IE44954B1

IE44954B1 - Maximum-demand electricity meter

Info

Publication number: IE44954B1
Application number: IE99877A
Authority: IE
Original assignee: Heliwatt Werke Elektrizitats G
Priority date: 1976-05-18
Filing date: 1977-05-16
Publication date: 1982-05-19
Also published as: DK148177A; FR2393313B1; GB1576760A; LU77360A1; DE2622576B2; IT1076867B; BE854669A; FR2393313A1; CH635439A5; NL7705001A; DE2622576A1; IE44954L

Abstract

The maximum-demand electricity meter contains in a common electrically shielded case a kilowatt hour meter (KW), a maximum-demand mechanism (MW), a power supply (SV), the control device for the indicating elements (AZ) and for a data output (DA) and possibly a ripple-control receiver (RE), which are integrated in a large-scale integrated circuit. The timing element used is a time base device allocated to the maximum-demand mechanism (MW), which can be used for setting time switching points. To store the measurement state in the event of a mains voltage failure, the power supply is associated with a battery which is continuously automatically charged to approximately maximum capacity, or an accumulator independent of the supply voltage is provided. Drum type registers or stepping mechanisms are used as indicating elements for storing the monthly maximums and for the resetting register. These measures allow the use of a common power supply, common shielding and common means for protection against overloads for all parts of the maximum-demand electricity meter.

Description

This invention relates to maximum-demand electricity meters..

According to the present invention, there is provided a maximum-demand electricity meter comprising an electronic kilowatt hour measurement means, an electronic maximum demand register, a generator for generating timing signals for determining switching instants in the.meter, 'a currant supply means, control means for indicator devices for indicating values in the meter, and an indicator device for indicating a maximum-demand value, the meter further comprising means for maintaining an existing indicated value in the event of a power failure and/or means for maintaining, in the event of a power failure, an electrical signal which represents an existing measurement value in tha meter.

For a 'better understanding of the invention and to show how the same maybe carried into effect, reference will now be made, by way of example, to the accompanying drawing, the single figure of which is a block circuit diagram of a maximum-demand electricity meter in accordance with the invention.

In conventional maximum-demand electricity meters, the measurement result of the electricity meter is continuously transmitted to a maximum-demand indicator device, and after the expiry of a predetermined measuring period, the measurement result shown by the indicating device (usually a mechanical device) is reset to aero.

Previously proposed maximum demand meters often employ a Ferraris movement having a mechanical maximum-demand register. The dis25 advantages of such arrangements include the cost of balancing the Ferraris measuring movement,, consumption of a relatively large amount of electrical energy for the requirement of the meter it- self, and relative’.}/ large overall dimensions.

The illustrated aaximum-deraand meter is generally improved' in the foregoing respeets, insofar as electronic components are used in place of mechanical components. Housed in a common electrically screened housing are a fully electronic kilowatt-hour measurement means w, a fully electronic maximum-demand register Β5ΐ.- a fully electronic current supply means SV, and a fully elec10 tronic control means AS for controlling indicator devices for indicating values in the meter. The above .fully electronic components are advantageously solid-state devices, and nay comprise one cr mere integrated circuit(s). The control means &2 is arranged to provide a data output signal to ? data output CA for external 15 recorder means, the data output signal representing data in the meter et any given time. A receiver RE is provided for receiving and decoding switching signals for the meter, which signals are sent fo the meter from a remote central control point.

Sy assembling the various component parts in the common housing, a common current supply, a common screening, and common protection mean3 against, over-voltage can be employed for all of the component parts.

Incorporated in the maximum demand register MW, is a timing signal generator for generating timing signals for determining switching instants in the meter. Tho timing signal generator may comprise an electronic frequency divider which is based upon a reference frequency (for example, mains frequency), and corresponds to ε running movement in a mechanically operated maximumdemand mater.

The illustrated maximum-demand meter operates generally as follows.

The output from the kilowatt-hour measuring means KW is fed continuously to the maximum-demand register MW, which records the maximum demand over a predetermined measuring period, typically a quarter of an hour, and is then reset to zero in response to a timing signal from the timing signal generator. Thus, the register M is arranged to be reset periodically a plurality of times each hour. The control means AZ feeds the present value of the-maximumdemand register MW to an indicator device and to the data output DA. A further indicator‘device is arranged to indicate the monthly maximum-demand value, and to be reset at monthly intervals in response to a switching signal from the receiver RE.

Advantageously, the maximum-demand meter is arranged to operate on any desired one of a plurality of different tariffs, and to switch from one tariff to another in response to a switching signal from the receiver RE.

The receiver RE is desirably incorporated into the .maximum- demand mater as a separate sub-assembly. However, the receiver RE may in fact be omitted altogether, and the use of the timing signal generator extended to provide, in addition to the quarterhourly resetting signals, the monthly resetting signals and the optional tariff change-over signals. Thus, the timing signal generator nay be arranged to generate substantially all of the required timing signals for the meter. Additionally, there may be provided in association v/ith the timing signal generator, a time indicator device, optionally including a date indication, which may be used for setting the instants at which desired timing signals take place.

