CA2239369C - Electronic measurement device - Google Patents
Electronic measurement device Download PDFInfo
- Publication number
- CA2239369C CA2239369C CA002239369A CA2239369A CA2239369C CA 2239369 C CA2239369 C CA 2239369C CA 002239369 A CA002239369 A CA 002239369A CA 2239369 A CA2239369 A CA 2239369A CA 2239369 C CA2239369 C CA 2239369C
- Authority
- CA
- Canada
- Prior art keywords
- measuring device
- correction factor
- converter
- value
- electronic measuring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/04—Testing or calibrating of apparatus covered by the other groups of this subclass of instruments for measuring time integral of power or current
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
- G01R21/133—Arrangements for measuring electric power or power factor by using digital technique
Abstract
In order to achieve an improvement in measurement accuracy for an electronic measuring device (1), whilst at the same time compensating for influences on the measurements, provision is made for a correction factor (K1) to be stored in a correction element (7a) when the measuring device (1) is first set up. During operation, provision is made for a test voltage (Vt) to be connected which is compared with a reference value (R1) stored during setting. If there is a difference between the two values (R1,R2), a new correction factor (K1,K2) is produced which compensates for any measurement signal effect. The measuring device (1) is particularly suitable for electricity meters.
Description
DESCRIPTION
Electronic measuring device The invention relates to an electronic measuring device, in particular a meter, having an A/D converter and a digital signal processing device.
WO 95/10781 discloses an electronic measuring device in which digitized measurement signals are monitored for a measurement error. If a measurement error occurs, a correction pulse is produced, so that the measurement error is compensated for. This measuring device is preferably used for measuring consumption, in particular for a meter.
If an A/D converter is used for such an electronic measuring device, said converter generally requires a reference voltage source. This is also the case if a sigma-delta modulator (SD modulator) is used. The reference voltage must meet high requirements, since the accuracy of the measuring device is directly dependent on the reference voltage. High measurement accuracy therefore also requires a precise reference voltage, which is very complicated to produce, and it is not necessarily possible to vouch for operational reliability.
The invention is based on the object of specifying a measuring device which exhibits high measurement accuracy whilst at the same time compensating for influences on the measurements.
The invention achieves the object with an electronic measuring device, comprising: at least one A/D
converter for receiving measurement signals including a test voltage having a value; a reference voltage source connected to said at least one A/D converter for operation; and a ' 20365-3872 digital signal processing device connected downstream of said at least one A/D converter; said signal processing device having a correction element with a first stored reference value and a resulting first correction factor for compensating for a measurement error in an upstream signal detection, said correction element producing a new correction factor when a difference exists between the first reference value and the value of the test voltage, and the new correction factor is one of the first correction factor corrected corresponding to the difference, and an additional correction factor.
In this manner, the entire measurement path for signal detection is based on the test voltage. This means that, for example, systematic errors, in particular the temperature response of the A/D converter or an effect of an upstream multiplexer, are detected and compensated for.
This produces dynamic measurement error compensation, as it were.
It is advantageous if a first correction factor adapted or corrected on the basis of the difference is used as the new correction factor. This makes simple dynamic adaptation of the correction factor possible. If necessary, the original value can also be saved in a further store as a precaution.
As an alternative to this, an additional correction factor can be used as the new correction factor.
This enables the original setting and the dynamic or instantaneous factor to be separated. The separate correction factor is responsible for dynamic adaptation during operation.
2a Advantageously, means for cyclically checking the difference or producing the new correction factor are provided. This means that the measurement accuracy is continuously checked and adapted in respect of a changed reference voltage or other influences on the measurements.
In this case, the cycle times can be prescribed depending on the measurement accuracy desired.
The measurement signals used can be current and voltage signals, the signal processing device comprising means for metering electrical power consumption. This constitutes a preferred application of the invention. The measuring device is then used as a meter.
The A/D converter advantageously has a sigma-delta modulator (SD modulator). This produces favorable interaction in terms of precise processing of measured values.
