Frequency modulation type KVVP2 type control cable searching device

Abstract

The invention relates to a frequency modulation type KVVP2 type control cable searching device which comprises a transmitting end and a receiving end. The transmitting end comprises a power supply, a signal generating unit, a signal processing unit, a control unit, a mode switching unit, a liquid crystal display unit and an output unit; the receiving end is composed of a power supply, a magnetic signal receiving unit, a signal processing unit, a control unit, a mode switching unit and an LED indicating unit. Wherein the power supply is connected with other units and provides working voltage for the system; the magnetic signal receiving unit ensures the anti-interference performance of the equipment; and the control unit is used for carrying out algorithm and filtering processing on the received signals and selecting different modes for output according to test requirements. The device has the advantages that the device is portable and quick, and can be directly controlled without stripping the line sheath; high-voltage protection: triggering circuit high-voltage protection to disconnect the circuit; and a small-amplitude high-frequency signal is used as a line inspection signal, so that normal reception of line inspection work can be ensured, and the whole protection system is not interfered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power secondary equipment maintenance, and particularly relates to a frequency modulation type KVVP2 control cable searching device. BACKGROUND

[0002] Control cable replacement is a part of substation integrated automation transformation, intelligent transformation, protection replacement and equipment replacement. The control cable to be removed is intact and has no fault point, and there are many surrounding operating cables and large interference signals. Since the control cables are arranged in the cable trench, it is not easy to find them, which leads to the fact that the waste cables after transformation cannot be extracted and are left in the cable trench, causing waste. Since the control cables are more and more, it increases the difficulty of laying new cables. The existing cable searching devices are mostly fault point searching devices and cable direction searching devices, and are only suitable for searching power cables, and there is no searching device for KVVP2 type control cables of secondary circuits.

[0003] In order to improve the efficiency and safety of control cable line searching, avoid the risk of misoperation of operating control cables, reduce the KVVP2 type control cable removal time, improve the waste cable removal rate, and generate economic benefits.

[0004] The frequency modulation type KVVP2 control cable searching device uses variable radio frequency and Fourier anti-interference algorithm to search for control cables, uses electromagnetic induction to identify signals without damaging the cables, is suitable for most control cable removal work, can distinguish the signals induced in similar cables, and ensures the uniqueness of the searched cables. SUMMARY

[0005] The present application is based on radio frequency technology and electromagnetic induction principle, uses anti-interference algorithm, provides a portable, efficient and accurate control cable searching device, and improves the efficiency, safety and accuracy of control cable line searching.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] The present application provides a frequency modulation type KVVP2 control cable searching device, which comprises a transmitting end and a receiving end.

[0008] The transmitting end includes a power supply, a signal generation unit, a signal processing unit, a control unit, a mode switching unit, an LCD display unit, and an output unit. The power supply is connected to the other units to provide the operating voltage for the system. The signal generation unit generates a square wave signal with a certain period and frequency, which is then converted into an output signal with the same period and frequency by the signal processing unit. The control unit controls the signal generation and the signal processing and mode switching units, selecting different output modes according to testing requirements. The LCD display unit clearly displays the signal output status and signal strength.

[0009] The receiving end consists of a power supply, a magnetic signal receiving unit, a signal processing unit, a control unit, a mode switching unit, and an LED indicator unit. The power supply is connected to the other units to provide the operating voltage for the system. The magnetic signal receiving unit collects and receives magnetic signals, and the signal processing unit filters and amplifies weak signals to ensure the device's anti-interference capability. The control unit performs algorithmic and filtering processing on the received signals, accurately acquiring the specific signals emitted by the transmitter. Finally, it selects different output modes according to testing requirements. The audio-visual output unit uses LED indicators and a buzzer to clearly indicate the strength of the received signal.

[0010] This invention relates to a line-finding device for KVVP2 type control cables in secondary circuits. It solves the problem of unclear identification between discarded and normally operating KVVP2 type control cables during substation renovation, avoiding the risk of accidental operation of operating control cables; it also reduces the time required to remove KVVP2 type control cables and improves the efficiency of discarded cable removal. The invention uses an adjustable radio frequency signal emitted from the transmitter to the cable. Utilizing the principle of electromagnetic induction, the receiver receives the signal and employs a Fourier series algorithm to set up an anti-interference unit to cancel interference from power frequency signals in normally operating cables, enabling accurate cable line tracing. Both the transmitter and receiver are equipped with protection and limiting units to prevent burnout due to overcurrent or overvoltage. The signal strength can limit the device's output signal to avoid affecting other circuits.

