell 44 of the socket adapter 40 
includes a base wall 90 and an annular side wall 92 disposed at the 
periphery of the base wall 90 and extending away from the base wall 90 to 
form an interior cavity or recess within the shell 44. The outer end of 
the annular side wall 92 is formed with a rim or mounting flange 64 for 
mating engagement with the mounting flange 66 on a watthour meter 34, as 
shown in FIG. 2 and described above. 
Surge protection strips 94 are mounted on the exterior peripheral edges on 
opposite sides of the mounting flange 64. Electrically conductive tabs 96, 
only one of which is shown in FIG. 4, extend from the strips 94 to the 
bottom wall 90. 
A plurality of terminal bosses, each denoted by reference number 98, are 
integrally formed on and extend outward from the bottom wall 90 into the 
cavity formed between the bottom wall 90 and the annular side wall 92. 
Each of the bosses 98 includes an internal bore 100 which mountingly 
receives a suitable jaw-type terminal. A plurality of apertures are formed 
in the bottom wall 90 and receive suitable fasteners, not shown, to attach 
the shell 44 to the bosses 74 in the base 42. 
It will be understood that the number, position and arrangement of the 
bosses 98 may vary from that shown in FIGS. 3 and 4 to other arrangements 
depending upon the particular electrical power requirements at a utility 
customer site 18 at which the socket adapter 40 and socket 30 are 
employed. 
A cutout or aperture 104 having an irregular shape is formed in the bottom 
wall 90 of the shell 44 for mounting of the automatic meter reading 
circuitry therethrough, partially within the interior cavity in the shell 
44 and partially within the interior cavity between the bottom wall 90 of 
the shell 44 and the central wall of the base 42. 
As shown in FIGS. 2, 3 and 12, a telephone line connector sleeve 106 is 
mounted to the annular side wall 92 of the shell 44 by suitable fasteners, 
not shown. The sleeve 106, in one embodiment, has a generally tubular 
construction with either a square, rectangular, circular, etc., cross 
sectional shape. 
As shown in FIG. 12, a metallic mounting plate 117 having a central 
aperture and fastener receiving apertures is mounted adjacent the flat 
portion formed in the bottom of the annular side wall 92 of the shell 44. 
A gasket 107 formed of a suitable seal material has the same configuration 
as the plate 117 and is sandwiched between the plate 117 and one end of 
the sleeve 106. 
Screws extend through certain of the apertures in the annular side wall 92 
of the shell 44, the plate 117, the gasket 107 and one end of the sleeve 
106 to securely and sealingly attach the sleeve 106 to the annular side 
wall 92 of the shell 44. 
A telephone connector 113 containing two female-type telephone jacks two 
conventional RJ11 telephone connection jacks 114A and 114B is mounted in a 
snap-in fit in the upper portion of the sleeve 106. The connector extends 
through the gasket 107, the mounting plate 117 and the annular side wall 
92 to dispose one of the connection jacks 114A within the interior of the 
shell 44. The telephone connection jack 114A removably receives a 
telephone jack 115 which is attached to telephone line conductors 116 
extending to the telephone modem circuitry in the AMR. The other telephone 
connector 114B is adapted to removably receive a telephone jack 108 
attached to one end of a telephone wire conductor 110. The telephone wire 
conductor 110 is connected in a known manner to a telephone junction box 
112 which is typically mounted at the utility customer site 18 adjacent to 
the watthour meter socket 30. Conventional telephone wires extend from the 
junction box 112 to the telephone wire network 22, as shown in FIG. 1. 
