Non-contact detection and positioning device and method for underground cable fault

Abstract

This invention discloses a non-contact detection and location device and method for buried cable faults. The device includes a detector, a wave trap, and a coupler. The detector includes a signal generation and data processing module, a digital-to-analog conversion module, a signal amplification module, a signal output coupling module, a signal receiving coupling module, a signal conditioning module, and an analog-to-digital conversion module. The wave trap is composed of a copper ring connected in series with an adjustable inductor, which is snapped onto the outer sheath of the cable under test and connected to the ground through a grounding pin. The coupler is a snap-fit ​​inductive coupler, including a first snap-fit ​​inductive coupler and a second snap-fit ​​inductive coupler, which are snapped onto the outer sheath of the cable under test. This invention is based on the reflection method and frequency conversion detection method. It achieves directional detection through the wave trap and achieves fault detection over both long and short distances through the dual snap-fit ​​inductive coupler. It has the advantages of online detection, non-contact coupling, directional detection, high accuracy, fast detection speed, strong anti-interference ability, and portable detection.

Description

Technical Field

[0001] The invention belongs to the technical field of underground cable fault detection, and in particular relates to a non-contact detection and positioning device and method for underground cable faults. Background Art

[0002] At present, the methods for locating cable faults at home and abroad are mainly divided into impedance method (bridge method), traveling wave method, acoustic magnetic method and reflection method; among them, the reflection method is one of the effective cable fault location methods. It is based on the same principle as radar. By sending a low-voltage and high-frequency signal to the cable to be tested, when the detection signal is transmitted to the impedance mismatch point caused by the fault (open circuit and short circuit, etc.), a reflection signal will be generated, and then the signal reflected from the cable terminal will be collected at the transmitting end. The time delay between the incident signal and the reflected signal is used to realize fault location and ranging.

[0003] The reflection method is also divided into two detection methods in cable fault location: contact and non-contact. The contact detection method requires the detection equipment to be directly connected to the cable, and the detection and positioning distance is long and accurate. However, for 10kv / 35kv buried cables, there are currently two problems with the contact detection method: first, since the detection equipment is directly connected to the cable, it is often necessary to cut off the power for detection, which affects the power supply reliability and leads to higher costs. Second, contact detection is generally performed at the cable terminal or switch cabinet, which limits the portability of the detection. The non-contact detection method uses a coupling device to couple the detection signal to the shielding layer of the buried cable, and uses the shielding-earth as the transmission channel for detection, which does not affect the normal operation of the cable. However, the non-contact detection method also has the following difficulties: First, taking the commonly used 10kv armored cable as an example, its cable structure includes a conductor, an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a metal shielding layer, a filler, a wrapping tape, an inner sheath, an armor layer and an outer sheath. This complex cable structure makes it more difficult to couple signals on site; second, the shielding-earth transmission channel has high noise, high attenuation and a complex environment, which further limits the non-contact detection of the cable; third, in order to form a shielding-earth transmission channel and detect faults in a direction, it is often necessary to perform detection at the cable grounding point in the substation, which limits the detection location, loses portability and increases the difficulty of detection. Summary of the invention

[0004] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a non-contact detection and positioning device and method for underground cable faults. The present invention uses a wave trap to connect the cable to be tested and the ground based on the reflection method to form a shielding layer-ground transmission loop, thereby realizing directional detection; based on the frequency conversion detection method, the detection signals of different frequencies emitted by the detector are coupled to the cable to be tested through a double-card inductive coupler, and the reflected signal is received and transmitted to the detector for judgment, thereby realizing long and short distance fault detection, and has the advantages of online detection, non-contact coupling, directional detection, high accuracy, fast detection speed, strong anti-interference ability and portable detection.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention provides a non-contact detection and positioning device for underground cable faults, the device comprising a detector, a wave trap and a coupler;

[0007] The detector includes a signal generation and data processing module, a digital-to-analog conversion module, a signal amplification module, a signal output coupling module, a signal receiving coupling module, a signal conditioning module and an analog-to-digital conversion module;

