Single-core cable metal sheath connection nuclear phase detection method and device

Abstract

The invention discloses a single-core cable metal sheath connection nuclear phase detection method and device, and the method comprises the steps: connecting measurement resistors in series at the head and tail ends of a three-phase line of a detected three-phase cable, transmitting a 24V voltage signal to the detected three-phase cable through a signal generation and control unit, measuring the current value of the detected three-phase cable through a signal measurement unit, and calculating the current value of the detected three-phase cable according to the measured current value. And calculating the resistance value of the three-phase line of the tested cable, and judging a nuclear phase result according to the resistance value. The input end of the cable is respectively connected with three resistors with different resistance values in series, the output end of the cable is also connected with three different resistors in series, after cross interconnection, the current passing through the three-phase cable is measured, the resistance is calculated, and therefore the purpose of phase checking is achieved, and due to the fact that current signal transmission is high in interference, free of attenuation and hysteresis and suitable for long-distance transmission, the phase checking precision is high. The external interference is greatly avoided, and the measurement accuracy is as high as 100%. The device has the advantages of being high in electronic integration, high in reliability, convenient to carry and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of power cable metal sheath detection, and in particular relates to a single-core cable metal sheath connection core phase detection method and device. Background Art

[0002] The existing technology usually performs phase testing by measuring high voltage signals, measuring frequency, measuring the number of pulses, measuring pulse width, etc. They all belong to measuring voltage signals, and the disadvantage is that the signal is attenuated during long-distance transmission. The transmission distance of voltage signals is relatively short, generally requiring a distance of 5m and a line resistance value of less than 1Ω. This is because voltage signals are easily affected by the capacitance of the transmission cable, resulting in hysteresis and distortion, as well as signal value attenuation and distortion due to the resistance along the line. Although voltage signal transmission may be more convenient in some cases, due to its limitations, current signal transmission is usually a better choice, especially in applications that require long-distance transmission or have high signal quality requirements. Summary of the invention

[0003] In order to solve the deficiencies in the prior art, the resistance measurement method used in the present invention belongs to the measurement of current signals. The advantages of current signal transmission include strong anti-interference, no attenuation, no hysteresis, and suitability for long-distance transmission. The general distance can reach 500m or even 1000m, and the influence on the capacitance of the cable and the resistance along the line is very small, and it is insensitive to changes in the load. In addition, current signal transmission also overcomes some limitations of voltage signal transmission, such as the voltage signal is easily affected by the capacitance of the transmission cable to produce hysteresis and distortion, and the signal value is attenuated and distorted due to the influence of the resistance along the line. The present invention provides a single-core cable metal sheath connection core phase detection device, which has the advantages of high electronic integration, high reliability, easy to carry, and low cost.

[0004] The present invention adopts the following technical solution.

[0005] The first aspect of the present invention provides a single-core cable metal sheath connection core phase detection method,

[0006] Connect measuring resistors in series at both ends of the three-phase line of the three-phase cable under test; send a 24V voltage signal through the signal generation and control unit and transmit it to the three-phase cable under test; measure the current value of the three-phase cable under test by the signal measurement unit, calculate the resistance value of the three-phase line of the cable under test, and judge the phase verification result according to the resistance value.

[0007] Preferably, the resistance values ​​measured at both ends of the same phase line of the three-phase cable under test are the same, and the resistance values ​​measured between different phase lines are different.

[0008] Preferably, the resistors connected in series at both ends of the three-phase cable under test meet the condition that the resistance values ​​measured for all correct phase sequences and all incorrect phase sequences are different.

[0009] The second aspect of the present invention provides a core phase detection device using the above-mentioned single-core cable metal sheath connection core phase detection method, comprising:

[0010] A central processing unit, a power supply unit connected thereto, and a signal generation and control unit, a signal measurement unit and a display unit connected to the central processing unit and the power supply unit at the same time; the central processing unit is used to control, receive and process data, the power supply unit is used to supply power to the nuclear phase detection device, the signal generation and control unit is used to send a voltage signal for measuring resistance, the signal measurement unit is used to measure the resistance value, and the display unit is used to display the measurement result;

[0011] The central processing unit includes a central processing unit circuit, the power supply unit includes a power supply circuit, the signal generation and control unit includes a signal generation circuit and a signal control circuit, the signal generation circuit is connected to the signal control circuit, the signal measurement unit includes a signal measurement circuit, and the display unit includes a display circuit; the signal measurement circuit includes a measurement resistor and an operational amplifier, and the measurement resistor is connected in series with the input end of the operational amplifier.

