Searching instrument and searching method for quickly positioning low-voltage cable fault without power failure

Abstract

The invention relates to the technical field of non-power-cut quick positioning of low-voltage cable faults, and discloses a searching instrument and a searching method for non-power-cut quick positioning of low-voltage cable faults, and the searching instrument comprises a portable host, a signal coupling clamp and a space signal detector, and is characterized in that the searching instrument is used for non-power-cut fault searching of low-voltage cables; the low-voltage cable refers to a 220V or 380V low-voltage cable, a fault current loop formed when the low-voltage cable breaks down is utilized, a feature code generated by the portable host is injected in a coupling mode through a neutral point of a transformer in a live-line state, the feature code can be overlaid into the fault current loop formed when the low-voltage cable breaks down, and the feature code is generated when the low-voltage cable breaks down. And then the space signal detector is utilized to realize non-power-off rapid positioning of the low-voltage cable fault according to the characteristic that the characteristic code obviously changes before and after the fault point. The method has the outstanding advantages of being simple, practical and easy to popularize.

Description

Technical Field

[0001] The invention relates to the technical field of rapid positioning of low-voltage cable faults without power outages, and in particular to a finder and a method for rapidly positioning low-voltage cable faults without power outages. Background Art

[0002] At present, the 220V or 380V low-voltage power distribution system has many branches and chaotic lines, with a high fault rate. Overhead lines and low-voltage cables are used together. If the fault occurs in the low-voltage cable part, the current search method is: pull the line and cut off the power for trial transmission, gradually narrow the fault interval, and combine further cable-by-cable card testing and other methods to first determine the faulty cable, then cut off the power, electrically separate the two ends of the faulty cable, take safety measures, and use a variety of test equipment to locate the fault. The basic test equipment includes: path meter, traveling wave rangefinder, acoustic and magnetic synchronous point meter, high-voltage power generator, etc. After the fault is repaired, it is necessary to restore the wiring and other work. The entire search process not only affects the normal power consumption of users, but also the detection process is cumbersome, time-consuming, and inefficient, and requires high quality of on-site personnel.

[0003] In the related technology, the situation of live fault detection of low-voltage cables at home and abroad is as follows: Germany's LV model is suitable for online detection of live 220V / 380V low-voltage cables. First, the faulty cable is confirmed, and then the following complex search process is carried out:

[0004] 1: Install one German SEBA LV at each of the two distribution boxes: LV02 and LV04.

[0005] 2: Clamp the current clamp included in the standard configuration of the German SEBA LV to the fault phase and track the fault current.

[0006] 3: Install PQ-Box200 power quality analyzer at these two distribution boxes and at each low-voltage cable terminal to test the power quality at each location, especially abnormal events such as voltage surges and dips, and current changes.

[0007] 4: According to the waveform detected and triggered by the German SEBA LV equipment, determine the defective low-voltage cable number and the scope of the fault.

[0008] Although the German Saiba test equipment realizes online detection of low-voltage cables, it only determines which cable is faulty, without further locating the fault point; moreover, it is necessary to install detection equipment on each cable, which is complicated to operate and inefficient. In terms of test principle, operation method, simplicity, etc., it is completely different from the present invention; in domestic public reports, no similar low-voltage cable fault locating instrument and method for fast positioning without power outage as the present invention has been found. Summary of the invention

[0009] 1. Technical issues to be resolved

[0010] In view of the many deficiencies in the existing low-voltage cable fault detection, such as: the detection process needs to be carried out under power-off conditions, which affects the normal power consumption of users; there are possible risks of falling from poles and electric shock; the operation is complex, requiring a variety of testing equipment with strong professionalism and high requirements for personnel quality; the fault location time is long, time-consuming and laborious. The present invention provides a finder and a finding method for quickly locating low-voltage cable faults without power-off, realizing the functions of no power-off, no pole climbing, no electrical separation and restoration operations, simple to use, and quickly locating low-voltage cable faults.