[0011] The advantages and beneficial effects of this invention are:

[0012] The frequency-modulated KVVP2 control cable locator described in this invention is portable and fast: when locating cable lines, it does not require stripping the cable sheath and can directly control the cable; cable tracing and identification are simple and quick to operate, and it can determine the location of line breaks. Conductor continuity (circuit) detection: this device can detect the continuity of the line using a transmitter.

[0013] Briefly press the on / off button on the transmitter. The red and black output clips will attach to both ends of the line under test, and the measurement results will be displayed on the screen. Mode switching function: This device has digital and analog line finding functions, allowing users to select either digital or analog line finding output mode according to different usage scenarios.

[0014] Output amplitude adjustment function: The amplitude of the output signal of this device 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, the low level can be used, resulting in lower power consumption and easier resolution for the receiving device. When testing long cables, cables buried at greater depths, or in environments with high loop impedance, the high level must be used; otherwise, a valid signal cannot be received.

[0015] Low voltage warning function: When the battery voltage at the transmitting end is lower than the operating voltage, the display screen will show a message indicating that timely charging is needed. Receiver with lighting function: This device is convenient to use in low-light conditions. High voltage protection: The transmitting end signal output terminal is connected to a voltage protection circuit exceeding 51V. If the transmitting end signal output terminal is mistakenly connected to 220V AC high voltage, the high voltage protection circuit will be triggered, disconnecting the circuit and achieving the protection purpose. No protection malfunction: This device uses a small-amplitude high-frequency signal as the line checking signal, ensuring normal reception during line checking without interfering with the entire protection system. Attached Figure Description

[0016] Figure 1 This is a block diagram of the transmitter principle.

[0017] Figure 2 This is a block diagram of the receiver principle.

[0018] Figure 3 This is a schematic diagram of the transmitter signal generation and control unit.

[0019] Figure 4 This is the signal processing unit for the transmitting end;

[0020] Figure 5 This is a transmitter mode switching unit;

[0021] Figure 6 This is a schematic diagram of the receiver signal processing unit.

[0022] Figure 7 This is the schematic diagram of the power amplifier output unit at the receiving end;

[0023] Figure 8 This is a schematic diagram of the receiver control unit.

[0024] Figure 9 Wiring diagram for cable tracing test site Figure 1 ;

[0025] Figure 10 Cable tracing test field wiring diagram Figure 2 . DETAILED DESCRIPTION

[0026] The application will be further described in detail below with reference to specific embodiments and schematic diagrams.

[0027] The application will be further described in detail below with reference to specific embodiments and schematic diagrams.

[0028] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings show typical embodiments of the present application. However, the present application can be applied to many different scenarios and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0029] It should be noted that all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing the specific embodiments and are not intended to limit the present application. Figure 1 and Figure 2 is a cable tracing test field wiring diagram of the test device of the present application.

[0030] Referring to Figure 3 , the main function of the transmitting end signal generation and control unit is to generate a set of periodic square wave signals and to control the driving chip, thereby controlling the switching state of the field effect tube to make it output intermittent periodic signals. The signal generation unit mainly consists of a single-chip microcomputer, which is programmed with C language. The 44-pin output of the single-chip microcomputer outputs regular PWM signals, which then control the driving chip.

[0031] Referring to Figure 4 , the main function of the transmitting end signal processing unit is to control the field effect tube to perform high-frequency periodic switching action after the PWM signals generated by the single-chip microcomputer are processed by the driving chip. The signal processing unit mainly consists of an integrated circuit U2 and peripheral diodes, electrolytic capacitors, filter capacitors, resistors, and field effect tubes. Among them, the 1st pin and the 3rd pin of U2 are connected to the power supply VCC, the 2nd pin is connected to the PWM signal output by the single-chip microcomputer, the 4th pin is connected to GND, the 5th pin is the output low end, connected to R14 and D6, the 6th pin is connected to the floating ground, and the 7th pin is the signal output high end, connected to R11 and D3. A diode FR107 and a 33uf electrolytic capacitor are connected between the 1st pin, the 6th pin, and the 8th pin of U2, which are boot diode and boot capacitor. The value of the boot diode and the boot capacitor should be appropriate to affect the output state of the chip. Diodes D3 and D6 enable the field effect tube to turn off quickly. The 5th pin, the 6th pin, and the 7th pin of U2 control the output of field effect tubes G1 and G2.