[0012] Preferably, the central processing unit circuit includes a single-chip microcomputer, and a crystal oscillator circuit, a reset circuit and a communication interface circuit connected thereto; the crystal oscillator circuit is used to provide a stable clock signal for the single-chip microcomputer to ensure the synchronous operation of various parts of the single-chip microcomputer; the reset circuit is used to return the single-chip microcomputer to an initial state when an abnormality occurs in the system or needs to be restarted; the communication interface circuit is used to allow the single-chip microcomputer to exchange data with other circuits to achieve communication between systems.

[0013] Preferably, the power supply circuit includes a switching circuit and a power conversion circuit. The switching circuit is connected to the power conversion circuit. The switching circuit is used to control the power on and off of the nuclear phase detection device. The power conversion circuit is used to convert the voltage provided in the switching circuit into a required value.

[0014] Preferably, the switching circuit includes a switching transistor, a MOS tube and a power supply battery, the collector of the switching transistor is connected to the gate of the MOS tube, the source of the MOS tube is connected to the power supply battery, the drain of the MOS tube outputs the first power supply voltage, and the switching transistor is used to control the conduction and shutdown of the MOS tube.

[0015] Preferably, the power conversion circuit comprises a power conversion chip, the input end of the power conversion chip is connected to the drain of the MOS tube, the drain of the MOS tube provides a first power supply voltage, and the output end of the power conversion chip is used to output a second power supply voltage.

[0016] Preferably, the signal generating circuit comprises a driving chip, an optocoupler and a DC isolation power supply, wherein the driving chip is connected to the optocoupler; and the optocoupler is connected to the DC isolation power supply.

[0017] Preferably, the signal measurement circuit comprises a measuring resistor and an operational amplifier, and the measuring resistor is connected in series with an input terminal of the operational amplifier;

[0018] The display circuit includes a communication chip and a screen, the communication chip is electrically connected to the screen, and the communication chip is used to transmit data. The beneficial effect of the present invention is that compared with the prior art,

[0019] The present invention adopts the technology of measuring current signal, generates 24V voltage signal through signal generating circuit, sends voltage signal into measured cable through signal control circuit, firstly disconnects the grounding of sheath of measured cable, connects three resistors with different resistance in series at input end of cable, connects three resistors with different resistance in series at output end, measures the current passing through three-phase cable after cross-connection, calculates resistance, thus achieves the purpose of phase checking, and because current signal transmission has strong interference, no attenuation, no hysteresis, is suitable for long-distance transmission, avoids external interference to a great extent, and has measurement accuracy up to 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A circuit diagram of a central processing unit according to an embodiment of the present invention;

[0021] Figure 2 This is a power supply circuit diagram of an embodiment of the present invention;

[0022] Figure 3 The signal generating circuit and the signal controlling circuit diagram of the embodiment of the present invention;

[0023] Figure 4 This is a signal measurement circuit diagram of an embodiment of the present invention;

[0024] Figure 5 A circuit diagram is shown for an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the correct cross-connection wiring of AC:BA:CB in an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the correct cross-connection wiring of AB:BC:CA in an embodiment of the present invention;

[0027] Figure 8 It is a structural schematic diagram of the single-core cable metal sheath connection core phase detection device of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The embodiment of the present invention provides a single-core cable metal sheath connection core phase detection method, including:

[0029] Connect the resistance in series at both ends of the three-phase line of the cable under test.

[0030] In a preferred but non-limiting embodiment of the present invention, the resistance values ​​measured at both ends of the same phase line of the three-phase cable under test are the same, and the resistance values ​​measured between different phase lines are different. Figure 6 and Figure 7 As shown, first, measuring resistance is connected in series at both ends of the three-phase line of the measured cable. In a preferred but non-limiting embodiment of the present invention, 1KΩ resistors are connected in series at both ends of the A-phase cable, 5KΩ resistors are connected in series at both ends of the B-phase cable, and 10KΩ resistors are connected in series at both ends of the C-phase cable.

[0031] In a preferred but non-limiting embodiment of the present invention, the resistance values ​​of the series resistors at the ends of the three-phase cable under test may also be different, as long as the condition that the resistance values ​​measured for all correct phase sequences and all incorrect phase sequences are different is met, which is not shown in the figure.