[0008] The wave trap is composed of a copper ring connected in series with an adjustable inductor, the copper ring is divided into two pieces, the upper and lower pieces, which are clamped on the outer sheath of the cable to be tested; the lead wire at the joint of the copper ring is connected in series with the adjustable inductor, and is connected to the ground through a grounding pin;

[0009] The coupler is a snap-on inductive coupler, including a first snap-on inductive coupler and a second snap-on inductive coupler, which are snap-on to the outer sheath of the cable to be tested;

[0010] The signal generation and data processing module, the digital-to-analog conversion module, the signal amplification module and the signal output coupling module are connected in sequence; the signal generation and data processing module, the analog-to-digital conversion module, the signal conditioning module and the signal receiving coupling module are connected in sequence;

[0011] The signal output coupling module of the detector is connected to the first card-type inductive coupler, and the signal receiving coupling module of the detector is connected to the second card-type inductive coupler;

[0012] The wave trap, the first clip-on inductive coupler and the second clip-on inductive coupler are sequentially installed on the cable to be tested.

[0013] As a preferred technical solution, the signal generation and data processing module generates SSTDR digital signals with different center frequencies through sinusoidal signal and pseudo-random sequence code modulation, which are used for fault detection and signal processing, and judge the fault type and fault distance, and upload them to the host computer.

[0014] As a preferred technical solution, the installation distance between the wave trap, the first snap-on inductive coupler and the second snap-on inductive coupler does not exceed 20 cm.

[0015] As a preferred technical solution, a high dielectric constant soft material is used to fill the gap between the copper ring of the wave trap and the cable to be tested. The impedance value Z of the wave trap is:

[0016]

[0017] Among them, R0 is the internal resistance of the wave trap, C is the capacitance value formed by the copper ring and the shielding layer of the cable to be tested, and L is the inductance value of the adjustable inductor.

[0018] As a preferred technical solution, the wave trap connects the cable to be tested and the earth, forms a shielding layer-earth transmission loop at any position of the cable to be tested, and performs a directional non-contact fault test on the cable to be tested.

[0019] As a preferred technical solution, the snap-on inductive coupler is a ferrite magnetic ring, and its coupling turns ratio is 1:1.

[0020] Another aspect of the present invention provides a non-contact detection and positioning method for underground cable faults. The non-contact detection and positioning device for underground cable faults is used to detect and position underground cable faults. The method comprises the following steps:

[0021] Installing the non-contact detection and positioning device for underground cable faults on the cable to be tested;

[0022] The non-contact detection and positioning device for underground cable faults sends a detection signal to perform fault detection on the cable to be tested;

[0023] The non-contact detection and positioning device for underground cable faults receives the reflected signal, performs calculations and outputs the detection results.

[0024] As a preferred technical solution, the non-contact detection and positioning device for the buried cable fault is installed on the cable to be tested, specifically:

[0025] The wave trap is clamped on the outer sheath of the cable to be tested, and the gap between the copper ring of the wave trap and the cable to be tested is filled with a high dielectric constant material; the wave trap is connected to the grounding pin through a lead wire to form a shielding layer-ground transmission loop with the ground to achieve directional signal transmission;

[0026] The first clamping inductive coupler and the second clamping inductive coupler are sequentially clamped on the cable to be tested along the detection direction;

[0027] The signal output coupling module of the detector is connected to the first clip-on inductive coupler through a coaxial cable, and the signal receiving coupling module of the detector is connected to the second clip-on inductive coupler through a coaxial cable.

[0028] As a preferred technical solution, the non-contact detection and positioning device for the buried cable fault is installed on the cable to be tested, specifically:

[0029] The wave trap is clamped on the outer sheath of the cable to be tested, and the gap between the copper ring of the wave trap and the cable to be tested is filled with a high dielectric constant material; the wave trap is connected to the grounding pin through a lead wire to form a shielding layer-ground transmission loop with the ground to achieve directional signal transmission;

[0030] The first clamping inductive coupler and the second clamping inductive coupler are sequentially clamped on the cable to be tested along the detection direction;

[0031] The signal output coupling module of the detector is connected to the first clip-on inductive coupler through a coaxial cable, and the signal receiving coupling module of the detector is connected to the second clip-on inductive coupler through a coaxial cable.

