CN101782621B - Method and device for judging fault point locations in cable protective layer fault detection - Google Patents
Method and device for judging fault point locations in cable protective layer fault detection Download PDFInfo
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- CN101782621B CN101782621B CN2010101304538A CN201010130453A CN101782621B CN 101782621 B CN101782621 B CN 101782621B CN 2010101304538 A CN2010101304538 A CN 2010101304538A CN 201010130453 A CN201010130453 A CN 201010130453A CN 101782621 B CN101782621 B CN 101782621B
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Abstract
The invention relates to a method and a device for judging fault point locations in cable protective layer fault detection, which belong to the technical field of cable sheath fault detection. A stable current rectangular wave signal is applied to a fault cable sheath through a controllable high-voltage DC constant current power supply, and the cable sheath directly flows into the ground through fault points or through a semi-conductor layer through the fault points; the signal is detected on the ground or on the surface of the cable sheath; and the locations of the fault points are judged by analyzing the duty cycle of the rectangular wave signal, and an indicator is used to display the wave form of the signal and clearly indicates the locations of the fault points. The device comprises the controllable high-voltage DC constant current power supply, a signal detector and a probe, can automatically track the changes to the ground potential with the judgment method, has the advantages of strong anti-interference capability, high detection flexibility and large scope of response, so as to improve the cable sheath fault defection efficiency, reduce the working strength, and reduce the requirements on the experience of a user.
Description
Technical field
Invention relate to a kind of in the cable sheath fault finding method and apparatus in failure judgement point orientation, belong to cable sheath Fault Defection Technology field.
Background technology
Present traditional cable sheath Fault Defection Technology, general working voltage ratio or resistance ratio method are found range, but these distance-finding methods can only be effective to Single Point of Faliure, then can't accurately find range for the multiple spot fault.Therefore can carry out on a large scale the direct localization of faults particularly the high resistive fault point become extremely important.
At present, the fault localization of power cable and location mainly contain following several method:
1, bridge method: this method is to utilize electrical bridge principle, carries out fault localization through the resistance that calculates earthing cable.But this method is not suitable for the sheath fault localization because of poor anti jamming capability.
2, sound magnetic-synchro method: this method uses high-tension apparatus to make Method of Cable Trouble Point disruptive discharge, utilizes receiver record discharge sound, and with field signal it is carried out synchronously, through analyzing sound waveform or earphone fault is found range and is fixed a point.But the voice signal that this method needs detection failure point to produce, and most trouble spots of sheath fault do not produce voice signal, so incompatibility sheath position determination of fault.
Traditional fix-point method " step voltage method "; Like Chinese patent 200410035595.0 disclosed " orientation of direct application type cable sheath fault and locating measurement method and measurement mechanism thereof "; It generally is the surge voltage signal that between the metal sheath of cable and the earth, applies a Millisecond through the impacting with high pressure signal generator; Or the injection one-period is tens seconds a direct current discontinuous signal; At this signal of ground location,, confirm direction of current and particular location through the polarity and the amplitude of direct judgement signal voltage.This surge voltage method is to be applied directly on the cable after leaning on capacitance energy storage, when fault resstance is smaller, can produce the dash current signal of very big Millisecond.When fault resstance was bigger, dash current was little, and the faint signal of Millisecond can be flooded by neighbourhood noise easily, and the probe response scope is little.Macrocyclic direct current signal injection method receives the influence of earth potential drift easily, the zeroing difficulty, and the probe response scope is little.
Summary of the invention
According to above deficiency of the prior art; The object of the present invention is to provide a kind of antijamming capability strong; That surveys is highly sensitive, and responding range is big, thereby improves the efficient of cable sheath fault finding; Reduce working strength, the method in failure judgement point orientation in the cable sheath fault finding that reduces that experience to the user requires.
Another object of the present invention is to provide a kind of device that can be implemented in the method in failure judgement point orientation in the cable sheath fault finding.
