[go: up one dir, main page]

CN102540008A - Cable fault detection instrument - Google Patents

Cable fault detection instrument Download PDF

Info

Publication number
CN102540008A
CN102540008A CN2010105954516A CN201010595451A CN102540008A CN 102540008 A CN102540008 A CN 102540008A CN 2010105954516 A CN2010105954516 A CN 2010105954516A CN 201010595451 A CN201010595451 A CN 201010595451A CN 102540008 A CN102540008 A CN 102540008A
Authority
CN
China
Prior art keywords
cable
detected
voltage signal
ground
galvanometer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN2010105954516A
Other languages
Chinese (zh)
Inventor
刘永恒
邓会君
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MCC Baosteel Technology Services Co Ltd
Original Assignee
MCC Baosteel Technology Services Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by MCC Baosteel Technology Services Co Ltd filed Critical MCC Baosteel Technology Services Co Ltd
Priority to CN2010105954516A priority Critical patent/CN102540008A/en
Publication of CN102540008A publication Critical patent/CN102540008A/en
Pending legal-status Critical Current

Links

Images

Landscapes

  • Locating Faults (AREA)

Abstract

The invention provides a cable fault detection instrument which comprises a voltage signal generator, a grounding detection instrument and two probes and the like. During detecting, a voltage signal output by the voltage signal generator is loaded between a cable to be detected and the ground, the two probes connected with the grounding detection instrument are inserted in the ground in which the cable to be detected is positioned; the position of a fault point is determined by observing if a pointer of a galvanometer of the grounding detection instrument is deflected, and the accurate position of the fault point is determined finally by continuously moving the positions of the probes, wherein the accuracy can be about 0.5m. The detection process of the cable fault detection instrument is simple and easy to implement.