[0032] The signal generation and control unit sends a 24V voltage signal to the three-phase cable under test. The signal measurement unit measures the current value of the three-phase cable under test, calculates the resistance value of the three-phase line of the cable under test, and determines the phase verification result based on the resistance value.

[0033] Figure 6 , 7 All of them are correct cross-connection methods. Figure 6 The measured resistance should be about 11K for phase A, about 6K for phase B, and about 15K for phase C. At this time, the phase verification result is AC:BA:CB. Figure 7 The measured resistance should be about 6K for phase A, about 15K for phase B, and about 11K for phase C. At this time, the phase check result is AB:BC:CA. Any other result is considered as a phase sequence error.

[0034] like Figure 1-8 As shown, the embodiment of the present invention also provides a single-core cable metal sheath connection core phase detection device, comprising:

[0035] A central processing unit, a power supply unit connected thereto, and a signal generation and control unit, a signal measurement unit and a display unit connected to both the central processing unit and the power supply unit. The central processing unit is used to control, receive and process data, the power supply unit is used to supply power to the nuclear phase detection device, the signal generation and control unit is used to send a voltage signal for measuring resistance, the signal measurement unit is used to measure the resistance value, and the display unit is used to display the measurement result.

[0036] Among them, the central processing unit includes a central processing unit circuit, the power supply unit includes a power supply circuit, the signal generation and control unit includes a signal generation circuit and a signal control circuit, the signal measurement unit includes a signal measurement circuit, and the display unit includes a display circuit.

[0037] like Figure 1 As shown, it is a circuit diagram of the central processing unit of an embodiment of the present invention. The central processing unit circuit comprises a single-chip microcomputer, and peripheral circuits such as a crystal oscillator circuit, a reset circuit and a communication interface circuit connected thereto: the crystal oscillator circuit is used to provide a stable clock signal for the single-chip microcomputer to ensure the synchronous operation of various parts of the single-chip microcomputer; the reset circuit is used to return the single-chip microcomputer to the initial state when the system is abnormal or needs to be restarted; the communication interface circuit is used to allow the single-chip microcomputer to exchange data with other circuits to realize communication between systems.

[0038] In a preferred but non-limiting embodiment of the present invention, the single-chip microcomputer adopts the MSP430F149 chip. In addition, the MSP430F149 chip also supports a variety of low-power modes, such as active mode (AM), low power mode 0 (LPM0), etc. These modes allow the MSP430F149 chip to adjust the power consumption according to actual needs to adapt to different application scenarios. For example, in low-power mode, the central processing unit CPU can signal to stop working, while the peripheral mode continues to work to reduce overall power consumption. These characteristics make the MSP430F149 chip particularly suitable for occasions that require long-term operation and have strict requirements on power consumption.

[0039] like Figure 2 The power circuit diagram provided by the embodiment of the present invention is shown. The power circuit includes a switch circuit and a power conversion circuit. The switch circuit is connected to the power conversion circuit. The switch circuit is used to control the power on and off of the nuclear phase detection device. The power conversion circuit is used to convert the voltage provided in the switch circuit into a required value. The switch circuit includes a switch transistor, a MOS tube and a power supply battery. The collector of the switch transistor is connected to the gate of the MOS tube, the source of the MOS tube is connected to the power supply battery, the drain of the MOS tube outputs a first power supply voltage, and the switch transistor is used to control the conduction and shutdown of the MOS tube. The power conversion circuit includes a power conversion chip. The input end of the power conversion chip is connected to the drain of the MOS tube. The drain of the MOS tube provides the first power supply voltage. The output end of the power conversion chip is used to output a second power supply voltage.

[0040] In a preferred but non-limiting embodiment of the present invention, the model of the switch transistor is S9013, and the model of the MOS tube is CMD85P03A. An S9013 switch transistor is used to control the on and off of the MOS tube CMD85P03A, ​​thereby controlling the subsequent power supply. The power supply battery adopts a 24V lithium battery, the power conversion chip signal is AMS1117-3.3, the first power supply voltage is +12V, and the second power supply voltage is +3.3V. The 24V lithium battery has the advantages of stable voltage, large capacity, and small size; the +3.3V power supply voltage is generated by the power conversion chip AMS1117-3.3. The power conversion chip AMS1117-3.3 is a positive low-dropout voltage regulator with an output voltage of +3.3V, which is suitable for high-efficiency linear voltage regulators and has the characteristics of large static current and small ripple.

