An underground cable fault detection apparatus

Abstract

This utility model discloses an underground cable fault detection device, including a high-voltage pulse generator, a magnetic field sensor, an acoustic sensor, a shielded signal cable, a microcontroller module, a touch screen display, and a power supply module. The output terminal of the high-voltage pulse generator is used to connect to one end of the underground cable under test and output a 0-30KV high-voltage pulse to the underground cable. Multiple magnetic field sensors and acoustic sensors are present, with one magnetic field sensor and one acoustic sensor forming a group, and each group of magnetic field sensors and acoustic sensors is spaced apart along the direction of the underground cable. The input terminal of the microcontroller module is electrically connected to the output terminals of the multiple magnetic field sensors and acoustic sensors through the shielded signal cable, and is used to receive and process the electromagnetic wave signals detected by the magnetic field sensors and the acoustic wave signals detected by the acoustic sensors. The input terminal of the touch screen display is electrically connected to the output terminal of the microcontroller, and is used to display fault information. This utility model has the advantages of high accuracy, fast response, and strong anti-interference capability.

Description

Technical Field

[0001] This utility model relates to the field of underground cable fault detection technology, and specifically to an underground cable fault detection device. Background Technology

[0002] Underground cables are used in places such as steel companies, chemical companies, mining companies, commercial buildings, airports, communication base stations, data centers, municipal engineering projects, and hospitals due to the need for stable operation. However, underground cable failures occur frequently.

[0003] One existing underground cable detection technology is the traveling wave method, which is based on the traveling wave transmission theory. It uses the traveling wave generated at the fault point to reach the bus end and then reflect back to the fault point. The distance to the fault point is determined by the time difference between the reflected wave and the time it takes to reach the bus end, as well as the traveling wave velocity.

[0004] However, the current traveling wave method has the following drawbacks:

[0005] 1. Sensitive to signal interference: The electromagnetic environment on site is often complex, with various sources of electromagnetic interference, such as nearby high-voltage equipment and communication equipment. These interferences may affect the transmission and detection of traveling wave signals, causing signal distortion, aberration, or submersion, thereby affecting the accuracy of fault location.

[0006] Second, precise wave velocity parameters are required: The propagation speed of traveling waves in cables is related to factors such as the cable's material, structure, and surrounding medium. Accurate fault location requires precise knowledge of the wave propagation speed within a specific cable. However, in practice, cable parameters may exhibit uncertainties and variations. For example, cable aging and temperature changes can alter the wave velocity, making precise wave velocity measurement difficult and consequently affecting location accuracy.

[0007] III. Multipath Reflection Problem: In complex cable networks, traveling waves may encounter multiple branches, joints, etc., resulting in multiple reflections and refractions. These multipath reflected traveling wave signals superimpose each other, making the received traveling wave signal complex, difficult to accurately identify and analyze, and increasing the difficulty of fault location.

[0008] Fourth, high equipment costs: The traveling wave method requires specialized traveling wave detection equipment, such as high-speed data acquisition cards and broadband sensors, which are typically expensive. Furthermore, to achieve comprehensive cable monitoring, monitoring equipment may need to be installed at multiple locations, further increasing the system's construction costs.

[0009] Fifth, the data analysis and processing are complex: Traveling wave signals contain a wealth of information, but accurately extracting fault characteristics and location information from these signals requires complex data analysis and processing. This necessitates professional technicians and advanced signal processing algorithms, and places high demands on the technical skills and experience of the operators.

[0010] Although the underground cable traveling wave method has significant advantages in fault location, such as high accuracy and fast response, it also has limitations such as susceptibility to interference, high cost, and complex analysis. In practical applications, it is necessary to comprehensively consider various factors and take effective measures to overcome its shortcomings in order to better play its role. Utility Model Content

[0011] The technical problem to be solved by this utility model is to provide an underground cable fault detection device with the advantages of high accuracy, fast response and strong anti-interference ability.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0013] An underground cable fault detection device includes a high-voltage pulse generator, a magnetic field sensor, an acoustic sensor, a shielded signal cable, a microcontroller module, a touch screen display, and a power supply module. The output of the high-voltage pulse generator is connected to one end of the underground cable under test and outputs a 0-30KV high-voltage pulse to the cable. Multiple magnetic field and acoustic sensors are present, with one magnetic field sensor and one acoustic sensor forming a group, and each group of magnetic field and acoustic sensors is spaced apart along the direction of the underground cable. The input of the microcontroller module is electrically connected to the outputs of the multiple magnetic field and acoustic sensors via the shielded signal cable, and is used to receive and process electromagnetic wave signals detected by the magnetic field sensors and acoustic wave signals detected by the acoustic sensors. The input of the touch screen display is electrically connected to the output of the microcontroller and is used to display fault information. The power supply module provides the operating voltage.