Description

The cable fault detector
Technical field
The invention belongs to construction fields such as electric maintenance, installation, particularly a kind of cable fault detector.
Background technology
When electric installation and electric maintenance, run into cable through regular meeting and break down, need utilize this moment pertinent instruments to find out the trouble spot after, could be according to the failure condition place under repair.On the domestic and international market, various types of cable fault surveying instrument is arranged, but all cost an arm and a leg, use the operation more complicated, and be difficult to intuitively confirm Method of Cable Trouble Point.
Therefore, the utmost point is necessary to provide a kind of cable detection equipment cheap, easy to use.
Summary of the invention
The object of the present invention is to provide a kind of simple in structure, with low cost and cable fault detector of being prone to execute.
Reach other purposes in order to achieve the above object, cable fault detector provided by the invention comprises:
Voltage signal generator is connected with cable to be detected, is used to provide a voltage signal between said cable to be detected and ground;
The earthing test appearance, it comprises: the galvanometer that is used to detect the electric current between said cable to be detected and the ground; The vagabond current that is connected with said galvanometer is eliminated circuit, is used to eliminate the interference current between said cable to be detected and the ground, so that galvanometer can detect the electric current that said cable to be detected produces because of the voltage that is loaded with voltage signal generator and provides; And power supply, eliminate circuit with said galvanometer and vagabond current and be connected;
Through insulator pin and two probes that said ground connection detector is connected, be used for inserting the on-site ground of said cable to be detected, respectively so that detect between the two probe positions whether have electric field.
Wherein, said cable to be detected is a direct-buried cable; The voltage signal that said voltage signal generator provides can be dc pulse signal etc.
Preferable, said voltage signal generator can comprise: the change-over circuit, the said direct supply of control that convert AC power into direct supply are so that said direct supply intermittence is carried in the control device between said cable to be detected and the ground; Said vagabond current is eliminated circuit and can be comprised: the current polarity by-pass cock that is connected with said power supply and be arranged on said earthing test instrument face, the potentiometer that is used for the regulating circuit electric current, reach the control device of control circuit all-in resistance; And then, be provided with the coarse adjustment switch that is connected with said potentiometer, and the accurate adjustment knob that is connected with said control device at said earthing test instrument face
In sum, cable fault detector of the present invention only needs d. c. voltage signal is carried between cable to be detected and the ground, through detection repeatedly, can detect the position of trouble spot, and its precision is about 0.5m.
Description of drawings
Fig. 1 is the synoptic diagram of cable fault detector of the present invention.
Fig. 2 is the embodiment synoptic diagram of the voltage signal generator of cable fault detector of the present invention.
Fig. 3 is the ground connection detector embodiment synoptic diagram of cable fault detector of the present invention.
Fig. 4 looses for cable to be detected forms and flows the electric field synoptic diagram.
Fig. 5 to Fig. 9 is the testing process synoptic diagram of cable fault detector of the present invention.
Embodiment
See also Fig. 1, cable fault detector of the present invention comprises: voltage signal generator, ground connection detector, and two probes.
Said voltage signal generator is connected with cable to be detected, is used to provide a voltage signal between said cable to be detected and ground.As shown in Figure 1; Cable said to be detected in the present embodiment is a direct-buried cable; " one " end that the heart yearn of said direct-buried cable one end (for example top) and screen layer extension line connect said voltage signal generator, "+" termination ground connection main line of said voltage signal generator.In addition, it should be appreciated by those skilled in the art that said cable to be detected is not to exceed with direct-buried cable, for example, can also be cable (as the pipe of passing by on one's way) of cable installation in pipe etc.Have, also not to be the above be restriction to the connected mode of said cable to be detected and said voltage signal generator again, for example, can be the heart yearn of said cable to be detected and "+" that the screen layer extension line connects said voltage signal generator holds etc.
Said voltage signal generator can comprise: with AC power convert into direct supply change-over circuit, control said direct supply so that said direct supply intermittence is carried in the control device between said cable to be detected and the ground; Specifically can be referring to Fig. 2, said change-over circuit comprises transformer BK, rectifier KD1-4, output capacitance etc.Said transformer BK boosts the 220V AC power that inserts into behind the 380V, pass through rectifier rectification again after, form the DC voltage of 340V at the output capacitance two ends.In addition, also be provided with the pulse time relay J1 as control device at output terminal, the setting valve through adjustment pulse time relay J1 can make 340V voltage be carried in by phased manner between cable to be detected and the ground, and one setting valve is 4-6 second.In addition, in the present embodiment, transformer also is provided with auxiliary winding, and being used for the 220V voltage transitions is the voltage of 36V, so that drive related device, for example, auxiliary reclay J, time relay sj, signal lamp HD, DL etc.
Those skilled in the art should understand that; Said voltage signal generator circuit is not that the above exceeds, in fact, as long as ability output dc voltage signal; Make this d. c. voltage signal current generated in ground the stray electric field in formed diffusing stream electric field and the ground a significantly difference is arranged; A kind of like this device can, at this, give an actual example no longer in addition and explain.