[0041] like Figure 3 The figure shows a signal generating circuit and a signal control circuit diagram in an embodiment of the present invention. The voltage signal generated by the signal generating circuit is directly provided by a battery and is directly connected to the signal control circuit. The voltage signal is sent to the measured cable through the signal control circuit. The signal generating circuit includes a driving chip, an optocoupler and a DC isolation power supply. The driving chip is connected to the optocoupler; the optocoupler is connected to the DC isolation power supply, and the optocoupler is used to control whether the signal control transistor is turned on; the signal control circuit includes: a signal control transistor and a relay. The signal control transistor is connected to the relay, and the signal control transistor is used to control whether the relay is working.

[0042] The signal generating circuit and the signal control circuit adopt electrical isolation control. The three optocouplers are driven by the driver chip. The three optocouplers control whether the emitter of the three signal-controlled transistors is turned on. The three signals control the transistors to control the relays. When the signal controls the transistors to turn on, the relay works. When the signal controls the transistors to cut off, the relay is disconnected. At the same time, a DC isolated power supply is used to work, which greatly reduces the impact on the signal control circuit during the signal transmission process.

[0043] In a preferred but non-limiting embodiment of the present invention, the driving chip is a ULN2003AN chip, the DC isolation power supply is a B1515S model, the optocoupler is a TLP521 model, and the signal control transistor model is S9013; the 14th, 15th and 16th pins of the driving chip ULN2003AN are respectively connected to two TLP521 optocouplers, which are used to drive three signal control transistors S9013, and the three signal control transistors S9013 are connected to the 2nd pins of the three relays U10, U11 and U12, and the DC isolation power supply B1515 is connected to the 1st pin of the relay.

[0044] like Figure 4The figure shows a signal measurement circuit diagram provided by an embodiment of the present invention. The signal measurement circuit includes a measurement resistor and an operational amplifier. The measurement resistor is connected in series with the input terminal of the operational amplifier.

[0045] In a preferred but non-limiting embodiment of the present invention, the operational amplifier model is LM358, the measuring resistors are R105, R106 and R107, wherein the measuring resistors are low temperature drift resistors, the measuring resistors are connected to the 3rd and 5th pins of the operational amplifier, and the output of the operational amplifier is connected to the single-chip microcomputer through R123, R124, R125, R126, R127 and R128; the measuring signal is processed by the operational amplifier and output to the single-chip microcomputer. LM358 is a dual operational amplifier. It includes two independent, high-gain, internal frequency-compensated operational amplifiers, which are suitable for single power supply with a wide power supply voltage range, and are also suitable for dual power supply working mode. Under the recommended working conditions, the power supply current is independent of the power supply voltage. Its scope of use includes sensor amplifiers, DC gain modules and all other occasions where operational amplifiers can be used with a single power supply. When the current signal is transmitted to the operational amplifier circuit through the measuring resistor, due to the infinite input resistance of the operational amplifier, the converted voltage signal has almost no attenuation, and the voltage signal is processed by the operational amplifier, and finally the signal is sent to the central processing unit circuit for processing.

[0046] like Figure 5 The figure shows a display circuit diagram provided by an embodiment of the present invention. The display circuit includes a communication chip and a screen. The communication chip is electrically connected to the screen, and the communication chip is used to transmit data.

[0047] In a preferred limiting embodiment of the present invention, the communication chip is SP3232, which is an RS-232 interface transceiver chip, and its main function is the conversion of serial to parallel and parallel to serial data. The screen uses a large color serial port screen, which supports the RS-232 communication protocol. The signal generated by the central processing unit circuit is TTL level, so it is necessary to use the SP3232 chip for level conversion. The data is sent to the SP3232 chip through the central processing unit circuit, and then sent to the screen after processing. Conversely, the data sent by the screen also needs to be processed by the SP3232 chip and sent to the central processing unit circuit.

[0048] The central processing unit circuit controls the signal control circuit and the signal generating circuit to send the voltage signal to the measured cable. The current signal is converted into a voltage signal through the signal measuring circuit and sent to the central processing unit circuit for calculation to calculate the measured resistance, thereby determining the phase sequence. The measurement result is sent to the screen through the display circuit.

