A cable coupling interference effect test system and method

Abstract

The application discloses a cable coupling interference effect test system and method. The system comprises a simulation cable coupling effect test device; the simulation cable coupling effect test device comprises a simulation shielded cable, a receiver, a first cable interface box and a second cable interface box; the simulation cable coupling effect test device is laid within 10 cm of a field interference cable, and the coupling length is greater than 3 m; at least one of the first cable interface box and the second cable interface box adopts a coaxial cable test structure; the coaxial cable test structure is used for measuring the shield layer induced current and the core line coupling voltage of the simulation shielded cable; the receiver is connected with a core line coupling voltage interface and a current probe in a current test cabin to reflect the coupling interference effect level. The application can accurately obtain the shield layer induced current and the cable core line induced voltage generated in the field environment, thereby evaluating the electromagnetic coupling interference level of the field electromagnetic environment on the cable, and providing theoretical data support for field test electromagnetic compatibility.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic testing technology, specifically to a cable coupling interference effect testing system and method. Background Technology

[0002] The new power generation equipment currently in use has dense internal cables and numerous substation devices, and is a high-power generation system. Generally speaking, the electromagnetic environment is complex, which can easily lead to electromagnetic interference affecting sensitive equipment on site. In particular, the interference problem caused by high voltage and high current is particularly prominent when using all-electric mode. According to past engineering experience, the coupling mode of this type of interference is mainly cable near-field coupling. Due to the size, power, load and other factors of power generation and substation equipment, various related electromagnetic compatibility tests must be completed in the field. This typical cable near-field coupling interference is mainly concentrated in low-frequency electromagnetic interference. Based on the analysis of electromagnetic compatibility factors in the field test, starting from spatial near-field electromagnetic field induction and line-to-line coupling induction, there is currently no targeted solution for the problem of low-frequency electromagnetic interference in the field. It is urgent to research and design a cable coupling interference effect testing technology that meets the requirements of field test. Summary of the Invention

[0003] In view of this, the present invention provides a cable coupling interference effect testing system and method, which can accurately obtain the shielding layer induced current and cable core wire induced voltage generated in the external environment, thereby evaluating the electromagnetic coupling interference level formed by the external electromagnetic environment on the cable, and providing theoretical data support for electromagnetic compatibility testing in the external field.

[0004] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0005] A cable coupling interference effect testing system includes a simulated cable coupling effect testing device; the simulated cable coupling effect testing device includes a simulated shielded cable, a first cable interface box, a second cable interface box, and a receiver A;

[0006] The simulated cable coupling effect testing device is laid within 10cm of the field interference cable to simulate the actual situation; the effective coupling length between the simulated shielded cable and the field interference cable is greater than 3m to simulate the actual situation; the simulated shielded cable is selected as a cable of the same model or with the same structural characteristics as the cable under test.

[0007] At least one of the first cable interface box and the second cable interface box adopts a coaxial cable test structure; the coaxial cable test structure is used to measure the shielding layer induced current and core coupling voltage of the simulated shielded cable;

[0008] The receiver A is used to connect to the core wire coupling voltage interface led out from the voltage test chamber in the coaxial cable test structure, and to measure the current probe in the current test chamber connected to the coaxial cable to reflect the level of coupling interference effect.

[0009] Preferably, the system further includes an external cable coupling effect testing device;

[0010] The field cable coupling effect testing device includes a current probe and a receiver B. The receiver B is connected to the current probe via a measuring coaxial cable. The current probe is installed on the cable under test and fitted with a shielding sheath. The distance between the current probe and the device end on the cable under test is less than 1m. The shielding sheath uses a metallic shielding material with a shielding effectiveness of not less than 30dB within the set test frequency range, and its installation size is adapted to the current probe. The receiver B measures the induced current data of the shielding layer of the cable under test, and converts the obtained induced current data of the shielding layer through transfer impedance data to obtain the coupling voltage data of the cable core wire, reflecting the level of coupling interference effect.

[0011] Preferably, the system further includes a data recording device;

[0012] The data recording device receives data input from receivers A and B, and uses the shielding layer induced current data of the test cable obtained by the external field cable coupling effect testing device to form a first shielding layer induced current spectrum curve with frequency on the horizontal axis and current amplitude logarithm on the vertical axis; and uses the cable core coupling voltage data of the test cable obtained by the external field cable coupling effect testing device to form a first cable core coupling voltage spectrum curve with frequency on the horizontal axis and voltage amplitude logarithm on the vertical axis.

[0013] The shielding layer induced current data of the simulated shielded cable obtained by the simulated cable coupling effect testing device are plotted with frequency on the horizontal axis and current amplitude logarithm on the vertical axis to form a second shielding layer induced current spectrum curve; the core wire coupling voltage data of the simulated shielded cable obtained by the simulated cable coupling effect testing device are plotted with frequency on the horizontal axis and voltage amplitude logarithm on the vertical axis to form a second cable core wire coupling voltage spectrum curve.