Said earthing test appearance comprises: galvanometer, vagabond current are eliminated circuit, are reached power supply etc.
As shown in Figure 3, said galvanometer is used to detect the galvanometer of the electric current between said cable to be detected and the ground.
Said vagabond current is eliminated circuit and is connected with galvanometer, is used to eliminate the interference current between said cable to be detected and the ground, so that galvanometer can detect the electric current that said cable to be detected produces because of the voltage that is loaded with voltage signal generator and provides.It comprises; Polarity switch, the potentiometer that is connected polarity switch one end, an end are connected the control device of tapped resistance series circuit of potentiometer and control circuit all-in resistance; Scope switch for example; Wherein, Resistance series circuit comprises resistance R 1, R2 and R3, and the first end N01 of scope switch is connected an end of resistance R 1, the common point that the second end N02 is connected resistance R 1 and resistance R 2, the common point that the 3rd end is connected resistance R 2 and R3.Said polarity switch part is outer to be exposed at said earthing test instrument face, so that manual shift; In addition, also be provided with the coarse adjustment switch that is connected with said potentiometer, and the accurate adjustment knob that is connected with said control device at said earthing test instrument face.
Said power supply is eliminated circuit with said galvanometer and vagabond current and is connected, and as shown in Figure 3, power supply can be a battery etc.
It should be appreciated by those skilled in the art that ground connection detector shown in Figure 3 is an illustration only, but not be used to limit the present invention; It can adopt other circuit to realize.
Said two probes are connected with said ground connection detector through insulator pin respectively, are used for inserting the on-site ground of said cable to be detected, so that detect between the two probe positions whether have electric field.As shown in Figure 3, two insulator pins connect binding post respectively.In the present embodiment, two probes adopt long 400mm, Φ 10 zinc-plated garden steel to process, and probe top is welded with the terminal that connects lead-in wire, and top can be made into handle shape, and the bottom breaks into needle-like, be convenient to probe is inserted in the ground, and said two insulator pins adopt 1.5mm 2Two of copper core polyethylene insulation flexible circuit conductors, every long about 20 meters etc.
Length, material that it should be appreciated by those skilled in the art that shape, length, material and the insulator pin of probe or the like all is not that the above exceeds.
Because on the cable to be detected during certain point failure, cable to be detected has cable core or the screen layer of electric current through the trouble spot and flows in the ground, and will form in the ground with the trouble spot is the diffusing stream electric field at center; As shown in Figure 4; Loose the stream electric field strong and weak under the constant situation of supply voltage that said cable to be detected inserts, determine that by feeding electric current power in the ground electric current power is determined by the earth fault insulation resistance value; The trouble spot signal is strong during low resistance, during high value a little less than the signal of trouble spot.
Yet, near the ground the trouble spot, not only remain leak electricity formed electric field of detection streamer to be existed; And possibly have the formed stray electric field of earthing device simultaneously by various electrical equipments such as the transformer station at cable burial place, interim supply transformers,, need said stray electric field (promptly disturbing) be eliminated for this reason.
Thus, above-mentioned earthing cable trouble spot testing process is following:
◆ remove the heart yearn of cable one end to be detected and screen layer extension line from connection terminal; Insert voltage signal generator (power supply AC220V); Wherein, voltage signal generator dc output end "+" termination ground connection main line, " one " termination heart yearn or shielding layer grounding extension line.Remove the heart yearn of the other end of cable or screen layer extension line, twine insulation respectively." the direct-buried cable trouble spot searches wiring schematic diagram " as shown in Figure 5.
◆ ground connection detector " E " terminal with probe is inserted cable to be detected top (the voltage signal input end is cable top) after probe is connected, " L " terminal with probe is inserted cable termination to be detected after probe is connected, as shown in Figure 5.
If ◆ the preliminary approximate location of the localization of faults, then can insert probe nearby, begin to survey.Otherwise the head end or the tail end that need to imbed from cable to be detected begin to insert probe, as surveying starting point.
The insertion depth of two probes is not less than 0.3 meter, and spacing is advisable with 20-40 rice, because the stream electric field that looses has leveled off to zero apart from the 20 meters local current potentials in addition in stream center that loose.Like probe spacing from too small, possibly flow because of loosing during bigness scale electric field a little less than, the potential difference (PD) between probe is little, makes galvanometer needle deflection amount also little, reacts not obvious; When excessive, might cross the trouble spot and test leakage like probe spacing.
◆ the vagabond current cancellation element power switch S that closes pushes N1 or N2 position, and the galvanometer power switch is dialled in the ON position, and galvanometer sensitivity adjusting knob need be looked concrete condition and be adjusted to the appropriate location.
◆ regulate coarse adjustment switch VR1 and accurate adjustment knob VR2, when the galvanometer pointer refers in zero-bit, explain that stray electric field eliminates.