The sleeve 106 is sealingly closed so as to be accessible separate from 
access to the interior of the socket adapter 40. A gasket 118 and a cover 
plate 119, each having the same configuration are attached to the opposite 
end of the sleeve 106 and secured thereto by means of fasteners, such as 
threaded studs which extend through certain apertures in the annular side 
wall 92 of the shell, the plate 117, the gasket 107, the sleeve 106, the 
gasket 118 and the cover plate 119. The exterior ends of the studs receive 
wing nuts 109 to securely and yet removably attach the cover plate 119 to 
the sleeve 106. The wing nuts 109 have apertures for receiving a 
conventional seal wire to provide tamper indication. A strain relief 105 
is mounted in a snap-in fit in the cover plate 119 and receives the 
telephone conductor 110 therethrough. In this manner, the high electrical 
power connections within the socket adapter 40 are separate from the 
telephone line connections within the sleeve 106. Telephone personnel may 
access the sleeve 106 by removing the cover plate 119 and inserting the 
telephone connector 110 and telephone jack 108 through the strain relief 
105 into connection with the telephone connector 114B mounted within the 
sleeve 106 to connect the AMR to the telephone junction box 112 and the 
telephone wire network 22. The wing nuts 109 are then threaded onto the 
studs to securely retain the cover plate 119 on the sleeve 106. A seal 
wire, not shown, is passed through the apertures in the wing nuts 109 to 
indicate a sealed, non-tampered condition for the telephone sleeve 106. 
It will also be understood that other types of telephone communication 
means, rather than hard wire conductors, may also be employed. Such 
communication means may include fiber optic cables as well as satellite, 
cellular, microwave or other telephone communication means. With such 
communication networks, suitable connectors will be provided in the sleeve 
106 attached to the shell 44 to provide electrical data communications 
between the automatic meter reader circuitry mounted within the socket 
adapter 40 and the telephone communication network to provide data 
communications between the automatic meter reader circuitry at each 
utility customer site 18 and the central utility site 10, as shown in FIG. 
1. 
AMR Circuitry 
A general block diagram of the major components of the automatic meter 
reader (AMR) circuitry denoted generally by reference number 120 which is 
mounted in each socket adapter 40 at each utility customer site 18 is 
shown in FIG. 5. The automatic meter reader circuit 120 includes a power 
supply 122, voltage and current sensing, analog to digital conversion 
circuits 124, a central processing unit and associated logic 126, a memory 
128, a telephone communication modem 130, an opto-communication port 254, 
a RAM clock 230, an auto-tampering switch 250 and a form C relay control 
252 with associated solid state switch. The details of each of these major 
components will now be described with reference to FIGS. 5-9. 
As shown in FIGS. 3, 4 and 15, the AMR circuitry is mounted within a 
housing 121 having a shape sized to fit within the opening 104 in the 
bottom wall 90 of the shell 44. By way of example only, the housing 121 
generally has a cubical rectangular shape. A threaded stud 123 extends 
outward from the back wall of the housing 121 and extends through an 
aperture formed in the central wall 70 of the base 42 where it is attached 
by a suitable nut to retain the housing 121 in a fixed relationship within 
the base 42. The housing 121 is provided with a back wall, side walls and 
a removable cover. The cover is removable to enable access to the 
components of the AMR circuitry mounted therein. As shown in FIG. 4, 
grommets 125 are mounted on the top and bottom and provide a sealed 
connection for various electrical conductors extending from the AMR 
circuitry exteriorly of the housing 121. 
The housing 121 is preferably formed of a suitable metal so as to provide 
an electric shield for the AMR circuitry mounted therein. Alternately, the 
housing 121 may be formed of a plastic, such as an injection molded 
plastic, with a thin metal coating sprayed or otherwise formed on the 
interior surface thereof to form the electrical shield. 
As is conventional, the electrical power distribution network 16 from the 
central utility company generating site typically carries 240 VAC at a 
residential or commercial level. A single-phase, three-wire power 
distribution network 16 is shown in FIGS. 1, 5 and 6 with three wires 
connected to the electrical power distribution network 16 at each utility 
customer site 18, as shown generally by reference number 132. Each line 
134 and 136 carries 120 VACRMS with respect to neutral or ground wire 138 
.+-.30% at 60 Hz. The customer conductors 132 are connected through the 
appropriate line contacts and terminals in the socket 30 and the socket 
adapter 40 to the power supply 122 of the automatic meter reader circuitry 
120. The general function of the power supply 122 is to provide regulated, 
low level DC power at the preferred .+-.DC levels required by the 
electronic components used in the automatic meter reader circuit 120. 