[0014] The four obtained spectrum curves are plotted on a single graph, with the left vertical axis representing the logarithmic value of the current amplitude, the right vertical axis representing the logarithmic value of the voltage amplitude, and the horizontal axis representing the frequency, reflecting the level of coupling interference effect.

[0015] Preferably, the coaxial cable test structure consists of a current test chamber and a voltage test chamber;

[0016] The current test chamber has an external through-hole interface through which the simulated shielded cable and the measuring coaxial cable are threaded. Inside the chamber, the current probe connected to the measuring coaxial cable is connected to the simulated shielded cable to perform shielding layer induced current testing.

[0017] The voltage test chamber is equipped with an impedance matching circuit with continuously adjustable impedance. The simulated shielded cable is connected to the impedance matching circuit through a through-hole. The voltage test chamber has a core-wire coupling voltage interface exposed to the outside. The coaxial cable test structure is tested for shielding effectiveness under laboratory conditions. The shielding effectiveness of the current test chamber and the voltage test chamber is better than 30dB within the set test frequency range.

[0018] Preferably, the system further includes a test system verification device prior to the simulated cable coupling effect test device, the test system verification device further including a low-frequency verification structure and a medium-frequency verification structure;

[0019] The low-frequency verification structure includes a low-frequency signal generator, an amplifier, a standard resistor, a receiver C, an oscilloscope, and a current probe. The low-frequency signal generator is connected to the amplifier, and the amplifier output is connected to the standard resistor. The current probe is connected to a single wire in the resistor loop, and the current probe output is connected to the receiver C. The oscilloscope is connected in parallel across the standard resistor. The signal generator applies a verification signal in the low-frequency range, selecting one frequency point at regular frequency intervals. The oscilloscope measures the current level, and simultaneously confirms that the current waveform is a sine wave. The receiver's measurement value is confirmed to be within ±3dB of the oscilloscope's current measurement value.

[0020] The intermediate frequency (IF) verification structure includes a current probe, a receiver D, an RF signal generator, a center conductor, and a coaxial load. The current probe is connected to the center conductor, and its output is connected to the receiver D. One end of the center conductor is connected to the coaxial load, and the other end is connected to the RF signal generator. The RF signal generator applies a verification signal within the test frequency band, selecting a certain number of frequency points per octave within the IF band. The receiver D measures the current in the center conductor and confirms that the measured value is within ±3dB of the amplitude of the verification signal applied by the signal generator.

[0021] Preferably, the system further includes a cable coupling interference effect pre-testing device prior to the simulated cable coupling effect test device and a simulated cable transfer impedance test device prior to the field cable coupling effect test device;

[0022] The cable coupling interference effect pre-testing device includes receiver E, receiver F, signal generating structure, transmitting circuit, coupling circuit, third cable interface box, fourth cable interface box, current probe, and standard resistor. The transmitting circuit, coupling circuit, and third and fourth cable interface boxes are laid out according to the laying configuration of the simulated cable coupling effect test device. The two ends of the transmitting circuit are respectively connected to the standard resistor and the signal generating structure. The current probe connected to receiver E is connected to the transmitting circuit, and the current probe connected to receiver F is connected to the coupling circuit in the third or fourth cable interface box. The current probe connected to receiver E is equipped with the shielding sleeve. The signal generating structure applies a verification signal to the transmitting circuit within a set test frequency range. Test frequency points are selected at regular intervals in the low-frequency band, and multiple test frequency points are selected per octave in the mid-frequency band. The control signal is at a fixed amplitude to keep the current of the transmitting circuit constant at each frequency, confirming that the deviation between the measured values ​​of receiver E and receiver F is within ±3dB.

[0023] The simulated cable transfer impedance testing device performs transfer impedance testing on cables of the same type or with the same structural characteristics as the cable under test under laboratory conditions, obtains a transfer impedance curve within a set test frequency range, and uses this curve as the transfer impedance data.

[0024] This invention also includes a method for testing cable coupling interference effects, comprising simulating cable coupling effect testing, the specific steps of which include:

[0025] Step 101: Lay the cable according to the requirements of the simulated cable coupling effect test device; connect both ends of the simulated shielded cable to the first cable interface box and the second cable interface box respectively, adjust the matching resistors in the two cable interface boxes and ensure that they are properly grounded; at least one of the first cable interface box and the second cable interface box adopts the coaxial cable test structure; connect the current probe in the coaxial cable test structure and the receiver A by measuring the coaxial cable; connect the core wire coupling voltage interface of the coaxial cable test structure and the receiver A by measuring the coaxial cable; install the current probe in the current test chamber of the coaxial cable test structure and connect it to the simulated shielded cable;

[0026] Step 102: Power on and run the equipment at both ends of the interference cable in the field until it reaches normal working condition. In the test software, set the receiver according to the specified bandwidth and measurement time, and scan within the set test frequency range to perform shielding layer induced current and core wire coupling voltage tests respectively.