[0032] As a preferred technical solution, the non-contact detection and positioning device for the buried cable fault receives the reflected signal and performs calculation to output the detection result, specifically:

[0033] The second card-type inductive coupler couples the reflected signal to the signal receiving coupler according to a 1:1 turns ratio, and then transmits it to the signal conditioning module to reduce the signal and filter and remove noise, and converts it into a digital signal through the analog-to-digital conversion module, and the input signal generation and data processing module processes it;

[0034] The signal generation and data processing module calculates the detection signal and the reflection signal, normalizes them to obtain the signal waveform, determines the fault type and fault distance, and uploads them to the host computer.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] In view of the problems of complex cable structure, large noise and attenuation during detection, complex environment and difficult detection, the present invention forms a shielding layer-earth transmission loop through a wave trap, adopts a coupler to realize non-contact injection of detection signals, and uses a detector to process and judge the reflected signals, so as to realize non-contact detection and positioning of buried cable faults. The advantages of the present invention are: 1. Power outage losses are avoided through non-contact fault detection and positioning; 2. The detector performs frequency conversion detection by generating SSTDR digital signals with different center frequencies, thereby realizing long and short distance fault detection; 3. The wave trap is grounded to form a loop with the earth at any position of the cable, and directional detection is realized through the high frequency and low resistance characteristics of the wave trap; 4. A double-clip inductive coupler is used to inject the received signal, thereby reducing the influence of coupler attenuation on the detection result and increasing the detection accuracy; 5. It can be widely used in cable fault detection in different environments, such as ships, mines, tunnels and other power supply systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is a schematic diagram of a non-contact detection and positioning device for underground cable faults in an embodiment of the present invention;

[0039] Figure 2 A connection diagram of a non-contact detection and positioning device for underground cable faults according to an embodiment of the present invention;

[0040] Figure 3 It is a schematic diagram of the structure of a detector in an embodiment of the present invention;

[0041] FIG4( a ) is a schematic diagram of a signal output direction without a wave blocker in an embodiment of the present invention;

[0042] FIG4( b ) is a schematic diagram of the signal output direction with a wave trap in an embodiment of the present invention;

[0043] Figure 5 Schematic diagram of a snap-on inductive coupler in an embodiment of the present invention;

[0044] FIG6( a ) is a schematic diagram of a single inductive coupler fault diagnosis waveform in an embodiment of the present invention;

[0045] FIG6( b ) is a schematic diagram of a fault diagnosis waveform of a dual inductive coupler in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0047] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0048] like Figure 1 As shown, the present invention performs fault detection and positioning based on the reflection method, uses a wave trap and the ground to form a shielding layer-ground transmission loop, generates a detection signal through a detector, and injects the detection signal into the cable to be tested through a coupler. According to the basic theory of transmission lines, when the detection signal encounters an impedance mismatch point caused by a fault (open circuit and short circuit, etc.), a reflection signal is generated, and the fault type is determined by the polarity of the reflected wave head. The fault location is achieved by the time delay between the incident signal and the reflected signal.

[0049] like Figure 2 As shown, the non-contact detection and positioning device for underground cable faults in this embodiment includes: a detector ①, a wave trap ② and a coupler;

[0050] Among them, the detector ① is as follows Figure 3 As shown, it includes a signal generation and data processing module, a digital-to-analog conversion module, a signal amplification module, a signal output coupling module, a signal receiving coupling module, a signal conditioning module and an analog-to-digital conversion module; the signal generation and data processing module, the digital-to-analog conversion module, the signal amplification module and the signal output coupling module are connected in sequence; the signal generation and data processing module, the analog-to-digital conversion module, the signal conditioning module and the signal receiving coupling module are connected in sequence;

[0051] Wave arrester ② is composed of a copper ring in series with an adjustable inductor. The copper ring is divided into two pieces, upper and lower, which are clamped on the outer sheath of the cable to be tested. The lead wire at the joint of the copper ring is in series with the adjustable inductor and connected to the ground through the grounding pin.

