IE45355B1

IE45355B1 - Energy meters

Info

Publication number: IE45355B1
Application number: IE141977A
Authority: IE
Original assignee: Heliowatt Werke
Priority date: 1976-07-09
Filing date: 1977-07-08
Publication date: 1982-08-11
Also published as: BE855873A; FR2357909A1; NL7704418A; GB1542814A; DE2631509A1; LU77710A1; DE2631509B2; IT1080626B; IE45355L; DK208277A

Abstract

A method of automatically controlling meters which are used to measure electrical or other energy consumption and contain a microcomputer and an indicating device and / or additional devices with a microcomputer, an indicating device and a device permanent memory. The read-only memory of the microcomputer contains a program by which the microcomputer and / or all the detectable devices of the electronic counter are checked at sufficient intervals, any recognized defect is announced and the further processing is blocked at the same time. and the recording of data; before the definitive blocking of the counter, the numerical values calculated until the appearance of a defect are entered in the permanent memory, and, to control said permanent memory, the computer triggers a reading process after each registration process and compares the two values, the locations of the memory being occupied by a sign once each in turn repeated The invention applies in particular to electronic meters with maximum indicator.

Description

This invention relates to the testing of meters which serve to meter electrical; or other energy.

Power supply organisations expect energy meters to operate reliably for a .number of decades. We believe that no reliability values exist at present for such long periods of time where application is made of modern technologies, for example the MOS technique, by which major switching networks are now largely constructed. Particularly with the complicated constructions, failures may occur for many reasons, some faults 1° arising only temporarily and/or in dependence upon t particular temperature ranges. according to the present invention, there is provided an energy meter which includes a microcomputer for processing data in the meter, the microcomputer being adapted in operation 15 by reason of a test program ttcred in a program store thereof to test at least a part of the meter, and means being provided for indicating when a fault is detected.

Typically, the meter may include a visual display device for displaying an output value of the meter, and the aforesaid 20 program store of the computer may be a read-only store.

Advantageously, the microcomputer is arranged to stop further data processing when a fault is detected. Preferably, the test program is operative to test all of the electronic circuitry of the meter that is capable of being monitored.

Advantageously, means may be provided for indicating visually when a fault is detected by the test program, and - 2 45355 a visual display device of the meter may be adapted also to indicate fault detection. For example, the visual display device may be arranged to visually indicate a fault by causing flashing of digits of the display device, or by displaying a signal composed of alpha-numeric characters. The meter may advantageously be so arranged that, upon detection of a fault, display of output va! es of the meter on the visual display device is suppressed.

Triggering of the test program at invervals is preferably controlled by a time base counter present in the microcomputer and wnich serves, for example, in a maximum-demand meter, to determine the duration of a measuring period. If no counter is present, there may usually be available to a meter a supply frequency from which a time base can be derived, or if no mains supply is ;resent, foi· example, as in the case of a heat meter, an incorporated freely-running oscillator nay be used. The test program may alternatively be carried out in response to an external order received by the meter.

When a fault is detected by the test program, an optical or other suitable fault indicating means must first be set in operation. Such a fault indication may be either constantly available or become available only upon interrogation or reading. 'i‘he following procedure may be decided in accordance with the nature of the fault u.u lu.e sii'-.cture of the test program,, In the case of minor faults, the equipment may be able to continue to operate satisfactorily in individual parts; 4S35S - ί in the case of serious faults, the com;uter preferably stops further data processing.

For testing a non-volatile semiconductor store, for example a MHOS store, should such a store be present, special uctions must be taken to take account of the . articular nature of said store. Such stores usually permit only a limited number of write cycles and require, before each relatively protracted write operation, an erasing operation which lasts, for example, one second. The information stored in such a non10 volatile semiconductor store must us-.ally be repeatedly refreshed at appropriate intervals. Therefore, in order to test such a non-volatile store, the computer may be so arranged that, whenever it has written a value into the non-volatile store, it should read out this value and compare it with the written-in value for the purpose of checking. However , a large part of the content of the store may be re-written only at very rare intervals or rally in the event of a refreshment.

A fault which has meanwhile arisen in such a rarely-used part of the store may therefore only be detected at the next refreshment cycle. Xn principle, this defect cannot be overcome without shortening the useful life of the said store. The number of additional possible read operations, however, is a few orders of magnitude higher than the number of write operations, so- that in principle, as long as a mains supply is present, it may be possible for all the data kept in the non-volatile store also to be carried in the work store of the computer; in this way, the agreement -44 535-5 of the two stor& contents can be checked at shorter intervals. Advantageously, the microcomputer can be arranged to write into the non-volatile store, upon the detection of a fault and before stopping processing in the meter, data processed in the meter prior to detection of the fault.

