CN205027853U - A pulse generating circuit for improving cable fault range accuracy - Google Patents
A pulse generating circuit for improving cable fault range accuracy Download PDFInfo
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- CN205027853U CN205027853U CN201520739229.7U CN201520739229U CN205027853U CN 205027853 U CN205027853 U CN 205027853U CN 201520739229 U CN201520739229 U CN 201520739229U CN 205027853 U CN205027853 U CN 205027853U
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- 238000000926 separation method Methods 0.000 claims description 21
- 230000004807 localization Effects 0.000 claims description 17
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- 239000007924 injection Substances 0.000 claims description 2
- 238000004458 analytical method Methods 0.000 abstract description 5
- 238000013461 design Methods 0.000 abstract description 2
- 238000005457 optimization Methods 0.000 abstract 1
- 238000001028 reflection method Methods 0.000 abstract 1
- 230000001629 suppression Effects 0.000 abstract 1
- 230000002123 temporal effect Effects 0.000 description 6
- 238000002310 reflectometry Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 206010019133 Hangover Diseases 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 2
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Abstract
The utility model discloses an improve the pulse optimization method and the circuit of cable fault range accuracy, when utilizing pulse time domain reflection method to carry out the cable fault range finding, because being used for the pulse of analysis in fact is fault point reflected pulse, it doesn't matter with transmitted pulse, so can design a circuit, produce a transmitted pulse voltage ripples, be connected to the both ends on the former limit of impulse transformer respectively, one of them transmitted pulse normally pours into the cable into, another offsets the transmitted pulse who pours into the cable into before the vice limit AD of impulse transformer gathers, AD just gathers in the signal the only reflected pulse of fault point like this, and there is not transmitted pulse, the wave form is succinct, it is clear, easily analysis, it normally pours into the trouble cable into simultaneously not influence the transmitted pulse signal again. Signal input gather to use keeps apart impulse transformer, can gather the pulse reflected signal on the cable, again can interference suppression, and the reliability is high.
Description
Technical field
The utility model relates to a kind of pulse generating circuit improving cable fault localization precision when utilizing pulse temporal reflectometry to carry out cable fault localization, belongs to electric and electronic technical field.
Background technology
Cable power supply with its safety, reliable, be conducive to the advantage such as beautifying city and industrial and mineral layout, be applied widely.But along with cable use amount is increasing, how cable fault, also in continuous increase, detects trouble spot distance and location rapidly and accurately, finds position of failure point, this just requires testing staff's detecting instrument that first selectivity is excellent, and correctly can identify waveform.
Pulse temporal reflectometry is the important method of cable fault localization, is applicable to the cable fault localization of low-resistance and broken string character.Cable is as transmission line, and when breaking down, position of failure point can cause impedance mismatch.According to the communication theory of electromagnetic wave in transmission line, electromagnetic wave can produce reflection at impedance mismatch place, utilizes this principle can measure the distance of Method of Cable Trouble Point.
The range finding of pulse temporal reflectometry is exactly that the pulse producer of detecting instrument produces a pulse voltage wave, be injected into cable fault at measuring junction by lead-in wire to go up mutually, this pulse voltage wave distally can be propagated along cable line, when running into trouble spot, due to impedance mismatch, reflection wave can be produced and turn back to measuring junction.Transponder pulse and reflected impulse can be recorded by the detecting instrument of measuring junction.The reference position mistiming according to transponder pulse on waveform and reflected impulse extrapolates fault distance.Disconnection fault reflected impulse is identical with transponder pulse polarity, and low resistance faults reflected impulse is identical with transponder pulse polarity.As shown in Figure 1.
The main deficiency existed in waveform acquisition, display, analysis based on the cable fault localization instrument of pulse temporal reflectometry design is at present: the pulse voltage wave of the transmitting of detecting instrument exists certain width, because the output impedance of instrument is not mated with the wave impedance of cable, cable measuring junction obtains transponder pulse can exist " smearing ", when range observation end in trouble spot is very near, trouble spot reflected impulse will be overlapping with transponder pulse, waveform cannot find the reference position of reflected impulse, cause and measure blind area significantly, as shown in Figure 2; In addition; instrument gathers simultaneously, show transponder pulse and reflected impulse; when trouble spot range observation end is far, due to the attenuation effect of cable, trouble spot reflected impulse amplitude can be far smaller than transponder pulse; in order to improve trouble spot reflected impulse amplitude; often need to improve instrumentation amplifier gain, do like this and instrument pulse signal acquisition amplifying circuit usually can be caused saturated, occur so-called " obstruction " phenomenon; cause signals collecting distortion, be unfavorable for wave form analysis.