[0052] The coupler is a snap-on inductive coupler, including a first snap-on inductive coupler ③ and a second snap-on inductive coupler ④, which are snap-on to the outer sheath of the cable to be tested;

[0053] The signal output coupling module of the detector is connected to the first card-type inductive coupler ③, and the signal receiving coupling module of the detector is connected to the second card-type inductive coupler ④;

[0054] Along the detection direction, the wave trap ②, the first clip-on inductive coupler ③ and the second clip-on inductive coupler ④ are sequentially installed on the cable to be tested.

[0055] Furthermore, in order to accurately locate the fault position, the signal generation and data processing module in the present invention generates SSTDR digital signals with different center frequencies through sinusoidal signals and pseudo-random sequence code modulation, which are used for fault detection and signal processing, and the fault type and fault distance are judged and uploaded to the host computer. When signals with different center frequencies are transmitted in the channel, the higher the frequency, the smaller the blind area, the greater the attenuation, and the shorter the detection distance; the lower the frequency, the larger the blind area, the smaller the attenuation, and the longer the detection distance. Therefore, when detecting a fault, detection starts from a high-frequency signal, short-distance fault detection is performed, and then the signal center frequency is reduced for long-distance fault detection. This frequency conversion detection method is used to achieve fault detection and positioning of cables of different lengths.

[0056] Furthermore, to ensure the accuracy of the detection result, the installation distance between the wave trap, the first snap-on inductive coupler and the second snap-on inductive coupler does not exceed 20 cm.

[0057] Furthermore, when installing the wave trap, a high dielectric constant soft material is used to fill the gap between the copper ring of the wave trap and the cable to be tested. At this time, the impedance value Z of the wave trap is:

[0058]

[0059] Among them, R0 is the internal resistance of the wave trap, C is the capacitance value formed by the copper ring and the shielding layer of the cable to be tested, and L is the inductance value of the adjustable inductor.

[0060] As shown in FIG4(a), when there is no wave trap, after the detection signal is coupled to the cable through the coupler, its transmission direction is transmitted to both sides, resulting in large noise and large attenuation of the received reflected signal, and low accuracy after being processed by the detector; while in the present invention, as shown in FIG4(b), the wave trap connects the cable to be tested and the ground, and forms a shielding layer-ground transmission loop at any position of the cable to be tested, and performs a directional non-contact fault test on the cable to be tested, realizing low resistance in a certain frequency band of high frequency, preventing the signal from being transmitted to the non-detection segment, reducing energy loss, and realizing directional detection.

[0061] Further, such as Figure 5As shown, the snap-on inductive coupler of the present invention is a ferrite magnetic ring, and the primary coil is 1 turn; since the cable to be tested is a secondary coil, which is usually 1 turn, the coupling turns ratio of the snap-on inductive coupler is 1:1; the coupler couples the signal to the cable shielding layer or receives it to the detector at a turns ratio of 1:1, which can realize non-contact fault detection of underground cables and avoid power outage losses.

[0062] To further illustrate the effectiveness of the dual inductive coupler, the present invention uses a single inductive coupler and a dual inductive coupler to perform cable fault diagnosis. The diagnostic results are shown in FIG. Figure 6(a) , 6(b) As shown; FIG6(b) uses a double-clip inductive coupler, and the signal received by the coupler is the superposition signal of the incident signal and the reflected signal; while FIG6(a) uses a single coupler, and only the reflected signal is affected by the attenuation of the inductive coupler and the wave trap. After correlation operation and normalization, the difference between the incident wave head and the reflected wave head is large, which affects the fault judgment; when a double coupler is used, the two signals are affected by the attenuation of the inductive coupler and the wave trap at the same time, and the amplitudes of the two signals are close. Therefore, after correlation operation and normalization, the size of the incident wave head and the reflected wave head of the fault point are close, which is conducive to the fault judgment and increases the detection accuracy.