The signal processing device preferably produces an error signal whenever the difference exceeds a prescribed limit value. This provides additional error monitoring.
The invention as well as other advantages and details are described in greater detail below with reference to an exemplary embodiment and to the drawing.
The figure shows an electronic measuring device 1 which is preferably used as a meter for electrical power. In principle, the measuring device can also be used for other applications, e.g. for temperature detection and processing, in which an analog signal is to be processed digitally.
For signal detection and processing, the measuring device 1 comprises a series circuit having a multiplexer 3, an A/D
converter 5 connected downstream of the latter and a subsequent digital signal processing device (called device 7 below). The device 7 preferably has a microcomputer and/or a digital signal processor for signal processing. All signal processing is therefore carried out with the aid of programs or program modules which may, if appropriate, also be used twice for different functions.
The device 7 has a control and display device 9 connected to it. This has, for example, display means or a display 13, a keypad 15 and/or an interface 11. This provides a comprehensive data input and output facility for the measuring device 1.
Signal detection involves initially feeding measurement signals, in particular a voltage V and a current I, to the measuring device 1, feeding them via the multiplexer 3 to the A/D converter 5 for digitization.
This signal detection can, of course, also be designed to be multichannel, e.g. for detecting multiphase voltages and currents or for detecting current and voltage separately. In such a case, a number of multiplexers and/or A/D converters might then be connected to the device 7 as appropriate.
In order for it to operate, the A/D converter 5 requires a reference voltage Vr, which is a DC voltage. This is supplied to the A/D converter from a reference voltage source 17. If the device 1 is designed as a module or semiconductor component, it is possible, for example, to produce the reference voltage input of the A/D converter 5 and the output of the reference voltage source 17 separately and, if appropriate, connect them to one another externally using a bridge. This makes checking operations possible, wherein a voltage from an external voltage source can then also be supplied to the A/D converter 5. The reference voltage source 17 is preferably a constituent part of the device 1.
The device 7 has a correction element 7a. A first correction factor K1, which corresponds to a first stored reference value R1, is saved in a store for the correction element 7a. In addition, the correction factor Kl may already contain further multiplication factors or other factors for the purpose of (computational) simplification.
In order to set or save the reference value R1 for the first time, as when it is set or adjusted in the factory for the first time, one input of the multiplexer 3 is initially connected, for example, to ground (shown as the ground symbol in the figure) and the resulting digitized voltage value is initially stored. This value corresponds to the DC component from signal detection. The input used for this purpose may be a special input or an input which is used for current or voltage.
In addition, a highly accurate test signal Vt (a test voltage used as a new reference or a new base) is applied to another input of the multiplexer 3. The resulting difference value between the voltage value of the DC component and the measured value of the test signal Vt corresponds to the actual value of the test signal Vt. This value is stored as the first reference value R1, thereby producing the resulting correction factor K1 for all other digitized measured values.
During operation of the measuring device 1, a further comparison with a test signal Vt is preferably carried out at cyclic intervals (which can be prescribed manually or automatically). This can be produced by the same voltage transmitter or, for example, by a voltage transmitter installed at the location where the device 1 is installed. The time intervals of the cycles can be prescribed as per requirements. The corresponding digitized value is stored as the second new reference value R2. After this, a comparison is made between the first reference value R1 and the second reference value R2. If they are different, a new correction factor is determined.
This can be done such that, for example, the first correction factor K1 is formed again or is overwritten, or that a completely new and separate correction factor K2 is placed in a further store which is then used for operation at that time.
This makes it possible to identify changes in the detected measured values, so that the measurement accuracy can be continuously adapted and maintained. For the first basic setting, the correction factor K2 can be equal to K1, or may have a default value, for example 1.
Should the difference between the values R1 and R2 exceed a prescribed limit value, it is possible that the device 7 will produce an error signal which will then be signalled via the control and display device 9 or via the interface 11 to a superordinate central control station. The error signal is then an indication that there is a significant measurement error.