The power supply 122 includes an electromagnetic interference filter 140 
formed of common mode inductors 142 and 143, noise capacitors denoted 
generally by reference numbers 144, 145 and 146, metal oxide varistors V2 
and V3, and de-coupling capacitors 147 and 148. A rectifier/filter circuit 
149 is connected to the filter 140. The rectifier/filter circuit 149 
includes a full-wave, diode bridge rectifier 150, voltage doubler 
capacitors 151 and 152 and a filter capacitor 153, which are connected as 
shown in FIG. 6. The rectifier/filter circuit 148 and the de-coupler 
capacitors 147 and 148 of the filter circuit 140 are connected to a 
flyback converter circuit 154 which converts the output of the diode 
bridge rectifier 150 to a precise +5 VDC power output, labelled "VCC". The 
flyback converter circuit 154 is conventionally constructed and includes a 
flyback transformer 155 and a power switching regulator 156, Model No. 
PWR-SMP210BN1 sold by Power Integration Company. Various capacitors, 
resistors and diodes are interconnected in a conventional manner in the 
flyback converter circuit 154 to provide the desired output voltage. 
As also shown in FIG. 6, the power supply 122 includes a boost circuit 160 
for boosting the +5 VDC output from the flyback converter 154 to the +12 
VDC for use with the various operational amplifiers employed in the 
automatic meter reader circuit 120. The boost circuit 160 includes boost 
inductors 162 and 164 as well as a boost regulator controller 166, such as 
a boost regulator controller Model No. MAX743EPE made by Maxim. 
The AMR circuit 120 also includes a voltage sensing network denoted in 
general by reference number 180 in FIG. 7. The voltage sensing network 
receives 120 VAC RMS 60 Hz input from the utility lead lines 132. One set 
of voltage inputs including voltage lead line connections 182 and 183 are 
between one lead line and neutral; while the other pair of inputs 184 and 
183 is between the other lead line conductor and neutral. The voltage lead 
connections are provided by means of a jumper tab 193 mounted on each 
electrical contact or jaw terminal in the socket adapter 40. A clip 192 is 
releasably engageable with the jumper tab 193 and carries one of the 
voltage lead line connections 182 or 184 thereon. The voltage lead 
connections 182 and 183 are input to a differential amplifier 185 which 
has a gain of 1/100 set by resistors 186 and 187. The output of the 
differential amplifier 185 is input to an A/D converter 124. The other 
line connections 183 and 184 are input to a similar combination of 
differential amplifiers thereby resulting in two separate voltage inputs 
as shown by reference numbers 190 and 191 in FIG. 7 which are connected to 
inputs of the A/D converter 124. The differential amplifier 185 and the 
corresponding amplifier for the other lead line conductors provide an 
instantaneous voltage corresponding to the lead line voltage present on 
the conductors 182, 183 and 184 which is within the input range of the A/D 
converter 124. It should be understood that the input voltages supplied to 
the A/D converter 124 are instantaneous voltages. 
The current sensing network of the AMR circuit 120 includes first and 
second current transformers 200 and 202, respectively, as shown in FIGS. 
4, 5 and 15. The current transformers 200 and 202 include a high 
permeability toroid which is disposed around each of the customer line 
contacts 182 and 184, respectively, in the socket adapter 40. 
The current transformers 200 and 202 are precision, temperature stable 
transformers which provide a .+-.10 volt output voltage signal in 
proportion to the instantaneous current flowing through the line 
conductors 134 and 136. In a physical mounting position, the current 
transformers 200 and 202 are disposed in the recess formed in the base 42 
of the socket adapter 40 around the blade terminals of the socket adapter 
40 extending through the recess between the shell 44 and the base 42 of 
the socket adapter 40. Each current transformer 200 and 202 may be 
eccentrically or concentrically disposed about the respective blade 
terminal. Further, the electrical conductive coil of each current 
transformer 200 and 202 is covered by a protective insulating coating, 
with the conductive coil leads or outputs extending into the housing 121. 