[0027] Preferably, this includes testing for coupling effects in outdoor cables, with specific steps including:

[0028] Step 201: Connect the current probe and receiver B via a measuring coaxial cable; connect the data recording device to receiver B; ensure that the devices at both ends of the test cable are powered off; install the current probe on the test cable and install the shielding sleeve.

[0029] Step 202: Power on and run all equipment except the devices at both ends of the cable under test until they reach normal operating status. Select and configure the current probe coefficient in the test software. Set receiver B according to the specified bandwidth and measurement time. Scan the shielding layer induced current data within the set test frequency range.

[0030] Step 203: The shield layer induced current data obtained from the external cable coupling effect test is plotted with frequency on the horizontal axis and current amplitude logarithm on the vertical axis to form a first shield layer induced current spectrum curve; The shield layer induced current data obtained from the external cable coupling effect test is converted through transfer impedance data to obtain cable core coupling voltage data, and the first cable core coupling voltage spectrum curve is plotted with frequency on the horizontal axis and voltage amplitude logarithm on the vertical axis.

[0031] Step 204: Plot the shielding layer induced current data obtained from the simulated cable coupling effect test on the horizontal axis as frequency and the vertical axis as the logarithm of the current amplitude to form a second shielding layer induced current spectrum curve; plot the core wire coupling voltage data obtained from the simulated cable coupling effect test on the horizontal axis as frequency and the vertical axis as the logarithm of the voltage amplitude to form a second cable core wire coupling voltage spectrum curve.

[0032] Step 205: Reflect the four obtained spectrum curves onto a graph, where the left vertical axis represents the logarithmic value of the current amplitude, the right vertical axis represents the logarithmic value of the voltage amplitude, and the horizontal axis represents the frequency.

[0033] Preferably, prior to step 101, pre-testing for cable coupling interference effects and verification of the test system are included:

[0034] The cable coupling interference effect pre-test includes:

[0035] Step 301: Lay the transmitting circuit, coupling circuit, and third and fourth cable interface boxes according to the laying conditions of the simulated cable coupling effect test device; connect a standard resistor and a signal generating structure to both ends of the transmitting circuit respectively; connect the current probe connected to receiver E to the transmitting circuit, and connect the current probe connected to receiver F to the coupling circuit in the third or fourth cable interface box, wherein the current probe connected to receiver E should be equipped with a shielding sleeve;

[0036] Step 302: The signal generation structure applies a verification signal to the transmitting circuit within the set test frequency range. Test frequency points are selected at regular intervals in the low frequency band, and a certain number of test frequency points are selected per octave in the mid frequency band. The control signal is at a fixed amplitude to keep the current of the transmitting circuit constant at each frequency, and the deviation between the measured values ​​of receiver E and receiver F is confirmed to be within ±3dB.

[0037] The test system verification specifically includes low-frequency band test system verification and mid-frequency band test system verification; verifying whether the measurement result error of the measurement receiver is within the acceptable range at each frequency point in the low-frequency and mid-frequency bands respectively.

[0038] Preferably, before step 201, a simulated cable transfer impedance test is included;

[0039] The simulated cable transfer impedance test specifically involves: for a cable of the same type or with similar structural characteristics as the simulated cable under test, a transfer impedance test is conducted under laboratory conditions according to the method specified in the national standard, and a transfer impedance curve is obtained within the set test frequency range, which is then used as the transfer impedance data.

[0040] Beneficial effects:

[0041] 1. This invention can accurately obtain the induced current in the cable shield and the coupling voltage of the core wire generated in an outdoor environment, thereby assessing the level of electromagnetic coupling interference caused by the outdoor electromagnetic environment on the cable, and providing theoretical data support for electromagnetic compatibility testing in the field. This method can be used for testing without affecting the cable condition, cable laying and installation, etc., with high testing efficiency, easy implementation, good practicality, and is also applicable to cable coupling interference effect testing on other platforms. It is platform-independent and has wide applicability.

[0042] 2. By setting up an external cable coupling effect testing device and a data recording device, this invention can more accurately obtain the shielding layer induced current and core wire coupling voltage of the cable generated in the external environment, thereby evaluating the level of electromagnetic coupling interference formed by the external electromagnetic environment on the cable.

[0043] 3. This invention uses data processing to make the test results intuitive and clear in a single chart.

[0044] 4. This invention, through the design of the coaxial cable test structure, makes the testing of induced current in the cable shield and coupling voltage of the core wire more accurate; the shielding effectiveness of the coaxial cable test structure and each test chamber is ≥30dB, which reduces test errors by shielding against the influence of external electromagnetic fields.

[0045] 5. This invention, through the design of a test system calibration device and its low-frequency and medium-frequency calibration structures, simply achieves the calibration of the instruments required by the system, providing further assurance for the system's accuracy and error elimination.

[0046] 6. This invention enables the accuracy of cable coupling interference effect testing to reach ±3dB through pre-testing, and the shielding effectiveness of the current probe shielding sheath is ≥30dB. By shielding the influence of external electromagnetic fields, the test results are more accurate.

