CN1130568C - High-accuracy current measuring method - Google Patents
High-accuracy current measuring method Download PDFInfo
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- CN1130568C CN1130568C CN 00123302 CN00123302A CN1130568C CN 1130568 C CN1130568 C CN 1130568C CN 00123302 CN00123302 CN 00123302 CN 00123302 A CN00123302 A CN 00123302A CN 1130568 C CN1130568 C CN 1130568C
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- copper
- resistance
- linear amplifier
- copper conductor
- measuring method
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- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Abstract
The present invention relates to a high-accuracy current measuring method in which one end of a varnished wire wound around a copper conductor is connected with the negative input end of a linear amplifier, and the other end is connected with one end of the copper conductor of which the other end is connected with the positive input end of the linear amplifier. The output end of the linear amplifier is grounded via a digital voltmeter, the negative input end is connected with the output end via R1, and the positive input end is grounded via R2. The copper conductor is connected in series with a line to be measured. A voltage value measured on the voltmeter is substituted to some formula (mentioned above), and then a current intensity value can be measured accurately with the measurement accuracy as high as 0.2% and a measurement range of 0.1-3000%. The present invention better than the existing various current transformers has the advantages of convenient operation, low cost, high safety and reliability.
Description
(1) technical field
The present invention relates to a kind of measuring method of electric current, particularly relate to a kind of measuring method of directly on triple-phase line, carrying out electric current.
(2) technical background
At present, electromagnetic current transducer is generally adopted in the measurement of electrical quantity in electric system, along with development and national economy, drive the tremendous development of electric system, power network schedule automation, unattended operation transformer station, intelligent switchboard, intelligent switch, intelligent breaker, equipment automatization, digitizing, networking, integrated have become inexorable trend.The requirement of electrical parameters detection is more and more higher, and electrical parameters detection not only reflects electric current, also reflects phase place, waveform, mutation rate.The estimated current detection method can be divided into four kinds substantially, i.e. electromagnetic current transducer, photo-electric current transformer, heap that formula current transformer, resistance type current mutual inductor.Current transformer need to finish its specific function under short-circuit conditions, and the primary current aperiodic component is big in the transient process in transient process, decay is slow, causes misoperation easily.Though the electromagnetic current transducer simple possible, along with improving constantly of electric power transfer capacity, electric pressure has reached 500KV, and next electric pressure may reach 750KV or 1000KV.At this moment, some limitation of traditional current transformer are more and more outstanding, and price is in continuous increase.In addition, current transformer also has its intrinsic magnetic saturation, ferroresonance, dynamic range is little, frequency band is narrow, power consumption is big, consume starting material such as a large amount of copper and silicon steel, and install, transportation difficulty, volume be big, heavy, and shortcomings such as oil is inflammable and explosive are arranged.Based on the current transformer of your effect principle of heap, possible in theory, but because the temperature coefficient of Hall element is big, poor stability so measuring accuracy is not high, brings very big restriction to application.Resistance type current sensor is based on the current measurement of Ohm law, and its electrical characteristics are good, and are simple in structure, but very easily damage if any short-circuit current, generally is applied at present in the following little current control system of 10A.
World's notice has focused on the photoelectric sense technology (optical current transformet is called for short OCT) based on FALADAY magneto-optic effect principle at present.Compare with traditional electromagnetic electric current mutual inductor, the photo-electric current transformer has that anti-electromagnetic interference (EMI), no saturated, measurement range are big, the little advantage such as in light weight of bandwidth, digital data transmission, volume.But because magneto-optic memory technique Fil moral number can not be very big, light must realize that in material (purpose is to increase light path in repeatedly reflection, improve sensitivity), and temperature influence, and there is design in accuracy that optical system requires and make difficulty, therefore little galvanic areas exists measures defective, though claim through 30 years companies such as effort 3M and to succeed in developing OCT, does not up to the present also see real commercial OCT.
(3) summary of the invention
Purpose of the present invention, provide a kind of simple to operate, measuring accuracy is high, the current measuring method of little, the naked puzzlement of temperature influence, volume not.
The technical scheme that adopts is:
Current measuring method comprises linear amplifier, digital voltmeter, resistance R
1, R
2, R
Copper, R
The copper temperature compensationR
CopperBe above copper conductor, R of one section 1cm
The copper temperature compensationIt is one section copper enameled wire.One end of copper enameled wire is fixedlyed connected with an end of copper conductor, and the copper enameled wire is entangled on the copper conductor, and the other end of copper enameled wire is connected with the input negative terminal of linear amplifier.The other end of copper conductor is connected with the input anode of linear amplifier.The output terminal of linear amplifier is through digital voltage Table V ground connection.The input negative terminal of linear amplifier is through R
1Be connected with its output terminal, the input anode of linear amplifier is through R
2Ground connection.Copper conductor is by on tested phase line.Direct read-out voltage V value on digital voltage.This magnitude of voltage is with strength of current, copper conductor resistance R
Copper, copper enameled wire resistance R
The copper temperature compensationVariation and change, that is:
So, can derive:
Wherein K is a constant.