[0063] In another embodiment of the present invention, a non-contact detection and positioning method for underground cable faults is provided. The method is applied to a non-contact detection and positioning device for underground cable faults to detect and position underground cable faults, and includes the following steps:

[0064] S1. Installing a non-contact detection and positioning device for underground cable faults on the cable to be tested, specifically including:

[0065] The wave trap is clamped on the outer sheath of the cable to be tested, and the gap between the copper ring of the wave trap and the cable to be tested is filled with high dielectric constant material; the wave trap is connected to the ground pin through a lead wire to form a shielding layer-ground transmission loop with the ground to achieve directional signal transmission;

[0066] The first clamping inductive coupler and the second clamping inductive coupler are sequentially clamped on the cable to be tested along the detection direction;

[0067] The signal output coupling module of the detector is connected to the first clip-on inductive coupler through a coaxial cable, and the signal receiving coupling module of the detector is connected to the second clip-on inductive coupler through a coaxial cable.

[0068] S2. The non-contact detection and positioning device for underground cable fault sends a detection signal to perform fault detection on the cable to be tested, specifically:

[0069] The signal generation and data processing module of the detector generates SSTDR digital signals with different center frequencies through modulation of sinusoidal signals and pseudo-random sequence codes, starting with high-frequency signals for short-distance fault detection, and then gradually reducing the signal center frequency for long-distance fault detection;

[0070] When performing fault detection, the SSTDR digital signal is converted into an analog signal through the digital-to-analog conversion module, and then the analog signal is amplified by the signal amplification module. Finally, the amplified analog signal is transmitted to the first card-type coupler through the signal output coupling module and coupled to the shielding layer of the cable to be tested according to a 1:1 turns ratio;

[0071] When SSTDR digital signals with different center frequencies are transmitted, the higher the frequency, the smaller the blind area, the greater the attenuation, and the shorter the detection distance; the lower the frequency, the larger the blind area, the smaller the attenuation, and the longer the detection distance.

[0072] S3. The non-contact detection and positioning device for underground cable fault receives the reflected signal, performs calculation and outputs the detection result, which is specifically:

[0073] The second card-type inductive coupler couples the reflected signal to the signal receiving coupler according to a 1:1 turns ratio, and then transmits it to the signal conditioning module to reduce the signal and filter and remove noise, and converts it into a digital signal through the analog-to-digital conversion module, and the input signal generation and data processing module processes it;

[0074] The signal generation and data processing module calculates the detection signal and the reflection signal, normalizes them to obtain the signal waveform, determines the fault type and fault distance, and uploads them to the host computer.

[0075] It should be noted that, for the sake of convenience, the aforementioned method embodiments are all expressed as a series of action combinations, but those skilled in the art should know that the present invention is not limited to the described order of actions, because according to the present invention, certain steps can be performed in other orders or simultaneously.

[0076] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A non-contact detection and positioning device for underground cable faults, characterized in that: The device comprises a detector, a wave trap and a coupler; The detector includes a signal generation and data processing module, a digital-to-analog conversion module, a signal amplification module, a signal output coupling module, a signal receiving coupling module, a signal conditioning module and an analog-to-digital conversion module; The wave trap is composed of a copper ring connected in series with an adjustable inductor, the copper ring is divided into two pieces, the upper and lower pieces, which are clamped on the outer sheath of the cable to be tested; the lead wire at the joint of the copper ring is connected in series with the adjustable inductor, and is connected to the ground through a grounding pin; The coupler is a snap-on inductive coupler, including a first snap-on inductive coupler and a second snap-on inductive coupler, which are snap-on to the outer sheath of the cable to be tested; The signal generation and data processing module, the digital-to-analog conversion module, the signal amplification module and the signal output coupling module are connected in sequence; the signal generation and data processing module, the analog-to-digital conversion module, the signal conditioning module and the signal receiving coupling module are connected in sequence; The signal output coupling module of the detector is connected to the first card-type inductive coupler, and the signal receiving coupling module of the detector is connected to the second card-type inductive coupler; The wave trap, the first clip-on inductive coupler and the second clip-on inductive coupler are sequentially installed on the cable to be tested.

2. The non-contact detection and positioning device for underground cable faults according to claim 1 is characterized in that: The signal generation and data processing module generates SSTDR digital signals with different center frequencies through modulation of sinusoidal signals and pseudo-random sequence codes, which are used for fault detection and signal processing, and judge the fault type and fault distance, and upload them to the host computer.