The present invention is achieved in that the method in failure judgement point orientation in the cable sheath fault finding, it is characterized in that, may further comprise the steps:
(1) in failure cable sheath to be measured, apply stable electric current square-wave signal through the controllable high-voltage dc constant flowing power, the dutycycle of this electric current square-wave signal is 1%-99%, but does not comprise 50%;
(2) the electric current square-wave signal flows directly into the earth or flows into the earth through the trouble spot through semiconductor layer through the trouble spot of cable sheath; Utilize an acquisition of signal appearance perhaps sensing point to be set, survey the voltage signal that this electric current square-wave signal forms on the cable sheath surface on ground;
(3) through the analytical voltage signal, change from the earthy drift of motion tracking, through phase correlation method or dutycycle pairing comparision, judge sense of current, and by indicator for displaying waveform voltage signal and trouble spot direction;
(4) along the sensing point of the trouble spot direction movable signal detection instrument of indicator for displaying, repeating step (3), the trouble spot direction that sight indicator shows is up to showing that the trouble spot direction changes the localization of faults.
Its preferred version is anodal probe and negative pole probe continuously detectable voltage signals and the earth potential drift variation of described acquisition of signal appearance through being provided with at interval.The setting that one in front and one in back keeps at a certain distance away of two probes, the big I of distance is adjusted according to the detectable signal size, forms sensing point.
Its principle can adopt the phase place determining method: when injecting the electric current square-wave signal of positive polarity; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; The direction that anodal probe is arranged on the cable other end is surveyed; The voltage signal that analyze the acquisition of signal appearance anodal probe and negative pole probe in detecting arrive, and carry out bit comparison mutually, both homophases with the electric current square-wave signal of injecting; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying voltage waveform and directional arrow; Otherwise; Voltage signal carries out bit comparison mutually with the electric current square-wave signal of injection; Both anti-phases are judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, and indicator for displaying voltage waveform and directional arrow are shown clearly.
Perhaps; When injecting the electric current square-wave signal of negative polarity; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction, and the direction that anodal probe is arranged on the cable other end is surveyed, and the acquisition of signal appearance is analyzed the voltage signal that anodal probe and negative pole probe in detecting arrive; And carry out bit comparison mutually with the electric current square-wave signal of injecting; Both anti-phases are judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying voltage waveform and directional arrow; Otherwise; Voltage signal carries out bit comparison mutually with the electric current square-wave signal of injection; Both homophases are judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, and indicator for displaying voltage waveform and directional arrow are shown clearly.
For simplifying the phase bit comparison of two signals, adopt and inject the unequal square-wave signal of high-low level.
Described electric current square-wave signal is the continuous signal of frequency stabilization, and its frequency is between 0.5Hz-2Hz, and dutycycle is 1%-99%, but does not comprise 50%.
It judges that principle can also adopt the dutycycle determining method:
A), when injecting positive polarity and dutycycle less than 50% current signal; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; Anodal probe is surveyed in the direction of the cable other end, the dutycycle of acquisition of signal appearance analytical voltage signal, and the voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is less than 50%; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying waveform voltage signal and directional arrow; Otherwise; The voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is greater than 50%; Be judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, indicator for displaying waveform voltage signal and directional arrow are shown clearly.
B), when injecting positive polarity and dutycycle greater than 50% current signal; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; Anodal probe is surveyed in the direction of the cable other end; The dutycycle of acquisition of signal appearance analytical voltage signal; The voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying waveform voltage signal dutycycle and directional arrow greater than 50%; Otherwise; The voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is less than 50%; Be judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, indicator for displaying waveform voltage signal and directional arrow are shown clearly.
C), when injecting negative polarity and dutycycle less than 50% current signal; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; Anodal probe is surveyed in the direction of the cable other end, the dutycycle of acquisition of signal appearance analytical voltage signal, and the voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is greater than 50%; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying waveform voltage signal and directional arrow; Otherwise; The voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is less than 50%; Be judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, indicator for displaying waveform voltage signal and directional arrow are shown clearly.