[0014] Furthermore, the underground cable fault detection device also includes a housing, in which the high-voltage pulse generator, microcontroller module, and power supply module are housed. The adjustment knob of the high-voltage pulse generator and the touch screen are located on the surface of the housing. The surface of the housing is provided with a cable inlet for connecting the underground cable, which is electrically connected to the high-voltage pulse generator. The surface of the housing is also provided with a signal line socket for connecting a shielded signal line, which is electrically connected to the input terminal of the microcontroller module.

[0015] Furthermore, a voltage detection module and a current detection module are provided between the output terminal of the high-voltage pulse generator and the cable inlet. The signal output terminals of the voltage detection module and the current detection module are electrically connected to the input terminal of the microcontroller module. The power supply module includes a 5V DC voltage and a 220V AC voltage. A relay and an NPN transistor are provided between the output terminal of the microcontroller module and the power supply terminal of the high-voltage pulse generator. The positive terminal of the relay coil is electrically connected to the positive terminal of the 5V DC voltage, the negative terminal of the relay coil is electrically connected to the collector of the NPN transistor, the normally open terminal of the relay is electrically connected to the L terminal of the power supply terminal of the high-voltage pulse generator, and the common terminal of the relay is electrically connected to the L terminal of the 220V AC voltage. The base of the NPN transistor is electrically connected to the output terminal of the microcontroller module, and the emitter is electrically connected to the GND terminal. The N terminal of the 220V AC voltage is electrically connected to the N terminal of the power supply terminal of the high-voltage pulse generator.

[0016] Furthermore, the enclosure contains a storage module, a USB module, and a communication module that are electrically connected to the output of the microcontroller module, with the USB port of the USB module located on the surface of the enclosure.

[0017] The beneficial effects of this utility model are:

[0018] The underground cable fault detection device provided by this utility model is based on the coordinated operation of electromagnetic wave induction method and acoustic-magnetic synchronization method. It achieves high-precision location of underground cable faults through the complementarity of the two physical signals. The fault information can be displayed on the touch screen. At the same time, the sensor and the microcontroller module are connected through shielded signal lines, which solves the problem of interference in the existing traveling wave method. It also has the advantages of high accuracy and fast response. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the box body according to an embodiment of the present utility model.

[0020] Figure 2 This is a schematic diagram of an embodiment of the present utility model.

[0021] Figure 3 This is a circuit diagram showing the connection between the microcontroller module, magnetic field sensor, sound sensor, storage module, touch screen, USB module, and communication module in an embodiment of this utility model.

[0022] Figure 4 This is a circuit diagram of the high-voltage pulse generator, voltage detection module, and current detection module according to an embodiment of the present invention.

[0023] The diagram is labeled as follows: 1. Housing; 11. Cable inlet; 12. Signal cable socket; 13. Power socket; 14. Power switch; 15. Handle; 2. High-voltage pulse generator; 21. Adjustment knob; 3. Magnetic field sensor; 4. Sound sensor; 5. Storage module; 6. Microcontroller module; 7. Touch screen; 8. Voltage detection module; 9. Current detection module; 10. USB module; 101. USB port; 20. Communication module. Detailed Implementation

[0024] The present invention will now be described in conjunction with the accompanying drawings. The specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Various modifications and improvements to the technical solutions of the present invention made by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope of the present invention.

[0025] like Figures 1 to 4 As shown, the underground cable fault detection device of this embodiment includes a housing 1, a high-voltage pulse generator 2, a magnetic field sensor 3, an acoustic sensor 4, a shielded signal line, a microcontroller module 6, a touch screen display 7, and a power module.

[0026] The high-voltage pulse generator 2, the microcontroller module 6, and the power supply module are all housed inside the enclosure 1, while the touch screen 7 is located on the surface of the enclosure 1.

[0027] In this embodiment, the high-voltage pulse generator 2 is a DG5000 Pro high-voltage pulse generator, which has an adjustable pulse voltage output function with a pulse voltage output range of 0-30KV. An adjustment knob 21 for adjusting the pulse voltage output is located on the surface of the housing 1. The output terminal of the high-voltage pulse generator 2 is used to connect to one end of the underground cable under test and outputs a 0-30KV high-voltage pulse to the underground cable, causing a transient discharge phenomenon at the cable insulation failure point (fault point). The discharge instantaneously generates high-frequency electromagnetic wave signals around the fault point. A cable inlet 11 for connecting the underground cable is provided on the surface of the housing 1. The cable inlet 11 is electrically connected to the high-voltage pulse generator 2. After the end of the underground cable is inserted into the cable inlet 11, the output terminal of the high-voltage pulse generator 2 is electrically connected to the underground cable.