[0047] 7. By optimizing the laying requirements and probe positions, this invention not only improves the accuracy and feasibility of the test, but also allows the entire test to better simulate the actual layout, making the test results more meaningful. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the verification principle of the 1kHz to 10kHz test system in this invention;

[0049] Figure 2 This is a schematic diagram of the verification principle of the 10kHz-10MHz test system in this invention;

[0050] Figure 3 This is a schematic diagram of the cable coupling effect interface box in this invention;

[0051] Figure 4 This is a schematic diagram of the pre-test principle for the 1kHz to 10kHz cable coupling interference effect in this invention;

[0052] Figure 5 This is a schematic diagram of the pre-test principle for the 10kHz-10MHz cable coupling interference effect in this invention;

[0053] Figure 6 This is a schematic diagram of the external field cable coupling effect test principle in this invention;

[0054] Figure 7 This is a schematic diagram of the test principle for simulating cable coupling effect in this invention. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] This invention provides a cable coupling interference effect testing system and method, the core idea of ​​which is:

[0057] The system includes a simulated cable coupling effect testing device; this device includes a simulated shielded cable, a first cable interface box, a second cable interface box, and receiver A; the simulated cable coupling effect testing device is laid within 10cm of the field interference cable, simulating the actual situation; the effective coupling length between the simulated shielded cable and the field interference cable is greater than 3m, simulating the actual situation; the simulated shielded cable is selected as a cable of the same type or with the same structural characteristics as the cable under test; at least one of the first and second cable interface boxes adopts a coaxial cable testing structure; the coaxial cable testing structure is used to measure the shielding layer induced current and core wire coupling voltage of the simulated shielded cable; receiver A is used to connect to the core wire coupling voltage interface led out from the voltage test chamber in the coaxial cable testing structure, and to reflect the level of coupling interference effect by measuring the current probe in the coaxial cable connection current test chamber.

[0058] As can be seen, this invention can accurately obtain the induced current in the cable shield and the coupling voltage of the core wire generated in an outdoor environment, thereby assessing the level of electromagnetic coupling interference caused by the outdoor electromagnetic environment on the cable, and providing theoretical data support for electromagnetic compatibility testing in the field. This method can be used for testing without affecting the cable condition, cable laying, installation, and layout on site. It has high testing efficiency, is easy to implement, and has good practicality. It is also applicable to cable coupling interference effect testing on other platforms, is platform-independent, and has wide applicability.

[0059] This invention mainly includes three parts: preparation, testing, and data processing. The following is a detailed description of the invention using an embodiment.

[0060] The preparatory work required before testing mainly includes: calibration of measuring instruments, transfer impedance testing of simulated cables, trial fabrication of coaxial cable test structures, and pre-testing of current probe shielding and cable coupling interference effects. Specifically:

[0061] I. Measurement instrument calibration is divided into 1kHz~10kHz calibration and 10kHz~10MHz calibration according to frequency band. The specific steps for 1kHz~10kHz calibration are as follows:

[0062] 1. According to Figure 1 The connection of the low-frequency verification structure of the test system verification device is specifically as follows:

[0063] 1.1 Connect the output of the low-frequency signal generator and amplifier to a standard resistive load;

[0064] 1.2 Connect the current probe to the single line of the resistive load circuit, connect the probe output to the measuring receiver, and connect the oscilloscope to both ends of the resistor.

[0065] 2. Apply a verification signal using a signal generator in the range of 1kHz to 10kHz, and select one frequency point every 1kHz in the range of 1kHz to 10kHz;

[0066] 3. Use an oscilloscope and resistor to measure the current level, and at the same time check whether the current waveform is a sine wave;

[0067] 4. The receiver is scanned in normal data scanning mode to confirm that the measured value is within ±3dB of the oscilloscope current measurement value;

[0068] 5. If the measured value deviation exceeds ±3dB, the cause of the error should be identified and corrected before testing.

[0069] The specific steps for verification in the 10kHz to 10MHz range are as follows:

[0070] 1. According to Figure 2 The connection of the intermediate frequency verification structure of the test system verification device is as follows:

[0071] 1.1. Attach the current probe to the center conductor of the calibration device, connect one end of the measuring coaxial cable to the current probe, and the other end to the measuring receiver;

[0072] 1.2 One end of the calibration device is connected to a 50Ω coaxial load, and the other end is connected to an RF signal generator;

[0073] 2. Power on the testing instruments and equipment, preheat them, and allow them to reach a stable operating state;

[0074] 3. Apply a verification signal using a signal generator within the test frequency band, selecting at least 5 frequency points per octave in the range of 10kHz to 10MHz;

[0075] 4. Use a measuring receiver to measure the current level of the center conductor of the calibration device. The measuring receiver should scan in the normal data scanning mode to confirm that the measured value is within ±3dB of the calibration signal amplitude applied by the signal generator.