The measuring device 1 is particularly suitable for use as a precision meter for class 0.5 or 0.2. In this instance, the test signal Vt fed to the measuring device 1 must be highly accurate and satisfy the appropriate calibration or standardization requirements.
The measuring device shown has the advantage that the entire signal detection process or the measuring system is based on the external test signal, in particular its reference voltage.
This obviates systematic errors, such as the effect of temperature on the multiplexer 5 or on the switch resistance when a sigma-delta modulator is used.
Of course, if the measuring device is used as a meter, the relevant regulations with regard to standardization etc. have to be taken into account. A particular application is conceivable, for example, for detecting consumption without any bearing on billing, e.g. in a company. The test signal Vt can be connected to an input permanently, for example. The test signal source necessary for this can be incorporated in the measuring device 1 or be connected externally.
Alternatively, it is also possible to make temporary connections or connections which are repeated at specifiable intervals.
Electronic measuring device The invention relates to an electronic measuring device, in particular a meter, having an A/D converter and a digital signal processing device.
WO 95/10781 discloses an electronic measuring device in which digitized measurement signals are monitored for a measurement error. If a measurement error occurs, a correction pulse is produced, so that the measurement error is compensated for. This measuring device is preferably used for measuring consumption, in particular for a meter.
If an A/D converter is used for such an electronic measuring device, said converter generally requires a reference voltage source. This is also the case if a sigma-delta modulator (SD modulator) is used. The reference voltage must meet high requirements, since the accuracy of the measuring device is directly dependent on the reference voltage. High measurement accuracy therefore also requires a precise reference voltage, which is very complicated to produce, and it is not necessarily possible to vouch for operational reliability.
The invention is based on the object of specifying a measuring device which exhibits high measurement accuracy whilst at the same time compensating for influences on the measurements.
The invention achieves the object with an electronic measuring device, comprising: at least one A/D
converter for receiving measurement signals including a test voltage having a value; a reference voltage source connected to said at least one A/D converter for operation; and a ' 20365-3872 digital signal processing device connected downstream of said at least one A/D converter; said signal processing device having a correction element with a first stored reference value and a resulting first correction factor for compensating for a measurement error in an upstream signal detection, said correction element producing a new correction factor when a difference exists between the first reference value and the value of the test voltage, and the new correction factor is one of the first correction factor corrected corresponding to the difference, and an additional correction factor.
In this manner, the entire measurement path for signal detection is based on the test voltage. This means that, for example, systematic errors, in particular the temperature response of the A/D converter or an effect of an upstream multiplexer, are detected and compensated for.
This produces dynamic measurement error compensation, as it were.
It is advantageous if a first correction factor adapted or corrected on the basis of the difference is used as the new correction factor. This makes simple dynamic adaptation of the correction factor possible. If necessary, the original value can also be saved in a further store as a precaution.
As an alternative to this, an additional correction factor can be used as the new correction factor.
This enables the original setting and the dynamic or instantaneous factor to be separated. The separate correction factor is responsible for dynamic adaptation during operation.
2a Advantageously, means for cyclically checking the difference or producing the new correction factor are provided. This means that the measurement accuracy is continuously checked and adapted in respect of a changed reference voltage or other influences on the measurements.
In this case, the cycle times can be prescribed depending on the measurement accuracy desired.
The measurement signals used can be current and voltage signals, the signal processing device comprising means for metering electrical power consumption. This constitutes a preferred application of the invention. The measuring device is then used as a meter.
The A/D converter advantageously has a sigma-delta modulator (SD modulator). This produces favorable interaction in terms of precise processing of measured values.
The signal processing device preferably produces an error signal whenever the difference exceeds a prescribed limit value. This provides additional error monitoring.
The invention as well as other advantages and details are described in greater detail below with reference to an exemplary embodiment and to the drawing.
The figure shows an electronic measuring device 1 which is preferably used as a meter for electrical power. In principle, the measuring device can also be used for other applications, e.g. for temperature detection and processing, in which an analog signal is to be processed digitally.