[0032] As shown in Figure 5 , the main function of the transmitting end mode switching unit is the switching of digital line searching and analog line searching output mode. The selection and switching of the mode are controlled by the single-chip microcomputer, which is mainly composed of buttons, resistors and capacitors. SW1 button is the digital line searching selection button, SW2 is the analog line searching selection button, and the functions of capacitors C21 and C22 are to resist interference. When SW1 button is pressed, the I / O port of the single-chip microcomputer controlling the button changes from high level to low level, and the single-chip microcomputer switches the output mode to digital line searching. When SW2 button is pressed, the I / O port of the single-chip microcomputer controlling the button changes from high level to low level, and the single-chip microcomputer switches the output mode to analog line searching mode.

[0033] As shown in Figure 6 , the main function of the receiving end signal processing unit is to realize the filtering and amplification processing of the sensor signal, which on the one hand solves the interference problem of 50Hz signal in the test site, and on the other hand amplifies the weak signal for the processing of the later stage. One end of the input signal is connected with one end of resistor R17 and one end of resistor R25, the other end of the input signal is connected with one end of resistor R27 and the other end of resistor R25, the other end of R17 is connected with one end of capacitor C19, one end of resistor R18 and the 3rd pin of integrated chip U5, the other end of R27 is connected with one end of capacitor C37, one end of resistor R29 and the 2nd pin of integrated chip U5, the 1st pin of U5 is connected with the adjusting end of potentiometer R1, the 8th pin of U5 is connected with one end of potentiometer R1, the 4th pin of U5 is connected with power supply GND, the 5th pin of U5 is connected with one end of resistor R28, the other end of R28 is connected with the other end of R18, the other end of R29, the other end of C19 and the other end of C37, the 6th pin of U5 is the output of the operational amplifier chip, the 7th pin of U5 is connected with one end of C21, one end of C29 and power supply VCC, the other end of C21 is connected with the other end of C29 and power supply GND. The main function of the integrated chip U5 and its peripheral circuit is to perform DC bias on the input signal, so that the input signal takes the reference voltage of the 5th pin as the reference, and to perform differential amplification on the input signal, and the amplification factor is determined by the resistance value between the 1st pin and the 8th pin. The DC bias processing and amplification of the signal are beneficial to the signal processing of the single power supply operational amplifier in the later stage, and can effectively suppress the common mode signal and reduce the influence of interference signals.

[0034] Resistors R19 and R20, capacitors C35, C33, and C34, along with resistor R26, form a 50Hz dual-T notch filter. The output signal of U5 is connected to the input of the notch filter, and the output signal of the notch filter is connected to the input of a voltage follower circuit composed of integrated chip U6A. The main function of this circuit is to attenuate and filter out power frequency interference signals in the input signal, allowing the useful signal to pass through to the next stage amplifier circuit composed of U6B. The voltage follower's main function is to ensure low output impedance while providing effective isolation to avoid interference between the preceding and following stages.

[0035] like Figure 7 As shown, the function of the receiver's power amplifier output unit is to amplify the received signal and drive the speaker output. The power amplifier output unit mainly consists of the core device LM386 and peripheral resistors and capacitors. The signal is input through pin 3 and output through pin 5. Pin 4 of pin 2 is connected to GND. Potentiometer P1 is used to adjust the speaker output volume. Pin 6 is connected to power supply VCC, providing operating power for chip U2. Capacitor C1 is the filter capacitor for the power input section, providing a stable operating voltage for U2. Capacitor C2 is connected between pins 1 and 8 of U7, its function being to control the closed-loop gain of the power amplifier and eliminate signal self-oscillation. Resistor R1 connected to pin 5 of U2 has a capacitor C3 connected in series below it, with the other end of C3 grounded. This forms a filter, which adjusts the input impedance. Capacitor C4 is connected to the speaker; this connection eliminates unnecessary DC signals.