[0076] 5. If the measured value deviation exceeds ±3dB, the cause of the error should be identified and corrected before testing.

[0077] By designing the test system calibration device and its low-frequency and medium-frequency calibration structures, the calibration of the instruments required by the system is realized in a simple way, providing further assurance for the system's accuracy and error elimination.

[0078] II. Transfer Impedance Test of Simulated Cables

[0079] For cables of the same type or with similar structural characteristics as the cables in the simulated system, a third-party testing organization shall conduct transfer impedance tests under laboratory conditions in accordance with the methods specified in national standards to obtain transfer impedance curves in the frequency band of 1kHz to 10MHz, which shall be used as test preparation data.

[0080] III. Prototype of Coaxial Cable Test Structure for Cable Interface Box

[0081] Based on the characteristics and interface type of the cable under test, a coaxial cable test structure was designed and prototyped as follows: Figure 3 As shown, the coaxial cable test structure mainly consists of a shielded layer induced current test chamber and a core-coupled voltage test chamber. The shielded layer induced current test chamber can realistically simulate the interface of the cable under test, with an external through-hole interface allowing the simulated cable to be directly inserted. Inside the chamber, a current probe can be connected to the cable for induced current testing. The core-coupled voltage test chamber has a core-coupled voltage test port and an impedance matching circuit with continuously adjustable impedance. The cable can be connected to the impedance matching circuit of the core-coupled voltage test chamber through the through-hole interface. This can simulate the impedance characteristics of the source and load ends as closely as possible, or simulate harsh environments by using a high-impedance mode for the voltage signal and a low-impedance mode for the current signal.

[0082] To eliminate the influence of interface box coupling interference during cable coupling interference effect testing and reduce the influence of spatial magnetic field factors measured by the current probe, shielding effectiveness testing should be conducted under laboratory conditions according to the methods specified in national standards to obtain shielding effectiveness in the 1kHz to 10MHz frequency band, confirming that the shielding effectiveness is better than 30dB.

[0083] By prototyping the coaxial cable test structure and its design, the testing of induced current in the cable shield and coupling voltage in the core wire has become more accurate. The shielding effectiveness of the coaxial cable test structure and its test chambers is ≥30dB, which reduces test errors by shielding against the influence of external electromagnetic fields.

[0084] IV. Current Probe Shielding Sheath

[0085] To reduce the influence of spatial magnetic fields on the current probe during cable coupling interference testing, a shielding sleeve for the current probe should be prepared before the test. The shielding sleeve should be made of metallic shielding material with a shielding effectiveness of not less than 30dB in the 1kHz to 10MHz frequency band, and its installation dimensions should be compatible with the current probe being tested. The shielding sleeve of the current probe makes the test results more accurate by shielding it from the influence of external electromagnetic fields.

[0086] V. Preliminary Test of Cable Coupling Interference Effect

[0087] To ensure the accuracy of on-site testing, a cable coupling interference effect pre-testing device can be set up on a fixed test stand for cable coupling interference in the laboratory for pre-testing. The pre-testing is conducted according to the test methods and configurations for sensitivity items such as CS101 and CS114 in GJB151B-2013, performing cable coupling interference effect tests under standard interference injection. The test principle diagram is shown below. Figure 4 , Figure 5 As shown, the specific steps are as follows:

[0088] 1. Assemble the cable coupling interference effect pre-testing device, and perform pre-testing from 1kHz to 10kHz according to... Figure 4 Connect the test instruments and meters, and perform a pre-test in the 10kHz to 10MHz range. Figure 5 Establish a connection;

[0089] 2. Connect current probe A to the transmitting circuit, and connect current probe B to the cable interface box and the coupling circuit. Current probe A should be equipped with a current probe shielding sleeve.

[0090] 3. Apply a verification signal in the range of 1kHz to 10MHz using a signal generator. In the range of 1kHz to 10kHz, select one frequency point every 1kHz using a low-frequency signal generator. In the range of 10kHz to 10MHz, select at least five frequency points per octave using an RF generator.

[0091] 4. When the signal generator is set to a fixed amplitude, the current in the transmitting circuit should be kept constant as much as possible for each frequency generated. At the same time, the readings of the receivers connected to current probes A and B should be recorded.

[0092] 5. Under the condition of keeping the transmitting circuit current consistent, repeat the test three times or change to different instruments, including receivers or spectrum analyzers, and compare whether the reading deviation of the receiver at the same location and frequency point three times is within ±3dB.

[0093] 6. If the deviation of repeated measurements exceeds ±3dB, the cause of the error must be identified and corrected.

[0094] This invention improves the accuracy of cable coupling interference effect testing to within ±3dB through pre-testing, making the test results more precise.