For signal detection and processing, the measuring device 1 comprises a series circuit having a multiplexer 3, an A/D
converter 5 connected downstream of the latter and a subsequent digital signal processing device (called device 7 below). The device 7 preferably has a microcomputer and/or a digital signal processor for signal processing. All signal processing is therefore carried out with the aid of programs or program modules which may, if appropriate, also be used twice for different functions.
The device 7 has a control and display device 9 connected to it. This has, for example, display means or a display 13, a keypad 15 and/or an interface 11. This provides a comprehensive data input and output facility for the measuring device 1.
Signal detection involves initially feeding measurement signals, in particular a voltage V and a current I, to the measuring device 1, feeding them via the multiplexer 3 to the A/D converter 5 for digitization.
This signal detection can, of course, also be designed to be multichannel, e.g. for detecting multiphase voltages and currents or for detecting current and voltage separately. In such a case, a number of multiplexers and/or A/D converters might then be connected to the device 7 as appropriate.
In order for it to operate, the A/D converter 5 requires a reference voltage Vr, which is a DC voltage. This is supplied to the A/D converter from a reference voltage source 17. If the device 1 is designed as a module or semiconductor component, it is possible, for example, to produce the reference voltage input of the A/D converter 5 and the output of the reference voltage source 17 separately and, if appropriate, connect them to one another externally using a bridge. This makes checking operations possible, wherein a voltage from an external voltage source can then also be supplied to the A/D converter 5. The reference voltage source 17 is preferably a constituent part of the device 1.
The device 7 has a correction element 7a. A first correction factor K1, which corresponds to a first stored reference value R1, is saved in a store for the correction element 7a. In addition, the correction factor Kl may already contain further multiplication factors or other factors for the purpose of (computational) simplification.
In order to set or save the reference value R1 for the first time, as when it is set or adjusted in the factory for the first time, one input of the multiplexer 3 is initially connected, for example, to ground (shown as the ground symbol in the figure) and the resulting digitized voltage value is initially stored. This value corresponds to the DC component from signal detection. The input used for this purpose may be a special input or an input which is used for current or voltage.
In addition, a highly accurate test signal Vt (a test voltage used as a new reference or a new base) is applied to another input of the multiplexer 3. The resulting difference value between the voltage value of the DC component and the measured value of the test signal Vt corresponds to the actual value of the test signal Vt. This value is stored as the first reference value R1, thereby producing the resulting correction factor K1 for all other digitized measured values.
During operation of the measuring device 1, a further comparison with a test signal Vt is preferably carried out at cyclic intervals (which can be prescribed manually or automatically). This can be produced by the same voltage transmitter or, for example, by a voltage transmitter installed at the location where the device 1 is installed. The time intervals of the cycles can be prescribed as per requirements. The corresponding digitized value is stored as the second new reference value R2. After this, a comparison is made between the first reference value R1 and the second reference value R2. If they are different, a new correction factor is determined.
This can be done such that, for example, the first correction factor K1 is formed again or is overwritten, or that a completely new and separate correction factor K2 is placed in a further store which is then used for operation at that time.
This makes it possible to identify changes in the detected measured values, so that the measurement accuracy can be continuously adapted and maintained. For the first basic setting, the correction factor K2 can be equal to K1, or may have a default value, for example 1.
Should the difference between the values R1 and R2 exceed a prescribed limit value, it is possible that the device 7 will produce an error signal which will then be signalled via the control and display device 9 or via the interface 11 to a superordinate central control station. The error signal is then an indication that there is a significant measurement error.
The measuring device 1 is particularly suitable for use as a precision meter for class 0.5 or 0.2. In this instance, the test signal Vt fed to the measuring device 1 must be highly accurate and satisfy the appropriate calibration or standardization requirements.
The measuring device shown has the advantage that the entire signal detection process or the measuring system is based on the external test signal, in particular its reference voltage.
This obviates systematic errors, such as the effect of temperature on the multiplexer 5 or on the switch resistance when a sigma-delta modulator is used.