◆ be added to the voltage rule of voltage signal generator output discontinuously between heart yearn or screen layer and the ground, observe the galvanometer pointer and whether do synchronous deflection with signal voltage.Need about 1 minute observing time approximately.When marking current is big (low resistance fault), observe than be easier to, need the time just short, otherwise will grow.Do not have synchronous deflection like pointer, explaining between two probes does not have the trouble spot.At this moment forward galvanometer power switch, vagabond current cancellation element power switch to close position, stop to add signal voltage, transfer to probe, prepare to survey next time.
◆ when surveying, detection method is the same with primary detection next time.The relative position of probe and earthing test appearance can replace by Fig. 6 successively.For example, measure for the first time relative position: probe A connects that earthing test appearance E terminal (cable top), probe C connect earthing test appearance L terminal (cable termination), B representes tester.When surveying for the second time, probe A moves to earthing test appearance B position, and earthing test appearance B moves to probe C position, and probe C moves 20 meters to cable termination.When surveying for the third time, probe A moves to tester B position for the second time, and earthing test appearance B moves to probe C position for the second time, and probe C moves 20 meters to cable termination.Going on so successively done directed synchronously deflection until on galvanometer, observing pointer and signal voltage.At this moment measure the position between two probes, trouble spot roughly.Usually, about 10 meters far away apart from the trouble spot position, can obviously observe the sign of trouble spot.
◆ accurate test failure point.
When preliminary observation arrived the deflection of galvanometer pointer and the synchronous orientation of signal voltage work, according to the mode of connection of Fig. 5, the trouble spot always was present in the reverse side of galvanometer needle deflection direction.The first time as shown in Figure 7 the measuring position, the deflection left of galvanometer pointer explains that the trouble spot is near the L probe.When carrying out secondary mobile spy side again,, the trouble spot is described, explains that simultaneously the trouble spot is clipped between L and the E1 probe near the E1 probe as finding (to the right) deflection in the opposite direction of galvanometer pointer; And if the deflection left of discovery galvanometer pointer is explained the trouble spot near the L1 probe, explain that simultaneously the trouble spot is clipped between L and the L1 probe, shown in the dotted line position of failure point.
After finding that the galvanometer needle deflection localization of faults is sandwiched between E, L two probes, at this moment, can be according to galvanometer needle deflection amount and yawing moment, the failure judgement point is to level off to which root probe.As shown in Figure 8, galvanometer needle deflection position 1, amount of deflection is big, and near partially probe 1 position, trouble spot is described.At this moment can probe 1 be moved to probe 2 positions to the trouble spot direction gradually, galvanometer needle deflection position 2, the needle deflection amount reduces; Probe moves to 3 positions; The galvanometer needle deflection is to 3 positions, and during galvanometer pointer convergence zero-bit, traveling probe as shown in Figure 9 is to 4 positions; This is put the trouble spot and equals the E probe to the trouble spot during apart from S apart from S, and inspection stream pin pointer 4 equals zero.1/2 position that two probe distances are described is the trouble spot.Also can continue alternately traveling probe E, L position, keep inspection stream pin pointer to equal zero.Make the distance of two probes more and more nearer.Alternately moving of such two probes, at last trouble location in 0.5 meter scope.
Some explanation;
◆ if the direct current signal electric current is when 5mA is above, just can on galvanometer, reflect needle deflection.Little marking current, the needle deflection amount is very little, needs careful the observation.
◆ for high resistive fault, need to improve direct-flow signal voltage, so that obtain the direct current signal electric current that can detect.
◆ as pressing martingale shown in Figure 5, the trouble spot always is present in the reverse side of galvanometer needle deflection direction.
◆ more at grounding body, when the complicated place of earth electric field was surveyed, vagabond current was eliminated difficulty, and the galvanometer pointer is difficult for being stabilized in zero-bit.In order to shorten probe time, when the bigness scale trouble spot, the vagabond current elimination differs too carefully customized.When the low-resistance fault, marking current is bigger especially, and pointer is observed easily with the phenomenon of the synchronous deflection swing of signal electric current.
◆ under one situation, accurate measurement finishes to the trouble spot from finding fault evidence, and only traveling probe can be localization of fault several times for need.This need do comprehensive judgement according to the distance of galvanometer needle deflection direction, amount of deflection, traveling probe.Accuracy of judgement is the prerequisite of shortening time.
◆ this detection method is applicable to the cable of directly buried installation.To the cable (as the pipe of passing by on one's way) of cable installation in pipe, can measure fault in this section pipeline with the method.
◆ when galvanometric sensitivity adjusting knob is transferred greatly,, be difficult for transferring to zero-bit though be quick on the draw.Revolve hour, little in probe spacing, under the situation that marking current was little when the trouble spot was bordering on the middle position of two probes, the needle deflection of inspection stream juice is faint, therefore galvanometric sensitivity adjusting knob need be looked concrete condition and regulates.
In sum, cable fault detector of the present invention is simple in structure, and testing process is convenient, and is practical, and with low cost.
The foregoing description is just listed expressivity principle of the present invention and effect is described, but not is used to limit the present invention.Any personnel that are familiar with this technology all can make amendment to the foregoing description under spirit of the present invention and scope.Therefore, rights protection scope of the present invention should be listed like claims.

Claims (9)

1. cable fault detector is characterized in that comprising:
Voltage signal generator is connected with cable to be detected, is used to provide a voltage signal between said cable to be detected and ground;
The earthing test appearance, it comprises:
Be used to detect the galvanometer of the electric current between said cable to be detected and the ground;
The vagabond current that is connected with said galvanometer is eliminated circuit, is used to eliminate the interference current between said cable to be detected and the ground, so that galvanometer can detect the electric current that said cable to be detected produces because of the voltage that is loaded with voltage signal generator and provides; With
Power supply is eliminated circuit with said galvanometer and vagabond current and is connected;
Through insulator pin and two probes that said ground connection detector is connected, be used for inserting the on-site ground of said cable to be detected, respectively so that detect between the two probe positions whether have electric field.
2. cable fault detector as claimed in claim 1 is characterized in that: said cable to be detected is a direct-buried cable.
3. cable fault detector as claimed in claim 1 is characterized in that: the voltage signal that said voltage signal generator provides is a dc pulse signal.
4. like claim 1 or 3 described cable fault detectors, it is characterized in that: said voltage signal generator comprises: with AC power convert into direct supply change-over circuit, control said direct supply so that said direct supply intermittence is carried in the control device between said cable to be detected and the ground.
5. said control device as claimed in claim 4 comprises pulse time relay
6. cable fault detector as claimed in claim 1; It is characterized in that: said vagabond current is eliminated circuit and is comprised: the current polarity by-pass cock that is connected with said power supply and be arranged on said earthing test instrument face, the potentiometer that is used for the regulating circuit electric current, reach the control device of control circuit all-in resistance; And then, be provided with the coarse adjustment switch that is connected with said potentiometer, and the accurate adjustment knob that is connected with said control device at said earthing test instrument face.
7. cable fault detector as claimed in claim 1 is characterized in that: the material of said two probes is a zinc-plated garden steel.
8. like claim 1 or 7 described cable fault detectors, it is characterized in that: said two probe tops are handle shape, and the bottom is needle-like.
9. cable fault detector as claimed in claim 1 is characterized in that: said insulator pin is a copper core polyethylene insulation flexible circuit conductor.
CN2010105954516A 2010-12-17 2010-12-17 Cable fault detection instrument Pending CN102540008A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN2010105954516A CN102540008A (en) 2010-12-17 2010-12-17 Cable fault detection instrument

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN2010105954516A CN102540008A (en) 2010-12-17 2010-12-17 Cable fault detection instrument

Publications (1)

Publication Number Publication Date
CN102540008A true CN102540008A (en) 2012-07-04

Family

ID=46347371

Family Applications (1)

Application Number Title Priority Date Filing Date
CN2010105954516A Pending CN102540008A (en) 2010-12-17 2010-12-17 Cable fault detection instrument

Country Status (1)

Country Link
CN (1) CN102540008A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106370976A (en) * 2016-08-22 2017-02-01 合肥德泰科通测控技术有限公司 Railway power supply cable outer jacket fault's precise position detection method
CN106814399A (en) * 2016-12-29 2017-06-09 江苏海上龙源风力发电有限公司 A kind of culture zone submarine cable location detection methods
CN108828408A (en) * 2018-07-11 2018-11-16 江阴市华能电热器材有限公司 The device and method of the buried skin-effect electric heating high resistance earthing fault of non-destructive determination
JP2019015749A (en) * 2013-11-19 2019-01-31 ヒュン チャン リー Mobile electric leakage search device
CN112403679A (en) * 2020-10-13 2021-02-26 河钢股份有限公司承德分公司 Method for verifying contact between anode plate and cathode wire of electrostatic dust removal electric field
CN112557830A (en) * 2020-12-29 2021-03-26 广东电网有限责任公司佛山供电局 Cable fault point positioning device and method
CN112557821A (en) * 2020-12-03 2021-03-26 广东电网有限责任公司江门供电局 Low-voltage cable fault magnetic detection fixed point method and system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3944914A (en) * 1974-04-29 1976-03-16 Perkins Research And Manufacturing Co. Fault detection method and apparatus for multiconductor cables
CN2096074U (en) * 1991-07-06 1992-02-12 天津电力试验研究所 Fault detector for rubber-plastic cable outer sheath damage
CN1674164A (en) * 2004-03-18 2005-09-28 斯考拉股份公司 Device for detecting interferences or interruptions of the inner fields smoothing layer of medium or high voltage cables
US20080036466A1 (en) * 2006-08-11 2008-02-14 Raber Monte B Method for detecting electrical ground faults
CN101576600A (en) * 2009-05-15 2009-11-11 重庆大学 Self-walking underground cable failure detection intelligent instrument

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3944914A (en) * 1974-04-29 1976-03-16 Perkins Research And Manufacturing Co. Fault detection method and apparatus for multiconductor cables
CN2096074U (en) * 1991-07-06 1992-02-12 天津电力试验研究所 Fault detector for rubber-plastic cable outer sheath damage
CN1674164A (en) * 2004-03-18 2005-09-28 斯考拉股份公司 Device for detecting interferences or interruptions of the inner fields smoothing layer of medium or high voltage cables
US20080036466A1 (en) * 2006-08-11 2008-02-14 Raber Monte B Method for detecting electrical ground faults
CN101576600A (en) * 2009-05-15 2009-11-11 重庆大学 Self-walking underground cable failure detection intelligent instrument

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
尹茂祥: "塑料通信电缆故障探测仪", 《电线电缆》, no. 4, 31 August 1984 (1984-08-31), pages 35 - 37 *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019015749A (en) * 2013-11-19 2019-01-31 ヒュン チャン リー Mobile electric leakage search device
US10996285B2 (en) 2013-11-19 2021-05-04 Hyun Chang Lee Method of detecting earth leaking point without interrupting a power supply
CN106370976A (en) * 2016-08-22 2017-02-01 合肥德泰科通测控技术有限公司 Railway power supply cable outer jacket fault's precise position detection method
CN106814399A (en) * 2016-12-29 2017-06-09 江苏海上龙源风力发电有限公司 A kind of culture zone submarine cable location detection methods
CN108828408A (en) * 2018-07-11 2018-11-16 江阴市华能电热器材有限公司 The device and method of the buried skin-effect electric heating high resistance earthing fault of non-destructive determination
CN108828408B (en) * 2018-07-11 2023-06-06 江阴市华能电热器材有限公司 Device and method for nondestructively measuring buried skin effect electric tracing high-resistance grounding fault
CN112403679A (en) * 2020-10-13 2021-02-26 河钢股份有限公司承德分公司 Method for verifying contact between anode plate and cathode wire of electrostatic dust removal electric field
CN112403679B (en) * 2020-10-13 2022-10-25 河钢股份有限公司承德分公司 Method for verifying contact between anode plate and cathode wire of electrostatic dust removal electric field
CN112557821A (en) * 2020-12-03 2021-03-26 广东电网有限责任公司江门供电局 Low-voltage cable fault magnetic detection fixed point method and system
CN112557830A (en) * 2020-12-29 2021-03-26 广东电网有限责任公司佛山供电局 Cable fault point positioning device and method

Similar Documents

Publication Publication Date Title
CN102540008A (en) Cable fault detection instrument
CN101266270B (en) Pile Foundation Tower Grounding Impedance Measuring Device and Method
US20140247063A1 (en) Earth Ground Tester With Remote Control
US20140015538A1 (en) Method of Measuring Earth Ground Resistance of a Pylon
EA202191916A1 (en) CURRENT AND VOLTAGE MEASUREMENT UNIT
US20040160227A1 (en) Apparatus and method for determining the status of an electric power cable
US12188889B2 (en) System and method for continuously and intelligently measuring water content of subgrade in real time
CN101504436A (en) Semi-wave DC detection method
CN106019013A (en) High voltage support lightning protection reliability integrated diagnosis method
CN103197195A (en) Detecting method and detecting system for multipoint earthing of voltage second loop neutral conductor network
CN103257266A (en) Portable all-insulation optical-fiber current detector
CN108776320B (en) Transformation ratio and polarity detection test method and device for current transformer
GB2227845A (en) Loop-impedance-tester
US8797019B2 (en) Handheld fiber optic current and voltage monitor for high voltage applications
CN201852886U (en) Multifunctional earth resistance tester
CN102662127B (en) Detecting method for long-distance and multi-bundled cables
CN213398688U (en) Multifunctional tester and testing system
CN205157654U (en) Mounting structure of ground resistance test system
CN106122774B (en) A kind of pipeline leakage detection method
CN108802498A (en) A kind of earth resistance tester
JP2008232737A (en) Electric leakage detection method and digital tester used in the same method
Shafiq et al. Online partial discharge diagnostics in medium voltage branched cable networks
US20130119976A1 (en) High voltage detection in power system electrical high voltage line
CN205844414U (en) A kind of earth resistance circuit structure measured based on split-core type meter
Zhao et al. Research on geo-electrical resistivity observation system specially used for earthquake monitoring in China

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C12 Rejection of a patent application after its publication
RJ01 Rejection of invention patent application after publication

Application publication date: 20120704