3. The non-contact detection and positioning device for underground cable faults according to claim 1 is characterized in that: The installation distance between the wave trap, the first clip-on inductive coupler and the second clip-on inductive coupler does not exceed 20 cm.

4. The non-contact detection and positioning device for underground cable faults according to claim 1, characterized in that: A high dielectric constant soft material is used to fill the gap between the copper ring of the wave trap and the cable to be tested. The impedance value Z of the wave trap is: Among them, R0 is the internal resistance of the wave trap, C is the capacitance value formed by the copper ring and the shielding layer of the cable to be tested, and L is the inductance value of the adjustable inductor.

5. The non-contact detection and positioning device for underground cable faults according to claim 1, characterized in that: The wave trap is connected to the cable to be tested and the earth, forming a shielding layer-earth transmission loop at any position of the cable to be tested, and performing a directional non-contact fault test on the cable to be tested.

6. The non-contact detection and positioning device for underground cable faults according to claim 1, characterized in that: The snap-on inductive coupler is a ferrite magnetic ring, and its coupling turns ratio is 1:

1.

7. A non-contact detection and positioning method for underground cable faults, characterized in that: The non-contact detection and positioning device for underground cable faults according to any one of claims 1 to 6 is used to detect and locate underground cable faults. The method comprises the following steps: Installing the non-contact detection and positioning device for underground cable faults on the cable to be tested; The non-contact detection and positioning device for underground cable faults sends a detection signal to perform fault detection on the cable to be tested; The non-contact detection and positioning device for underground cable faults receives the reflected signal, performs calculations and outputs the detection results.

8. The non-contact detection and positioning method for underground cable faults according to claim 7, characterized in that: The non-contact detection and positioning device for underground cable faults is installed on the cable to be tested, specifically: The wave trap is clamped on the outer sheath of the cable to be tested, and the gap between the copper ring of the wave trap and the cable to be tested is filled with a high dielectric constant material; the wave trap is connected to the grounding pin through a lead wire to form a shielding layer-ground transmission loop with the ground to achieve directional signal transmission; The first clamping inductive coupler and the second clamping inductive coupler are sequentially clamped on the cable to be tested along the detection direction; The signal output coupling module of the detector is connected to the first clip-on inductive coupler through a coaxial cable, and the signal receiving coupling module of the detector is connected to the second clip-on inductive coupler through a coaxial cable.

9. The non-contact detection and positioning method for underground cable faults according to claim 8, characterized in that: The fault detection of the cable to be tested is specifically performed as follows: The signal generation and data processing module of the detector generates SSTDR digital signals with different center frequencies by modulating sinusoidal signals and pseudo-random sequence codes, starts with high-frequency signals for short-distance fault detection, and then gradually reduces the signal center frequency for long-distance fault detection; When performing fault detection, the SSTDR digital signal is converted into an analog signal through the digital-to-analog conversion module, and then the analog signal is amplified by the signal amplification module. Finally, the amplified analog signal is transmitted to the first card-type coupler through the signal output coupling module and coupled to the shielding layer of the cable to be tested according to a 1:1 turns ratio; When the SSTDR digital signals with different center frequencies are transmitted, the higher the frequency, the smaller the blind area, the greater the attenuation, and the shorter the detection distance; The lower the frequency, the larger the blind area, the smaller the attenuation, and the longer the detection distance.

10. The non-contact detection and positioning method for underground cable faults according to claim 9, characterized in that: The non-contact detection and positioning device for the buried cable fault receives the reflected signal, performs calculation and outputs the detection result, specifically: The second card-type inductive coupler couples the reflected signal to the signal receiving coupler according to a 1:1 turns ratio, and then transmits it to the signal conditioning module to reduce the signal and filter and remove noise, and converts it into a digital signal through the analog-to-digital conversion module, and the input signal generation and data processing module processes it; The signal generation and data processing module calculates the detection signal and the reflection signal, normalizes them to obtain the signal waveform, determines the fault type and fault distance, and uploads them to the host computer.

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