In order to eliminate the impact of transponder pulse on measurement result, eliminate " smearing ", also patented technology is had to mention a kind of impedance balance network, as shown in Figure 3, be exactly in element simulation cable resistance network characteristics such as instrument internal resistance, electric capacity, inductance, pulse transformers, realize instrument internal impedance and cable resistance coupling, reach the object eliminating transponder pulse impact, but this method cannot solve above-mentioned pre-amplification circuit signal " obstruction " problem; Meanwhile, because simulated impedance cannot be mated completely with cable actual impedance, a large amount of transformer elements is employed again, when cable is longer, the inductance of cable and electric capacity and transformer T2 can make transponder pulse form more serious concussion, cause waveform mixed and disorderly, cannot differentiate.
In actual measurement, above-mentioned weak point can cause wave form analysis difficulty, not easily determines the initial time of reflected impulse, easily judges by accident, cause unnecessary economic loss.
Summary of the invention
For the weak point of above-mentioned existing detecting instrument, through a large amount of explorations and summary of experience, the utility model proposes a kind of pulse generating circuit for improving cable fault localization precision, substantially reduce the range hole of detecting instrument on the one hand, concussion waveform can not be produced during measurement, avoid " obstruction " phenomenon of pulse signal acquisition amplifying circuit simultaneously.New pulse generating circuit make cable fault localization waveform succinct, clear, be easy to analyze.
According to the technical scheme that the utility model provides, the described pulse generating circuit for improving cable fault localization precision comprises: transponder pulse produces circuit, single order passive high three-way filter, the transponder pulse separation circuit of 2 tunnel symmetries, cable interface circuit and pulse transformer, the output that transponder pulse produces circuit connects single order passive high three-way filter, the output of single order passive high three-way filter connects the two ends on the former limit of pulse transformer respectively by the transponder pulse separation circuit of 2 tunnel symmetries, wherein riches all the way penetrates pulse-separating circuit also stube cable interface circuit, the secondary of pulse transformer connects the circuit of AD collection, described transponder pulse produces circuit and specific width pulse is exported transponder pulse by driving N channel enhancement mosfet triode, then by the low frequency component in single order passive high three-way filter filtered signal, transponder pulse separation circuit again through 2 tunnel symmetries produces 2 transponder pulses that amplitude is identical, polarity is identical on the former limit of pulse transformer, wherein riches all the way penetrates pulse also by cable interface circuit injection failure cable, and described cable interface circuit is simultaneously for receiving Method of Cable Trouble Point reflected impulse signal.
Concrete, described pulse transformer adopts Isolated Pulse Transformer.
In described 2 road transponder pulse separation circuits, first transponder pulse separation circuit comprises: diode D1 negative electrode connects the output of single order passive high three-way filter, diode D1 anode connects one end of TVS pipe TVS1, one end of resistance R5, one end of electric capacity C2 respectively, the electric capacity C2 other end is one end of contact resistance R6 and one end of pulse transformer T1 former limit winding respectively, the TVS pipe TVS1 other end, the resistance R5 other end, resistance R6 other end ground connection; Second transponder pulse separation circuit comprises: diode D2 negative electrode connects the output of single order passive high three-way filter, diode D2 anode connects one end of TVS pipe TVS2, one end of resistance R7, one end of electric capacity C3 and cable interface circuit respectively, the electric capacity C3 other end is one end of contact resistance R8 and the other end of pulse transformer T1 former limit winding respectively, the TVS pipe TVS2 other end, the resistance R7 other end, resistance R8 other end ground connection.
The utility model has the advantages that: the method utilizes the transponder pulse separation circuit of 2 tunnel symmetries to produce two identical transponder pulses simultaneously, utilize pulse transformer T1 characteristic, cancel out each other on the former limit of T1, Method of Cable Trouble Point reflected impulse is only had in the signal that such AD collects, and there is no transponder pulse, waveform is succinct, clear, be easy to analyze; Not affecting again transponder pulse signal normally injects failure cable simultaneously.Signal input gathers and uses Isolated Pulse Transformer, can gather the pulse-echo signal on cable, and can suppress again interference, reliability is high.
Accompanying drawing explanation
Fig. 1 is pulse temporal shooting method ranging waveform.
Fig. 2 is transponder pulse hangover, overlapping with reflected impulse, cannot differentiate the schematic diagram of reflected impulse.
