CN201397372Y - Single-phase ground fault location device for distribution network - Google Patents
Single-phase ground fault location device for distribution network Download PDFInfo
- Publication number
- CN201397372Y CN201397372Y CN2008201233032U CN200820123303U CN201397372Y CN 201397372 Y CN201397372 Y CN 201397372Y CN 2008201233032 U CN2008201233032 U CN 2008201233032U CN 200820123303 U CN200820123303 U CN 200820123303U CN 201397372 Y CN201397372 Y CN 201397372Y
- Authority
- CN
- China
- Prior art keywords
- signal
- voltage
- detector
- transformer
- output
- 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.)
- Expired - Lifetime
Links
- 230000005672 electromagnetic field Effects 0.000 claims abstract description 7
- 239000004973 liquid crystal related substance Substances 0.000 claims description 7
- 238000005259 measurement Methods 0.000 claims description 5
- 230000005355 Hall effect Effects 0.000 claims description 4
- 230000005674 electromagnetic induction Effects 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 7
- 230000007935 neutral effect Effects 0.000 abstract description 5
- 238000005516 engineering process Methods 0.000 abstract description 4
- 230000004807 localization Effects 0.000 description 13
- 238000010586 diagram Methods 0.000 description 8
- 239000003990 capacitor Substances 0.000 description 6
- 210000000080 chela (arthropods) Anatomy 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 238000005070 sampling Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000035800 maturation Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
Landscapes
- Locating Faults (AREA)
Abstract
本实用新型公开了一种配电网单相接地故障定位新方法，该方法适用于3～60kV中性点非有效接地电网。定位方法原理为：首先在线路始端注入高压直流信号，沿线路检测直流信号确定故障区域；然后在线路始端注入高压交流信号，沿线路检测交流信号确定故障点位置。基于本实用新型研制的定位装置由高压信号源和信号检测器两个部分组成，高压信号源由电压逆变器、恒流源、变压器、整流桥组成，用于注入高压直流信号和交流信号；信号检测器分为直流检测器和交流检测器，直流检测器由霍尔直流检测器、蓝牙无线发送器以及蓝牙无线接收器组成，用于测量直流信号；交流检测器由交流电磁场感应器及信号处理显示环节组成，用于测量交流信号。本实用新型技术成熟、可靠性高。
The utility model discloses a new method for locating single-phase grounding faults in a distribution network. The method is suitable for 3-60kV neutral point non-effectively grounding power grids. The principle of the positioning method is as follows: first inject high-voltage DC signal at the beginning of the line, detect the DC signal along the line to determine the fault area; then inject high-voltage AC signal at the beginning of the line, and detect the AC signal along the line to determine the location of the fault point. The positioning device developed based on the utility model is composed of a high-voltage signal source and a signal detector. The high-voltage signal source is composed of a voltage inverter, a constant current source, a transformer, and a rectifier bridge, and is used to inject high-voltage DC signals and AC signals; The signal detector is divided into a DC detector and an AC detector. The DC detector is composed of a Hall DC detector, a Bluetooth wireless transmitter and a Bluetooth wireless receiver, and is used to measure DC signals; the AC detector is composed of an AC electromagnetic field sensor and a signal detector. The processing and display link is used to measure the AC signal. The utility model has mature technology and high reliability.
Description
Technical field
The utility model belongs to a kind of power technology and equipment, is applicable to 3～60kV neutral non-effective grounding electrical network, can accurately locate singlephase earth fault.
Background technology
China 3～60kV power distribution network extensively adopts the neutral non-effective grounding mode, is called small current neutral grounding system again, and the fault overwhelming majority of small current neutral grounding system is a singlephase earth fault.When singlephase earth fault took place, ground current was very little, can continue operation 1～2 hour under failure condition, but must find the trouble spot as early as possible, and this has just proposed fault-location problem.
The one-phase earthing failure in electric distribution network orientation problem is not well solved for a long time, and artificial line walking has not only expended a large amount of manpower and materials, and has prolonged power off time, influences power supply safety.Have document to propose to inject high-frequency signal from PT, road along the line is detected this signal and is determined abort situation, but because line distribution capacitance forms path to high-frequency signal, therefore the location is inaccurate when resistance grounded.
Summary of the invention
The purpose of this utility model is the deficiency that overcomes on the prior art, proposes new localization method, and a kind of locating device at one-phase earthing failure in electric distribution network is provided.The localization of faults quickly and accurately of this locating device, and be applicable to metallic earthing, through arcing ground, through various faults situations such as transition resistance eutral groundings.