[0011] (II) Technical solutions

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] A finder and a finding method for quickly locating low-voltage cable faults without power-off, used for detecting live faults of low-voltage cables. The low-voltage cables refer to 220V or 380V low-voltage cables, including a portable main unit, a signal coupling clamp, and a space signal detector. The portable main unit generates a unique signature using a composite frequency. Through the signal coupling clamp, when the low-voltage power distribution system is live, it is clamped onto the transformer neutral point grounding bar, and the signature is coupled and injected into the entire low-voltage power supply area. The signature will be superimposed on the fault current loop formed when the low-voltage cable fails, that is, the fault current loop formed by the transformer neutral point grounding bar, the cable or overhead wire, the fault point, the ground, and the transformer neutral point grounding bar. Then, using the space signal detector, based on the characteristics that the signature changes significantly before and after the fault point, the low-voltage cable fault can be quickly located without power-off.

[0014] Preferably, the finder and the finding method for quickly locating low-voltage cable faults without power-off can be used for quickly locating low-voltage cable faults without power-off, and can also be used for quickly locating overhead line faults without power-off.

[0015] Preferably, when the space signal detector detects along the fault current loop, it calculates the path of the low-voltage cable or overhead line in real time while determining the fault point of the low-voltage cable or overhead line, accompanied by sound and light prompts to ensure ease of use during rapid movement.

[0016] Preferably, the portable main unit generates a unique signature using a composite frequency. The signature is generated by a combination of multiple frequencies far from the power frequency and its harmonics, has a unique characteristic identifier, and is used as a synchronization signal at the dock, adopting an output mode with a fixed time interval.

[0017] Preferably, the space signal detector uses the synchronization signal at the dock in the signature to collect the signature at a fixed time interval, reducing the error rate and realizing anti-interference testing in a live environment.

[0018] (3) Beneficial effects

[0019] Compared with the prior art, the present invention provides a finder and a finding method for quickly locating low-voltage cable faults without power interruption, having the following beneficial effects:

[0020] 1. Through method innovation, the present invention realizes the quick location of low-voltage cable faults without power interruption. The entire location process does not affect the normal power consumption of users, and the service level of power supply enterprises is greatly improved.

[0021] 2. Through space induction technology, the present invention realizes non-contact with live bodies, no pole climbing, and no box opening, avoiding possible pole climbing falls and electric shock risks, and greatly improving safety.

[0022] 3. The present invention eliminates most of the workload required by traditional low-voltage cable fault finding methods, greatly improves work efficiency, and shortens the fault location time from days to about 20 minutes.

[0023] 4. In the present invention, one set of equipment replaces multiple sets of equipment. Professional cable fault finding equipment is relatively expensive. Therefore, the equipment investment of users is greatly reduced.

[0024] 5. The present invention simultaneously presents the low-voltage cable path detection and fault point location to the user, is simple and easy to use, has clear sound and light prompts, has low requirements for the professionalism of operators, and has good usability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the principle of the present invention;

[0026] Figure 2 is a block diagram of the principle of the portable host of the present invention;

[0027] Figure 3 is a block diagram of the principle of the space signal detector of the present invention;

[0028] Figure 4 is a composite frequency schematic diagram of the signature code of the present invention;

[0029] Figure 5 is a digital coding schematic diagram of the signature code of the present invention.

[0030] In the figure: 1. Portable host; 2. Signal coupling clamp; 3. Space signal detector; DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be further described below in conjunction with the drawings and embodiments.

[0032] Refer to the attached Figure 1, This figure shows a low-voltage power distribution system that uses overhead lines and low-voltage cables in combination. The figure simulates a fault in cable 2. At this time, a fault current loop will be formed in the entire low-voltage power distribution system, as shown in the red marked part in the figure, that is: the transformer neutral point grounding bar, the overhead wire, the fault point on cable 2, the earth, and the transformer neutral point grounding bar form the fault current loop.

[0033] A finder and a finding method for quickly locating low-voltage cable faults without power interruption, including: a portable host 1, a signal coupling clamp 2, and a space signal detector 3.