D), when injecting negative polarity and dutycycle greater than 50% current signal; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; Anodal probe is surveyed in the direction of the cable other end, the dutycycle of acquisition of signal appearance analytical voltage signal, and the voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is less than 50%; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying waveform voltage signal and directional arrow; Otherwise; The voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is greater than 50%; Be judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, indicator for displaying waveform voltage signal and directional arrow are shown clearly.
According to above method; The device in failure judgement point orientation in the cable sheath fault finding; Comprise failure cable and probe, it is characterized in that also comprising controllable high-voltage dc constant flowing power and acquisition of signal appearance, the output terminal of described controllable high-voltage dc constant flowing power connects an end of failure cable; Probe connects the input end of acquisition of signal appearance; Described acquisition of signal appearance comprises input protection unit, magnification processing, computer processing unit, indicator and signal trace zeroing unit, and probe is through the input end of input protection unit connection magnification processing, and the output terminal of magnification processing connects the input end of computer processing unit; The output terminal of computer processing unit is through the input end of signal trace zeroing unit connection magnification processing, and the output terminal of computer processing unit is link indicator also.
The controllable high-voltage dc constant flowing power applies stable electric current square-wave signal in the sheath of failure cable, the acquisition of signal appearance is obtained this signal through probe, and carries out Treatment Analysis, display result.
Described controllable high-voltage dc constant flowing power comprises square-wave signal generation circuit, feedback control circuit, power supply input rectifying filtering circuit, inverter circuit, high-frequency transformer, high-voltage rectifier and isolation feedback circuit; The input end of power supply input rectifying filtering circuit connects civil power; Its output terminal connects the input end of inverter circuit; The output terminal of inverter circuit connects the high-voltage rectifier input end through high-frequency transformer; The output terminal of high-voltage rectifier is connected inverter circuit through isolation feedback circuit with feedback control circuit; The output terminal of square-wave signal generation circuit connects feedback control circuit, and the output terminal of high-voltage rectifier is the output terminal of controllable high-voltage dc constant flowing power.Square-wave signal generation circuit provides given signal, and the output terminal of high-voltage rectifier applies power supply and this signal to the sheath of failure cable.
Its prioritization scheme is that the output terminal of described computer processing unit connects the input end of signal trace zeroing unit through digital to analog converter.
The beneficial effect that method and apparatus had in the present invention failure judgement point orientation in the cable sheath fault finding is: this method is injected the method for continuous signal and waveform duty cycle analysis through using the controllable high-voltage dc constant flowing power; Failure judgement point direction, can be directly by the indicator for displaying signal waveform and clearly indicate fault direction; This device can change from the motion tracking earth potential, and antijamming capability is strong, detection highly sensitive, and responding range is big, thereby improves the efficient of cable sheath fault finding, reduces working strength, reduces the experience requirement to the user.
Description of drawings
Fig. 1 is a working state schematic representation of the present invention;
Fig. 2 is a decision flow chart of the present invention;
Fig. 3 is the functional-block diagram of controllable high-voltage dc constant flowing power of the present invention;
Fig. 4 is an electrical principle block scheme of the present invention;
Wherein: 1; Controllable high-voltage dc constant flowing power 2; Semiconductor layer 3; Trouble spot 4; Acquisition of signal appearance 5; 16; Probe 6; Aluminium sheath 7; Main insulating layer 8; Heart yearn 9; Square-wave signal generation circuit 10; Feedback control circuit 11; Power supply input rectifying filtering circuit 12; Inverter circuit 13; High-frequency transformer 14; High-voltage rectifier 15; Isolation feedback circuit 16; Input protection unit 17; Magnification processing 18; Signal trace zeroing unit 19; Magnification processing 20; Computer processing unit 21; Indicator.
Embodiment
Come process in detail below in conjunction with accompanying drawing.
