CN202177678U - Circuit for detecting terminal outside primary measurement captive test (CT) secondary side connection state - Google Patents
Circuit for detecting terminal outside primary measurement captive test (CT) secondary side connection state Download PDFInfo
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- CN202177678U CN202177678U CN 201120278041 CN201120278041U CN202177678U CN 202177678 U CN202177678 U CN 202177678U CN 201120278041 CN201120278041 CN 201120278041 CN 201120278041 U CN201120278041 U CN 201120278041U CN 202177678 U CN202177678 U CN 202177678U
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Abstract
The utility model discloses a circuit for detecting terminal outside primary measurement captive test (CT) secondary side connection state, which comprises a testing CT, a self-oscillation circuit, a wave shaping circuit and a single-chip microcomputer circuit. The self-oscillation circuit comprises a secondary side of the testing CT, the input end of the wave shaping circuit is connected with the self-oscillation circuit, the output end of the wave shaping circuit is connected with a single-chip microcomputer, an output waveform of the self-oscillation circuit is input to the single-chip microcomputer after being shaped, the single-chip microcomputer calculates frequency on the specific point, status information of an open circuit or a short circuit or partial short circuit or normal of a detected CT secondary side circuit can be obtained according to corresponding relationship between frequency value and theoretical value. The circuit solves the problem that the existing detecting technique can not detect the partial short circuit of the CT secondary side, and effectively improves electricity-stealing resisting level. Furthermore, the circuit is simple, reliable, low in price and convenient to produce.
Description
Technical field
The utility model relates to the circuit that CT secondary side wiring state is once measured in a kind of sense terminals outside.
Background technology
At present, large-scale power user power utilization electric current both domestic and external reaches tens of to thousands of amperes.Generally convert the current supply electricity management terminal metering use of 5A or 1A into through current transformer (once measuring CT).Some lawless persons come stealing through the mode that will once measure CT secondary circuit short-circuit or disconnection.The short-circuit condition of opening of once measuring the CT secondary side through outside, terminal inner circuit supervision terminal prevents that stealing from having become important need.
Electric current or phase change that present existing technology can only once be measured the secondary side of the built-in CT that CT links to each other through test and outside are discerned the open circuit, short circuit of tested CT secondary side, are normally used electricity condition.And come the behavior of stealing not have effective detection means through will once measuring CT secondary side partial short circuit for some lawless persons.
The utility model content
The purpose of the utility model is to provide a kind of terminal inner circuit that can utilize once to measure open circuit, short circuit, partial short circuit, normal electricity consumption status detection method and the circuit thereof of CT secondary side in the identification terminal outside quickly and accurately.
The circuit of CT secondary side wiring state is once measured in the sense terminals outside that the utility model provides; Comprise test CT, self-maintained circuit, waveform shaping circuit, single chip circuit; Wherein self-maintained circuit comprises the secondary side of testing CT; The input end of waveform shaping circuit is connected with self-maintained circuit, and output terminal is connected with single-chip microcomputer, and the output waveform of self-maintained circuit is carried out importing single-chip microcomputer after the shaping; Single-chip microcomputer calculates the frequency of specified point, draws exterior of terminal according to the corresponding relation of frequency values and theoretical value and once measures open circuit or short circuit or the partial short circuit of CT secondary side circuit or status information normally.
The utility model utilizes the different principle of inductance value under CT secondary side open circuit, partial short circuit, all short circuits, the normal electricity consumption situation to obtain open circuit, short circuit, partial short circuit, normal four kinds of status informations of electricity consumption of this tested CT secondary side; Solve the situation that can not detect CT secondary side partial short circuit in the detection technique in the past, improved anti-electricity-theft level effectively.And this circuit is simple, reliable, cheap, convenient to be produced.
Description of drawings
Fig. 1 is the structural representation of the utility model.
Fig. 2 is the circuit structure diagram of the utility model.
Fig. 3 is the self-maintained circuit of the utility model.
Fig. 4 is the waveform shaping circuit of the utility model.
Fig. 5 is the single chip circuit of the utility model.
Fig. 6 is the utility model workflow diagram.
Embodiment
Can know that by Fig. 1 the utility model is that the test CT primary side that tested CT secondary side and terminal is built-in links to each other, obtain the wiring state information of this tested CT secondary side circuit through the inductance of built-in circuit test test CT secondary side.