[0095] The testing process in this application mainly includes field cable coupling effect testing and simulated cable coupling effect testing, specifically:

[0096] I. For outdoor cable coupling effect testing, first test the induced current in the shielding layer, then calculate the core coupling voltage using the transfer impedance. The test shall be conducted according to the following steps:

[0097] 1. Connect and assemble the field cable coupling effect testing device and the data recording device. Connect one end of the coaxial cable to the current probe and the other end to the measuring receiver; connect the data recording device to the measuring receiver, as shown in the specific connection diagram. Figure 6 As shown.

[0098] 2. The equipment at both ends of the cable under test is in the off state;

[0099] 3. Install a shielding sleeve on the current probe and connect it to the coupling cable under test. It is preferred to place it 5cm away from the connector of the device under test end of the cable under test. Alternatively, a distance of 10cm, 50cm, or 1m can be selected according to the site layout. The maximum distance must be ≤1m.

[0100] By optimizing and limiting the probe position, not only can the accuracy and feasibility of the test be improved, but the entire test can also better simulate the actual layout, making the test results more realistic.

[0101] 4. Power on and run all equipment except for the devices at both ends of the cable under test and ensure they are in normal working condition. Select and configure the current probe coefficient in the test software. Set the receiver according to the bandwidth and measurement time specified in GJB 151B-2013. Scan within the test frequency range of 1kHz to 10MHz. Save the shielding layer induced current spectrum data at this time, and record the data file number and the working status of other devices at this time.

[0102] II. Simulated Cable Coupling Effect Test: A simulated cable coupling measurement device, consisting of a simulated shielded cable and a cable interface box, is installed near the interfering cable in the field. The induced current in the shielding layer and the induced voltage in the core wire are obtained through direct testing. The test is conducted according to the following steps:

[0103] 1. For example Figure 7 As shown, the connection and assembly of the simulated cable coupling effect test device includes the following specific steps:

[0104] 1.1. Based on the source / load characteristics of the cable under test, adjust the matching resistance of the coaxial cable test structure and lay the simulated shielded cable within 10cm of the field interference source of interest, or simulate the distance of a real boat. The coupling length of the simulated cable under test should be at least 3m, simulating that of a real boat.

[0105] By optimizing and limiting the laying requirements, not only can the accuracy and feasibility of the test be improved, but the entire test can also better simulate the actual layout situation, making the test results more realistic.

[0106] 1.2 The two ends of the simulated shielded cable can both use coaxial cable test structures, or one end can use a coaxial cable test structure and the other end can be connected to an appropriate impedance. In this device, two cable interface boxes are usually selected: the first cable interface box and the second cable interface box, both of which are well grounded; the first cable interface box uses a coaxial cable test structure.

[0107] 1.3 Connect one end of the measuring coaxial cable to the current probe and the other end to the measuring receiver. Also connect the core wire coupling voltage interface on the coaxial cable test structure to the measuring receiver using the measuring coaxial cable.

[0108] 1.4 Connect the data recording device to the measurement receiver;

[0109] 2. Install the current probe inside the shielded induced current test chamber of the coaxial cable test structure and connect it to the simulated shielded cable;

[0110] 3. Power on and run the equipment at both ends of the interference cable and ensure it is in normal working condition. In the test software, set the receiver according to the bandwidth and measurement time specified in GJB 151B-2013, and scan within the test frequency range of 1kHz to 10MHz. Perform shielding layer induced current and core wire voltage tests respectively. Save the shielding layer induced current spectrum data and core wire voltage spectrum data at this time, and record the data file number and the working status of other equipment at this time.

[0111] This application requires data processing after testing, specifically including the following steps:

[0112] 1. Data processing for outdoor cable coupling effect test

[0113] 1.1 The shielding layer induced current data obtained from the test are plotted on the horizontal axis as frequency (Hz) and the vertical axis as amplitude (dBμA) in a logarithmic coordinate system to form a spectrum curve of the shielding layer induced current.

[0114] 1.2. Convert the transfer impedance data measured by the third-party testing agency to obtain the cable core coupling voltage data, and form a cable core coupling voltage spectrum curve by using a logarithmic coordinate system with frequency (Hz) on the horizontal axis and amplitude (dBμV) on the vertical axis.

[0115] 2. Data processing for simulated cable coupling effect test

[0116] 2.1 The shielding layer induced current data obtained from the test are plotted on the horizontal axis as frequency (Hz) and the vertical axis as amplitude (dBμA) in a logarithmic coordinate system to form a spectrum curve of the shielding layer induced current.

[0117] 2.2. The core coupling voltage data obtained from the test are plotted on a logarithmic coordinate system with frequency (Hz) on the horizontal axis and amplitude (dBμV) on the vertical axis to form a cable core voltage spectrum curve.

[0118] 3. Reflect the processed data from 1.2 and 2.2 onto a graph, where the left vertical axis represents the current amplitude, the right vertical axis represents the voltage amplitude, and the horizontal axis represents the frequency (Hz), using a logarithmic coordinate system.

[0119] This invention enables the testing of induced current in the shielding layer and induced voltage in the core wire. Data processing allows the test results to be presented intuitively and clearly in a single graph.