Of course, if the measuring device is used as a meter, the relevant regulations with regard to standardization etc. have to be taken into account. A particular application is conceivable, for example, for detecting consumption without any bearing on billing, e.g. in a company. The test signal Vt can be connected to an input permanently, for example. The test signal source necessary for this can be incorporated in the measuring device 1 or be connected externally.
Alternatively, it is also possible to make temporary connections or connections which are repeated at specifiable intervals.
Claims (5)
1. An electronic measuring device, comprising:
at least one A/D converter for receiving measurement signals including a test voltage having a value;
a reference voltage source connected to said at least one A/D converter for operation; and a digital signal processing device connected downstream of said at least one A/D converter;
said signal processing device having a correction element with a first stored reference value and a resulting first correction factor for compensating for a measurement error in an upstream signal detection, said correction element producing a new correction factor when a difference exists between the first reference value and the value of the test voltage, and the new correction factor is one of the first correction factor corrected corresponding to the difference, and an additional correction factor.
at least one A/D converter for receiving measurement signals including a test voltage having a value;
a reference voltage source connected to said at least one A/D converter for operation; and a digital signal processing device connected downstream of said at least one A/D converter;
said signal processing device having a correction element with a first stored reference value and a resulting first correction factor for compensating for a measurement error in an upstream signal detection, said correction element producing a new correction factor when a difference exists between the first reference value and the value of the test voltage, and the new correction factor is one of the first correction factor corrected corresponding to the difference, and an additional correction factor.
2. The electronic measuring device according to claim 1, including a device for cyclically checking the difference.
3. The electronic measuring device according to claim 1, wherein said at least one A/D converter receives current and voltage signals as the measurement signals, and said signal processing device includes a device for metering electrical power consumption.
4. The electronic measuring device according to claim 1, wherein said at least one A/D converter includes a sigma-delta modulator.
5. The electronic measuring device according to claim 1, wherein said signal processing device presents an error signal whenever the difference exceeds a prescribed limit value.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19545511 | 1995-12-05 | ||
| DE19545511.8 | 1995-12-05 | ||
| PCT/DE1996/002215 WO1997021106A2 (en) | 1995-12-05 | 1996-11-20 | Electronic measurement device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2239369A1 CA2239369A1 (en) | 1997-06-12 |
| CA2239369C true CA2239369C (en) | 2003-02-04 |
Family
ID=7779351
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002239369A Expired - Fee Related CA2239369C (en) | 1995-12-05 | 1996-11-20 | Electronic measurement device |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US6084394A (en) |
| EP (1) | EP0866976B1 (en) |
| CA (1) | CA2239369C (en) |
| DE (1) | DE59606645D1 (en) |
| ES (1) | ES2155218T3 (en) |
| WO (1) | WO1997021106A2 (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6566882B2 (en) | 2001-06-29 | 2003-05-20 | Hubbell Incorporated | Method and apparatus for device-dependent calibration of relays for high accuracy operation at zero-crossing of input power signal |
| US6815942B2 (en) * | 2001-09-25 | 2004-11-09 | Landis+Gyr, Inc. | Self-calibrating electricity meter |