Can know that by Fig. 2 the hardware circuit part of the utility model comprises self-maintained circuit, waveform shaping circuit, single chip circuit.Tested CT secondary side links with test CT primary side, and test CT secondary side and electric capacity, phase inverter are formed self-maintained circuit.The waveform of self-maintained circuit output is imported single-chip microcomputer through after the shaping.Single-chip microcomputer calculates the frequency of specified point, and the circuit that draws the Current Transformer Secondary side according to the corresponding relation of frequency values and theoretical value is opened short-circuit condition information.
Can know by Fig. 3; The self-maintained circuit of the utility model is made up of test CT secondary side, capacitor C 1, capacitor C 2, phase inverter D1, and the secondary side number of turn of wherein testing CT is not higher than 6 circles, and establishing tested CT secondary side equivalent inductance is L1; Test CT primary side equivalent inductance is L2; Test CT secondary side equivalent inductance is L3, and test CT coefficient of mutual inductance is M, and test CT primary side and secondary side turn ratio are n.When resonance frequency big (more than the 1KHz), the reactance parameter of CT and mutual inductor is far longer than wire resistor.Therefore, in equivalent electrical circuit, can ignore coiling and line resistance.Can obtain Fig. 3 self-maintained circuit equivalent inductance thus is:
Circuit resonant frequencies:
When occurring that CT short circuit or open circuit etc. are any to cause the situation that inductance L changes, circuit resonant frequencies changes thereupon, judges tested CT secondary side wiring situation thus, below is two kinds of extreme cases.
During short circuit, L1=0, equivalent inductance
；
During open circuit; L1=
, equivalent inductance
For improving the reliability that detects, the design demand emphasis of test CT is considered following two aspects:
One. select magnetic permeability than higher core material.Magnetic permeability is high; The inductance value of nature CT both sides also increases a lot;
value just alters a great deal accordingly, so just than being easier to distinguish variation inductance;
Two. reduce the number of turn of secondary side.Though the primary side number of turn has tailed off, inductance value also diminishes, and also can make L
Open: L
NormallyValue become big, help distinguishing open circuit and subnormal change of frequency.Through actual test, the number of turn of test CT secondary side is when 3 to 6 circles, and the test effect is best.
The means of stealing now are included in exterior of terminal and once measure the CT secondary side and shunt stealing, are exactly the so-called incomplete short circuit of electric current of going up, such as being short to 3A from the 5A shunting.This with power on directly that to flow to 3A be different because be shorted to 3A the impedance of primary side is changed, its equivalent inductance value diminishes.And the impedance of normally going up its primary side of 3A electric current is constant, thus electric current be near zero frequency can be than 3A on normal in the frequency of current zero-crossing point much bigger, just at this moment frequency is not the resonance frequency under the specific currents.
The foundation of minimum frequency detection algorithm is: under the situation of the influence of not considering magnetic hysteresis, the reflection of self-oscillatory minimum frequency be exactly electric current frequency when being zero.Therefore, this frequency has been eliminated the influence of electric current, and situation is the same during with CT loop no current, and this frequency can reflect the short-circuit state of opening of CT.
Because not exclusively short circuit is different with the impedance that direct upward electric current exterior of terminal in zero crossing once measures the CT secondary side; Its equivalent inductance value is exactly different so; So the frequency values of zero crossing is exactly different, thereby know that its minimum frequency value also is different.Therefore, the minimum frequency detection method can detect this exterior of terminal once to measure the CT secondary side be normal electricity consumption or partial short circuit.
Tested CT secondary side open circuit, short circuit both of these case are with the difference of partial short circuit, normal electricity consumption both of these case: when tested CT secondary side open circuit or short circuit, the waveform that the self-maintained circuit of being made up of test CT secondary side and electric capacity, phase inverter is exported is the waveform of a frequency stabilization; And when tested CT secondary side partial short circuit or normal electricity consumption, the waveform that the self-maintained circuit of being made up of test CT secondary side and electric capacity, phase inverter is exported contains the power frequency composition.Therefore, whether containing the power frequency composition according to the self-sustained oscillation output waveform can distinguish.Still short circuit is according to self-sustained oscillation output waveform frequency separation for tested CT secondary side open circuit, and tested CT secondary side is that partial short circuit or normal electricity consumption are then distinguished according to the minimum frequency value of self-maintained circuit output waveform.