The technical solution of the utility model is as follows:
A kind of single-phase earth fault positioning device for electrical power distribution network, this single-phase earth fault positioning device is made up of high-voltage signal source and two parts of signal detector, described high-voltage signal source comprises voltage inverter, constant current source, transformer, rectifier bridge, voltage inverter, constant current source, transformer, four parts of rectifier bridge connect in turn, described voltage inverter is an alternating voltage with vehicle-mounted DC voltage inversion, this alternating voltage is successively by constant current source and transformer, output terminal at transformer obtains the constant ac high-voltage signal of an output current, described transformer output terminal also is connected to described rectifier bridge by switchgear, the high direct voltage signal of rectifier bridge output behind overcommutation, by converting switch device, described high-voltage signal source selects to draw ac high-voltage signal and high direct voltage signal;
Described signal detector comprises DC detector and ac detector, described DC detector is made up of Hall DC detector, blue teeth wireless transmitter and blue teeth wireless receiver, the Hall DC detector has pincers type opening, be used to overlap link, utilize Hall effect that direct current signal is detected, the Hall DC detector is connected with the blue teeth wireless transmitter, and blue teeth wireless receiver and transmitter are by wireless connections, and receiver is shown to the result on the liquid crystal; Ac detector is made up of ac magnetic field inductor and signal Processing display device, the ac magnetic field inductor is used to detect AC signal, utilize the electromagnetic induction of external electromagnetic field that AC signal is measured, measurement result is shown on the liquid crystal by the signal Processing display device.
Fault locator of the present utility model realizes localization of fault by following principle:
Localization of fault was divided into for two steps, at first determined fault section, the localization of faults then.Behind the open failure circuit, inject high-voltage dc signal at line fault phase top, according to Kirchhoff's law, direct current signal necessarily constitutes the loop by the trouble spot, circuit top can measure the direct current signal of injection to the path of trouble spot, but not the fault zone can not measure (comprising after non-fault branch and the trouble spot) direct current signal of injection.Road therefore along the line is detected the direct current signal that each affluent-dividing is crossed at crucial take-off point place with signal detector, can detect direct current signal if find a certain branch, the downstream of trouble spot in this branch is described, if detect less than direct current signal, the trouble spot is described in the upstream, section until localization of faults place.
When definite fault section in the 1000m scope with after interior, inject high-voltage AC signal at line fault phase top because line length is shorter in the section, so the capacitance current influence is very little, the amplitude variation more than 5 times will appear in the AC signal before and after the trouble spot.AC signal is detected with signal detector in road along the line, can determine the accurate position of fault.
Advantage of the present utility model is as follows:
1, accurate position that can the localization of faults.
2, be not subjected to the influence of line distribution capacitance, can effectively solve the orientation problem under the high resistance ground situation.
3, not be used in erecting device on every circuit, utilize a covering device can carry out the location of many circuits, save cost greatly.
4, high-voltage signal source adopts the vehicle power power supply, and signal detector adopts hand held structures, utilizes powered battery, is convenient to field operation, the dirigibility height.
5, adopt high-voltage signal source, can guarantee to puncture earth fault, make fault recurrence; Adopt the 60Hz AC signal, can guarantee not to be subjected to the interference of power frequency component, improve measuring accuracy.
6, technology maturation, reliability height are applicable to 3～60kV power distribution network, are applicable to metallic earthing, through arcing ground, through various faults situations such as transition resistance eutral groundings.
Description of drawings
Fig. 1 is a structural representation of the present utility model;
Fig. 2 is the schematic diagram of high-voltage signal source;
Fig. 3 is the schematic diagram of constant current source;
Fig. 4 is the circuit diagram of rectifier bridge;
Fig. 5 A is the Hall DC detector synoptic diagram in the direct current signal detecting device, and Fig. 5 B is the wiring diagram of sampling processing circuit and blue teeth wireless transmitter, and Fig. 5 C is the wiring diagram of blue teeth wireless receiver and LCD MODULE;
Fig. 6 is the schematic diagram of alternating current signal detection device.
Embodiment
, the technical solution of the utility model is described in further detail as figure below in conjunction with instructions by specific embodiment.
A kind of new localization method that the utility model proposes, its principle are to determine section, the localization of faults then earlier.Behind the open failure circuit, fault is injected high-voltage dc signal mutually at circuit top, and road along the line is detected the direct current signal that each affluent-dividing is crossed at crucial take-off point place with signal detector, according to the section at the variation localization of faults place of direct current signal.When fault section during less than 1000m, fault is injected high-voltage AC signal mutually at circuit top, and AC signal is detected with signal detector in road along the line, determines the accurate position of fault.This method belongs to initiative.