As shown in Figure 1, buried cable is made up of heart yearn 8, main insulating layer 7, aluminium sheath 6 and semiconductor layer 2, and when cable sheath broke down, aluminium sheath 6 formed short circuit at 3 places, trouble spot and the earth of semiconductor layer 2.
During detection, in failure cable aluminium sheath 6 to be measured, apply stable electric current square-wave signal through controllable high-voltage dc constant flowing power 1, the dutycycle of this electric current square-wave signal is 1%-99%, but does not comprise 50%; The electric current square-wave signal flows directly into the earth or flows into the earth through trouble spot 3 through semiconductor layer 2 through the trouble spot 3 of cable sheath, and forming with trouble spot 3 is the voltage drop that reduces successively outward in the center of circle.The variation of this voltage drop is relevant with amplitude size, the frequency of electric current square-wave signal.Utilize two probes 5 (forming) setting that one in front and one in back keeps at a certain distance away of acquisition of signal appearance 4, form sensing point, survey the voltage signal that this electric current square-wave signal forms by A pin, B pin; Acquisition of signal appearance 4 changes from the earthy drift of motion tracking through the analytical voltage signal, through phase place determining method or dutycycle determining method, judges sense of current, and by indicator 4 display voltage signal waveforms and trouble spot direction; At last, along the sensing point of the trouble spot direction movable signal detection instrument 4 of indicator for displaying, the trouble spot direction that sight indicator shows is up to showing that the trouble spot direction changes the localization of faults.
The electric current square-wave signal is preferably the continuous signal of frequency stabilization, and its frequency is between 0.5Hz-2Hz, and dutycycle is 5%-95%, but does not comprise 50%.
The dutycycle of acquisition of signal appearance analytical voltage signal, and compare with the electric current square-wave signal, both are identical, are judged to be the trouble spot on the cable of the sensing point other end, indicator for displaying voltage waveform and directional arrow; Otherwise the dutycycle of voltage signal is compared with the electric current square-wave signal, and both are opposite, is judged to be the trouble spot on the cable between sensing point and the controllable high-voltage dc constant flowing power, and indicator for displaying waveform voltage signal and directional arrow are shown clearly.
As shown in Figure 2; During acquisition of signal appearance 4 analytic signals, the signal of probe in detecting carries out the A/D data sampling through computer processing unit, then signal calculated dc shift amount; Return to zero through zeroing circuit; Calculate the dutycycle of input signal, judge at last: if dutycycle greater than 50%, shows direction of arrow A-B; If dutycycle less than 50%, shows direction of arrow B-A.
Specific embodiment:
Embodiment 1:
The electric current square-wave signal is a positive polarity; Dutycycle is 1% o'clock; When left side in Method of Cable Trouble Point 3 of two probes 5 contact of acquisition of signal appearance 42 (on the cable between trouble spot 3 and the controllable high-voltage dc constant flowing power), the square wave dutycycle of its indicator for displaying is less than 50%, the A probe of demonstration arrow points probe 5; Traveling probe 5 continues sight indicator, until showing the trouble spot.When right side in Method of Cable Trouble Point 3 of two probes 5 contact of signal receiver 42 (trouble spot opposite side cable), the square wave dutycycle of its indicator for displaying shows the B probe of arrow points probe 5 greater than 50%.
Embodiment 2:
The electric current square-wave signal is a positive polarity; Dutycycle is 49% o'clock; When two probes 5 contact of acquisition of signal appearance 42 left side (on the cable between trouble spot 3 and the controllable high-voltage dc constant flowing power) in Method of Cable Trouble Point 3; The square wave dutycycle of its indicator for displaying shows the A probe of arrow points probe 5 less than 50%.When right side in Method of Cable Trouble Point 3 of two probes 5 contact of signal receiver 42 (trouble spot opposite side cable), the square wave dutycycle of its indicator for displaying shows the B probe of arrow points probe 5 greater than 50%.