Can know that by Fig. 4 waveform shaping circuit is made up of capacitor C 5, resistance R 1, phase inverter D2, D3.The function of this circuit is that the sine wave that self-maintained circuit is exported is converted into square wave, makes things convenient for the single-chip microcomputer calculated rate.
Can know that by Fig. 5 single-chip microcomputer D4 external power supply and crystal oscillator, single-chip microcomputer are received from the waveform of excited oscillation circuit output through a common IO pin.
Can know that by Fig. 6 software judges that flow process is:
The first step, continuous coverage surpass each square wave frequency of the self-maintained circuit output of a power frequency period time span;
Second step, whether contain the power frequency composition through differentiating this waveform, the wiring of CT secondary side is divided into two kinds of situation: open circuit or short circuit, normal electricity consumption or partial short circuit;
The 3rd step, distinguish open circuit and short circuit through survey frequency, distinguish normal electricity consumption and partial short circuit through minimum frequency;
In the 4th step,, then export the result if test result conforms to certain wiring theoretic frequency value.If the result who records not in the theoretical value scope, then tests again.
The software flow of minimum frequency method part is when the rising edge of square wave arrives, to produce an interruption.First interruption enables timer and zero clearing register; Work below each interrupt routine is accomplished afterwards: the counter register numerical value when opening up two word address space ADD1 and ADD2 and preserving nearest secondary interruption successively; Suppose it is to interrupt for the N time at present, then should preserve the counter register numerical value of the N-1 time and N-2 time.The register value comparison of reading the N time interruption counter register numerical value and reading with the N-1 time interruption; As if the register value of interrupting reading greater than N-1 time; Then cover N-2 counter register numerical value with N-1 time counter register numerical value; Cover N-1 time counter register numerical value with the N time interruption counter register numerical value, otherwise do not deal with.After experience was greater than a power frequency period, the numerical value that reads ADD1 was the minimum frequency value, was the frequency (this value usually very big) of circuit when not having resonance and preserve the ADD2 address.In order to make the method have stronger anti-interference, preferably remember 4 values near minimum frequency, calculate its mean value then.The frequency minima of being got, does not compare when frequency is lower than the open circuit frequency greater than the reference value of open circuit frequency, directly skips.
The different principle of inductance value under this techniques make use CT secondary side open circuit, partial short circuit, all short circuits, the normal electricity consumption situation; The test CT primary side that tested CT secondary side and terminal is built-in links to each other; Connect electric capacity and phase inverter composition self-maintained circuit for test CT secondary side, the frequency of utilizing built-in single-chip microcomputer to test this self-maintained circuit output waveform obtains the wiring state information of this tested CT secondary side.
The circuit part that this technology is used comprises test CT, self-maintained circuit, waveform shaping circuit, single chip circuit.Tested CT secondary side links with test CT primary side, and test CT secondary side and electric capacity, phase inverter are formed self-maintained circuit.The waveform of self-maintained circuit output is imported single-chip microcomputer through after the shaping.Single-chip microcomputer calculates the frequency of specified point, draws the wiring state information of this tested CT secondary side according to the corresponding relation of frequency values and theoretical value.
This technology solved in the detection technique in the past can not detection place CT secondary side partial short circuit situation.With the CT secondary side open circuit that can detect, short circuit, normal three kinds of states of electricity consumption in the past, bring up to open circuit, short circuit, partial short circuit, normal four kinds of states of electricity consumption, improved anti-electricity-theft level effectively.And this circuit is simple, reliable, cheap, convenient to be produced.
Claims (3)
1. the circuit of CT secondary side wiring state is once measured in a sense terminals outside; It is characterized in that this circuit comprises test CT, self-maintained circuit, waveform shaping circuit, single chip circuit; Wherein self-maintained circuit comprises the secondary side of testing CT; The input end of waveform shaping circuit is connected with self-maintained circuit, and output terminal is connected with single-chip microcomputer, and the output waveform of self-maintained circuit is carried out importing single-chip microcomputer after the shaping; Single-chip microcomputer calculates the frequency of specified point, draws open circuit or short circuit or the partial short circuit or the normal status information of tested CT secondary side circuit according to the corresponding relation of frequency values and theoretical value.