Locating device based on the utility model development is made up of high-voltage signal source and two parts of signal detector.Described high-voltage signal source is made up of voltage inverter, constant current source, transformer, rectifier bridge, four parts connect in turn, the external vehicle power of voltage inverter, can be alternating voltage with vehicle-mounted DC voltage inversion, this alternating voltage raises to High AC voltage by constant current source and transformer and guarantees that the output current amplitude is constant, and rectifier bridge is DC voltage, electric current with alternating voltage, current commutates.High-voltage signal source is externally drawn four HV Terminal, draws high-voltage AC signal and high-voltage dc signal respectively, and selects direct current or exchange output by change-over switch.
Described signal detector is divided into DC detector and ac detector, DC detector is made up of Hall DC detector, blue teeth wireless transmitter and blue teeth wireless receiver, and ac detector is made up of ac magnetic field inductor and signal Processing demonstration link.The Hall DC detector has pincers type opening, be used to overlap link, utilize Hall effect that direct current signal is detected, the Hall DC detector is connected with the blue teeth wireless transmitter, blue teeth wireless receiver and transmitter carry out reliable wireless connections in the 10m scope, receiver is shown to the result on the liquid crystal.The ac magnetic field inductor is used to detect AC signal, can utilize the electromagnetic induction of external electromagnetic field that AC signal is measured in the 10m scope, and measurement result is shown on the liquid crystal.Signal detector adopts hand held structures, utilizes powered battery.
Localization of fault was divided into for two steps, at first determined fault section, the localization of faults then.Behind the open failure circuit, inject high-voltage dc signal at line fault phase top, according to Kirchhoff's law, direct current signal necessarily constitutes the loop by the trouble spot, circuit top can measure the direct current signal of injection to the path of trouble spot, but not the fault zone can not measure (comprising after non-fault branch and the trouble spot) direct current signal of injection.Road therefore along the line is detected the direct current signal that each affluent-dividing is crossed at crucial take-off point place with signal detector, can detect direct current signal if find a certain branch, the downstream of trouble spot in this branch is described, if detect less than direct current signal, the trouble spot is described in the upstream, section until localization of faults place.
When definite fault section in the 1000m scope with after interior, inject high-voltage AC signal at line fault phase top because line length is shorter in the section, so the capacitance current influence is very little, the amplitude variation more than 5 times will appear in the AC signal before and after the trouble spot.AC signal is detected with signal detector in road along the line, can determine the accurate position of fault.
As shown in Figure 1, locating device is made up of high-voltage signal source and two parts of signal detector, open failure circuit after the generation earth fault, the lead-out terminal one of high-voltage signal source is terminated at circuit top fault to be gone up mutually, the other end is connected on the earth, adjusts change-over switch and selects direct current output or exchange output.Utilize fault detector road along the line that direct current signal or AC signal are detected, finally find position of failure point.
The high-voltage signal source principle is made up of voltage inverter, constant current source, transformer, rectifier bridge as shown in Figure 2, and four parts connect in turn.R represents voltage inverter, externally draws input port R1+, a R1-, be connected on during use on the both positive and negative polarity of vehicle-mounted 12V power supply, and can be the alternating voltage of 220V, 60Hz with the inversion of vehicle-mounted 12V DC voltage; Z represents constant current source, and electric current that can the control transformer low-pressure side is constant 3A, thereby the electric current that guarantees the transformer high-voltage side is constant 200mA; T represents the double winding step-up transformer, and no-load voltage ratio is 1: 14, original edge voltage can be raise to be the alternating voltage of 3000V, 60Hz; D represents the high-voltage rectifying bridge, can be DC voltage, electric current with alternating voltage, current commutates.High-voltage signal source is externally drawn two high-voltage output end mouths, and wherein K1+, K1-represent to draw high-voltage AC signal, and K2+, K2-represent to draw high-voltage dc signal, by the type of change-over switch K control output signal.
The constant current source principle as shown in Figure 3.The ac voltage output mouth of the external inverter R of input port AN, current transformer is used to measure the current in loop amplitude, x1 is connected with CPU as the secondary side of current transformer with x2, CPU detects the electric current in loop and trigger pulse G1, G2 by driving circuit control controllable silicon K1, K2, constitutes close-loop feedback control.When current in loop was lower than setting value, trigger pulse reduces the silicon controlled conduction angle increased loop current; When current in loop was higher than setting value, trigger pulse increases the silicon controlled conduction angle reduced loop current, has guaranteed the steady current of loop current for setting like this.