[0049] Pins 2, 3, and 4 of the microcontroller are connected to resistors R126, R127, and R128 of the signal measurement circuit respectively, pins 34 and 35 are connected to R81 and R80 of the display circuit, the 12V output end of the power supply circuit is connected to pin 8 of LM358 of the signal measurement circuit and pin 1 of B1515s of the signal generating circuit, +3.3V is connected to pins 1 and 64 of the microcontroller and pin 16 of the display circuit SP3232, and pins 2, 3, and 4 of H1 of the signal generating circuit are connected to pins 13, 14, and 15 of the processor.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A single-core cable metal sheath connection core phase detection, characterized in that: A measuring resistor is connected in series at both ends of the three-phase line of the three-phase cable under test, and a 24V voltage signal is sent out by the signal generation and control unit and transmitted to the three-phase cable under test. The current value of the three-phase cable under test is measured by the signal measurement unit, and the resistance value of the three-phase line of the cable under test is calculated, and the phase verification result is judged according to the resistance value.

2. The nuclear phase detection method according to claim 1, characterized in that: The resistance values ​​measured at both ends of the same phase line of the three-phase cable under test are the same, while the resistance values ​​measured between different phase lines are different.

3. The nuclear phase detection method according to claim 1, characterized in that: The resistors connected in series at both ends of the three-phase cable under test meet the condition that the resistance values ​​measured by all correct phase sequences and all incorrect phase sequences are different.

4. A phase detection device using the single-core cable metal sheath connection phase detection method according to any one of claims 1 to 3, characterized in that: include: A central processing unit, a power supply unit connected thereto, and a signal generation and control unit, a signal measurement unit and a display unit connected to the central processing unit and the power supply unit at the same time; the central processing unit is used to control, receive and process data, the power supply unit is used to supply power to the nuclear phase detection device, the signal generation and control unit is used to send a voltage signal for measuring resistance, the signal measurement unit is used to measure the resistance value, and the display unit is used to display the measurement result; The central processing unit includes a central processing unit circuit, the power supply unit includes a power supply circuit, the signal generation and control unit includes a signal generation circuit and a signal control circuit, the signal generation circuit is connected to the signal control circuit, the signal measurement unit includes a signal measurement circuit, and the display unit includes a display circuit; the signal measurement circuit includes a measurement resistor and an operational amplifier, and the measurement resistor is connected in series with the input end of the operational amplifier.

5. The single-core cable metal sheath connection core phase detection device according to claim 4 is characterized in that: The central processing unit circuit includes a single-chip microcomputer, and a crystal oscillator circuit, a reset circuit and a communication interface circuit connected thereto; the crystal oscillator circuit is used to provide a stable clock signal for the single-chip microcomputer to ensure the synchronous operation of various parts of the single-chip microcomputer; the reset circuit is used to return the single-chip microcomputer to its initial state when the system is abnormal or needs to be restarted; The communication interface circuit is used to allow the microcontroller to exchange data with other circuits to achieve communication between systems.

6. The single-core cable metal sheath connection core phase detection device according to claim 4 is characterized in that: The power supply circuit includes a switching circuit and a power conversion circuit. The switching circuit is connected to the power conversion circuit. The switching circuit is used to control the power on and off of the nuclear phase detection device. The power conversion circuit is used to convert the voltage provided in the switching circuit into a required value.

7. The single-core cable metal sheath connection core phase detection device according to claim 6 is characterized in that: The switch circuit includes a switch transistor, a MOS tube and a power supply battery. The collector of the switch transistor is connected to the gate of the MOS tube, the source of the MOS tube is connected to the power supply battery, the drain of the MOS tube outputs a first power supply voltage, and the switch transistor is used to control the conduction and shutdown of the MOS tube.

8. The single-core cable metal sheath connection core phase detection device according to claim 7 is characterized in that: The power conversion circuit includes a power conversion chip, the input end of the power conversion chip is connected to the drain of the MOS tube, the drain of the MOS tube provides a first power supply voltage, and the output end of the power conversion chip is used to output a second power supply voltage.

9. The single-core cable metal sheath connection core phase detection device according to claim 4 is characterized in that: The signal generating circuit comprises a driving chip, an optical coupler and a DC isolation power supply, wherein the driving chip is connected to the optical coupler; and the optical coupler is connected to the DC isolation power supply.

10. The single-core cable metal sheath connection core phase detection device according to claim 4, characterized in that: The signal measurement circuit includes a measuring resistor and an operational amplifier, wherein the measuring resistor is connected in series with an input terminal of the operational amplifier; The display circuit includes a communication chip and a screen. The communication chip is electrically connected to the screen and is used to transmit data.

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