In a preferred embodiment, each of the toroids forming the current 
transformers 200 and 202 is fixedly connected to opposite sides of the 
housing 121, preferably adjacent one end thereof, as shown in FIGS. 4 and 
15. The toroids 201 of each current transformer are preferably disposed 
substantially in line with the back wall of the housing 121 so as to be 
disposed between the bottom wall 90 of the shell 44 and the back wall of 
the base. The central aperture in each toroid 201 is sized to be disposed 
about the jaw terminals mounted in the socket adapter and extending 
through the base 70 and the shell 44. 
The outputs from the current transformer 200 are input to a conditioning 
circuit which adjusts the burden voltage between -10 volts to +10 volts by 
means of a burden resistor 204 shown in FIG. 7. The outputs of the current 
transformer 200 are each supplied to a separate amplifier 206 and 208, the 
outputs of which are respectively supplied as inputs to a differential 
amplifier 210. The output of the differential amplifier 210 which 
represents the scaled instantaneous current in the line conductor 134 is 
supplied as an input to the A/D converter 124 as shown in FIG. 7. 
A similar signal conditioning circuit is provided for the current 
transformer 202. The outputs from the current transformer 202 are supplied 
to separate differential amplifiers 211 and 212, the outputs of which are 
connected as inputs to a differential amplifier 213. The output of the 
differential amplifier 213 is also supplied as a separate input to the A/D 
converter 124. 
The outputs of the voltage and current sense circuits are input to the A/D 
converter 124. In a preferred embodiment, the A/D converter 124 is a 
twelve-bit +/-, self-calibrating, A/D converter, such as an A/D converter, 
Model No. LM12458C1V, sold by National Semiconductor Corporation. Clock 
input signals to the A/D converter are selected to provide a 64 per line 
cycle sample rate. In this manner, each of the voltage and current input 
signals supplied from the voltage sensing network 180 and the current 
sensing network 199 are sampled 64 times per cycle. 
The clock input signals are generated by a clock signal 125 from a 
microcontroller 220, described hereafter, which is input to a J-K flip 
flop 127; FIG. 8A. The Q output 129 of the flip flop 127 is connected to 
the clock input of the A/D converter 124 to provide the desired sample 
rate. 
The A/D converter 124 includes internal sample and hold circuits to store 
continuous voltage and current signal representations before transmitting 
such instantaneous voltage and current representations to other portions 
of the AMR circuitry 120, as described hereafter. 
A 2.5 v voltage reference circuit, such as voltage reference circuit Model 
No. LT1029A CN8-2.5 sold by Linear Technologies, provides a voltage 
reference signal to the A/D converter 124 as shown in FIG. 7. 
The outputs from the A/D converter 124 are connected to a central 
processing unit 126. The central processing unit 126, in a preferred 
embodiment which will be described hereafter by way of example only, is a 
16 bit microcontroller, Model No. HPC36004V20, sold by National 
Semiconductor Corporation. This microcontroller is a 16 bit 
microcontroller which executes a control program stored in the memory 128, 
as described hereafter, to control the operation of the AMR circuit 120. 
The microcontroller 220 also drives a display means 222, such as a liquid 
crystal display, for displaying, for example, the total kilowatt hours and 
KVA of power usage and instantaneous voltage, current and power factor 
values. Such a display 222 can be mounted, for example, at a suitable 
location on the socket 30, for example, for easy visibility. The display 
222, in a preferred embodiment, contains 16 characters including nine 
decimal digits divided into six significant digits and three decimal 
digits. 