The circuit diagram of rectifier bridge as shown in Figure 4.High AC voltage after U2, i2 represent to boost, electric current, VT1, VT2, VT3, VT4 are represented four high-voltage diodes, and C represents flat wave capacitor, and R represents load.VT1 and the VT4 brachium pontis that partners, bearing voltage U 2 at the positive half cycle of U2 is conducting, turn-offs when the U2 zero passage.VT2 and VT3 form another to brachium pontis, and bearing voltage-U2 at the U2 negative half period is conducting, turn-off when the U2 zero passage.Capacitor C plays flat ripple effect, and when voltage U 2 was higher than voltage on the capacitor C, voltage U 2 was powered to load R to the electric capacity charging simultaneously; And when voltage U 2 was lower than voltage on the capacitor C, capacitor C was powered to load R.Therefore rectifier bridge can guarantee provide DC voltage, electric current to load when the input sinusoidal voltage, and guarantees that by flat wave capacitor DC voltage, current amplitude are constant.
The direct current signal detector concept is shown in Fig. 5 A-5C, and detecting device comprises Hall DC detector, blue teeth wireless transmitter and blue teeth wireless receiver.Fig. 5 A is the Hall DC detector, and there is pincers type opening in its edge, is used to overlap link, and pincers type open interior embeds Hall element, can utilize Hall effect that direct current signal is detected.Fig. 5 B is sampling processing circuit and blue teeth wireless transmitter, can amplify detection signal, Filtering Processing, and signal is carried out the AD conversion be transferred to the blue teeth wireless transmitter.Wherein 8051F310 is a central processing unit, and CA3140 is an operational amplifier, and CRM2400 is a bluetooth radio module.Fig. 5 C is the blue teeth wireless receiver, can received signal and the result is shown on the liquid crystal.Wherein 8051F310 is a central processing unit, and CA3140 is an operational amplifier, and CRM2400 is a bluetooth radio module, and LCM046 is a LCD MODULE.After circuit injects direct current signal, need step on bar on the line with the socket of detecting device pincers type mouth, the blue teeth wireless transmitter below circuit can show measurement result automatically.
Alternating current signal detection device principle as shown in Figure 6, the alternating current signal detection device shows that by ac magnetic field inductor and signal Processing link constitutes.When the injection signal is the 60Hz AC signal, can produce the 60Hz alternating electromagnetic field at the circuit surrounding space.The ac magnetic field inductor is the inductive coil of a multiturn number, and the external electromagnetic field signal can induce ac voltage signal in the 10m scope on inductor, and this voltage magnitude is directly proportional with current amplitude on the circuit.After the amplification of induced voltage signal process, the Filtering Processing, the result is shown on the liquid crystal.LF347 is an operational amplifier, is used for the 60Hz ac voltage signal of sensing is amplified, and is convenient to measure.LM317 is a stabilivolt, is used to guarantee the battery supply steady operation.UAF42 is a wave filter, is used for the filtering interfering noise signal, extracts useful 60Hz AC signal.After circuit injects the 60Hz AC signal, below circuit, just can detect and show measurement result automatically signal.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008201233032U CN201397372Y (en) | 2008-10-24 | 2008-10-24 | Single-phase ground fault location device for distribution network |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008201233032U CN201397372Y (en) | 2008-10-24 | 2008-10-24 | Single-phase ground fault location device for distribution network |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201397372Y true CN201397372Y (en) | 2010-02-03 |
Family
ID=41619891
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2008201233032U Expired - Lifetime CN201397372Y (en) | 2008-10-24 | 2008-10-24 | Single-phase ground fault location device for distribution network |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201397372Y (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102928739A (en) * | 2012-11-02 | 2013-02-13 | 华北电力大学（保定） | Method and system used for locating power grid single-phase ground faults and based on wireless sensor network |
| CN103140765A (en) * | 2010-10-07 | 2013-06-05 | 东芝三菱电机产业系统株式会社 | Failure detecting apparatus |
| CN103513161A (en) * | 2013-09-27 | 2014-01-15 | 孙双春 | Power transmission and transformation system fault searching locating instrument and searching method |
| CN105259467A (en) * | 2015-11-18 | 2016-01-20 | 南京国电南自电网自动化有限公司 | Single-phase fault analysis method considering star-triangle transformation |