2. once measure the circuit of CT secondary side wiring state according to the said sense terminals of claim 1 outside, it is characterized in that said self-maintained circuit is made up of test CT secondary side, two electric capacity (C1, C2), phase inverter (D1).
3. once measure the circuit of CT secondary side wiring state according to claim 1 or 2 said sense terminals outsides, the core material that it is characterized in that said test CT is selected the core material of high magnetic permeability, and the secondary side number of turn of test CT is not higher than 6 circles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120278041 CN202177678U (en) | 2011-08-02 | 2011-08-02 | Circuit for detecting terminal outside primary measurement captive test (CT) secondary side connection state |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120278041 CN202177678U (en) | 2011-08-02 | 2011-08-02 | Circuit for detecting terminal outside primary measurement captive test (CT) secondary side connection state |
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| Publication Number | Publication Date |
|---|---|
| CN202177678U true CN202177678U (en) | 2012-03-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201120278041 Expired - Lifetime CN202177678U (en) | 2011-08-02 | 2011-08-02 | Circuit for detecting terminal outside primary measurement captive test (CT) secondary side connection state |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102411112A (en) * | 2011-08-02 | 2012-04-11 | 长沙威胜信息技术有限公司 | Method and circuit for detecting secondary side wiring state of primary metering CT (Computed Tomography) outside terminal |
| CN102981031A (en) * | 2011-09-05 | 2013-03-20 | 江苏林洋电子股份有限公司 | Electric energy meter and electricity larceny prevention circuit thereof |
| CN107015095A (en) * | 2017-03-23 | 2017-08-04 | 中国电力科学研究院 | A kind of method and system that secondary loop of mutual inductor state is judged based on Transient Method |
| CN110488137A (en) * | 2019-09-03 | 2019-11-22 | 广东电网有限责任公司 | A kind of apparatus and method detecting CT secondary circuit integrality |
| CN113848381A (en) * | 2021-09-23 | 2021-12-28 | 石家庄科林电气股份有限公司 | Device and method for judging current bypass event |
-
2011
- 2011-08-02 CN CN 201120278041 patent/CN202177678U/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102411112A (en) * | 2011-08-02 | 2012-04-11 | 长沙威胜信息技术有限公司 | Method and circuit for detecting secondary side wiring state of primary metering CT (Computed Tomography) outside terminal |
| CN102981031A (en) * | 2011-09-05 | 2013-03-20 | 江苏林洋电子股份有限公司 | Electric energy meter and electricity larceny prevention circuit thereof |
| CN102981031B (en) * | 2011-09-05 | 2015-04-22 | 江苏林洋电子股份有限公司 | Electric energy meter and electricity larceny prevention circuit thereof |
| CN107015095A (en) * | 2017-03-23 | 2017-08-04 | 中国电力科学研究院 | A kind of method and system that secondary loop of mutual inductor state is judged based on Transient Method |
| CN110488137A (en) * | 2019-09-03 | 2019-11-22 | 广东电网有限责任公司 | A kind of apparatus and method detecting CT secondary circuit integrality |
| CN113848381A (en) * | 2021-09-23 | 2021-12-28 | 石家庄科林电气股份有限公司 | Device and method for judging current bypass event |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 410205 No. 468 west slope, Changsha hi tech Industrial Development Zone, Changsha, Hunan, Yuelu District, Tongzi Patentee after: WILLFAR INFORMATION TECHNOLOGY Co.,Ltd. Address before: 410205 No. 468 west slope, Changsha hi tech Industrial Development Zone, Changsha, Hunan, Yuelu District, Tongzi Patentee before: HUNAN WEISHENG INFORMATION TECHNOLOGY CO.,LTD. Address after: 410205 No. 468 west slope, Changsha hi tech Industrial Development Zone, Changsha, Hunan, Yuelu District, Tongzi Patentee after: HUNAN WEISHENG INFORMATION TECHNOLOGY CO.,LTD. Address before: 410205 No. 468 west slope, Changsha hi tech Industrial Development Zone, Changsha, Hunan, Yuelu District, Tongzi Patentee before: CHANGSHA WASION INFORMATION TECHNOLOGY Co.,Ltd. |
|
| CP01 | Change in the name or title of a patent holder | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120328 |
|
| CX01 | Expiry of patent term |