As shown in FIGS. 13 and 14, the display 222 can optionally be mounted in a 
separate cover 223 which includes a circular front wall and an annular 
side wall or flange 225. The display 222 is mounted in the cover 223 and 
has a suitable electrical connector 221 extending therefrom for connection 
to the AMR circuitry in the socket adapter when the cover 223 is mounted 
on the socket adapter 40. A resilient protective material layer 227 is 
mounted interiorly on the back side of the cover 223 to protect the 
display 222. The cover 223 is mounted on the socket adapter 40 in place of 
the watthour meter 34 and is fixedly attached thereto by means of a 
conventional sealing ring in the same manner as the sealing ring 68 used 
to attach the watthour meter 34 to the socket adapter 40. The display 222 
will sequence between five different data values, including accumulated 
KWH and KVA and instantaneous voltage, current and power factor. 
The memory 128, as shown in FIG. 8C, includes a plurality of separate 
memory sections. The first memory section includes, by way of example 
only, two 32K.times.8 bit EPROM memories 226 and 228. Two eight bit 
address busses 231A and 231B, FIGS. 8A and 8C, are output from the 
microcontroller 220 and pass through octal latches 238 to the address 
lines of the memories 226 and 228. Data buses 235A and 235B are also 
connected between the memories 226 and 228 and the microcontroller 220. 
The memory 128 also includes a non-volatile 8K.times.8 bit clock RAM 
memory 230. The memory 230 acts as a timekeeping RAM clock. The memory 230 
is provided with time information via an address bus from the 
microcontroller 220 after a power outage. The memory 230 stores the date 
and time of any and all power outages and outputs such power outage 
information via an output data bus which is connected between the memory 
230 and the microcontroller 220. Finally, two 32K.times.8 EEPROM memories 
232 are provided as data storage for optional load survey information. The 
memories 232 are connected by the address buses 231A and 231B and the 
memory data buses 235A and 235B to the microcontroller 220 as shown in 
FIG. 8C. The memories 232 are available to store load versus time 
information in the form of KVAR and KWH. 
As shown in FIG. 5, and in greater detail in FIG. 9, the modem 130 receives 
inputs from the microcontroller 220 as well as from the A/D converter 124 
and provides suitable data communication connections and data flow over 
the telephone conductors 22 connected thereto. By way of example only, the 
modem 130 is a two-way, 300 baud, reverse handshake modem, such as a 
single chip Bell 103 standard compatible modem data pump, which may be 
used on a call-in or called basis as described hereafter. 
The modem 130 includes a single chip modem circuit 240, Model No. 
SS173K312, sold by Silicon Systems, which receives data signals from the 
microcontroller 220 and controls the serial transfer of data to and from 
the microcontroller 220. The transmit and receive pins of the modem 
circuit 240 are connected to corresponding pins on a direct access circuit 
242, Model No. PN73M9001, sold by Silicon Systems, Inc. which is connected 
to a relay 244 having two form contacts 245. The contacts 245 are 
connected to the coil of a relay 246. It should be noted that the RING and 
TIP input connections from the telephone network at the remote site are 
connected to both the circuit 242 and the relay 246. 
As shown in FIG. 5, the anti-tampering switch 250 is mounted within the 
housing 121 to detect any unauthorized movement of the housing 121 and the 
surrounding socket adapter 40 as would accompany an unauthorized attempt 
to remove the socket adapter 40 and/or watthour meter 34 from the socket 
housing 30 or to insert wires through the socket adapter 40 into the 
socket housing 30. The switch 250 may be any suitable electrical switch 
which senses motion. For example, a reed-type mercury switch may be 
employed to detect any movement of the AMR after it has been installed in 
its use location by an authorized person. 
The form C relay 252 is mounted in a separate housing 253 which is 
attachable to the housing 121 as shown in FIG. 3. An opto signal 
transmitter 255 mounted in a window in the housing 121 is activated by the 
microcontroller 220 and transmits a light signal to an opto receiver 255 
mounted in a window in the C relay housing 253. The opto receiver 255 
activates the C relay 252 to switch the state of the contact 257 of the C 
relay 252. The double throw, single pole contact 257 may be employed for 
any suitable function, such as demand management load control devices, 
i.e., a disconnect switch or other external device to shed loads, 
terminate electrical service, etc. In the preferred embodiment, the relay 
252 may be selectively activated so as to energize the contacts once 
during each 24 hour period. 