The data output DA may serve to output all of the date occurring in the meter, such as, for example, the quarter-hourly maxima, the kilowatt-hour values, the monthly maxima, and the time and date indications. This data may be recorded on an external recorder means, such as, for example, aa optical character render or on a punched tape.

Because of the electronic nature of the maximum demand meter, it is necessary to provide means for maintaining essential measured values in the event of a power failure. Thus, for maintaining, in the event of a power failure, an electrical signal which represents an existing measurement value in the meter, there is provided a battery which is γaromatically kapt substantially fully charged during normal operation of the meter, and which serves to provide sufficient power to enable essential electrical signals to bs stored, until the normal power supply is restored. As an alternative to, or in addition co the battery, there nay be provided a non-volatile store (for example, a MSOS store), which can be used for storing numerical values and logical conditions without a supply voltage.

For the electronic component elements of the maximum demand meter, metal oxide semiconductor elements (CMOS) are preferably employed. This is particularly advantageous as it minimises the meter's own power requirement, and hence requires negligible energy consumption during battery operation, in the event of the power failure.

As a further precaution in ths event of a power failure, there is advantageously employed for indieating a maximum-demand value (either or both of ths monthly maximum value and the quarterhourly maximum value) an electro-mechanical indicator device which can maintain an existing indicated value in ths event of a power failure. For example, the or each such electro-mechanical indicator dei'ice may comprise a cumulative counter having a step4 4 ® s ping motor qr a roller-type counter, or a step-by-step switching means (such as is used, f or example, in telephone charge meters ).

However, the electro-mechanical indicator device(s) maybe dispensed with and replaced by, e.g. an electronic display, if the battery and/or non-volatile store is capable of making available the desired prevailing value(s) in the event of a power failure.

Claims

1. A maximum-demand electricity meter comprising an electronic kilowatt-hour measurement mean;;, an electronic maximum demand register, ε generator for generating timing signals for determining 3 switching instants in the meter, a current supply means, control means for indicator devices for indicating values in the mater, and an indicator device for indicating the maximum-demand value, the meter further comprising means for maintaining an existing indicated valuv in the event of a power failure and/or means for 10 maintaining, ia the event of a power failure- an electrical signal which represents an existing measurement value in the meter

2. A meter according to claim 1, wherein the kilowatt-hour measurement means, the maximum demand register, the timing signal generator, the current supply means, and said control means are 15 housed in a -trwron electrically screened housing.

3. Α ra’-sr according to claim 2, wherein the kilowatt-hour sisaaurSiW-it means the r-i: =.. ·;:ί demand rsyi&tjf, the timing signal generator, the currant supply means, and na;d control means are substantially fully electronic. 20

4. , A meter according to claim 3, wherein the kilowatt-hour measurement means, the maximum demand register, the timing signal generator, the current supply meant», and said control means are solid-state devices.

5. Ά. meter according to claim 4. wherein the kilowatt-hour 25 measurement means, the maximum register, the timing signal generator, the current supply means, and said control means comprise one or more integrated circr.it (s).

6. A meter according to any one of the preceding claims, wherein the timing signal generator is incorporated in the maximum demand register.

7. A meter according to any one of the preceding claims, wherein said control means is arranged to provide a data output signal for external-recorder means, which signal represents data in the meter.

8. A meter according to any one of the preceding claims, wherein said means for maintaining an existing indicated value and/or said means for maintaining an electrical signal in the event of a power failure comprises a battery whieh is kept substantially fully charged during normal operation of the meter.

9. A meter according to any one of the preceding claims, wherein said means for maintaining an existing indicated value and/or said means for maintaining an electrical signal in the event of a power failure comprises a non-volatile store.

10. A meter according to any one of the preceding claims, wherein said indicator device is an electro-mechanical indicator device comprising a stepping motor, a roller-type counter, or a step-by-step switching means.

11. A meter according to any one of the preceding claims, wherein said indicator device is arranged to indicate a monthly maximum-demand value and to be reset at monthly intervals.

12. A meter according to any one of the preceding claims, wherein the maximum demand register is arranged to be reset periodically, a plurality of times each hour.

13. A meter according to claim 12, wherein a present value of the maximum demand register is arranged to be indicated on the or a further said electro-mechanical indicator device.

14. A meter according to any one of the preceding claims, wherein the timing signal generator is arranged to generate substantially all of the required timing signals for the meter.

15. A meter according to any one of claims 1 to 13, including means for receiving and decoding switching signals for the meter and sent to the meter from a remote point.

16. A meter according to any one of the preceding claims, 5 wherein the meter is arranged to operate on any desired one of a plurality of different tariffs, and to switch from one tariff to another in response to a said timing signal or a said switching signal.

17. A maximum-demand electricity meter substantially as 10 hereinbefore described with reference to the accompanying drawing