Embodiment 3:
The electric current square-wave signal is a positive polarity; Dutycycle is 30% o'clock; When two probes 5 contact of acquisition of signal appearance 42 left side (on the cable between trouble spot 3 and the controllable high-voltage dc constant flowing power) in Method of Cable Trouble Point 3; The square wave dutycycle of its indicator for displaying shows the A probe of arrow points probe 5 less than 50%.When right side in Method of Cable Trouble Point 3 of two probes 5 contact of signal receiver 42 (trouble spot opposite side cable), the square wave dutycycle of its indicator for displaying shows the B probe of arrow points probe 5 greater than 50%.
Embodiment 4:
The electric current square-wave signal is a positive polarity; Dutycycle is 51% o'clock; When two probes 5 contact of acquisition of signal appearance 42 left side (on the cable between trouble spot 3 and the controllable high-voltage dc constant flowing power) in Method of Cable Trouble Point 3; The square wave dutycycle of its indicator for displaying shows the B probe of arrow points probe 5 greater than 50%.When right side in Method of Cable Trouble Point 3 of two probes 5 contact of signal receiver 42 (trouble spot opposite side cable), the square wave dutycycle of its indicator for displaying shows the A probe of arrow points probe 5 less than 50%.
Embodiment 5:
The electric current square-wave signal is a positive polarity; Dutycycle is 99% o'clock; When two probes 5 contact of acquisition of signal appearance 42 left side (on the cable between trouble spot 3 and the controllable high-voltage dc constant flowing power) in Method of Cable Trouble Point 3; The square wave dutycycle of its indicator for displaying shows the B probe of arrow points probe 5 greater than 50%.When right side in Method of Cable Trouble Point 3 of two probes 5 contact of signal receiver 42 (trouble spot opposite side cable), the square wave dutycycle of its indicator for displaying shows the A probe of arrow points probe 5 less than 50%.
Embodiment 6:
The electric current square-wave signal is a positive polarity; Dutycycle is 70% o'clock; When two probes 5 contact of acquisition of signal appearance 42 left side (on the cable between trouble spot 3 and the controllable high-voltage dc constant flowing power) in Method of Cable Trouble Point 3; The square wave dutycycle of its indicator for displaying shows the B probe of arrow points probe 5 greater than 50%.When right side in Method of Cable Trouble Point 3 of two probes 5 contact of signal receiver 42 (trouble spot opposite side cable), the square wave dutycycle of its indicator for displaying shows the A probe of arrow points probe 5 less than 50%.
Embodiment 7-embodiment 12:
The electric current square-wave signal is a negative polarity, and dutycycle adopts 1%, 30%, 49%, 51%, 70% and respectively at 99% o'clock, and after the test, the square wave of indicator for displaying is identical with embodiment 1-embodiment 6, can clearly indicate the trouble spot direction.
Embodiment 13:
When injecting the electric current square-wave signal of positive polarity; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; The direction that anodal probe is arranged on the cable other end is surveyed; The voltage signal that analyze the acquisition of signal appearance anodal probe and negative pole probe in detecting arrive, and carry out bit comparison mutually, both homophases with the electric current square-wave signal of injecting; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying voltage waveform and directional arrow; Otherwise; Voltage signal carries out bit comparison mutually with the electric current square-wave signal of injection; Both anti-phases are judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, and indicator for displaying voltage waveform and directional arrow are shown clearly.
Embodiment 14:
When injecting the electric current square-wave signal of negative polarity; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; The direction that anodal probe is arranged on the cable other end is surveyed; The voltage signal that analyze the acquisition of signal appearance anodal probe and negative pole probe in detecting arrive, and carry out bit comparison mutually, both anti-phases with the electric current square-wave signal of injecting; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying voltage waveform and directional arrow; Otherwise; Voltage signal carries out bit comparison mutually with the electric current square-wave signal of injection; Both homophases are judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, and indicator for displaying voltage waveform and directional arrow are shown clearly.