[0120] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cable coupling interference effect testing system, characterized in that, The device includes a simulated cable coupling effect testing apparatus; the simulated cable coupling effect testing apparatus includes a simulated shielded cable, a first cable interface box, a second cable interface box, and a receiver A; The simulated cable coupling effect testing device is laid within 10cm of the field interference cable to simulate the actual situation; the effective coupling length between the simulated shielded cable and the field interference cable is greater than 3m to simulate the actual situation; the simulated shielded cable is selected as a cable of the same model or with the same structural characteristics as the cable under test. At least one of the first cable interface box and the second cable interface box adopts a coaxial cable test structure; the coaxial cable test structure is used to measure the shielding layer induced current and core coupling voltage of the simulated shielded cable; The receiver A is used to connect to the core wire coupling voltage interface led out from the voltage test chamber in the coaxial cable test structure, and to reflect the level of coupling interference effect by measuring the current probe in the coaxial cable connection current test chamber. The system also includes an outdoor cable coupling effect testing device; The field cable coupling effect testing device includes a current probe and a receiver B; the receiver B is connected to the current probe via a measuring coaxial cable, the current probe is installed on the cable under test and is fitted with a shielding sheath; The current probe is installed on the cable under test at a distance of less than 1 m from the end of the equipment. The shielding sheath uses a metallic shielding material with a shielding effectiveness of not less than 30dB within the set test frequency range, and is installed with dimensions adapted to the current probe; the receiver B measures the shielding layer induced current data of the cable under test, and converts the obtained shielding layer induced current data through transfer impedance data to obtain the cable core coupling voltage data, reflecting the level of coupling interference effect; The coaxial cable test structure consists of a current test chamber and a voltage test chamber. The current test chamber has an external through-hole interface through which the simulated shielded cable and the measuring coaxial cable are threaded. Inside the chamber, the current probe connected to the measuring coaxial cable is connected to the simulated shielded cable to perform shielding layer induced current testing. The voltage test chamber is equipped with an impedance matching circuit with continuously adjustable impedance. The simulated shielded cable is connected to the impedance matching circuit through a through-hole. The voltage test chamber has a core-wire coupling voltage interface exposed to the outside. The coaxial cable test structure is tested for shielding effectiveness under laboratory conditions. The shielding effectiveness of the current test chamber and the voltage test chamber is better than 30dB within the set test frequency range.

2. The cable coupling interference effect testing system as described in claim 1, characterized in that, The system further includes a data recording device; The data recording device receives data input from receivers A and B, and uses the shielding layer induced current data of the test cable obtained by the external field cable coupling effect testing device to form a first shielding layer induced current spectrum curve with frequency on the horizontal axis and current amplitude logarithm on the vertical axis; and uses the cable core coupling voltage data of the test cable obtained by the external field cable coupling effect testing device to form a first cable core coupling voltage spectrum curve with frequency on the horizontal axis and voltage amplitude logarithm on the vertical axis. The shielding layer induced current data of the simulated shielded cable obtained by the simulated cable coupling effect testing device are plotted with frequency on the horizontal axis and current amplitude logarithm on the vertical axis to form a second shielding layer induced current spectrum curve; the core wire coupling voltage data of the simulated shielded cable obtained by the simulated cable coupling effect testing device are plotted with frequency on the horizontal axis and voltage amplitude logarithm on the vertical axis to form a second cable core wire coupling voltage spectrum curve. The four obtained spectrum curves are plotted on a single graph, with the left vertical axis representing the logarithmic value of the current amplitude, the right vertical axis representing the logarithmic value of the voltage amplitude, and the horizontal axis representing the frequency, reflecting the level of coupling interference effect.

3. The cable coupling interference effect testing system as described in claim 1, characterized in that, The system further includes a test system verification device prior to the simulated cable coupling effect test device, the test system verification device further including a low-frequency verification structure and a medium-frequency verification structure; The low-frequency verification structure includes a low-frequency signal generator, an amplifier, a standard resistor, a receiver C, an oscilloscope, and a current probe. The low-frequency signal generator is connected to the amplifier, and the amplifier output is connected to the standard resistor. The current probe is connected to a single wire in the resistor loop, and the current probe output is connected to the receiver C. The oscilloscope is connected in parallel across the standard resistor. The signal generator applies a verification signal in the low-frequency range, selecting one frequency point at each set frequency interval. The oscilloscope measures the current level, and simultaneously confirms that the current waveform is a sine wave. The receiver's measurement value is confirmed to be within ±3dB of the oscilloscope's current measurement value. The intermediate frequency (IF) verification structure includes a current probe, a receiver D, an RF signal generator, a center conductor, and a coaxial load. The current probe is connected to the center conductor, and its output is connected to the receiver D. One end of the center conductor is connected to the coaxial load, and the other end is connected to the RF signal generator. The RF signal generator applies a verification signal within the test frequency band, selecting a set number of frequency points per octave within the IF band. The receiver D measures the current in the center conductor and confirms that the measured value is within ±3dB of the amplitude of the verification signal applied by the signal generator.