The temperature compensation of above-mentioned R copper also can be the sheet of copper resistance of a tape insulation layer or the tubular copper resistance of a tape insulation layer.The temperature compensation of R copper also can be arranged on copper conductor inside.
Therefore, the above-mentioned formula of read-out voltage value substitution just can be measured strength of current from the digital voltmeter.
Above-mentioned measuring method also can adopt in copper conductor inside or a plurality of copper temperature compensation of outer setting resistance, linear amplifier and the metering circuit that D.C. voltmeter is formed.All in the example of protection.
Environment temperature-40 ℃～85 ℃, under the situation of conductor temperature-50～200 ℃, the current measurement precision can reach 2 ‰, and measurement range is 1 ‰～3000%.Measuring accuracy is high, is better than known various current transformers.Also have advantages such as easy to operate, cheap, safe and reliable, easy to carry in addition.
(4) description of drawings
Fig. 1 is the metering circuit schematic diagram of a kind of embodiment of the present invention, Fig. 2 be Fig. 1 etc. discharge change plan.
(5) embodiment
Current measuring method comprises the copper conductor 2, linear amplifier 3, digital voltmeter 4 and the resistance R that are wound with enameled wire 1
1, R
2The resistance of enameled wire 1 is R
The copper temperature compensationThe resistance of copper conductor 2 is R
CopperOne end of enameled wire 1 is fixedlyed connected the input negative terminal of its other end wiring amplifier 3 with an end of copper conductor, the input anode of the other end wiring amplifier 3 of copper conductor 2.The defeated negative terminal of putting of linear amplifier 3 is through resistance R
1The output terminal of wiring amplifier 3.The input anode of linear amplifier 3 is through R
2Ground connection, linear amplifier 3 is through digital voltmeter 4 ground connection.R
1Be 600 Ω, R
2Be that 20 Ω, linear amplifier are 3140, digital voltmeter is 3150 tables.Copper conductor 12 is serially connected in the test line, by recording voltage V value, and passes through formula:
Can get current value, degree of accuracy reaches 2 ‰.
Claims (3)
1, current measuring method comprises the first resistance (R
1), the second resistance (R
2), resistance R copper, the temperature compensation of resistance R copper, linear amplifier (3), digital voltmeter (4), it is characterized in that:
A, R copper are copper conductor (2), the input anode of a termination linear amplifier (3) of copper conductor (2), and the temperature compensation of its other end connecting resistance R copper, the other end of resistance R copper temperature compensation is connected with the input negative terminal of linear amplifier (3); The input negative terminal of linear amplifier is through the first resistance (R
1) be connected with the output terminal of linear amplifier (3); The input anode is through the second resistance (R
2) ground connection;
B, copper conductor (2) are serially connected in the test line;
C, the magnitude of voltage V substitution formula that will read from digital voltmeter (4):
Can measure the strength of current value.
2, current measuring method according to claim 1 is characterized in that the temperature compensation of described resistance R copper is enameled wire (1), and enameled wire (1) is wrapped on the copper conductor (2).
3, current measuring method according to claim 1 is characterized in that the temperature compensation of described resistance R copper is sheet of copper resistance or the tubular copper resistance that is arranged on the outside or inner tape insulation layer of copper conductor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00123302 CN1130568C (en) | 2000-11-24 | 2000-11-24 | High-accuracy current measuring method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00123302 CN1130568C (en) | 2000-11-24 | 2000-11-24 | High-accuracy current measuring method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1295253A CN1295253A (en) | 2001-05-16 |
| CN1130568C true CN1130568C (en) | 2003-12-10 |
Family
ID=4589759
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 00123302 Expired - Fee Related CN1130568C (en) | 2000-11-24 | 2000-11-24 | High-accuracy current measuring method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1130568C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101509881B (en) * | 2009-02-27 | 2012-06-27 | 东莞市康汇聚线材科技有限公司 | On-line electrical leakage detecting method for enameled wire |
| DE102016014130B3 (en) * | 2016-11-25 | 2017-11-23 | Isabellenhütte Heusler Gmbh & Co. Kg | Current measuring device |
-
2000
- 2000-11-24 CN CN 00123302 patent/CN1130568C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1295253A (en) | 2001-05-16 |
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| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20031210 Termination date: 20121124 |