[0028] In this embodiment, a voltage detection module 8 and a current detection module 9 are provided between the output end of the high-voltage pulse generator 2 and the cable inlet 11. The signal output ends of the voltage detection module 8 and the current detection module 9 are electrically connected to the input end of the microcontroller module 6. The high-voltage pulse generator 2 and the cable inlet 11 are connected by a wire. The voltage detection module 8 is connected in parallel on the wire, and the current detection module 9 is connected in series on the wire. This is used to detect the voltage and current at the output end of the high-voltage pulse generator 2 in real time and send the detection signal to the microcontroller module 6.

[0029] like Figure 3 and Figure 4 As shown, the microcontroller module 6 in this embodiment uses an STC15W4K56S4 microcontroller as its core. The voltage detection module 8 includes a ZMPT107 voltage sensor U7 and an operational amplifier U8. The voltage transformer U7 is connected in parallel to the circuit. Specifically, pin 1 of the voltage transformer U7 is connected to the circuit. The voltage transformer U7 collects the voltage of the circuit through its internal coil and iron core. The voltage signal is input to the operational amplifier U8 and reduced proportionally. Finally, it is input to the microcontroller module 6 (pin P0.1) through the output terminal of the operational amplifier U8. The microcontroller module 6 converts the voltage signal into a voltage value.

[0030] like Figure 4 As shown, the current detection module 9 in this embodiment includes an LMZ1-0.66 current transformer U5 and an operational amplifier U6. The current transformer U5 is connected in series in the circuit, that is, pins 1 and 2 of the current transformer U5 are connected in series in the circuit. The current of the circuit is collected through the coil of the current transformer U5 and through electromagnetic induction. The current collection signal is input to the input terminal of the operational amplifier U6, reduced proportionally, and then input to the microcontroller module 6 (P0.2 pin) through the output terminal of the operational amplifier U6. The microcontroller module 6 converts the current signal into a current value.

[0031] The power supply module in this embodiment includes a 5V DC voltage and a 220V AC voltage. A relay (K1) and an NPN transistor (Q3) are installed between the output terminal of the microcontroller module 6 and the power supply terminal of the high-voltage pulse generator 2. The positive terminal of the relay coil is electrically connected to the positive terminal of the 5V DC voltage, the negative terminal of the relay coil is electrically connected to the collector of the NPN transistor, the normally open terminal of the relay is electrically connected to the low-side (L) terminal of the power supply terminal of the high-voltage pulse generator 2, and the common terminal of the relay is electrically connected to the low-side (L) terminal of the 220V AC voltage. The base of the NPN transistor is electrically connected to the output terminal of the microcontroller module 6, and the emitter is electrically connected to the GND terminal. The neutral (N) terminal of the 220V AC voltage is electrically connected to the neutral (N) terminal of the power supply terminal of the high-voltage pulse generator 2.

[0032] The microcontroller module 6 has voltage and current thresholds. When the voltage and current detected by the voltage detection module 8 and the current detection module 9 are both within the set thresholds, the microcontroller module 6 outputs a high level to the NPN transistor, causing the NPN transistor and the relay to conduct, and the high-voltage pulse generator 2 to conduct and operate normally. When either the voltage or the current detected by the voltage detection module 8 and the current detection module 9 exceeds the set threshold, the microcontroller module 6 outputs a low level to the NPN transistor, causing the NPN transistor and the relay to de-conduct, the high-voltage pulse generator 2 to stop conducting, and the high-voltage pulse generator 2 to stop working, thereby ensuring the safety of equipment and personnel.

[0033] Multiple magnetic field sensors 3 and acoustic sensors 4 are included. In this embodiment, the magnetic field sensor 3 is an FCS-100 type magnetic field sensor, and the acoustic sensor 4 is an AS-200 type acoustic sensor. Each magnetic field sensor 3 and acoustic sensor 4 forms a group, and each group is spaced along the underground cable's path on the ground, for example, every 5-10 meters. The magnetic field sensor 3 is used to collect the electromagnetic wave signal generated during cable discharge. When placed, a sensor mounting bracket is used to keep it perpendicular to the ground to ensure the accuracy of capturing the electromagnetic wave signal generated by the cable fault. The acoustic sensor 4 is used to collect the sound wave signal generated during cable discharge. When placed, a magnetic base is used to fix the acoustic sensor, ensuring that the sensor does not shift during detection. A soundproof cover made of sound-absorbing material can be installed outside the acoustic sensor 4 to effectively reduce interference from external environmental noise. Each group of magnetic field sensors 3 and acoustic sensors 4 has a battery to provide its operating voltage. The number of magnetic field sensors 3 and acoustic sensors 4 in the circuit is for illustrative purposes only and does not indicate that the device has only two magnetic field sensors 3 and acoustic sensors 4.

