WO1990000741A1 - Improvements relating to electric current measuring devices - Google Patents
Improvements relating to electric current measuring devices Download PDFInfo
- Publication number
- WO1990000741A1 WO1990000741A1 PCT/GB1988/000523 GB8800523W WO9000741A1 WO 1990000741 A1 WO1990000741 A1 WO 1990000741A1 GB 8800523 W GB8800523 W GB 8800523W WO 9000741 A1 WO9000741 A1 WO 9000741A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- amplifier
- solid state
- output
- metering device
- sensing device
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/32—Compensating for temperature change
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
Definitions
- the object of this invention is to provide an alternating current meter which is self-compensating for long term stability.
- Alternating current meters such as electricity meters are widely used in consumer supply lines to monitor power consumption and generally consist of rotating parts driven by induced magnetic fields, or solid state current sensing devices which require a number of adjustment potentiometers to allow setting up.
- the rotating parts in the former case cause wear and create errors and in the latter type temperature variations cause problems as do the ageing and changing of value of components.
- a metering device for measuring alternating electric current comprising a solid state sensing device adapted to measure the flux of an alternating magnetic field, and connected to a high gain ampli ⁇ bomb, the amplifier output being connected to a long time-constant integrating amplifier which will remove slow D.C. offset changes in the sensing device and the high gain amplifier, the output from the integrating amplifier being connected to the input of the high gain amplifier.
- the preferred form of solid state sensing device comprises a Hall effect sensor but another suitable device would be a magneto resistor sensor.
- the solid state sensing device could be located adjacent to a conductor to which the alternating current is to be applied.
- the solid state sensing device will incorporate temperature sensitivity compensation circuitry.
- the output from the high gain amplifier may be connected to any voltmeter or any power calculating and measuring system, the addition of which will create an electricity meter.
- Figure 1 shows a solid state current measuring device positioned to measure current in an A.C. line
- Figure 2 is a circuit diagram of the solid state device illustrated in Figure 1 ;
- FIG. 3 shows the solid state device with an auto compensation amplifier system of this invention.
- a solid state device 1 is inserted into the magnetic field 2 of a conductor 3 (which is of negligible impedance) so as to provide a measure of flux which in turn provides a measure of.current flowing in the conductor and in the load .
- the current is generated by the alternating power source 5.
- a typical solid state device 1 consists of a Hall effect element 6 giving an output 7.
- the element 6 is constructed to incorporate some compensation for sensitivity changes with temperature.
- Another suitable solid state device is a magneto resistor. Again, this would be provided with compensation for sensitivity changes with temperature.
- the output of the solid state device 1 is applied to a high gain amplifier 8 as shown in Figure 3.
- the circuit includes an auto compensating amplifier 10 which cures the drift problems associated with the amplifier 8 and with the device 1.
- the time constant of a capacitor 11 and a resistor 12 is made long with respect to the sinusoidal supply frequency generating the measured current.
- the auto compensating amplifier 10 will not attenuate the output signal of the amplifier 8.
- all D.C. components at the output of the amplifier 8 will be removed.
- slow changes due to temperature and ageing of components will have no effect.
- Another benefit is that D.C. offsets in the output of the solid state device 1 will be removed without the requirement for a trimming potentiometer.
- the output signal summed value will always be zero.
- the compensated output from the amplifier 8 is fed to a unit 13 which can be any suitable voltmeter or any power calculating and measuring system, the addition of which will create an electricity meter.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The output from a solid state sensing device associated with an electrical supply line is fed to a differential amplifier (8). The output from the amplifier (8) is fed to an auto compensating amplifier (10), the time-constant of which is determined by a capacitor (11) and a resistor (12). This time-constant is made long with respect to the sinusoidal supply frequency generating the measured current. By this means all D.C. components at the output of the amplifier (8) will be removed so that slow changes due to temperature and age of components in the solid state device (1) and the amplifier (8) will not affect the output from the amplifier (8).
Description
"Improvements relating to electric current measuring devices" .
The object of this invention is to provide an alternating current meter which is self-compensating for long term stability.
Alternating current meters such as electricity meters are widely used in consumer supply lines to monitor power consumption and generally consist of rotating parts driven by induced magnetic fields, or solid state current sensing devices which require a number of adjustment potentiometers to allow setting up. The rotating parts in the former case cause wear and create errors and in the latter type temperature variations cause problems as do the ageing and changing of value of components.
According to the present invention there is provided a metering device for measuring alternating electric current comprising a solid state sensing device adapted to measure the flux of an alternating magnetic field, and connected to a high gain ampli¬ fier, the amplifier output being connected to a long time-constant integrating amplifier which will remove slow D.C. offset changes in the sensing device and the high gain amplifier, the output from the integrating amplifier being connected to the input
of the high gain amplifier.