The opto-coupler 254 is also mounted in the socket adapter and connected to 
the microcontroller 220. The opto-coupler 254 is responsive to light 
signals, such as infrared light signals, and functions to covert such 
light signals to electronic data signals. The coupler 254 includes a 
receiving unit 256 which is mounted in an aperture 255 in the shell 44 of 
the socket adapter 40 and extends outward from the shell 44. A cover, not 
shown, may be provided to sealingly enclose the receiving unit 256 of the 
optocoupler 254 when the opto-coupler 254 is not in use. The optocoupler 
254 may be employed to receive light signals from transmitters on adjacent 
water and gas meters, for example, and to convert such light signals to 
electrical data signals which can be relayed by the microcontroller 220 
via the telephone modem 22 to the central utility site 10 for subsequent 
data processing. In addition, the opto-coupler 254 may be employed to set 
AMR parameters, such as voltage levels, clock signals, time windows, etc., 
directly at the remote customer site. 
Remote AMR Control Program 
FIGS. 10 and 11 depict the control program stored in non-volatile memory 
226 and 228 which controls the operation of each remote AMR 18. After a 
power up, step 260 in FIG. 10, the control program recovers the set up 
conditions for each particular AMR 18. Such set up condition recovery, 
step 262, occurs after the initial power up and after the power up 
occurring after each power loss. The reset conditions are used to reset 
the microcontroller 220 and provide data concerning the primary and 
alternate window dates and times of the particular AMR. 
Next, in step 264, the current date/time stored in the RAM clock memory 230 
is compared with the primary window date (day) and time (hour and minute) 
stored in the set up conditions for the particular AMR 18. If the current 
date/time does not equal the primary or alternate date/time window, step 
266 is executed which disables the telephone ring detect circuit. Next, 
the power connections are checked in step 268. If the power connections 
are good, the data is displayed in step 270 before the control program 
returns to the data/time equal primary window step 264. 
In step 268, the power check step tests the L1 and L2 conductors for the 
presence of voltage on both conductors, the proper voltage, and voltage 
within or outside of the specified voltage range. In the event that the 
power connections are determined to be bad in step 268, the super cap 
charger is disconnected in step 272. This disconnects the charging circuit 
to the real time clock RAM 230. The type of failure is recorded in step 
274 and the type of failure, i.e., whether complete or other, is checked 
in step 276. If the failure is a complete failure, the control program 
ceases execution until the next power up occurs. If a non-complete failure 
occurs, the super cap charging circuit is reconnected in step 278, the 
data displayed in step 270 and program control returns to step 264. 
The control program stored in the memory 226 and 228 is devised to store 
data relating to a plurality of separate power outages. For example only, 
data pertaining to ten different power outages may be stored in the memory 
226 and 228 via step 224 in the control program described above. Such data 
includes the number of power outage currents as well as the month, day, 
hour, minute of the occurrence of the power outage and the duration in 
minutes and hours of each power outage. This data is transferred from the 
AMR to the central computer during normal data reporting, as described 
hereafter. 
If the date/time check in step 264 determines that the current date/time 
equals the primary or alternate programmed window, the AMR is moved into 
an answer mode in step 280. If the AMR is programmed to receive data, 
thereby indicating a proper answer mode condition, the control program 
causes the AMRto enable the telephone ring detect circuit in step 282 
before looping to step 268. If an answer mode is not entered in step 280, 
the pickup detection circuit is enabled in step 284 and telephone modem 
communication is then initiated in step 286. The pick-up detection circuit 
will detect the occurrence of a customer picking up the telephone during a 
data transfer. When this occurs, a subroutine labelled pick-up detect 
interrupt request (IRQ), step 288 in FIG. 11, is executed. In this 
subroutine, which occurs only when the pick-up detection circuit has been 
enabled and a customer picks up the telephone during a data transfer to 
the central utility site 10, the AMR will release its connection to the 
customer telephone line in step 290 and enable the alternate window for 
later data transfer. The day, hour and minute of the alternate or 
secondary windrow is stored in the memory 226 and 228. This information is 
initially programmed into the memory 226 and 228 by the central computer 
12 during initialization of the remote AMR. Control then returns to the 
primary program loop described above. 
After the modem communication has been initiated in step 286, data will be 
transferred from the remote AMR 18 to the central utility site 10 in step 
292, FIG. 10. Finally, the pick-up detection circuit is disabled in step 
294 to complete this program loop. 
Various interrupt subroutines are shown in FIG. 11. The timed interrupt 
request (timed IRQ) 300 is a non-masked interrupt and occurs at all times 
and with a primary status over all other interrupt requests. Timed IRQ, 
step 300, occurs every 260.4 microseconds based on 64 samples per cycle. 
When this interrupt request occurs, data acquisition starts in step 302 in 
which the A/D converter values are read into the microcontroller 220, the 
calculations, described hereafter, are performed on such data in step 304 
and the results stored in memory 226 and 228 in step 306. At the 
completion of the memory storage step 306, control returns to the primary 
program loop described above and shown in FIG. 10. 
At the periodic sample rate of 64 samples per cycle, or once every 260.4 
microseconds, the digital values corresponding to the instantaneous 
voltage and current will be input to the micorcontroller 220, as described 
above. The microcontroller 220 then executes a calculation subroutine to 
determine the kilowatt hours of electrical power consumed since the last 
sample. According to the equation: 
EQU KWH=K.multidot.Vrms.multidot.Irms.multidot.(T2-T1), where 
K is a calibration constant 
T1 is the preceding sample time 
T2 is the current sample time 
The control program also calculates the power factor, KVAR, according to 
known electrical power factor and VAR equations. 
Furthermore, the instantaneous current and voltage data at the sample rate 
is input to the microcontroller 220 for each separate line L1 and L2 or 
phase of electrical power. Separate power, instantaneous voltage and 
current and power factor data is stored in the memory 226 and 228 by the 
microcontroller 220 for each phase or line at each sample period. 
When a ring detect interrupt request (IRQ) occurs in step 308, the control 
program will enable the pick-up detect circuit in step 310 and initiate 
modem communication in step 312 via a conventional handshake protocol. 
Data stored in the memories 226 and 228 is then transferred in step 314 
via the telephone modem 130 and telephone line conductors to the central 
utility site 10. In step, 316, the pick-up detection circuit is disabled 
and the telephone line is then released in step 318. 
Finally, a subroutine labelled RS-232 detect IRQ, step 320, detects a 
request for serial data communication. When this interrupt occurs, serial 
communication is initiated in step 322 and the data is transferred in step 
324 via opto-coupler 254. The end of communication is detected in step 326 
before control returns to the primary control loop. 
It should also be noted that the RS-232 detect interrupt request and the 
ring detect interrupt request signals, steps 308 and 320, are mutually 
exclusive such that when the ring detect is enabled, the RS-232 interrupt 
request is disabled and vice versa. Similarly, when the timed IRQ 
subroutine, step 300, interrupt request is received, the RS-232 interrupt 
detect is disabled. At the completion of the timed IRQ subroutine, the 
RS-232 detect interrupt request is re-enabled and, if previously 
interrupted, will complete its serial data communication. 
In summary, there has been disclosed a unique remote automatic meter 
reading apparatus which senses, calculates and stores electrical power 
consumption values at each of a plurality of electrical utility customer 
sites and communicates such power consumption values at predetermined 
times to a centrally located utility site. The apparatus of the present 
invention also includes a unique socket adapter mountable in a watthour 
meter socket which contains the remote AMR circuitry for each remote site 
in a compact package thereby eliminating the need for extra enclosures at 
each remote customer site.