| CN107024639A (en) * | 2016-02-02 | 2017-08-08 | 天津理工大学 | A kind of miniature FLU Fault Location Unit and method for region direct-flow distribution system |
| CN111077410A (en) * | 2019-12-28 | 2020-04-28 | 天津浩源慧能科技有限公司 | Power distribution network fault positioning instrument and detection method |
| CN115453258A (en) * | 2022-08-04 | 2022-12-09 | 国网河北省电力有限公司保定供电分公司 | Low-voltage ground fault point searching device and method |
| CN115932483A (en) * | 2023-02-09 | 2023-04-07 | 青岛鼎信通讯股份有限公司 | Low-voltage power grid leakage fault positioning device and method |
-
2008
- 2008-10-24 CN CN2008201233032U patent/CN201397372Y/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103140765A (en) * | 2010-10-07 | 2013-06-05 | 东芝三菱电机产业系统株式会社 | Failure detecting apparatus |
| CN102928739A (en) * | 2012-11-02 | 2013-02-13 | 华北电力大学（保定） | Method and system used for locating power grid single-phase ground faults and based on wireless sensor network |
| CN103513161A (en) * | 2013-09-27 | 2014-01-15 | 孙双春 | Power transmission and transformation system fault searching locating instrument and searching method |
| CN103513161B (en) * | 2013-09-27 | 2017-07-14 | 中国石油化工股份有限公司 | Electrical power trans mission/distribution system trouble shoot position indicator and lookup method |
| CN105259467A (en) * | 2015-11-18 | 2016-01-20 | 南京国电南自电网自动化有限公司 | Single-phase fault analysis method considering star-triangle transformation |
| CN107024639A (en) * | 2016-02-02 | 2017-08-08 | 天津理工大学 | A kind of miniature FLU Fault Location Unit and method for region direct-flow distribution system |
| CN111077410A (en) * | 2019-12-28 | 2020-04-28 | 天津浩源慧能科技有限公司 | Power distribution network fault positioning instrument and detection method |
| CN115453258A (en) * | 2022-08-04 | 2022-12-09 | 国网河北省电力有限公司保定供电分公司 | Low-voltage ground fault point searching device and method |
| CN115932483A (en) * | 2023-02-09 | 2023-04-07 | 青岛鼎信通讯股份有限公司 | Low-voltage power grid leakage fault positioning device and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101382577B (en) | Single-phase ground fault location device for distribution network | |
| CN201397372Y (en) | Single-phase ground fault location device for distribution network | |
| CN201765290U (en) | Single-phase ground fault location device for cable and overhead line hybrid system | |
| CN101266270B (en) | Pile Foundation Tower Grounding Impedance Measuring Device and Method | |
| CN204559246U (en) | Based on the magnet coupled resonant type wireless power transfer of low frequency PWM rectifier | |
| CN101551432A (en) | Power distribution network fault positioning method | |
| CN103439637B (en) | A kind of wave of oscillation production method for local discharge of electrical equipment test | |
| CN102636689B (en) | Non-contact power voltage measuring method | |
| CN102520248A (en) | Insulation resistance and grounding resistance comprehensive tester based on programmable power supply | |
| CN102221660A (en) | On-line positioner of small current earth fault | |
| CN104166072A (en) | Intelligent polarity detection device and method for four-star type voltage transformer | |
| CN102928802B (en) | Method for detecting alternating current-direct current standard-based direct current resistance performance of current transformer | |
| CN101504436B (en) | Semi-wave DC detection method | |
| CN101789334A (en) | Relay zero crossing disconnection arc extinguishing method | |
| CN117630583A (en) | Device and method for detecting capacitance current and grounding resistance of power distribution network | |
| CN204903655U (en) | Tower grounding resistance measurement device of disconnect ground downlead exempts from | |
| CN102103179A (en) | Distance-measuring and positioning method and device for failure of power transmission line | |
| CN201477147U (en) | Current detection circuit in energy feedback system | |
| Xiong et al. | Design and effect analysis of wireless energy transmission device for electric vehicle | |
| CN201302600Y (en) | Single-phase AC power supply line electric leakage and stealing recognition and indication circuit | |
| CN112962101A (en) | Multi-reference-electrode potentiostat for buried pipeline and use method thereof | |
| CN203054156U (en) | Power distribution network single phase grounding fault positioning device based on direct current signal detector | |
| CN204008956U (en) | A kind of four stars type voltage transformer (VT) intelligence device for detecting polarity | |
| CN205564013U (en) | Circuit system suitable for differential capacitive sensor signal of long distance transmission | |
| CN104345218A (en) | Reactance value measurement system and method for three-phase reactor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20100203 |