| US6748344B2 (en) | 2002-04-29 | 2004-06-08 | Eaton Corporation | Method and apparatus employing a scaling factor for measuring and displaying an electrical parameter of an electrical system |
| JP2004021067A (en) * | 2002-06-19 | 2004-01-22 | Sanyo Electric Co Ltd | Liquid crystal display and method for adjusting the same |
| US6996488B2 (en) * | 2002-10-15 | 2006-02-07 | Advanced Custom Sensors, Inc. | Sensor signal conditioner |
| US7164355B2 (en) * | 2004-05-19 | 2007-01-16 | Rosemount Inc. | Process transmitter with a plurality of operating modes |
| US7511468B2 (en) * | 2006-11-20 | 2009-03-31 | Mceachern Alexander | Harmonics measurement instrument with in-situ calibration |
| US7920976B2 (en) * | 2007-03-27 | 2011-04-05 | Electro Industries / Gauge Tech. | Averaging in an intelligent electronic device |
| DE102007045416A1 (en) * | 2007-09-21 | 2009-04-02 | Continental Teves Ag & Co. Ohg | Electronic circuit for correcting at least one digital measurement signal |
| DE102011102185B4 (en) | 2011-05-21 | 2018-09-13 | Bob Holding Gmbh | Voltage-dependent counter |
| EP2720063B1 (en) * | 2012-10-12 | 2020-02-05 | ALSTOM Transport Technologies | Automatic calibration of energy meter central unit |
| US8981972B2 (en) * | 2013-03-14 | 2015-03-17 | Analog Devices, Inc. | Background calibration of ADC reference voltage due to input signal dependency |
| US9677907B2 (en) * | 2013-03-14 | 2017-06-13 | Itron Inc | Intelligent receptacle |
| CN114121121B (en) * | 2022-01-27 | 2022-04-26 | 合肥悦芯半导体科技有限公司 | Test circuit |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3824588A (en) * | 1973-02-09 | 1974-07-16 | Us Navy | Analog to digital converter having digital offset correction |
| DE2630959C2 (en) * | 1976-07-07 | 1986-04-30 | Heliowatt Werke Elektrizitäts- Gesellschaft mbH, 1000 Berlin | Kilowatt hour meter with static measuring mechanism |
| US4200933A (en) * | 1976-07-30 | 1980-04-29 | Systron-Donner Corporation | Method of automatically calibrating a microprocessor controlled digital multimeter |
| US4127811A (en) * | 1976-09-03 | 1978-11-28 | Hewlett-Packard Company | Auto-calibrating voltmeter |
| DE2708075A1 (en) * | 1977-02-22 | 1978-08-24 | Heliowatt Werke | PROCEDURE FOR ELECTRONIC KILOWATT-HOUR METERS |
| JPS60110006A (en) * | 1983-11-18 | 1985-06-15 | Ohkura Electric Co Ltd | Multi-range controller |
| DK152458C (en) * | 1984-11-20 | 1988-07-25 | Total Electronic Enterprise | STATIC ELECTRIC ELECTRIC MEASUREMENT FOR POWER AND ENERGY MEASURED FROM A POWER SUPPLY NETWORK |
| CH673714A5 (en) * | 1985-05-02 | 1990-03-30 | Zellweger Uster Ag | |
| EP0240102A3 (en) * | 1986-03-31 | 1988-07-27 | Robinton Products Inc. | Power meter having self-test function |
| US4800513A (en) * | 1986-08-01 | 1989-01-24 | Motorola, Inc. | Auto-calibrated sensor system |
| US4951052A (en) * | 1989-07-10 | 1990-08-21 | General Electric Company | Correction of systematic error in an oversampled analog-to-digital converter |
| US5122735A (en) * | 1990-06-14 | 1992-06-16 | Transdata, Inc. | Digital power metering |
| DE4334766A1 (en) * | 1993-10-12 | 1995-04-13 | Siemens Ag | Electronic measuring device |
-
1996
- 1996-11-20 DE DE59606645T patent/DE59606645D1/en not_active Expired - Fee Related
- 1996-11-20 ES ES96945888T patent/ES2155218T3/en not_active Expired - Lifetime
- 1996-11-20 CA CA002239369A patent/CA2239369C/en not_active Expired - Fee Related
- 1996-11-20 WO PCT/DE1996/002215 patent/WO1997021106A2/en active IP Right Grant
- 1996-11-20 EP EP96945888A patent/EP0866976B1/en not_active Expired - Lifetime
-
1998
- 1998-06-05 US US09/092,129 patent/US6084394A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1997021106A3 (en) | 1997-08-07 |
| CA2239369A1 (en) | 1997-06-12 |
| EP0866976B1 (en) | 2001-03-21 |
| WO1997021106A2 (en) | 1997-06-12 |
| US6084394A (en) | 2000-07-04 |
| ES2155218T3 (en) | 2001-05-01 |
| EP0866976A2 (en) | 1998-09-30 |
| DE59606645D1 (en) | 2001-04-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |