Low-voltage cable integrated tracing device

Abstract

The application belongs to the field of cable detection, and discloses a low-voltage cable comprehensive line searching device, which comprises a transmitter and a receiver; the transmitter comprises a power module, a modulation unit, an oscillation unit, a chopping unit, a voltage transformation unit, an isolation protection unit and an output unit; and the receiver comprises a cable identification sensor, a path detection sensor, a line searching signal detection unit, a power supply unit, a filter amplification unit, a power amplifier unit and an acoustic surface output unit. The device integrates cable path testing, cable identification and cable core line searching functions, and is lower in cost, portable and simple to operate, compared with the traditional cable path tester and cable identification instrument which are single-function devices, and can quickly solve the cable line inspection function and identification task in the transformer substation, complete the accurate cable line searching work, improve the work efficiency of the transformer substation cable inspection and replacement, and reduce or even eliminate the safety risk of the transformer substation reconstruction and expansion construction.

Description

Technical Field

[0001] This invention belongs to the field of cable inspection and relates to a comprehensive cable inspection device for low-voltage cables. Background Technology

[0002] The numerous cables connecting secondary equipment to control and measurement systems within substations make secondary cable tracing and verification time-consuming. Traditional tracing devices consist of a DC power supply and low-resistance light-emitting or sound-emitting components. At the near end, the positive and negative terminals of the DC power supply are connected to the conductor being checked and the ground busbar, respectively. At the far end, low-resistance light-emitting or sound-emitting components are connected to the unknown conductor and ground busbar, using sound and light indications to identify the conductor being checked. This method, when tracing existing equipment in expanded substations, carries the risk of accidental contact with live circuits leading to DC grounding and malfunctions in protection and switching equipment. Furthermore, traditional tracing devices only perform tracing functions and cannot perform cable path testing or cable identification. However, with the accumulation of substation automation and intelligent upgrades, abandoned cables in the cable trenches become haphazardly arranged. During the removal of abandoned cables, the dense arrangement of cables in the trenches, along with firewalls and fire-retardant coatings, makes it difficult to distinguish the cables to be removed, leaving construction personnel helpless and posing safety risks such as accidental removal and omissions. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing cable inspection devices in the prior art, such as low safety and limited functionality, and to provide a comprehensive cable inspection device for low-voltage cables.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A low-voltage cable inspection device includes a transmitter and a receiver. The transmitter includes a power module, a modulation unit, an oscillation unit, a chopper unit, a transformer unit, an isolation protection unit, and an output unit. The receiver includes a cable identification sensor, a path detection sensor, an inspection signal detection unit, a power supply unit, a filtering and amplification unit, a power amplifier unit, and a surface acoustic wave (SAW) output unit. The modulation unit generates a first square wave signal and sends it to the oscillation unit. The oscillation unit generates a second square wave signal and intermittently sends the second square wave signal to the chopper unit based on the first square wave signal. The chopper unit receives the power signal sent by the power module and periodically outputs a power signal to the transformer unit based on the second square wave signal. The transformer unit increases or decreases the amplitude of the power signal to obtain a transformer signal and an identification and path detection signal, and sends the transformer signal and the identification and path detection signal to the output unit. The output unit sends a transformer signal to the isolation protection unit, which isolates the live signal of the cable and generates a cable inspection signal based on the transformer signal, which is then sent to the output unit. The output unit is also used to switch between the output of the identification and path detection signals and the cable inspection signals, and sends them to the cable inspection signal detection unit via cable. The cable inspection signal detection unit receives the cable inspection signal and sends it to the filtering and amplification unit. Both the cable identification sensor and the path detection sensor are used to detect the identification and path detection signals in the cable, generating cable identification signals and path detection signals respectively, and sending them to the filtering and amplification unit. The filtering and amplification unit filters and amplifies the cable inspection signal, cable identification signal, and path detection signal, and then sends them to the power amplifier unit for secondary amplification. The power amplifier unit sends the secondary amplified cable inspection signal, cable identification signal, and path detection signal to the surface acoustic wave (SAW) output unit for sound output or instrument display.

[0006] A further improvement of the present invention is as follows:

[0007] The modulation unit includes an integrated chip, a first capacitor, a second capacitor, a first resistor, a second resistor, and a third resistor. The integrated chip is an 8-pin timer integrated circuit NE555. Pin 1 of the integrated chip is connected to the first terminal of the second capacitor, the negative terminal of the first capacitor, the first terminal of the third resistor, and ground (GND). Pin 2 of the integrated chip is connected to pin 6 of the integrated chip, the first terminal of the first resistor, and the positive terminal of the first capacitor. The second terminal of the first resistor is connected to the first terminal of the second resistor and pin 7 of the integrated chip. The second terminal of the second resistor is connected to the power supply VCC, pin 4 of the integrated chip, and pin 8 of the integrated chip. Pin 3 of the integrated chip is connected to the second terminal of the third resistor. Pin 5 of the integrated chip is connected to the second terminal of the second capacitor. Pin 3 of the integrated chip is the output terminal of the modulation unit and is connected to the oscillation unit.

[0008] The oscillation unit includes an integrated chip, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, and a fourth resistor. The integrated chip is an 8-pin timer integrated circuit NE555. Pin 1 of the integrated chip is connected to the first terminal of the first capacitor, the first terminal of the second capacitor, the first terminal of the fourth resistor, and ground (GND). Pin 2 of the integrated chip is connected to pin 6 of the integrated chip, the first terminal of the first resistor, and the second terminal of the second capacitor. The second terminal of the first resistor is connected to the first terminal of the second resistor and pin 7 of the integrated chip. The second terminal of the second resistor is connected to the power supply (VCC) and pin 8 of the integrated chip. Pin 3 of the integrated chip is connected to the first terminal of the third resistor. The second terminal of the third resistor is connected to the second terminal of the fourth resistor. The second terminal of the third resistor is the output terminal of the oscillation unit and is connected to the chopper unit. Pin 5 of the integrated chip is connected to the second terminal of the first capacitor. Pin 4 of the integrated chip is connected to the output terminal of the modulation unit. When the signal at pin 4 of the integrated chip is low, the oscillation unit outputs a low-level signal; when the signal at pin 4 of the integrated chip is high, the oscillation unit outputs a high-level signal.

[0009] The chopper unit includes a MOS transistor, the drain of which is connected to the transformer unit, the gate of which is connected to the output terminal of the oscillation unit, and the source of which is grounded to GND. The MOS transistor switches periodically according to the second square wave signal.

[0010] The transformer unit includes a pulse transformer and a switch. The first terminal of the primary side of the pulse transformer is connected to the power supply VCC, and the second terminal is connected to the output terminal of the chopper unit. The secondary side of the pulse transformer is provided with a common terminal, a first tap, a second tap, a third tap, and a fourth tap. One end of the switch is provided with pins 1, 2, and 3, and the other end is provided with pin 4. The first tap is connected to pin 1, the second tap is connected to pin 2, the third tap is connected to pin 3, and pin 4 is connected to the output unit for outputting identification and path detection signals. The fourth tap is connected to the output unit for outputting line detection signals. The common terminal is connected to both the output unit and the isolation protection unit.

[0011] The isolation protection unit includes an isolation transformer and a capacitor; the first end of the primary side of the isolation transformer is connected to the output unit to receive the transformer signal sent by the output unit; the first end and the second end of the secondary side of the isolation transformer are both connected to the output unit to send the line check signal to the output unit; the second end of the primary side of the isolation transformer is connected to the transformer unit; and the second end of the secondary side of the isolation transformer is connected to the output unit through the capacitor.

[0012] The isolation protection unit further includes a light-emitting diode, a first optocoupler integrated chip, a second optocoupler integrated chip, a first resistor, a second resistor, and a third resistor; the first terminal of the secondary side of the isolation transformer is connected to the first terminal of the second resistor; the end of the capacitor away from the isolation transformer is connected to both pin 2 of the second optocoupler integrated chip and pin 1 of the first optocoupler integrated chip; the second terminal of the second resistor is connected to the first terminal of the first resistor; the second terminal of the first resistor is connected to both pin 2 of the first optocoupler integrated chip and pin 1 of the second optocoupler integrated chip; pin 4 of the first optocoupler integrated chip is connected to pin 4 of the second optocoupler integrated chip and the power supply VCC; pin 3 of the first optocoupler integrated chip is connected to pin 3 of the second optocoupler integrated chip and the first terminal of the third resistor; the second terminal of the third resistor is connected to the positive terminal of the light-emitting diode; and the negative terminal of the light-emitting diode is connected to ground GND.

[0013] The output unit includes a resistor, a first switch, and a second switch. The first switch has a first set of contacts and a second set of contacts. The second switch has a third set of contacts and a fourth set of contacts. The first end of the first set of contacts is connected to a transformer unit to receive identification and path detection signals output by the transformer unit. The second end of the first set of contacts is suspended. The common end of the first set of contacts is connected to the first end of the resistor. The first end of the second set of contacts is suspended. The second end of the second set of contacts is connected to the transformer unit to receive the transformer signal output by the transformer unit. The common end of the second set of contacts is connected to an isolation protection unit to output the transformer signal to the isolation protection unit. The first end of the third set of contacts is connected to the second end of the resistor. The first end of the fourth set of contacts is connected to the transformer unit. The second ends of both the third and fourth sets of contacts are connected to the isolation protection unit to receive line detection signals. The third ends of the third and fourth sets of contacts are the output terminals of the output unit and are connected to a cable to output line detection signals or identification and path detection signals.

[0014] The cable detection signal unit includes an isolation transformer, a first optocoupler integrated chip, a second optocoupler integrated chip, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a light-emitting diode, a first Zener diode, a second Zener diode, a diode, a first capacitor, a second capacitor, a third capacitor, and a MOSFET. The cable detection signal unit is equipped with a first input terminal and a second input terminal. The first ends of both the first and second input terminals are connected to a cable. The second end of the first input terminal is connected to the first end of the first capacitor, pin 1 of the second optocoupler integrated chip, and pin 2 of the first optocoupler integrated chip. The second end of the second input terminal is connected to the first end of the third resistor and the first end of the primary side of the isolation transformer. The second end of the third resistor is connected to the first end of the first resistor. The second end of the first resistor is connected to pin 2 of the second optocoupler integrated chip and pin 1 of the first optocoupler integrated chip. The second end of the first capacitor is connected to the second end of the primary side of the isolation transformer. The isolation transformer's secondary side is connected to the first terminal of the fifth resistor. The second terminal of the fifth resistor is connected to the cathode of the first Zener diode, the first terminal of the fourth resistor, and the gate of the MOSFET. The second terminal of the isolation transformer's secondary side is connected to the cathode of the LED, the anode of the first Zener diode, the second terminal of the fourth resistor, the source of the MOSFET, the anode of the second Zener diode, and the first terminal of the third capacitor. The anode of the LED is connected to the first terminal of the second resistor. The second terminal of the second resistor is connected to pins 3 of both the first and second optocoupler chips. Pins 4 of both the first and second optocoupler chips, the power supply VCC, and the first terminal of the sixth resistor are connected to the drain of the MOSFET, the cathode of the second Zener diode, the first terminal of the third capacitor, and the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the anode of the diode, and the cathode of the diode is connected to the filter amplification unit.

[0015] Both the power module and the power supply unit are lithium batteries. The SAW output unit includes a speaker and a pointer-type ammeter, both of which are connected to the output terminals of the power supply unit and the power amplifier unit.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The modulation unit generates a first square wave signal to control the oscillation unit to intermittently send a second square wave signal to the chopper unit. The chopper unit chops the power signal, and the chopped power signal is sent to the transformer unit for transformation, obtaining a transformer signal and an identification and path detection signal, which are then sent to the output unit. The transformer signal is then sent to the isolation protection unit to obtain a cable detection signal, which is also sent to the output unit. Thus, the output unit receives both the identification and path detection signal and the cable detection signal. Switching between the output unit and the cable detection signal allows the transmitter to emit two different signals. Simultaneously, a cable identification sensor, a path detection sensor, and a cable detection signal detection unit are included. The cable identification sensor and the path detection sensor detect the identification and path detection signals, respectively obtaining the cable identification signal and the path detection signal. The cable detection signal is detected... The output unit receives the cable inspection signal, realizing the reception of cable inspection signals, cable identification signals, and path detection signals. The signals are then filtered, and weak signals are amplified to ensure the equipment's anti-interference capability. The signal power is then amplified to meet the driving capacity of the SAW output unit, helping the operator judge the test results and complete cable path finding, identification, and core wire inspection functions. It integrates cable path testing, cable identification, and cable core wire inspection functions into one device. Compared to traditional cable path testers and cable identification instruments, which are separate, single-function devices, it reduces costs, is portable, and easy to operate. It can quickly solve the cable inspection and identification tasks within substations, and accurately perform cable inspection work, improving the efficiency of substation cable inspection and replacement, and reducing or even eliminating the safety risks of substation renovation and expansion construction. Furthermore, based on the design of the modulation unit, oscillation unit, chopper unit, and transformer unit, the amplitude of the cable inspection signal output by the transmitter can be adjusted, allowing the use of small-amplitude, high-frequency signals as the cable inspection signal. This ensures normal reception during cable inspection without interfering with the entire protection system, preventing potential malfunctions of the protection system during the inspection process.

[0018] Furthermore, the transformer unit includes a pulse transformer and a switch. The secondary side of the pulse transformer is equipped with a first tap, a second tap, and a third tap. By switching the three taps, different taps can be selected for outputting identification and path detection signals. Different taps correspond to different amplitudes of identification and path detection signals, thus achieving an output amplitude switching function. The amplitude of the identification and path detection signal can be switched between high and low levels to meet the testing requirements of cables of different lengths. When testing short cables or in environments with low loop impedance, a low amplitude can be used, resulting in lower power consumption and easier identification by the receiving device. When testing long cables, cables buried at greater depths, or in environments with high loop impedance, a high amplitude must be used; otherwise, a valid signal cannot be received.

[0019] Furthermore, the second terminal of the secondary side of the isolation transformer is connected to the output unit through a capacitor to achieve a live protection function, which can avoid the risk of equipment damage caused by accidental contact with live cables during testing.

[0020] Furthermore, the isolation protection unit also includes a light-emitting diode, a first optocoupler integrated chip, a second optocoupler integrated chip, a first resistor, a second resistor, and a third resistor. During the test, if a live cable is accidentally touched, the light-emitting diode will illuminate to indicate the live alarm function and remind the operator to pay attention to safety.

[0021] Furthermore, the entire integrated line inspection device is powered by a lithium battery, making it easy to carry, simple to connect, user-friendly to operate, and highly efficient and reliable in testing. Attached Figure Description

[0022] Figure 1 This is a block diagram of the transmitter principle of the present invention;

[0023] Figure 2 This is a block diagram of the receiver principle of the present invention;

[0024] Figure 3 This is a schematic diagram of the modulation unit of the present invention;

[0025] Figure 4 This is a schematic diagram of the oscillation unit of the present invention;

[0026] Figure 5 This is a schematic diagram of the chopper unit of the present invention;

[0027] Figure 6 This is a schematic diagram of the transformer unit of the present invention;

[0028] Figure 7 This is a schematic diagram of the isolation protection unit of the present invention;

[0029] Figure 8 This is a schematic diagram of the output unit of the present invention;

[0030] Figure 9 This is a schematic diagram of the filtering and amplification unit of the present invention;

[0031] Figure 10 This is a schematic diagram of the power amplifier unit of the present invention;

[0032] Figure 11 This is a schematic diagram of the line detection signal detection unit of the present invention;

[0033] Figure 12 This is the wiring diagram for the path test of the present invention;

[0034] Figure 13 This is a field wiring diagram for cable identification according to the present invention;

[0035] Figure 14This is a field wiring diagram for core wire inspection according to the present invention.

[0036] Among them: 1-path detection sensor; 2-cable; 3-cable identification sensor; 4-local terminal box; 5-control room wiring cabinet. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] See Figure 1 , 2 According to sections 12-14, the low-voltage cable integrated tracing device of the present invention includes a transmitter, a receiver, a path detection sensor 1, a cable identification sensor 3, and a tracing signal detection unit. The transmitter is connected to the receiver via a cable 2, and both the path detection sensor 1 and the cable identification sensor 3 are connected to the receiver. The transmitter injects a communication signal of a specific frequency into the cable 2, and then, based on the principle of electromagnetic induction, the path detection sensor 1, the cable identification sensor 3, the tracing signal detection unit, and the receiver realize the functions of tracing the path of the cable 2, identifying it, and tracing its connection.

[0041] The transmitter includes a power supply module, a modulation unit, an oscillation unit, a chopper unit, a transformer unit, an isolation protection unit, and an output unit. The power supply module is connected to the modulation unit, oscillation unit, chopper unit, transformer unit, and isolation protection unit, providing the transmitter with operating voltage. The power supply module uses a lithium battery. The modulation unit generates a first square wave signal. In this embodiment, the period of the first square wave signal is 2 seconds, and the duty cycle is 10%. The output of the modulation unit is directly connected to the input of the oscillation unit. The oscillation unit generates a second square wave signal. In this embodiment, the period of the second square wave signal is 10 kHz, and the duty cycle is 50%. Under the control of the first square wave signal from the modulation unit, the oscillation unit intermittently outputs the second square wave signal. The output of the oscillation unit is directly connected to the input of the chopper unit. The main function of the chopper unit is to control the switching devices to perform periodic switching actions using the second square wave signal output from the oscillation unit. This periodically switches the power signal sent from the power supply module according to the oscillation unit signal, thereby driving the transformer unit of the transmitter. The output of the chopper unit is directly connected to the input of the transformer unit. The transformer unit's main function is to increase or decrease the amplitude of the third-party wave signal. The transformer unit's output is connected to both the isolation protection unit and the output unit. The isolation protection unit prevents damage to the transmitter from external live loads and provides corresponding protection alerts. Its output is directly connected to the output unit, which converts between different output signals, allowing selection of the output signal based on testing requirements.

[0042] See Figure 3 The main function of the modulation unit is to generate a periodic first square wave signal to control the oscillation unit, causing the oscillation unit to output a discontinuous periodic second square wave signal. The modulation unit mainly consists of an integrated chip U1 and external capacitors and resistors. The integrated chip U1 uses an 8-pin timer IC NE555. Pin 1 of the integrated chip U1 is connected to the first terminal of capacitor C2, the negative terminal of capacitor C1, the first terminal of resistor R8, and ground (GND). Pin 2 of the integrated chip U1 is connected to pin 6 of the integrated chip U1, the first terminal of resistor R1, and the positive terminal of capacitor C1. The second terminal of resistor R1 is connected to the first terminal of resistor R2 and pin 7 of the integrated chip U1. The second terminal of resistor R2 is connected to the power supply VCC, pin 4 of the integrated chip U1, and pin 8 of the integrated chip U1. Pin 3 of the integrated chip U1 is connected to the second terminal of resistor R8. Pin 5 of the integrated chip U1 is connected to the second terminal of capacitor C2. Pin 3 of the integrated chip U1 is the output terminal OUT1 of the modulation unit and also the input terminal of the oscillation unit. The output signal of the modulation unit is a periodic first square wave signal. The duty cycle and frequency of the first square wave signal are determined by resistors R1, R2 and C1 in the circuit. By adjusting the parameters of resistors R1, R2 and C1, the duty cycle and frequency of the first square wave signal can be changed.

[0043] See Figure 4 The main function of the oscillation unit is to generate an intermittent high-frequency second square wave signal to control the chopper unit, causing it to perform intermittent periodic switching operations. The oscillation unit mainly consists of an integrated chip U2 and external capacitors and resistors. The integrated chip U2 uses an 8-pin timer IC NE555. Specifically, pin 1 of the integrated chip U2 is connected to the first terminals of capacitors C4 and C5, the first terminal of resistor R11, and ground (GND). Pin 2 of the integrated chip U2 is connected to pin 6, the first terminal of resistor R3, and the second terminal of capacitor C5. The second terminal of resistor R3 is connected to the first terminal of resistor R4 and pin 7 of the integrated chip U2. The second terminal of resistor R4 is connected to the power supply VCC and pin 8 of the integrated chip U2. Pin 3 of the integrated chip U2 is connected to the first terminal of resistor R9. The second terminal of resistor R9 is connected to the second terminal of resistor R11, and the second terminal of resistor R9 serves as the output terminal OUT2 of the oscillation unit. Pin 4 of the integrated chip U2 is connected to the output terminal OUT1 of the modulation unit. Pin 5 of the integrated chip U2 is connected to the second terminal of capacitor C4. Pin 4 of integrated chip U2 is connected to the output terminal OUT1 of the modulation unit. Its function is to control the output signal of the oscillation unit. When the signal on this pin is low, the oscillation unit outputs a low level; when the signal on this pin is high, the oscillation unit operates normally and outputs a high-level signal. The duty cycle and period of the high-frequency second square wave signal output by the oscillation unit are determined by resistors R3, R4, and capacitor C5 in the circuit. Therefore, the output signal OUT2 of the oscillation unit is jointly determined by the signal on pin 3 of integrated chip U2, resistors R3, R4, and C5. The signal on pin 3 of integrated chip U2 controls the discontinuous interval, while resistors R3, R4, and C5 control the period and duty cycle of the second square wave signal.

[0044] See Figure 5 The main function of the chopper unit is to control the periodic switching of the MOSFET Q1 using the second square wave signal output from the oscillation unit, thereby driving the transformer unit. The drain of MOSFET Q1 is connected to the transformer unit, the gate of MOSFET Q1 is connected to the output terminal OUT2 of the oscillation unit, and the source of MOSFET Q1 is grounded to GND. The output signal of the chopper unit is the input signal of the transformer unit, controlling the period and amplitude of the transformer unit's output signal.

[0045] See Figure 6The main function of the transformer unit is to transform the output signal of the chopper unit, changing its amplitude to meet the output requirements of different tests. The first terminal of the primary side of the pulse transformer is connected to the power supply VCC, and the second terminal is connected to the output terminal of the chopper unit, i.e., the drain of MOSFET Q1. The secondary side of the pulse transformer has four taps: the first tap is connected to pin 1 of switch S3, the second tap to pin 2, the third tap to pin 3, and the fourth tap of switch S3 is the LJ terminal of the transformer unit, which is connected to the output unit. The first, second, and third taps are mainly used to switch the signal amplitude between high, medium, and low levels during path testing. The fourth tap of the pulse transformer is the CX terminal of the transformer unit, which is connected to the output unit. The fourth tap provides a signal source for line checking. The common terminal of the pulse transformer is the common terminal COM of the chopper unit, which is connected to both the output unit and the isolation protection unit. Therefore, the main function of the transformer unit is to provide an effective signal source for line checking and path detection, and the signal source strength can be switched and adjusted during the path test.

[0046] See Figure 7The main function of the isolation protection unit is to isolate the cable inspection signal from the external system power supply, while ensuring that external live signals will not damage the integrated cable inspection device. Specifically, the first terminal of the primary side of the isolation transformer T2 is the CX1 terminal of the isolation protection unit, which is connected to the output unit; the second terminal is connected to the common terminal COM of the transformer unit. The first terminal of the secondary side of the isolation transformer T2 is the CX OUT1 terminal of the isolation protection unit, which is connected to the first terminal of resistor R16 and the output unit. The second terminal of the secondary side of the isolation transformer T2 is connected to the first terminal of capacitor C7, and the second terminal of capacitor C7 is the CX OUT2 terminal of the isolation protection unit. The OUT2 terminal is connected to pin 2 of optocoupler integrated chip U4, pin 1 of optocoupler integrated chip U3, and the output unit. The second terminal of resistor R16 is connected to the first terminal of resistor R15. The second terminal of resistor R15 is connected to pin 2 of optocoupler integrated chip U3 and pin 1 of optocoupler integrated chip U4. Pin 4 of optocoupler integrated chip U3 is connected to pin 4 of optocoupler integrated chip U4 and the power supply VCC. Pin 3 of optocoupler integrated chip U3 is connected to pin 3 of optocoupler integrated chip U4 and the first terminal of resistor R17. The second terminal of resistor R17 is connected to the positive terminal of LED D9, and the negative terminal of LED D9 is connected to ground GND. The input signal of the isolation protection unit is isolated by isolation transformer T2 and then output. This output signal serves as the input of the trace detection signal source for the output unit. In addition, capacitor C7 effectively prevents external charged signals from entering this integrated trace detection device, while the signal of this integrated trace detection device can pass through effectively. When an external energized signal enters the isolation protection unit, the optocoupler integrated chip U3 and optocoupler integrated chip U4 are driven by the external energized signal, which causes the light-emitting diode D9 to light up, indicating that the external cable 2 is energized.

[0047] See Figure 8The output unit mainly consists of switches S4 and S5, used to switch the output of the line detection signal and the path detection signal. Specifically, the first terminal of the first group of contacts of switch S4 is connected to the LJ terminal of the transformer unit, the second terminal of the first group of contacts of switch S4 is suspended, and the common terminal of the first group of contacts of switch S4 is connected to the first terminal of resistor R18. The first terminal of the second group of contacts of switch S4 is suspended, the second terminal of the second group of contacts of switch S4 is connected to the CX terminal of the transformer unit, and the common terminal of the second group of contacts of switch S4 is connected to the CX1 terminal of the isolation protection unit. The second terminal of resistor R18 is connected to the first terminal of the first group of contacts of switch S5, the second terminal of the first group of contacts of switch S5 is connected to the CX OUT1 terminal of the isolation protection unit, the first terminal of the second group of contacts of switch S5 is connected to the COM terminal of the transformer unit, the second terminal of the second group of contacts of switch S5 is connected to the CX OUT2 terminal of the isolation protection unit, the common terminal of the first group of contacts of switch S5 is connected to the first terminal of the output terminal, and the common terminal of the second group of contacts of switch S5 is connected to the second terminal of the output terminal. When both the first and second sets of contacts of switches S4 and S5 are switched to the first position, the output terminal outputs a path detection signal; when both the first and second sets of contacts of switches S4 and S5 are switched to the second position, the output terminal outputs a wire detection signal. Different types of signals can be output through switches S4 and S5 to meet different testing requirements.

[0048] The receiver includes a cable identification sensor 3, a path detection sensor 1, a cable inspection signal detection unit, a power supply unit, a filtering and amplification unit, a power amplifier unit, and a surface acoustic wave (SAW) output unit. The power supply unit is connected to the filtering and amplification unit, the power amplifier unit, and the SAW output unit, providing the receiver with operating voltage. The filtering and amplification unit filters the signals collected by the path detection sensor 1, the cable identification sensor 3, and the cable inspection signal detection unit, and amplifies weak signals to ensure the equipment's anti-interference capability. The input of the filtering and amplification unit is connected to the outputs of the path detection sensor 1, the cable identification sensor 3, and the cable inspection signal detection unit, and the output of the filtering and amplification unit is directly connected to the input of the power amplifier unit. The power amplifier unit amplifies the signal power to drive the audio output device or meter indication capability. The output of this unit is directly connected to the SAW output unit. The SAW output unit includes an audio output device and / or an ammeter. Its main function is to indicate signal characteristics through the volume of the sound output or the amplitude of the meter's swing, helping the operator judge the test results. In use, the transmitter is connected to cable 2 via a local terminal box 4, and the receiver is connected to cable 2 via a control room junction box 5.

[0049] See Figure 9The main function of the cable inspection signal detection unit is to isolate and protect the received signal during cable inspection, preventing damage to the receiver from contact with live signals. It also indicates whether the cable 2 is live. The output of the cable inspection signal detection unit is connected to the input of the filter amplification unit. The cable inspection signal detection unit includes an isolation transformer T1, optocoupler integrated chips U11 and U12, and a light-emitting diode. Its main function is to achieve isolated signal reception, ensuring the receiver is not damaged by live signals, and providing a live indication. The first input terminal of the line detection signal unit is connected to the first terminal of capacitor C6, pin 1 of optocoupler integrated chip U12, and pin 2 of optocoupler integrated chip U11. The second input terminal of the line detection signal unit is connected to the first terminal of resistor R55 and the first terminal of the primary side of isolation transformer T1. The second terminal of resistor R55 is connected to the first terminal of resistor R52. The second terminal of resistor R52 is connected to pin 2 of optocoupler integrated chip U12 and pin 1 of optocoupler integrated chip U11. The second terminal of capacitor C6 is connected to the second terminal of the primary side of isolation transformer T1. The first terminal of the secondary side of isolation transformer T1 is connected to the first terminal of resistor R57. The second terminal of resistor R57 is connected to the cathode of Zener diode D4, the first terminal of resistor R56, and the gate of MOSFET D5. The second terminal of the secondary side of isolation transformer T1 is connected to the first terminal of resistor R57. The two terminals are connected to the negative terminal of LED D3, the positive terminal of Zener diode D4, the second terminal of resistor R56, the source of MOSFET D5, the positive terminal of Zener diode D6, and the first terminal of capacitor C11. The positive terminal of LED D3 is connected to the first terminal of resistor R53. The second terminal of resistor R53 is connected to the third pin of optocoupler integrated chip U11 and the third pin of optocoupler integrated chip U12. The fourth pin of optocoupler integrated chip U11 is connected to the fourth pin of optocoupler integrated chip U12, power supply VCC, and the first terminal of resistor R58. The second terminal of resistor R58 is connected to the drain of MOSFET D5, the negative terminal of Zener diode D6, the first terminal of capacitor C11, and the first terminal of capacitor C8. The second terminal of capacitor C8 is connected to the positive terminal of diode D7. The negative terminal of diode D7 is connected to the input terminal of the filter amplifier unit. When the external cable 2 under test becomes energized, the energized signal is isolated by capacitor C6 and will not enter the isolation transformer T1, ensuring that the receiver is not damaged by the energized cable 2. Additionally, the energized signal can drive optocoupler integrated chip U11 or U12, causing LED D3 to light up and provide an energized alarm. When the cable detection unit detects a specific signal emitted by the transmitter, this signal enters the primary coil of the isolation transformer T1 through capacitor C6. A signal of equal amplitude is induced in the secondary coil of the isolation transformer T1. This signal then drives MOSFET D5 to perform periodic switching, sending the signal to the filtering and amplification unit. This process detects whether the specific signal emitted by the transmitter is present on cable 2, thus realizing the cable detection function.