The preferred form of solid state sensing device comprises a Hall effect sensor but another suitable device would be a magneto resistor sensor. As part of an integrated unit to be connected, for example into an electricity supply line, the solid state sensing device could be located adjacent to a conductor to which the alternating current is to be applied. Ideally the solid state sensing device will incorporate temperature sensitivity compensation circuitry.
The output from the high gain amplifier may be connected to any voltmeter or any power calculating and measuring system, the addition of which will create an electricity meter.
The invention may be performed in various ways and a preferred embodiment thereof will now be described with reference to the accompanying drawings, in which:-
Figure 1 shows a solid state current measuring device positioned to measure current in an A.C. line;
Figure 2 is a circuit diagram of the solid state device illustrated in Figure 1 ; and
Figure 3 shows the solid state device with an auto compensation amplifier system of this invention. • As shown in Figure , a solid state device 1 is inserted into the magnetic field 2 of a conductor 3 (which
is of negligible impedance) so as to provide a measure of flux which in turn provides a measure of.current flowing in the conductor and in the load . The current is generated by the alternating power source 5. Referring to Figure 2, a typical solid state device 1 consists of a Hall effect element 6 giving an output 7. The element 6 is constructed to incorporate some compensation for sensitivity changes with temperature. Another suitable solid state device is a magneto resistor. Again, this would be provided with compensation for sensitivity changes with temperature. The output of the solid state device 1 is applied to a high gain amplifier 8 as shown in Figure 3. The circuit includes an auto compensating amplifier 10 which cures the drift problems associated with the amplifier 8 and with the device 1. The time constant of a capacitor 11 and a resistor 12 is made long with respect to the sinusoidal supply frequency generating the measured current. The auto compensating amplifier 10 will not attenuate the output signal of the amplifier 8. However, all D.C. components at the output of the amplifier 8 will be removed. Hence slow changes due to temperature and ageing of components will have no effect. Another benefit is that D.C. offsets in the output of the solid state device 1 will be removed
without the requirement for a trimming potentiometer. The output signal summed value will always be zero.
The compensated output from the amplifier 8 is fed to a unit 13 which can be any suitable voltmeter or any power calculating and measuring system, the addition of which will create an electricity meter.
Claims
1. A metering device for measuring alternating electric current comprising a solid state sensing device adapted to measure the flux of an alternating magnetic field, and connected to a high gain ampli- fier, the amplifier output being connected to a long time-constant integrating amplifier which will remove slow D.C. offset changes in the sensing device and the high gain amplifier, the output from the integrating amplifier being connected to the input of the high gain amplifier.
2. A metering device according to claim 1, wherein the solid state sensing device is a Hall effect sensor.
3. A metering device according to claim 1, wherein the solid state sensing device is a magneto resistor sensor.
4. A metering device according to any one of claims 1 to 3, wherein the solid state sensing device is located adjacent to a conductor to which the alternating current is to be applied.
5. A metering device according to any one of claims 1 to 4, wherein the solid state sensing device incorporates temperature sensitivity compensation circuitry.
6. A metering device according to any one of claims 1 to 5, wherein the output from the high gain amplifier is connected to a power calculation and measuring system, the addition of which will create an electricity meter.
7. A metering device according to any one of claims 1 to 6, wherein the output from the high gain amplifier- is fed to a counter display device.
8. A metering device according to claim 1 and substantially as herein described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/GB1988/000523 WO1990000741A1 (en) | 1988-07-05 | 1988-07-05 | Improvements relating to electric current measuring devices |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/GB1988/000523 WO1990000741A1 (en) | 1988-07-05 | 1988-07-05 | Improvements relating to electric current measuring devices |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1990000741A1 true WO1990000741A1 (en) | 1990-01-25 |
Family
ID=10629762
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/GB1988/000523 WO1990000741A1 (en) | 1988-07-05 | 1988-07-05 | Improvements relating to electric current measuring devices |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO1990000741A1 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3226168A1 (en) * | 1982-07-13 | 1984-02-23 | Siemens AG, 1000 Berlin und 8000 München | Device for integrating alternating voltages |
| EP0163460A1 (en) * | 1984-05-18 | 1985-12-04 | Pilkington Brothers P.L.C. | A system for measuring the electrical consumption of a load |
| EP0208590A1 (en) * | 1985-06-28 | 1987-01-14 | CHAUVIN-ARNOUX, Société en commandite par actions | Hall effect current-measuring probe |
-
1988
- 1988-07-05 WO PCT/GB1988/000523 patent/WO1990000741A1/en unknown
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3226168A1 (en) * | 1982-07-13 | 1984-02-23 | Siemens AG, 1000 Berlin und 8000 München | Device for integrating alternating voltages |
| EP0163460A1 (en) * | 1984-05-18 | 1985-12-04 | Pilkington Brothers P.L.C. | A system for measuring the electrical consumption of a load |
| EP0208590A1 (en) * | 1985-06-28 | 1987-01-14 | CHAUVIN-ARNOUX, Société en commandite par actions | Hall effect current-measuring probe |
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