Note: Descriptions are shown in the official language in which they were submitted.
~35~
llME 126
-- 1 --
E:LECTRONIC DEMAND REGISTER
_ACKGROUND OF THE INVENTION
The present invention relates to electric
meters and, more particularly to demand registers for
electric meters.
Conventional electric meters employ an
aluminum disk driven as a rotor o~ a small induction
motor by an electric field at a speed which is
proportional to the electric power being consumed by a
load. Geared dials, or cyclometer discs, integrate
the disk motion to indicate the total energy consumed,
conventionally measured in kilowatt hours (one
kilowatt hour equals one thousand watts of power
consump-tion for one hour).
In addition to the above measurement of
consumption, some eLectric meters contain demand
registers haviny means for separating the consumption
into those parts of consumption occurring during peak
and off-peak hours (however defined) and for recording
maximum demand during any one of a contiguous set of
demand intervals over a predetermined period of time
in order to adjust billing accordiny to such
parameters. In one such meter disclosed in U.S.
Patent 3,586,97~ - D. M. Ham et al issued ~une 22,
1971, a mechanical demand reyister records -the maximum
3~
llME 126
~ _
demand during a predetermined period of time and
stores the value for reading~ The predetermined
period of time may be, for example, the time between
meter readings, or a period of time corresponding to
the billing period of the u-tility providing the
power. A clockwork mechanism restarts the demand
register at ~he end o~ each demand interval which may
be, for example, a Eraction oE an hour, so that, at
the end of -the predetermined period, the stored value
represents the highest value of power usage occurring
during any one of the demand intervals in the
predetermined period.
Demand registers o-E the mechanical type,
such as disclosed in the above U.S. Patent, have
limited flexibility. Once their design is completed
for a particular meter physical configuration, the
design is not transferrable to a meter having a
different physical configuration. Also, the
demand-measurement functions cannot be redefined
without major mechanical redesign.
When a power outage occurs, the clockwork
motor driving the demand register is halted.
Following the restoration of power, the clockwork
motor driving the demand register is restarted without
recognizing the fact tha-t a power outage has
occurred~ ~here is some cluestion whether resumption
of operation can be performed in this way while
strictly abiding by the regulations for demand
metering as definecl b~ the commissic)ns haviny
jurisdiction over the utility provicling the electric
power and without penalizing a custo~ler for ~n
apparent very high demand which is the result oE the
power outage and resumption and not the fault of the
customer.
S:l~
llME 126
-- 3 --
Maximum demand metering is conventionally
clefined as the maximum amount of power consumed in any
one contiguous demand interval during the time
interval of interest; that is, the maximum amount of
power ~onsumed in any one of the interval~ oE, for
e~ample, 15 minutes, 30 minutes or one hour. If the
accumulation of actual usage during one of such demand
intervals i~ paused by a power outage and then
res~llned, the demand accumulated at the end of the
interrupted time period consist of an initial portion
before the outage interruption and a final portion
following the outage interruption. Not only does the
intervention of the outage interruption appear to
violate the definition of demand metering, but also,
lS if the customer load includes a substantial number of
motors or other devices having a large starting load
compared to their running load, when power is
restored, all or most of such motors and devices may
be forced to go through their starting sec~uence at the
~0 same time. Under normal conditions, some of the
customer's motors may run continuously and others may
cycle on and off in an unsynchronized manner . Thus,
the motor starting loads are normally distributed over
time and their effect on demand metering is similarly
distributed over time. As is well known, the starting
load imposed by a motor is much higher than the
running load. By synchronizing all or most of the
customer's startiny load in a single time periocl
followiny restoration of power, an unnaturally ~ h
demand may be registered in -that time period when, in
fact, the unnaturally high demand is the r~sult of the
utility permitting a power outage to occur and not the
result of the customer load producing the registered
maximum demand.
3~
llME 126
-- 4 --
In addition to the above limitations o~
mechanical demand metering, a useful demand metering
technique known as rolling demand is not practically
~easible using mechanical demand registers. In
rolling demand meteriny, a demand interval is divided
into N contiyuous subintervals. The usage during each
demand subinterval is summed with the demand recorde~
during the precediny N-l subintervals. At the end of
each subinterval, the total demand recorded is the
demancl for N subintervals, i.e. for the entire
preceding demand interval. The maximum demand may
then be -taken as the maximum over any interval sensed
at the end o a subinterval. The use of such rolling
demand metering avoids distortion in the billing data
which could otherwise occur due to short-term extremes
in the usage data which would otherwise become lost in
the averaging process over an entire demand interval.
Greater Elexibility in demand metering may
be obtainable using electronic acquisition,
integration and processing of power usage. An
electronic processor such as, ~or example, a
microprocessor, may be employed to manage the
acquisition, storage, processing and display o~ the
usage and demand data. U.S. Patents ~,179,65~ -
W. R. Germer issued December 18, 1979; 4,197,582 -
P. M. Johnston et al issued April 8, 1980; 4,229,795 -
G. Viewig et al issued October 21, 1980; ~,2833,772 -
P~ M. Johns-ton issued August 11, 1981; ~,301,508 -
J. A. Anderson issued November 17, 1981: ~,361,872
A. Spalti issued November 30, 1982; ~,368,519 -
S. P. Kennedy issued ~anuary 11, 1983, among others,
illustrate the Elex:ibility that electronic processing
brings to the power and energy usage measurement.
Each of these electronic measurement devices includes
means ~or producing an electronic signal having a
characteristic such as, for example, a ~requency or a
:~3~5:~
- 5 - llME 126
pulse repetition rate, which is rela-ted to the rate of
power usage. The eleetronic processor is substituted
for the mechanical demand regis-ter of the prior art to
keep track of the demand during defined periods of
time.
An electronic processor of an electronic
demand recJister eonventionally employs volati.le random
access memory for the h:igh speed and low power
consump-tion characteristics offered by such devices.
When a power outaye occurs, iE steps are not taken to
prevent it, all data in such volatile storaye may be
lost. This could .include both prior demand data as
well as a sense of where, in a time period, the outaye
occurred. The loss of demand data has an obvious
negative impact on billing. The loss of time sense
would require that all users in the area affected by
the power outage MUSt beyin a new time period for
accumulation of demand. Such synehronization of
demand meteriny is eonsidered undesirable by a.t least
some utilities. Canadian Patent Applieation Serial
No. 484,608, filed on June 20, 1985, Germer
discloses means for storing data in non~volatile
memory when a power outaye oecurs and for ignoring or
tolerating certain normal devia-tions of the line
power, such as, for example, momentary overvoltaye,
surges, noise and momentary power outages enduring for
a very short -time period, This new capability to
store demand billincJ data and procJrammed constants ln
non-volatile memo:ry permits re-thinkiny the manner in
whieh demand data aecumulated before and after an
outaye interruption may be handled so as to provide
fairness both to the eonsumer and to the uti:Lity.
OBJECTS AND SUMMARY OF T~:[E INVENTION
Aeeordinyly, it is an object of the
invention to provide an eleetronie demand reyister for
an eleetrie meter whieh overeomes the drawbaeks of the
35~
llME 126
-- 6 --
prior art.
~ t is a fur-ther object of -the invention to
provide an electronic demand reyister of the type
employing a digi-tal processor and a random access
memory which includes means or storing volatile data
in a non-volatile atorage medium during periods when
the inteyrity of the data may otherwise be threatened
and ~or retrieviny the data from the non-volatile
storage medium and resuming normal operation following
the threatening condition in a manner which re-tains
relevant billing data accumulated before the
threatening condition occurred.
Briefly stated, the present invention
provides an electronic demand register having a
processor or calculating a demand in a demand
subinterval. At the end of each demand subinte~val,
the calculated demand is summed with the demand in the
preceding N-l subintervals to derive an interval
demand over N contiguous subintervals. The interval
demand is compared to a previously recorded maximum
- demand, and if the interval demand exceeds the maximum
demand, its value is substituted for the maximum
demand for use in subsequent comparisons. The
processor employs volatile memory. A non-volatile
memory is provided for storing the billing data and
programmed constants in the event oE an impending
power outage. A power monitor detec-ts the possibility
of an impending power outage and, operating on stored
energy, both enable~ and powers the transfer oE data
to the non-volatile memory. ~len power is resumed,
the power monitor enabLes resetting the processor and
retransferring the data from the non-volatile to the
volatile memory for resumption of demand metering. A
grace period is provided after the resumption of power
before beginning demand metering to permit the energy
user's starting loads to pass before demand metering
33~
llME 126
-- 7 ~
begins. Provision i5 made for treating the beginning
and ending of a -test operating mode similar to a power
outac3e. ~n addi-tion, the demand register responds to
its removal from, and it5 replacement in, the electric
meter in a mannar similar to its response to a power
outage. Ln this manner, when the demand register i9
rertloved from the electric meter, the billing and other
data is saEely stored in the non-volatile memory, from
which it can be copied, to a replacement demand
:L0 register. When the original or replacement demand
register is replaced in the electric meter, the demand
register treats the replacement in the same manner
that it treats the resumption of power ~ollowing a
power outage.
According to an embodiment of the invention,
there is provided a demand register for an electric
meter comprising a processor, means in the processor
for calculating a rolling demand including means Eor
summing a demand in a subinterval with demands in a
preceding N-l subintervals to derive an interval
demand over N contiguous subintervals, means for
storing a maximum demand, means for replacing the
maximum demand with the interval demand if the
interval demand exceeds the maximum demand, the
processor including a volatile memory, a non-volatile
memory, means responsive to a predetermined reduction
in a voltage fed to the electric meter for enabling a
fir~t transfer O~e at least the maximum demand and a
plurality o~ programmed constants from the volatile
memory to the non-volatile memory, means respon~ive to
a predetermined restoration in a voltage fed to the
electric meter for enabling a second transeer Oe the
maximum demand and the plurality of constants erom the
non-volatile memory to the volatile memory and means
for resuming operation of the demand regis-ter
~ollowing the second transfer at a time in a first
l'Z~35~
llME 12
-- 8 --
subinterval corresponding to a time at which a prior
subinterval was interrupted by the first transfer.
The above, and other objects, features and
advantages of the present invention will become
apparent rom the following description read in
conjunction with the accompanying drawings, in which
like reference nuTnerals designate the same elements.
BRIEF DESCRIP'rION OF TH~ DR~WINGS
E'ig. 1 i3 a schematic dia~ram of an electric
meter to which the present invention may be applied.
Fig. 2 is a block diagram of a demand
register of Fig. 1 according to an embodiment o~ the
invention.
DETAILED D~SCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is a demand metering
system whose detailed functions are performed by a
number of elements which represent separate inventions
and for which Canadian Patent Applications have been
filed. Since the detailed disclosures of the elements
making up the system are fully detailed in their
xespective patent applications, the present
application omits the fuLl detail but provides
reference to the individual applications for such
detail. Instead of presenting the full detail, the
present application summarizes the disclosures of each
of the applications to the extent required for an
understanding of the system beiny disclosed hereill.
Although the present invention may be
adapted to any 9Ui table type of electric meter which
employs an element rotating at a speed proportlonal to
power consumption, including, for example, sing:Le
phase or polyphase meter~ with one or more current and
voltage coils, for concreteness, the detaile~
description which follows is directed towa.rd an
illustrative example of a 2-wire single phase meter of
the type having a single current coil and a sinyle
~Z~3~
llME 126
_ g _
voltage ~oil.
~ eEerring now to Fig. 1, there is shown,
generally at 10, an electric meter which includes a
small induction motor 12 driving a register 1~.
Induction motor 12 includes a stator 16 made up oE a
voltacJe coil 18 and a current coil 20 disposed on
opposite sides of a disk 22. Voltage coil 18 employs
a core 2~ upon which is wound a large number oE turns
of fine wire. Voltage coil 18 is connected across
lines 26 and 28 which feed power to a load (not
shown). Current coil 20 employs a core 30 upon w'hich
a small number of turns, typically two or more, oE
heavy conductor are wound. Current coil 20 is
connected in series with the power being fed to the
load on line 26.
Disk 22 is affi~ed to a shaft 32 which is
supported on suitable bearings (not shown) to permit
concerted rotation of disk 22 and shaft 32 under the
influence of a rotating magne-tic field produced by the
combined in~luence of voltage coil 18 and current
coil 20. A permanent magnet 34, having its poles
disposed on opposite sides of disk 22, applies a
retarding force which is proportional to the
rotational speed o-f disk 22. The rotational torque
produced by voltage coil 18 and current coil 20
combined with the retarding torque produced by
permanent magnet 3~ is effective to rotate dis'k 22 at
a speed which is proportional to the product of the
voltage and the current: that is, the power, con~umed
by the load.
Register 1~ includes a watthour register 36
which may include, for e~ample, a plurality of
diaLs 38 w'hich are suitably geared and driven by a
mechanical coupling ~0 in proportion to the rotation
of shaEt 32. ~n the embodiment shown, mechanical
coupling ~0 includes a worm ~2, which may be
integrally formed in shaEt 32, engaging and rotating a
-~Z~3351~3
llM~ 126
-- 10 --
worm gear 44. Additional elements may be present in
mechanical coupling 40 for coupling the rotation o~
worm gear 44 to watthour register 36 wi-th or without
change in speed and direction according to the design
of the particular electric meter lO. As is
conventional, watthour register 36 totals the number
of revolutions oE shaft 32, suitably sca:Led by the
gear ratios employed, for billing purposes.
~ demand register ~6, shown schematically as
a box in E'ig. l, i9 also connected by a suitable
coupling means ~ to respond to -the rotation of
shaft 32. In the prior art, demand register ~6 is
conven-tionally a mechanical register having dials, or
other indicating devices (not shown), and coupling
means ~ is conventionally a mechanical arrangement
including shafts and gearing driven by rotation of
shaft 32. The dials, or indicating devices, in the
mechanical embodiment of demand register 46 are urged
forward for a fixed demand interval by a pusher
mechanism (not shown). The pusher mechanism is reset
and restarted at the end of each of the demand
intervals, leaving the indicating devices with an
indication proportional to the power usage (the
demand) during the demand interval. The indication on
the indicating devices at any time is, therefore, the
maximum demand which has occurred during any one of
the demand intervals since the last time the
indicating devices were reset. The recorded maximum
demand is employed in billing.
When a power outage occur~, the timiny motor
driving the gearing oE mechanical demancd register ~6
is hal-ted at whatever stacJe in the demand interval and
at whatever demand readings existed on demand
register ~6 at the time the power outage occurred. At
the end of the power outage, the timLng motor again
begins driving the gear train and dials from the
~23~
~ llME 126
positions they had at the beginning of the power
outage and demand metering is resumed from the same
position within the demand interval as existed
a-t -the beginning of the power outage. This
practice may fail to rigorously satisfy the
c1efinition oE demand metering and may also impose
an unfair hurden on the user. This sys-tem does
have -the one desirable feature, however that,
since -the demand meteriny picks up a-t the same
point in the demand interval that it had when
the outage occurred, it proceeds to complete the
demand interval and thus a power outage does
not have the efEect of synchronizing all of the
demand registers in the affected area.
In the present invention, demand
register 46 is an electronic demand register.
Referring to Fig. 2, there is shown a
simplified block diagram of a demand register 46
according to an emhodiment of the invention. For
present purposes, it is sufficient to note that the
- signal related to power usage fed from coupling
means 48 to demand register 46 is an electronic signal
having a characteristic such as, for example, a
frequency or pulse repetition rate, which is variable
in dependence on the rate of power usage. Any
suitable electronic signal generating apparatus
may be employed to produce a power usage signal
which is applied on a line 50 to processor 52 in
demand register 46.
Processor 52 appropriately perEorms
calculations on the usage data, such as, for example,
countiny pulses and scalincJ, to clerive desired demand
parameters and stores the resul-t. In particular,
processor 52 perEorms rolling demand metering as more
,?.
~Z33~
- 12 ~ llME 126
fully detailed in Canadian Patent Application Serial
~o. 48~,615~ filed June 20, 1985, Germer. srieEly
described, rolling demand metering divides a demand
interval into N equal demand subintervals. The
demand is accumulated over the current subinterval
ancl, at the end of the curren-t subinterval, the
demand in the just-completed subinterval is summed
w:ith the demands in the preced:iny N-:L demand
subintervals to derive a curren-t demand interval value.
The current demand interval value is compared with a
previously stored rnaximum demand and, if the current
demand interval value exceeds the previous maximum
demand, the previous maximum demand is replaced with
the current demand interval value.
Rolling demand metering, as summarized
above, and as fully detailed in the referenced Canadian
Patent ~pplication, avoids losing revenue such as may
occur by the use of a large demand interval which tends
to average out actual peaks in demand, and also avoids
distortion in demand data which may occur due to
fortuitous straddling of a demand peak over an end of
one demand interval and the beginning of the next
demand interval.
In addi-tion to calculating and recording
demand, processor 52 may provide an output on a
line 5~ suitable for driving a display 56. The stored
data may be transmitted on a line 58 to a remote
location (not shown) for ~urther analysis and/or
billing.
Due to the extremes oE env:i.ronment in which
electric meters may be used, clisplay 56 may need
special compensation for environmen-tal parameters.
Such special compensation may include a display
temperature compensator 60 whose detailed structure
and operation are fully disclosed in Canadian Patent
Application Serial No. ~80,605, filed ~ay 2, 1985,
~233~
llME 126
-- 13
6 ~P~ R . For the present
application, it is suf~icient to note that a threshold
voltaye exists ~or turnin~ liquid crystal display
elements on and of~. 'rhis threshold voltage is
non-linearly dependent on temperature. Display
temperature compensator 60 is opera-tive -to con-trol a
set of supply voltages fed to display 56 in a
non-linear relationship to temperature in a manner
which generally tracks the non~linear -temperature
dependence o-~ the threshold voltage.
As previously noted, processor 52
conventionally employs vola-tile random access memory
elements which lose any data stored in them in the
event o~ a power outa~e~ rrhis i8 usually not
acceptable in an electric meter where such loss of
usage and/or demand data has a negative financial
impact on the utility supplying the electric power.
Mon-volatile storage elements such as, for example,
electrically erasable programmable read only memory
elements, are well known for use with processor 52.
~Iowever, such non-volatile storage elements normally
have relatively slow write and erase times on the
order of 10 or 20 milliseconds. This is too slow ~or
most applications. Besides this drawback, the power
required -to erase and write such memory elements is
quite high compared to that required by volatile
memory elements of processor 52. Finally, a wear-out
mechanism in electrically erasable programmable read
only memory cells limits the number of times they can
be erased and re-recorded. About lO,000 cycles of
write and erase bring~ such a memory element to the
end of its reliable useful life. '~'he volatile memory
elements in processor 52 must, of course, be written
and erased many thousands of times a day. 'rhus, an
electrically erasable proyrammable read only m~mory
would have a very short life as the operatin~ memory
~33.~g
- 14 - llME 126
for processor 52.
In order to provide sa~e storage for data
and/or programmed cons-tants during a power outaye or
during -test operation, a eonventional non-volatile
memory 6~ is provided into which such data and
constants can be written and from which the data and
constants ca:n ayain be read upon res-tora-tion of normal
condi-tions. In their role in non-volatile memory 6~,
eleetrically erasable programmable read o:nly memory
elements are erased and rewri-tten only when a
relatively serious power outage occurs and possibly
during a relatively small number of test cycles. Such
operations are not expeeted to occur on a frequenk
enough basis in demand register 46 of eleetric meter 10
to represent a limit on the life of the register.
An incompatibility exists between the protocols
required for transmitting and receiving data between
some commereially available types of processor
52 and non-volatile memory 64. In order to
adjust the protocols of the two devices, processor 52
formats an output message for transmission to
non-volatile memory 64 in a manner which fools
non-volatile memory 64 into recognizing a received
word as one havlng the correct protocol. Similarly,
processor 52 operates on a message reeeived from
non-volatile memory 6~ using appropriate shift
teehni.ques to align the data in -the reeeived message
into a format whieh processor 52 can accept. A full
disclosure o;~ the apparatus and Eune-tions involved in
perform:ing the above memory interface is contained in
Canadian Patent Applicat:ion Ser:ial No. ~81,268, Eiled
May 10, 19~5, Simon.
A power supply ancl power monitor 66 receives
AC power from lines 26 and 28 or the production of a
regulated DC voltaye which is appliecl on a line 68 to
all circuits in demand register 46 requiring such
~2~3~
- 15 - llME 126
power. In addition to producing regulated DC power,
power supply and power monitor 66 also monitors the
condition oE the AC power on lines 26 and 23 and, in
response -to detected conditions indicating the
possibility an impeding power outage or the actuali-ty
of such a power outage, applies an emergency store
signal on a line 70 to processor 52 which controls the
transfer oE data rom processor 52 to non-volatile
memory 6~ in the event of an apparent power outage and
resets processor 52 in the even-t of an actual power
outaye. Prior -to transferring the da-ta and programmed
constants to non-volatile memory 64, processor 52
checks -to determine whether the demand during the
current interval up to the time of the power outage
exceeds the maximum demand previously recorded. If
the demand in the current interval does exceed the
maximum demand, the demand for the current interval is
substituted for the maximum demand and the thus-
modified data is transmitted to non-volatile memory
6~ for storage. Upon restoration of power, power
supply and power monitor 66 applies a reset signal
on line 70 to processor 52 for initiating
the sequence for resuming demand metering, as
will be explained. A full disclosure of the
structure and function of power supply and power
monitor 66 is contained in aforementioned Canadian
Patent App:Lica-tion Serial No. ~3~,60~.
Resumption of demand metering Eollowing a
power outage is clesirably perEormed to accomp:Lish the
EollowincJ objec-tives:
1. A grace per:iod should be provided for
permitting the energy user's motor starting
loads, and other load peaks which are due
totally or princ:Lpally by the power outage,
to be comple-ted beEore demand meteriny is
begun. This avoids penaliziny energy users
,
~Z~3~
llME 126
- 16 -
for peak loads which are caused by the power
outage and not by their intentional creation
of peak demand.
2. A new partial demand subinterval should be
begun Eollowing the grace period at point in
a partial demand subinterval correspondiny
to the point where the prior subinterval was
interrupted by the power outage. This
avoids synchroniziny demand intervals and
subinterval~ throughout the area aEEected by
the power outage.
3. A new demand interval should be begun
æimultaneously with the new demand
subinterval with demands in the prior N-l
subintervals set to ~ero.
4. The previously stored value of maximum
demand should be re-stored for comparison
with the on~going interval demands.