[0050] See Figure 10 The main function of the filtering and amplification unit is to filter and amplify the signals collected by the path detection sensor 1, cable identification sensor 3, and cable detection signal detection unit. This addresses the interference from the 50Hz signal at the test site and amplifies weak signals for easier processing in subsequent stages. Specifically, the first input terminal of the filtering and amplification unit is connected to the first terminals of resistors R117 and R125. The second input terminal is connected to the first terminals of resistors R127 and R125. The second terminal of resistor R117 is connected to the first terminals of capacitor C119, resistor R118, and pin 3 of integrated chip U5 (which uses an AD623 operational amplifier). The second terminal of resistor R127 is connected to the first terminals of capacitor C137, resistor R129, and pin 2 of integrated chip U5. Pin 1 of integrated chip U5 is connected to potentiometer R101 for adjustment. Pin 8 of integrated chip U5 is connected to the first terminal of potentiometer R101. Pin 4 of integrated chip U5 is grounded (GND). Pin 5 of integrated chip U5 is connected to the first terminal of resistor R128. The second terminal of resistor R128 is connected to the second terminals of resistor R118, resistor R129, capacitor C119, and capacitor C137. Pin 6 of integrated chip U5 is the output of integrated chip U5. Pin 7 of integrated chip U5 is connected to the first terminals of capacitor C121 and C129, as well as the power supply VCC. The second terminal of capacitor C121 is connected to the second terminal of capacitor C129 and grounded (GND). The main function of the integrated chip U5 and its peripheral circuits is to DC bias the input signal, making the input signal referenced by the reference voltage of pin 5 of the integrated chip U5. At the same time, it performs differential amplification on the input signal, and the amplification factor is determined by the resistance value of potentiometer R101 between pins 1 and 8 of the integrated chip U5. DC biasing and amplifying the signal is beneficial to the signal processing of the subsequent single-supply operational amplifier, while also effectively suppressing common-mode signals and reducing the influence of interference signals.

[0051] Resistors R119 and R120, capacitors C135, C133, and C134, and resistor R126 form a 50Hz dual-T notch filter. The output signal of integrated chip U5 is connected to the input of the dual-T notch filter, and the output signal of the dual-T notch filter is connected to the input of a voltage follower circuit composed of integrated chip U6A, which uses an operational amplifier TL972. The main function of this part of the circuit is to attenuate and filter out the power frequency interference signal in the input signal, allowing the useful signal to pass into the next stage amplifier circuit composed of integrated chip U6B, which also uses an operational amplifier TL972. The main function of the voltage follower is to ensure a low output impedance and provide effective isolation to avoid interference between the preceding and following stage signals.

[0052] See Figure 11 The power amplifier unit mainly consists of integrated chip U7 and its peripheral circuitry. Integrated chip U7, using the LA4140, primarily amplifies the output signal from the filter amplifier unit to drive subsequent audio output devices and instrument pointers. The output terminal of the filter amplifier unit is connected to the first terminal of capacitor C112, and the second terminal of capacitor C112 is connected to pin 2 of integrated chip U7. After coupling, the signal is input to integrated chip U7. Pin 3 of integrated chip U7 is connected to the positive terminal of capacitor C104. The negative terminal of capacitor C104 is connected to the first terminals of resistors R64 and R65. The second terminals of resistors R64 and R65 are connected to ground (GND), primarily controlling the closed-loop gain of the power amplifier. Pin 1 of integrated chip U7 is connected to the first terminal of capacitor C105, and the second terminal of capacitor C105 is connected to pin 4 of integrated chip U7. This connection eliminates signal self-oscillation, ensuring stable module operation. Pin 5 of integrated chip U7 is grounded to GND. Pin 7 of integrated chip U7 is connected to the power supply VCC and the positive terminal of capacitor C107. The negative terminal of capacitor C107 is grounded to GND, providing power to the power amplifier unit. Pin 8 of integrated chip U7 is connected to the positive terminal of capacitor C103. The negative terminal of capacitor C103 is connected to pin 6 of integrated chip U7, the first terminal of capacitor C101, the positive terminal of capacitor C109, and the positive terminal of capacitor C110, achieving voltage bootstrapping and increasing the power supply voltage. Pin 9 of integrated chip U7 is connected to the positive terminal of capacitor C102, and the negative terminal of capacitor C102 is grounded, achieving the effect of power supply filtering. Pin 6 of integrated chip U7 is the output pin of the power amplifier unit, directly connected to an ammeter to indicate the output signal strength. After being clamped by a diode connected in reverse parallel, it directly drives the audio output device, such as a buzzer or speaker.