Fig. 3 is a kind of impedance balance network that prior art uses.
Fig. 4 is the pulse generating circuit schematic diagram that the utility model uses.
Fig. 5 is the Module Division figure of the utility model pulse generating circuit.
Fig. 6 is the collection oscillogram implementing method described in the utility model.Wherein Fig. 6 (a) be trouble spot range observation end very near time fault localization waveform, Fig. 6 (b) be trouble spot range observation end far time fault localization waveform.
Embodiment
Below in conjunction with drawings and Examples, the utility model is described in further detail.
When utilizing pulse temporal reflectometry to carry out cable fault localization, due to the in fact just trouble spot reflected impulse of the pulse for analyzing, it doesn't matter with transponder pulse, so a kind of circuit can be designed, produce a transponder pulse voltage wave, two-way is divided to be connected to the two ends on the former limit of pulse transformer, wherein riches all the way penetrates pulse and normally injects cable, the transponder pulse injecting cable is offset on another road before pulse transformer secondary AD gathers, such AD collects the reflected impulse just only having trouble spot in signal, and does not have transponder pulse.
Pulse generating circuit of the present utility model comprises transponder pulse and produces circuit 1, single order passive high three-way filter 2, the transponder pulse separation circuit 3 of 2 tunnel symmetries, 4, cable interface circuit 5 and pulse transformer T1, as shown in Figure 5, the output that transponder pulse produces circuit 1 connects single order passive high three-way filter 2, the output of single order passive high three-way filter 2 is connected the two ends on the former limit of pulse transformer T1 respectively by the first transponder pulse separation circuit 3 and the second transponder pulse separation circuit 4, wherein stube cable interface circuit 5 gone back by the second transponder pulse separation circuit 4, the secondary of pulse transformer T1 connects the circuit of AD collection.
In circuit as shown in Figure 4, N channel enhancement mosfet triode VT1, resistance R1, R2, electrochemical capacitor CD1, diode D3, resistance R3 form transponder pulse and produce circuit, specific width pulse is exported transponder pulse by driving triode VT1, increase exomonental energy, by exomonental amplitude from VDD(5V) be amplified to V(tens volts), thus ensure that cable fault localization scope can from several meters to dozens of kilometres.Wherein, N channel enhancement mosfet triode VT1 grid connects initial transponder pulse, meet supply voltage VDD by resistance R1 simultaneously, VT1 drain electrode connects electrochemical capacitor CD1 positive pole, and meet the voltage V higher than VDD through resistance R2, electrochemical capacitor CD1 negative pole connects diode D3 anode and through resistance R3 ground connection, is connected to single order passive high three-way filter simultaneously, diode D3 negative electrode connects voltage V, VT1 source ground.
The single order passive high three-way filter that electric capacity C1 and resistance R4 is formed, suppresses the low frequency component in circuit.
Diode D1, TVS pipe TVS1, resistance R5, R6, electric capacity C2 and diode D2, TVS pipe TVS2, resistance R7, R8, electric capacity C3 form the transponder pulse separation circuit of 2 road full symmetrics, make to produce 2 transponder pulses that amplitude is identical, polarity is identical on the former limit of pulse transformer T1, utilize transformer characteristic, the transponder pulse that T1 secondary exports is cancelled, and just only has the reflected impulse of Method of Cable Trouble Point in the signal that AD gathers.Wherein, first transponder pulse separation circuit comprises: diode D1 negative electrode connects the output of single order passive high three-way filter, diode D1 anode connects one end of TVS pipe TVS1, one end of resistance R5, one end of electric capacity C2 respectively, the electric capacity C2 other end is one end of contact resistance R6 and one end of pulse transformer T1 former limit winding respectively, the TVS pipe TVS1 other end, the resistance R5 other end, resistance R6 other end ground connection; Second transponder pulse separation circuit comprises: diode D2 negative electrode connects the output of single order passive high three-way filter, diode D2 anode connects one end of TVS pipe TVS2, one end of resistance R7, one end of electric capacity C3 and cable interface circuit respectively, the electric capacity C3 other end is one end of contact resistance R8 and the other end of pulse transformer T1 former limit winding respectively, the TVS pipe TVS2 other end, the resistance R7 other end, resistance R8 other end ground connection.