Another main task of the non-volatile store can be, on failure of a mains supply, to save all data that will be required after restoration of the mains supply. For this purpose, a write operation is normally carried out when a mains failure is detected. The meter then advantageously comprises means for maintaining power, after a power failure, for a sufficiently long time to enable data to be transferred, to the non-volatile store and to enable the computer to read out the data once after if has been written and to check the IS accuracy thereof in order that a fault signal may be set up when a fault is detected, before the supply voltage of the electronic system collapses. By virtue of its nature, the fault signal may be retainable only in a non-volatile store element. Therefore, it may be registered by being written into the non-volatile store. I? the fault signal is to be maintained also in the event of a defect in the non-volatile store, an additional storage element , for example a bistable relay, may be provided.

So-called walking bit patterns are commonly employed for the tasting of stores. In such cases, all the locations of a store are occupied in cyclic sequence by a test bit pattern, -545355 or word. This method may be applied in. refreshment of a nonI volatile store, so that after a few refreshment cycles, each stored value has occupied once each storage location present. This method is particularly desirable when, for example, one of the stored numerical values serves principally for testing purposes. In the case of an electronic maximum electrical energy demand meter, for- example, demand-prpportional pulses supplied by a kilowatt-hour metersay be summated by a microcomputer and displayed on an indicating device in the form of a kilowatt-hour indication . If the kilowatt-hour meter has its own kilowatt-hour display means, comparison of the two . meter readings can show whether the maximum register is operating correctly. In the event of mains failure, the existing reading of the electronic kilowatt-hour register is written into the non-volatile store. When a defect arises even at only one storage location it will be shown d’ter some time, on cyclic occupation of the storage locations, by the fact that the two kilowatt-hour indications no longer agree.

Claims

1. An energy meter which includes a microcomputer for processing data in the meter, the microcomputer being adapted in operation by reason of a test program stored in a program store thereof to test at least a part of the meter, and means being provided for indicating when a fault is detected.

2. A meter according to claim 1, including a visual displaydevice for displaying an output value of the meter.

3. A meter according to claim 1 or 2, wherein said program store is a. read-only store.

4. A meter according to claim 1, 2 or 3, wherein the microcomputer is arranged to stop further data processing when a fault is detected.

5. A meter according to any one of the preceding claims, including a ncn-volatile store.

6. A meter according : ::· claims 4 and 5, wherein the microcomputer is arranged to write into the non-volatiie store, upon detection of a fault and before stopping processing in the meter, Guta processed in the meter prior no detection of the fault.

7. A meter- according tc claim 5 or 6, wherein the microcomputer is arranged to test the non-volatile store- by reading each store location immediately after a value has been written therein and oom -aring the value aa read cut from, with the value as written into, the store location.

8. A meter- according to claim 7, wherein the microcomputer is -7arr'anged to shift values cyclically through the non-volatile store, for testing of the store.

9. Λ meter according to any one of the preceding claims, wherein the test program is arranged to be carried out at intervals determined by a counter of the microcomputer^

10. A meter according to any one of claims 1 to 8, wherein the test program is arranged to be carried out in response to an external instruction received by the meter.

11. A meter according to any one of thA preceding claims, wherein the test program is operative to test all of the electrdnic circuitry of the meter that is capable of being monitored.

12. A meter according to claim 5 or to any one of claims 6 to 11 as appendant thereto, wherein the meter includes means for maintaining, after a power failure, power supply for a sufficiently long time to enable data to be transferred into the non-volatile store.

13. A meter according to any one of the preceding ·“ claims, including means for indicating visually when a fault is detected.

14. A meter according to claims 2 and 13, wherein said visual display device is adapted to indicate visually when a fault is detected.

15. A meter according to claim 14, wherein said visual display device is arranged to visually indicate a fault by causing flashing of digits of the display device. -845355

16. A meter according to claim 14, wherein said visual display device is arranged to visually indicate a fault by displaying a signal composed of alpha-numeric characters. 1?. A meter according to claim 2 or any dependent claim 5 thereof, wherein, upon detection of a fault, display of output values of the meter on said visual display device is suppressed, 18o A meter according to claim 7 or any dependent claim thereof, wherein the microctv«.’cuter is arranged to test the non-volatile store by writing a test word into the non-volatile store and 10 comparing the test word as read out from, with the test word as written into, the store.

17. 19. A meter according to ary preceding claim, for metering electrical energy consumption,

18. 20. An energy meter according to olaim 1 and substantially 15 us . described herein.