[0034] Fault location process: Without power interruption in the entire low-voltage power distribution system, first, connect the portable host 1 to the signal coupling clamp 2. Secondly, clamp the signal coupling clamp 2 onto the transformer neutral point grounding bar, and couple and inject the characteristic code generated by the portable host 1 into the entire low-voltage power supply area. The characteristic code will be superimposed on the fault current loop formed when the low-voltage cable fails. Then, use the space signal detector 3 to start detecting from the transformer and continue detecting according to the path prompt of the space signal detector 3. The space signal detector 3 simultaneously displays the signal strength of the characteristic code. According to the characteristic that the characteristic code changes significantly before and after the fault point, quickly locate the low-voltage cable fault without power interruption.

[0035] The space signal detector 3 is also applicable to detecting the signal strength of the characteristic code in the overhead line and also has a path indication function, enabling a low-voltage power distribution system that uses overhead lines and low-voltage cables in combination as shown in the attached Figure 1 to also quickly locate low-voltage cable faults without power interruption.

[0036] The space signal detector 3 supports continuous detection along the path and also supports the "dichotomy" detection method. The entire finding process realizes: no power interruption, no contact with live bodies, no pole climbing, no box opening, no need to electrically separate the faulty cable, and the operation is simple. A set of equipment replaces the traditional complex operations.

[0037] Refer to the attached Figure 2 , which is the principle block diagram of the portable host 1 of the present invention, including: a CPU controller, an oscillator, frequency multiplication amplification, mixing modulation, power output, a man-machine interface, and a battery.

[0038] Refer to the attached Figure 3 , which is the principle block diagram of the space signal detector 3 of the present invention, including: a CPU controller, an oscillator, frequency multiplication amplification, mixing detection, signal acquisition, filtering amplification, a man-machine interface, and a battery.

[0039] Refer to the attached Figure 4, is a schematic diagram of the composite frequency of the feature code of the present invention. The portable host 1 generates a unique feature code using the composite frequency. The feature code is generated by a combination of multiple frequencies far from the power frequency and its harmonics and has a unique feature identifier. The dock uses it as a synchronization signal and sends the feature code at fixed time intervals. The space signal detector 3 uses the dock in the feature code as a synchronization signal and collects the feature code at fixed time intervals, realizing anti-interference testing in a live environment.

[0040] Refer to the appendix Figure 5 , is a schematic diagram of the digital encoding of the feature code of the present invention. A corresponding digital code, that is, a unique feature code, is generated according to the frequency change.

Claims

1. A finder and method for quickly locating low-voltage cable faults without power outage, comprising a portable host, a signal coupling clamp, and a space signal detector, characterized in that: Used for low-voltage cable fault detection without power outage, the low-voltage cable refers to a 220V or 380V low-voltage cable. The fault current loop formed when the low-voltage cable fails is used. In the energized state, the feature code generated by the portable host is injected through the transformer neutral point coupling. The feature code will be superimposed on the fault current loop formed when the low-voltage cable fails. Then, the spatial signal detector is used to realize rapid positioning of the low-voltage cable fault based on the characteristics of the obvious changes of the feature code before and after the fault point.

2. The device and method for quickly locating low-voltage cable faults without power outage according to claim 1, characterized in that: It can be used to quickly locate low-voltage cable faults without power outages, and can also be used to quickly locate overhead line faults without power outages.

3. The device and method for quickly locating low-voltage cable faults without power outage according to claim 1, characterized in that: The spatial signal detector calculates the path of the low-voltage cable or overhead line in real time and determines the fault point of the low-voltage cable or overhead line.

4. The device and method for quickly locating low-voltage cable faults without power outage according to claim 1, characterized in that: The portable host generates a unique characteristic code by using a composite frequency. The characteristic code is generated by a combination of multiple frequencies far away from the industrial frequency and its harmonics, has a unique characteristic identifier, and is used as a synchronization signal by the terminal, and is output in a fixed time interval.

5. The device and method for quickly locating low-voltage cable faults without power outage according to claim 1, characterized in that: The spatial signal detector uses the terminal in the feature code as a synchronization signal, collects the feature code at fixed time intervals, and realizes anti-interference testing in a live environment.

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