Electric capacity C4, voltage dependent resistor (VDR) RV1, BNC accessory power outlet W1 form the interface circuit of detecting instrument and cable, and by this circuit, transponder pulse can inject failure cable; Simultaneously for receiving Method of Cable Trouble Point reflected impulse signal.Diode D2 anode in second transponder pulse separation circuit connects one end of electric capacity C4, the electric capacity C4 other end through voltage dependent resistor (VDR) RV1 ground connection, and through BNC accessory power outlet W1 core stube cable measuring junction, the bonding of BNC accessory power outlet W1.
Apply cable fault localization waveform of the present utility model as shown in Figure 5, from waveform, can't see transmitting pulse waveform completely, eliminate waveform " hangover response ", also there is no waveform reforming phenomena, substantially reduce and measure blind area; When detecting long cable, in order to see clearer reflection configuration, can regulate gain to greatest extent, the AD that can not occur to cause because transponder pulse exists gathers amplifying circuit " obstruction " phenomenon simultaneously.Waveform is succinct, clear, be easy to analyze.
Claims (3)
1. for improving the pulse generating circuit of cable fault localization precision, it is characterized in that: comprise transponder pulse and produce circuit, single order passive high three-way filter, the transponder pulse separation circuit of 2 tunnel symmetries, cable interface circuit and pulse transformer, the output that transponder pulse produces circuit connects single order passive high three-way filter, the output of single order passive high three-way filter connects the two ends on the former limit of pulse transformer respectively by the transponder pulse separation circuit of 2 tunnel symmetries, wherein riches all the way penetrates pulse-separating circuit also stube cable interface circuit, the secondary of pulse transformer connects the circuit of AD collection, described transponder pulse produces circuit and specific width pulse is exported transponder pulse by driving N channel enhancement mosfet triode, then by the low frequency component in single order passive high three-way filter filtered signal, transponder pulse separation circuit again through 2 tunnel symmetries produces 2 transponder pulses that amplitude is identical, polarity is identical on the former limit of pulse transformer, wherein riches all the way penetrates pulse also by cable interface circuit injection failure cable, and described cable interface circuit is simultaneously for receiving Method of Cable Trouble Point reflected impulse signal.
2. as claimed in claim 1 for improving the pulse generating circuit of cable fault localization precision, it is characterized in that: described pulse transformer adopts Isolated Pulse Transformer.
3. as claimed in claim 1 for improving the pulse generating circuit of cable fault localization precision, it is characterized in that: in described 2 road transponder pulse separation circuits, first transponder pulse separation circuit comprises: diode D1 negative electrode connects the output of single order passive high three-way filter, diode D1 anode connects one end of TVS pipe TVS1, one end of resistance R5, one end of electric capacity C2 respectively, the electric capacity C2 other end is one end of contact resistance R6 and one end of pulse transformer T1 former limit winding respectively, the TVS pipe TVS1 other end, the resistance R5 other end, resistance R6 other end ground connection; Second transponder pulse separation circuit comprises: diode D2 negative electrode connects the output of single order passive high three-way filter, diode D2 anode connects one end of TVS pipe TVS2, one end of resistance R7, one end of electric capacity C3 and cable interface circuit respectively, the electric capacity C3 other end is one end of contact resistance R8 and the other end of pulse transformer T1 former limit winding respectively, the TVS pipe TVS2 other end, the resistance R7 other end, resistance R8 other end ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520739229.7U CN205027853U (en) | 2015-09-22 | 2015-09-22 | A pulse generating circuit for improving cable fault range accuracy |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201520739229.7U CN205027853U (en) | 2015-09-22 | 2015-09-22 | A pulse generating circuit for improving cable fault range accuracy |
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| CN201520739229.7U Withdrawn - After Issue CN205027853U (en) | 2015-09-22 | 2015-09-22 | A pulse generating circuit for improving cable fault range accuracy |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137291A (en) * | 2015-09-22 | 2015-12-09 | 国家电网公司 | Pulse optimization method used for increasing ranging accuracy of cable faults and pulse generating circuit |
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2015
- 2015-09-22 CN CN201520739229.7U patent/CN205027853U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137291A (en) * | 2015-09-22 | 2015-12-09 | 国家电网公司 | Pulse optimization method used for increasing ranging accuracy of cable faults and pulse generating circuit |
| CN105137291B (en) * | 2015-09-22 | 2018-02-06 | 国家电网公司 | For improving the pulse optimization method and pulse generating circuit of cable fault localization precision |
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| AV01 | Patent right actively abandoned |
Granted publication date: 20160210 Effective date of abandoning: 20180206 |
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| AV01 | Patent right actively abandoned |