Like Fig. 3, shown in Figure 4; For realizing a kind of device of this method: comprise failure cable, probe 16, controllable high-voltage dc constant flowing power 1 and acquisition of signal appearance 4; The output terminal of controllable high-voltage dc constant flowing power connects an end of failure cable; Probe 16 connects the input end of acquisition of signal appearance; Described acquisition of signal appearance comprises input protection unit 17, magnification processing 19, computer processing unit 20, indicator 21 and signal trace zeroing unit 18, and probe 16 is through the input end of input protection unit 17 connection magnification processing 19, and the output terminal of magnification processing 19 connects the input end of computer processing unit 20; The output terminal of computer processing unit 20 is through the input end of signal trace zeroing unit 18 connection magnification processing 19, and the output terminal of computer processing unit 20 is link indicator 21 also.The output terminal of computer processing unit 20 connects the input end of signal trace zeroing unit 18 through digital to analog converter.
Controllable high-voltage dc constant flowing power 1 comprises square-wave signal generation circuit 9, feedback control circuit 10, power supply input rectifying filtering circuit 11, inverter circuit 12, high-frequency transformer 13, high-voltage rectifier 14 and isolation feedback circuit 15; The input end of power supply input rectifying filtering circuit 11 connects civil power; Its output terminal connects the input end of inverter circuit 12; The output terminal of inverter circuit 12 connects high-voltage rectifier 14 input ends through high-frequency transformer 13; The output terminal of high-voltage rectifier 14 is connected inverter circuit 12 through isolation feedback circuit 15 with feedback control circuit 15; The output terminal of square-wave signal generation circuit 9 connects feedback control circuit 15, and the output terminal of high-voltage rectifier 14 is the output terminal of controllable high-voltage dc constant flowing power 1.
Two probes 16 are surveyed input voltage signal, through input protection unit 17, and signal trace zeroing unit 18; Magnification processing 19; By computer processing unit 20 calculating of returning to zero, judge the dutycycle of calculating input signal, by the direction of indicator 21 shows signal waveforms and indication fault point.
Above-described indicator 21 can be the LCD LCD, also can be the indicating device of other types, and waveform shows and clear and definite direction prompting all can as long as can carry out.Computer processing unit 20 adopts can single-chip microcomputer, also can adopt micro computer PC, and input protection unit 17 adopts the normal signal holding circuits.Signal trace zeroing unit 18 is an operational amplifier.Power supply input rectifying filtering circuit 11, inverter circuit 12, high-frequency transformer 13 and high-voltage rectifier 14 are common existing product, can buy from the market.
Principle of work and process:
Square-wave signal generation circuit 1 provides given signal, and the output terminal of high-voltage rectifier 14 applies power supply and this signal to the sheath of failure cable.Two probes 16 are surveyed input voltage signal; Through input protection unit 17; Signal trace zeroing unit 18, magnification processing 19 is by computer processing unit 20 calculating of returning to zero; Judge and calculate phase of input signals or dutycycle, by the direction of indicator 17 shows signal waveforms and indication fault point.
Claims (8)
1. the method in a failure judgement point orientation in the cable sheath fault finding is characterized in that: may further comprise the steps:
(1) in failure cable sheath to be measured, apply stable electric current square-wave signal through the controllable high-voltage dc constant flowing power, the dutycycle of this electric current square-wave signal is 1%-99%, but does not comprise 50%;
(2) the electric current square-wave signal flows directly into the earth or flows into the earth through the trouble spot through semiconductor layer through the trouble spot of cable sheath; Utilize an acquisition of signal appearance perhaps sensing point to be set, survey the voltage signal that this electric current square-wave signal forms on the cable sheath surface on ground;
(3) through the analytical voltage signal, change from the earthy drift of motion tracking, through phase correlation method or dutycycle pairing comparision, judge sense of current, and voltage waveform and the trouble spot direction surveyed by indicator for displaying;
(4) along the sensing point of the trouble spot direction movable signal detection instrument of indicator for displaying, repeating step (3), voltage waveform and trouble spot direction that sight indicator shows are up to the trouble spot direction variation that shows, the localization of faults.