[0034] The input terminal of the microcontroller module 6 is electrically connected to the output terminals of multiple magnetic field sensors 3 and acoustic sensors 4 via shielded signal lines. This allows it to receive and process electromagnetic wave signals detected by the magnetic field sensors 3 and acoustic wave signals detected by the acoustic sensors 4. The shielded signal lines employ a double-layer shielding structure to effectively reduce the impact of external electromagnetic interference on signal transmission. The surface of the housing 1 is provided with signal line jacks 12 for connecting the shielded signal lines, which are electrically connected to the input terminal of the microcontroller module 6.

[0035] The input terminal of the touch screen 7 is electrically connected to the output terminal of the microcontroller module 6 to display fault information. Parameters can also be set through the touch screen 7. In this embodiment, the touch screen 7 is model XPT2046, which is represented by J5 in the circuit.

[0036] Inside the housing 1 are a storage module 5, a USB module 10, and a communication module 20, which are electrically connected to the output of the microcontroller module 6.

[0037] Among them, the storage module 5 uses the W25Q64 chip, which is represented by U10 in the circuit. The storage module 5 is used to store fault information generated by the microcontroller module 6.

[0038] The USB module 10 includes a USB interface circuit and a USB-to-serial port circuit. The interface end of the USB interface circuit corresponds to the USB port 101 of the USB module 10, which is located on the surface of the housing 1. Its output end is electrically connected to the input end of the USB-to-serial port circuit, and the output end of the USB-to-serial port circuit is electrically connected to the input end of the microcontroller module 6. The USB interface circuit uses a MINI_USB chip (represented by J1 in the circuit), and the USB-to-serial port circuit uses a CH340G chip (represented by U2 in the circuit). The USB-to-serial port circuit is used to convert the communication level between the microcontroller module 6 and the external device into a communication level that is mutually recognized by both parties. In use, external devices can be connected via USB module 9 and a USB data cable to send the data generated by microcontroller module 5 to the external devices for data storage. In the circuit, the USB interface circuit is also connected to an AMS1117-3.3V voltage regulator chip (represented by U1 in the circuit). After connecting to an external device, such as a computer host, via the USB data cable, the AMS1117-3.3V voltage regulator chip and its peripheral circuits can convert the 5V voltage to 3.3V voltage and power the entire device.

[0039] The communication module 20 is a WiFi module, which uses the ESP8266_01 chip (represented by J10 in the circuit). It can connect to a wireless network (WiFi) and wirelessly send the data generated by the microcontroller module 6 to the mobile terminal.

[0040] In addition, the surface of the housing 1 is also provided with a power socket 13, a power switch 14 and a handle 15. The power socket 13 is used to connect to the mains power.

[0041] This invention is based on the synergistic operation of electromagnetic wave induction and acoustic-magnetic synchronization methods, and achieves high-precision location of underground cable faults through the complementarity of the two physical signals.

[0042] Among them, the electromagnetic wave induction method is based on the propagation characteristics of electromagnetic signals, and its principle implementation process is as follows:

[0043] 1. High-voltage pulse triggers discharge at the fault point

[0044] High-voltage pulse generator 2 injects a 30kV adjustable high-voltage pulse into the faulty cable, generating a transient discharge phenomenon at the point of insulation damage (fault point) in the cable.

[0045] The discharge moment will generate high-frequency electromagnetic wave signals (frequency up to 500MHz) around the fault point.

[0046] 2. Propagation and Detection of Electromagnetic Wave Signals

[0047] Electromagnetic waves propagate along the cable conductor and the surrounding medium at speeds close to the speed of light (approximately 3 × 10^8 m / s).

[0048] A magnetic field sensor 3, arranged along the cable path, captures electromagnetic wave signals and records their arrival time and amplitude attenuation characteristics.

[0049] 3. Time difference positioning

[0050] The microcontroller module 6 has a built-in computer program that calculates the fault distance based on the time difference of electromagnetic waves propagating from the fault point to different sensors, combined with the cable length and path topology, using the time domain reflection method (TDR), thereby determining the location of the fault.

[0051] Simplified representation of the formula:

[0052]

[0053] (In the formula, L is the fault distance, v) 电磁波 Let Δt be the propagation speed of electromagnetic waves in the cable, and Δt be the time between pulse transmission and reception.