[0036] like Figure 8 As shown, the receiver control unit processes the received signal, works with the microcontroller programming, applies Fourier series algorithms to set up an anti-interference unit to cancel interference from power frequency signals in the normally operating cable, and controls the signal strength indicator and output mode switching for precise cable tracing. Capacitor C42 is the power supply filter capacitor, providing a stable operating voltage for chip U9. Resistor R61 and capacitor E6 are the chip's reset resistor and capacitor.

[0037] This invention integrates functions such as digital cable tracing, analog cable tracing, cable continuity detection, and cable break point location determination. Digital cable tracing uses a 1MHz square wave signal as the signal source, transmitting signals with a 1ms period, achieving a detection range of less than 1 meter and a tracing distance of less than 1000 meters. Analog cable tracing uses an 800kHz square wave signal as the signal source, transmitting signals with a 500µs period, achieving a detection range of less than 1 meter and a tracing distance of less than 3000 meters. The cable continuity detection function can detect the continuity of the line. The cable break point location determination function is similar to the cable tracing function, determining the location of the cable break point segment by the magnitude or presence / absence of the received signal. The cable tracing signal uses a small amplitude signal as the measurement signal to ensure that it will not cause malfunctions in the protection system. Protection units are designed at both the transmitting and receiving ends to prevent damage to the measuring device. The entire device is powered by a lithium battery, making it portable, easy to wire, user-friendly, and highly efficient and reliable in testing.

[0038] 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 portable, efficient, and accurate control cable locator based on radio frequency technology and electromagnetic induction principles, utilizing anti-interference algorithms to improve the efficiency, safety, and accuracy of control cable locating.

[0039] See Figure 9 This is the first wiring method, which is convenient to use;

[0040] Connect the red clip of the transmitter to any core wire at the beginning of the cable, ground the black clip of the transmitter, and ground the corresponding core wire at the end of the cable. The receiver can then be used to locate the cable at any point in the middle of the cable.

[0041] See Figure 10 This is the second wiring method, which has strong anti-interference capabilities;

[0042] Connect the red clip of the transmitter to any wire at the beginning of the cable, and the black clip to the other wire. Short-circuit the corresponding two wires at the end of the cable. The receiver can then locate the cable at any point in the middle. This wiring method is slightly more complicated, but it offers stronger anti-interference capabilities.

[0043] In this embodiment, the above-described embodiments merely illustrate one implementation of the present invention, and while the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. Any modifications, substitutions, or improvements made within the spirit and principles of the present invention are within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A frequency-modulated KVVP2 type control cable locating device, characterized in that: The frequency modulation KVVP2 type control cable locator includes a transmitter and a receiver.

2. The frequency modulation KVVP2 type control cable locating device according to claim 1, characterized in that: The transmitter includes a transmitter power supply, a transmitter signal generation unit, a transmitter signal processing unit, a transmitter control unit, a transmitter mode switching unit, a transmitter LCD display unit, and a transmitter output unit. The transmitter power supply is connected to the other units to provide the operating voltage for the system. The transmitter signal generation unit generates a square wave signal with a certain period and frequency, which is then converted into an output signal with the same period and frequency by the transmitter signal processing unit. The transmitter control unit controls the generation of the signal and controls the signal processing unit and the mode switching unit to select different output modes according to the test requirements. The transmitter LCD display unit can clearly display the signal output status and signal strength.

3. The frequency modulation KVVP2 type control cable locating device according to claim 1, characterized in that: The receiving end includes a receiving end power supply, a receiving end magnetic signal receiving unit, a receiving end signal processing unit, a receiving end control unit, a receiving end mode switching unit, and a receiving end LED indicator unit. The receiver power supply is connected to the other units to provide the operating voltage for the system. The magnetic signal receiving unit at the receiver end is responsible for collecting the received magnetic signals. The signal processing unit at the receiver end filters and amplifies the weak signals to ensure the equipment's anti-interference capability. The receiver control unit is used to perform algorithmic and filtering processing on the received signals. It needs to accurately collect the specific signals emitted by the transmitter end. Finally, it selects different output modes according to the test requirements. The receiver audio-visual output unit uses LED indicators and buzzer prompts at the receiver end to indicate the strength of the received signal.

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