2. method according to claim 1 is characterized in that: anodal probe and negative pole probe continuously detectable voltage signals and the earth potential drift variation of described acquisition of signal appearance through being provided with at interval.
3. method according to claim 1 is characterized in that: described electric current square-wave signal is the continuous signal of frequency stabilization, and its frequency is between 0.5Hz-2Hz.
4. method according to claim 1; It is characterized in that: the determination methods of described step (3) is: when injecting the electric current square-wave signal of positive polarity; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction, and the direction that anodal probe is arranged on the cable other end is surveyed, and the acquisition of signal appearance is analyzed the voltage signal that anodal probe and negative pole probe in detecting arrive; And carry out bit comparison mutually with the electric current square-wave signal of injecting; Both homophases are judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying voltage waveform and directional arrow; Otherwise; Voltage signal carries out bit comparison mutually with the electric current square-wave signal of injection; Both anti-phases are judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction, and indicator for displaying voltage waveform and directional arrow are shown clearly.
5. method according to claim 1; It is characterized in that: the determination methods of described step (3) is: when injecting positive polarity and dutycycle less than 50% current signal; The negative pole probe of acquisition of signal appearance is arranged on controllable high-voltage dc constant flowing power direction; Anodal probe is surveyed in the direction of the cable other end, the dutycycle of acquisition of signal appearance analytical voltage signal, and the voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is less than 50%; Be judged to be the trouble spot on the cable of the other end of the sensing point of anodal probe direction, indicator for displaying voltage waveform and directional arrow; Otherwise the voltage signal dutycycle that two probes of acquisition of signal appearance are gathered is judged to be the trouble spot on the sensing point and the cable between the controllable high-voltage dc constant flowing power of negative pole probe direction greater than 50%, and indicator for displaying voltage waveform and directional arrow are shown clearly.
6. device according to the described method of claim 1 failure judgement point orientation in the cable sheath fault finding; Comprise failure cable and probe; It is characterized in that: also comprise controllable high-voltage dc constant flowing power and acquisition of signal appearance; The output terminal of described controllable high-voltage dc constant flowing power connects an end of failure cable, and probe connects the input end of acquisition of signal appearance, and described acquisition of signal appearance comprises input protection unit, magnification processing, computer processing unit, indicator and signal trace zeroing unit; Probe connects the input end of magnification processing through the input protection unit; The output terminal of magnification processing connects the input end of computer processing unit, and the output terminal of computer processing unit is through the input end of signal trace zeroing unit connection magnification processing, and the output terminal of computer processing unit is link indicator also.
7. device according to claim 6; It is characterized in that: described controllable high-voltage dc constant flowing power comprises square-wave signal generation circuit, feedback control circuit, power supply input rectifying filtering circuit, inverter circuit, high-frequency transformer, high-voltage rectifier and isolation feedback circuit; The input end of power supply input rectifying filtering circuit connects civil power; Its output terminal connects the input end of inverter circuit; The output terminal of inverter circuit connects the high-voltage rectifier input end through high-frequency transformer; The output terminal of high-voltage rectifier is connected inverter circuit through isolation feedback circuit with feedback control circuit, and the output terminal of square-wave signal generation circuit connects feedback control circuit, and the output terminal of high-voltage rectifier is the output terminal of controllable high-voltage dc constant flowing power.
8. device according to claim 6 is characterized in that: the output terminal of described computer processing unit connects the input end of signal trace zeroing unit through digital to analog converter.
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| CN2010101304538A CN101782621B (en) | 2010-03-23 | 2010-03-23 | Method and device for judging fault point locations in cable protective layer fault detection |
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|---|---|---|---|---|
| CN102998592A (en) * | 2011-09-13 | 2013-03-27 | 中国二十冶集团有限公司 | Determining method for cable high-resistance fault points |
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