[0053] This invention relates to a low-voltage cable comprehensive inspection device that integrates three functions: cable path detection, cable identification, and cable inspection. The cable path detection uses an intermittent 10kHz signal as the signal source, with a transmission power exceeding 50W. It can effectively test both short and long cables and offers high and low power settings. Shorter cables can be tested at low power, while longer cables can be tested at high power, achieving a detection depth of approximately 3 meters. The output signal for cable identification is the same as the path detection signal, except that the receiving device uses a current coil for acquisition. The presence or magnitude of the received signal determines whether the tested cable is the target cable. The inspection signal uses a small amplitude signal to ensure it does not cause malfunctions in the substation protection system. Both the transmitter and receiver are designed with protection units against accidental contact with live signals to prevent damage to the comprehensive inspection device. The entire device is powered by a lithium battery, making it portable, easy to wire, user-friendly, and highly efficient and reliable. Compared to traditional cable path testers and cable identification devices, which are independent, single-function devices without cable tracing capabilities, these devices lack versatility. Furthermore, the first two types of devices have no upper limits on frequency and amplitude for their application environments, making them unsuitable for use in UHV substations where signal frequency and equipment power requirements are clearly defined. Additionally, traditional testing equipment uses AC power, making it inconvenient for field use, and its large size and portability further complicate matters.

[0054] In summary, this invention overcomes the shortcomings of traditional equipment, such as limited functionality, lack of versatility in frequency and protection requirements, difficulty in providing AC power on-site, and large size making it inconvenient to carry. It develops a method based on the transmission of communication signals through the core medium of cable 2 to achieve functions such as cable path finding, identification, and core wire inspection. A transmitter injects a specific frequency communication signal into cable 2, and then, based on the principle of electromagnetic induction, different receiving devices realize the cable path finding, identification, and inspection functions, providing a simple, efficient, and accurate low-voltage cable inspection device.

[0055] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A comprehensive low-voltage cable inspection device, characterized in that, It includes a transmitter and a receiver; the transmitter includes a power module, a modulation unit, an oscillation unit, a chopper unit, a transformer unit, an isolation protection unit, and an output unit; the receiver includes a cable identification sensor (3), a path detection sensor (1), a cable detection signal detection unit, a power supply unit, a filtering and amplification unit, a power amplifier unit, and a surface acoustic wave output unit; The modulation unit is used to generate a first square wave signal and send it to the oscillation unit. The oscillation unit is used to generate a second square wave signal and send the second square wave signal to the chopper unit intermittently according to the first square wave signal. The chopper unit is used to receive the power signal sent by the power module and output the power signal to the transformer unit according to the periodic second square wave signal. The transformer unit is used to increase or decrease the amplitude of the power signal to obtain the transformer signal and the identification and path detection signal, and send the transformer signal and the identification and path detection signal to the output unit. The output unit sends the transformer signal to the isolation protection unit. The isolation protection unit is used to isolate the live signal of the cable (2) and generate a line detection signal according to the transformer signal and send it to the output unit. The output unit is also used to switch the output of the identification and path detection signal and the line detection signal and send it to the line detection signal detection unit through the cable (2). The cable inspection signal detection unit is used to receive the cable inspection signal and send it to the filtering and amplification unit. The cable identification sensor (3) and the path detection sensor (1) are both used to detect the identification and path detection signals in the cable (2), generate the cable identification signal and the path detection signal respectively and send them to the filtering and amplification unit. The filtering and amplification unit filters and amplifies the cable inspection signal, the cable identification signal and the path detection signal and sends them to the power amplifier unit for secondary amplification. The power amplifier unit sends the secondary amplified cable inspection signal, the cable identification signal and the path detection signal to the sound output unit for sound output or instrument display. The isolation protection unit is used to prevent damage to the transmitter from external energized loads and to provide protection alerts; The transformer unit includes a pulse transformer and a switch; The first terminal of the primary side of the pulse transformer is connected to the power supply VCC, and the second terminal is connected to the output terminal of the chopper unit. The secondary side of the pulse transformer is equipped with a common terminal, a first tap, a second tap, a third tap, and a fourth tap. One end of the switch is equipped with pins 1, 2, and 3, and the other end is equipped with pin 4. The first tap is connected to pin 1, the second tap is connected to pin 2, the third tap is connected to pin 3, and pin 4 is connected to the output unit for outputting identification and path detection signals. The fourth tap is also connected to the output unit for outputting line detection signals. The common terminal is connected to both the output unit and the isolation protection unit. The isolation protection unit includes an isolation transformer and a capacitor; The first terminal of the primary side of the isolation transformer is connected to the output unit to receive the transformer signal sent by the output unit. The first terminal and the second terminal of the secondary side of the isolation transformer are both connected to the output unit to send the line check signal to the output unit. The second terminal of the primary side of the isolation transformer is connected to the transformer unit. The second terminal of the secondary side of the isolation transformer is connected to the output unit through a capacitor. The modulation unit includes an integrated chip, a first capacitor, a second capacitor, a first resistor, a second resistor, and a third resistor. The integrated chip is an 8-pin timer integrated circuit NE555. Pin 1 of the integrated chip is connected to the first terminal of the second capacitor, the negative terminal of the first capacitor, the first terminal of the third resistor, and ground GND. Pin 2 of the integrated chip is connected to pin 6 of the integrated chip, the first terminal of the first resistor, and the positive terminal of the first capacitor. The second terminal of the first resistor is connected to the first terminal of the second resistor and pin 7 of the integrated chip. The second terminal of the second resistor is connected to the power supply VCC, pin 4 of the integrated chip, and pin 8 of the integrated chip. Pin 3 of the integrated chip is connected to the second terminal of the third resistor. Pin 5 of the integrated chip is connected to the second terminal of the second capacitor. Pin 3 of the integrated chip is the output terminal of the modulation unit and is connected to the oscillation unit. The line detection signal unit includes an isolation transformer, a first optocoupler integrated chip, a second optocoupler integrated chip, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a light-emitting diode, a first Zener diode, a second Zener diode, a diode, a first capacitor, a second capacitor, a third capacitor, and a MOSFET. The line detection signal unit is provided with a first input terminal and a second input terminal. The first end of both the first input terminal and the first end of the second input terminal are connected to the cable (2). The second end of the first input terminal is connected to the first end of the first capacitor, the first pin of the second optocoupler integrated chip, and the second pin of the first optocoupler integrated chip. The second end of the second input terminal is connected to the first end of the third resistor and the first end of the primary side of the isolation transformer. The second end of the third resistor is connected to the first end of the first resistor. The second end of the first resistor is connected to the second pin of the second optocoupler integrated chip and the first pin of the first optocoupler integrated chip. The second end of the first capacitor is connected to the second end of the primary side of the isolation transformer. The first end of the secondary side of the isolation transformer is connected to the first end of the fifth resistor. The second end of the fifth resistor is connected to the negative terminal of the first Zener diode, the first end of the fourth resistor, and the gate of the MOSFET. The second end of the secondary side of the isolation transformer is connected to the negative terminal of the light-emitting diode, the positive terminal of the first Zener diode, and the second end of the fourth resistor. The first terminal of the first optocoupler is connected to the source of the MOS transistor, the positive terminal of the second Zener diode, and the first terminal of the third capacitor. The positive terminal of the LED is connected to the first terminal of the second resistor. The second terminal of the second resistor is connected to the third pin of the first optocoupler integrated chip and the third pin of the second optocoupler integrated chip. The fourth pin of the first optocoupler integrated chip is connected to the fourth pin of the second optocoupler integrated chip, the power supply VCC, and the first terminal of the sixth resistor. The second terminal of the sixth resistor is connected to the drain of the MOS transistor, the negative terminal of the second Zener diode, the first terminal of the third capacitor, and the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the positive terminal of the diode. The negative terminal of the diode is connected to the filter amplification unit. When the cable (2) is energized, the energized signal is isolated by the first capacitor to prevent the energized signal from entering the isolation transformer. At the same time, the energized signal drives the first optocoupler integrated chip or the second optocoupler integrated chip to light up the LED to make an energized alarm prompt. The low-voltage cable inspection device only requires a lithium battery for power.