[0054] The acoustic-magnetic synchronization method is based on the coordinated localization of sound waves and electromagnetic waves. Its principle and implementation process are as follows:

[0055] 1. Discharge at the fault point is accompanied by the generation of sound waves.

[0056] When a cable fault discharges, in addition to electromagnetic waves, mechanical vibrations caused by electric arcs or local overheating will also generate sound wave signals (frequency 20Hz-20kHz).

[0057] 2. Detection of acoustic signals

[0058] Sound sensor 4 captures sound wave signals. Sound waves travel slowly in soil or air (approximately 340 m / s), creating a significant time difference with electromagnetic waves.

[0059] Dual-mode signal synchronization analysis

[0060] The microcontroller module 6 performs time synchronization marking on electromagnetic wave and acoustic wave signals and calculates the time difference (Δt_acoustic-magnetic) between the two signals when they arrive at the same sensor.

[0061] The location of the underground cable fault is calculated using the computer program built into the microcontroller module 6, using the following formula:

[0062] L = (v electromagnetic wave * v sound wave * Δt sound-magnetic) / (v electromagnetic wave - v sound wave).

[0063] In summary, the underground cable fault detection device provided by this utility model is based on the coordinated operation of electromagnetic wave induction method and acoustic-magnetic synchronization method. It achieves high-precision location of underground cable faults through the complementarity of the two physical signals. The fault information can be displayed on the touch screen 7. At the same time, the sensor and the single-chip microcomputer module 6 are connected through a shielded signal line, which solves the problem of interference in the existing traveling wave method. It also has the advantages of high accuracy and fast response.

Claims

1. A fault detection device for underground cables, characterized in that: It includes a high-voltage pulse generator, a magnetic field sensor, an acoustic sensor, shielded signal cables, a microcontroller module, a touch screen display, and a power supply module; The output terminal of the high-voltage pulse generator is used to connect to one end of the underground cable under test and output 0-30KV high-voltage pulses to the underground cable; there are multiple magnetic field sensors and acoustic sensors, with one magnetic field sensor and one acoustic sensor forming a group, and each group of magnetic field sensors and acoustic sensors are spaced apart along the direction of the underground cable; the input terminal of the microcontroller module is electrically connected to the output terminals of multiple magnetic field sensors and acoustic sensors through shielded signal lines, and is used to receive and process the electromagnetic wave signals detected by the magnetic field sensors and the acoustic wave signals detected by the acoustic sensors; the input terminal of the touch screen is electrically connected to the output terminal of the microcontroller, and is used to display fault information; the power supply module is used to provide the working voltage.

2. The underground cable fault detection device according to claim 1, characterized in that: It also includes a housing, in which the high-voltage pulse generator, microcontroller module, and power supply module are housed. The adjustment knob of the high-voltage pulse generator and the touch screen are located on the surface of the housing. The surface of the housing is provided with a cable inlet for connecting underground cables, which is electrically connected to the high-voltage pulse generator. The surface of the housing is also provided with a signal line socket for connecting shielded signal lines, which is electrically connected to the input terminal of the microcontroller module.

3. The underground cable fault detection device according to claim 2, characterized in that: A voltage detection module and a current detection module are provided between the output end of the high-voltage pulse generator and the cable inlet. The signal output ends of the voltage detection module and the current detection module are electrically connected to the input end of the microcontroller module. The power supply module includes 5V DC and 220V AC voltages. A relay and an NPN transistor are installed between the output terminal of the microcontroller module and the power supply terminal of the high-voltage pulse generator. The positive terminal of the relay coil is electrically connected to the positive terminal of the 5V DC voltage, the negative terminal of the relay coil is electrically connected to the collector of the NPN transistor, the normally open terminal of the relay is electrically connected to the low-side (L) terminal of the high-voltage pulse generator, and the common terminal of the relay is electrically connected to the low-side (L) terminal of the 220V AC voltage. The base of the NPN transistor is electrically connected to the output terminal of the microcontroller module, and the emitter is electrically connected to the GND terminal. The neutral (N) terminal of the 220V AC voltage is electrically connected to the neutral (N) terminal of the high-voltage pulse generator.

4. The underground cable fault detection device according to claim 2, characterized in that: The enclosure contains a storage module, a USB module, and a communication module that are electrically connected to the output of the microcontroller module. The USB port of the USB module is located on the surface of the enclosure.

5. The underground cable fault detection device according to claim 2, characterized in that: The surface of the enclosure is also equipped with a power socket, a power switch, and a handle.

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