~he preceding objectives are achieved in
processor 52 in cooperation with power supply and
power monitor 66 and non-volatile memory 64 in the
' ~3 manner fully disclosed in Canadian Patent Application
ji ~ NoO ~ filed J~e~d,l1 ~
It is desirable to provide means ~or testing
~5 demancl register 46 in the shop or in the field without
compromising stored billing data and programmed
constants. A manual input 62 is provided for suitably
changing the Eunctional operation of demand
register ~6 by applying an appropriate signal to
proce~sor 52. When test operation is begun,
processor 52 responds to it as though a power outage
were occurring. That isl processor 52 checks to
determine whether the presen-t interval demand exceeds
the maximum demand and, if it does, stores the present
interval demand as the new maximum demand, and then
transfers subinterval timiny, maximum demand and
~233S~9
llME 126
- 17
progra~Jned constants to non-vola-tile memory 6~. This
permits test opera-tion of processor 52 under control
of, ~or example, switches in manual input 62 to
manipulate the data in processor 52 and to provide ~or
display of data on display 56 which is not displayed
duriny normal u~e of demand reyister 46. At the end
of test operation, normal operation is resumed in a
manner identical to the manner o~ resumption of
operation EoLlowiny a power outage. That i~, demand
accumulation i~ begun during a partial subinterval, a
new demand interval is begun with demand in the prior
N-1 subintervals set to zero and the previous maximum
demand and the programmed constants are retrieved ~rom
non-volatile memory 6~ and re-stored in processor 52
for use as previously described. Test operation o~
demand register 46 is ~ully disclosed in Canadian
~ ~ Patent Application Serial No. ~4~d~ ~iled JU~4JIq~
- In order to adapt demand register 46 of the
present invention to as wide a range o~ electric
meters as possible, a single electronic design is
employed. The programmed constants which are employed
in processor 52 customize processor 52 ~or the
particular style of electric meter 10 in which it is
installed and for the particular customer
installation. The programmed constants are stored in
non-volatile memory 6~ using a conventional, or
especially adapted, EEPROM programmer beore demand
register ~6 is installed in electric meter 10. When
demand register ~6 is installed and connected to a
power line, a power-up sequence identical to that
perEormed a~ter a power outage, and previously
described herein, is per~ormed. That is, the
programmed constants are read into processor 52 and
demand metering is begun in the manner described.
llME 126
- 18 -
In the case o~ equipment ~ailure in the
field, one convenient troubleshooting method employs
the substitution of a replaceable module for a module
which may ~e defective~ Such a troubleshooting method
is foreseen for use with the system of the present
invention. Such a troubleshooting method raises the
problem o~ defininy a practical way of copying the
unique set o~ programmed constants and billing data
from a non-volati:le memory 64 in a demand register ~6
being replaced into a non-volatile memory 64 of a
replacement demand register 46. This copying function
is performed in a programmer (not shown) which reads
out the data from a non-volatile memory 64 when its
demand register 46 has been removed from the circuit,
temporarily stores this data, and then copies the
temporarily stored data into non-volatile memory 64 in
the replacement unit. This copying function is
enabled by the manner in which demand register 46
responds to the apparent loss of power and its
resumption. That is, when demand register 46 is
removed from electric meter lO, power supply and power
monitor 66 senses this as a power outage and stores
the described data in non-volatile memory 64 which it
can be read using the programmer~ When power is
restored to the replacement demand register 46, power
supply and power monitor 66, processor 52 and
non-volatile memory 64 respond as though to a normal
resumption of power following a power outage. That
is, bi:llinc~ data and programmed constants are
trans~erred from non-volatile memory 6~ to processor
52 and the described po~t-power-outage sequence is
followecl. Since the particular programmer used to
read, temporarily store and to copy the data from a
non-volatile memory 64 being replace to -the
replacement element may be conventional, a full
~3~
- 19 - llME 126
description and illustration thereof is omitted from
-the presen-t disclosure. A full disclosure of the
apparatus and method for the copying function is
provided in Canadian Patent Application Serial
No. 484,614, filecl June 20, 1985, Germer.
I-laving described pre-ferred embodlments of
the :invention wi-th reference -to the accompanying
drawinys, it i5 to be understood that the invention is
not limited to those precise embodimen-ts, and that
various changes and modifica-tions may be effected
therein by one skilled in the art without departing
from the scope or spirit o the invention as defined
in the appended claims.