2. The low-voltage cable comprehensive inspection device according to claim 1, characterized in that, The oscillation unit includes an integrated chip, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, and a fourth resistor. The integrated chip is an 8-pin timer integrated circuit NE555. Pin 1 of the integrated chip is connected to the first terminal of the first capacitor, the first terminal of the second capacitor, the first terminal of the fourth resistor, and ground (GND). Pin 2 of the integrated chip is connected to pin 6 of the integrated chip, the first terminal of the first resistor, and the second terminal of the second capacitor. The second terminal of the first resistor is connected to the first terminal of the second resistor and pin 7 of the integrated chip. The second terminal of the second resistor is connected to the power supply (VCC) and pin 8 of the integrated chip. Pin 3 of the integrated chip is connected to the first terminal of the third resistor. The second terminal of the third resistor is connected to the second terminal of the fourth resistor. The second terminal of the third resistor is the output terminal of the oscillation unit and is connected to the chopper unit. Pin 5 of the integrated chip is connected to the second terminal of the first capacitor. Pin 4 of the integrated chip is connected to the output terminal of the modulation unit. When the signal at pin 4 of the integrated chip is low, the oscillation unit outputs a low-level signal; when the signal at pin 4 of the integrated chip is high, the oscillation unit outputs a high-level signal.

3. The low-voltage cable comprehensive inspection device according to claim 1, characterized in that, The chopper unit includes a MOS transistor, the drain of which is connected to the transformer unit, the gate of which is connected to the output terminal of the oscillation unit, and the source of which is grounded to GND. The MOS transistor switches periodically according to the second square wave signal.

4. The low-voltage cable comprehensive inspection device according to claim 1, characterized in that, The isolation protection unit also includes a light-emitting diode, a first optocoupler integrated chip, a second optocoupler integrated chip, a first resistor, a second resistor, and a third resistor; The first terminal of the secondary side of the isolation transformer is connected to the first terminal of the second resistor. The end of the capacitor away from the isolation transformer is connected to pin 2 of the second optocoupler integrated chip and pin 1 of the first optocoupler integrated chip. The second terminal of the second resistor is connected to the first terminal of the first resistor. The second terminal of the first resistor is connected to pin 2 of the first optocoupler integrated chip and pin 1 of the second optocoupler integrated chip. Pin 4 of the first optocoupler integrated chip is connected to pin 4 of the second optocoupler integrated chip and the power supply VCC. Pin 3 of the first optocoupler integrated chip is connected to pin 3 of the second optocoupler integrated chip and the first terminal of the third resistor. The second terminal of the third resistor is connected to the positive terminal of the light-emitting diode (LED). The negative terminal of the LED is connected to ground (GND).

5. The low-voltage cable comprehensive inspection device according to claim 1, characterized in that, The output unit includes a resistor, a first switch, and a second switch; the first switch has a first set of contacts and a second set of contacts; the second switch has a third set of contacts and a fourth set of contacts. The first end of the first group of contacts is connected to the transformer unit to receive the identification and path detection signal output by the transformer unit. The second end of the first group of contacts is suspended. The common end of the first group of contacts is connected to the first end of the resistor. The first end of the second group of contacts is suspended. The second end of the second group of contacts is connected to the transformer unit to receive the transformer signal output by the transformer unit. The common end of the second group of contacts is connected to the isolation protection unit to output the transformer signal to the isolation protection unit. The first end of the third group of contacts is connected to the second end of the resistor. The first end of the fourth group of contacts is connected to the transformer unit. The second ends of the third group of contacts and the second ends of the fourth group of contacts are both connected to the isolation protection unit to receive the line checking signal. The third end of the third group of contacts and the third end of the fourth group of contacts are the output terminals of the output unit and connected to the cable (2) to output the line checking signal or the identification and path detection signal.

6. The low-voltage cable comprehensive inspection device according to claim 1, characterized in that, Both the power module and the power supply unit are lithium batteries. The SAW output unit includes a speaker and a pointer-type ammeter, both of which are connected to the output terminals of the power supply unit and the power amplifier unit.

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