4. The cable coupling interference effect testing system as described in claim 1, characterized in that, The system further includes a cable coupling interference effect pre-testing device prior to the simulated cable coupling effect test device and a simulated cable transfer impedance test device prior to the field cable coupling effect test device; The cable coupling interference effect pre-testing device includes receiver E, receiver F, signal generating structure, transmitting circuit, coupling circuit, third cable interface box, fourth cable interface box, current probe, and standard resistor. The transmitting circuit, coupling circuit, and third and fourth cable interface boxes are laid out according to the laying configuration of the simulated cable coupling effect test device. The two ends of the transmitting circuit are respectively connected to the standard resistor and the signal generating structure. The current probe connected to receiver E is connected to the transmitting circuit, and the current probe connected to receiver F is connected to the coupling circuit in the third or fourth cable interface box. The current probe connected to receiver E is equipped with the shielding sleeve. The signal generating structure applies a verification signal to the transmitting circuit within a set test frequency range. Test frequency points are selected at regular intervals in the low-frequency band, and multiple test frequency points are selected per octave in the mid-frequency band. The control signal is at a fixed amplitude to keep the current of the transmitting circuit constant at each frequency, confirming that the deviation between the measured values ​​of receiver E and receiver F is within ±3dB. The simulated cable transfer impedance testing device performs transfer impedance testing on cables of the same type or with the same structural characteristics as the cable under test under laboratory conditions, obtains a transfer impedance curve within a set test frequency range, and uses this curve as the transfer impedance data.

5. A method for testing cable coupling interference effects based on any one of the test systems in claims 1-4, characterized in that, This includes simulating cable coupling effect testing, with specific steps including: Step 101: Lay the cable according to the requirements of the simulated cable coupling effect test device; connect both ends of the simulated shielded cable to the first cable interface box and the second cable interface box respectively, adjust the matching resistors in the two cable interface boxes and ensure that they are properly grounded; at least one of the first cable interface box and the second cable interface box adopts the coaxial cable test structure; connect the current probe in the coaxial cable test structure and the receiver A by measuring the coaxial cable; connect the core wire coupling voltage interface of the coaxial cable test structure and the receiver A by measuring the coaxial cable; install the current probe in the current test chamber of the coaxial cable test structure and connect it to the simulated shielded cable; Step 102: Power on and run the equipment at both ends of the interference cable in the field until it reaches normal working condition. In the test software, set the receiver according to the specified bandwidth and measurement time, and scan within the set test frequency range to perform shielding layer induced current and core wire coupling voltage tests respectively.

6. The cable coupling interference effect test method as described in claim 5, characterized in that, This includes testing for the coupling effect of outdoor cables, with specific steps including: Step 201: Connect the current probe and receiver B via a measuring coaxial cable; connect the data recording device to receiver B; ensure that the devices at both ends of the test cable are powered off; install the current probe on the test cable and install the shielding sleeve. Step 202: Power on and run all equipment except the devices at both ends of the cable under test until they reach normal operating status. Select and configure the current probe coefficient in the test software. Set receiver B according to the specified bandwidth and measurement time. Scan the shielding layer induced current data within the set test frequency range. Step 203: The shield layer induced current data obtained from the external cable coupling effect test is plotted with frequency on the horizontal axis and current amplitude logarithm on the vertical axis to form a first shield layer induced current spectrum curve; The shield layer induced current data obtained from the external cable coupling effect test is converted through transfer impedance data to obtain cable core coupling voltage data, and the first cable core coupling voltage spectrum curve is plotted with frequency on the horizontal axis and voltage amplitude logarithm on the vertical axis. Step 204: Plot the shielding layer induced current data obtained from the simulated cable coupling effect test on the horizontal axis as frequency and the vertical axis as the logarithm of the current amplitude to form a second shielding layer induced current spectrum curve; plot the core wire coupling voltage data obtained from the simulated cable coupling effect test on the horizontal axis as frequency and the vertical axis as the logarithm of the voltage amplitude to form a second cable core wire coupling voltage spectrum curve. Step 205: Reflect the four obtained spectrum curves onto a graph, where the left vertical axis represents the logarithmic value of the current amplitude, the right vertical axis represents the logarithmic value of the voltage amplitude, and the horizontal axis represents the frequency.

7. The cable coupling interference effect test method as described in claim 5 or 6, characterized in that, Prior to step 101, the following steps are included: Pre-testing of cable coupling interference effects and verification of the test system: The cable coupling interference effect pre-test includes: Step 301: Lay the transmitting circuit, coupling circuit, and third and fourth cable interface boxes according to the laying conditions of the simulated cable coupling effect test device; connect a standard resistor and a signal generating structure to both ends of the transmitting circuit respectively; connect the current probe connected to receiver E to the transmitting circuit, and connect the current probe connected to receiver F to the coupling circuit in the third or fourth cable interface box, wherein the current probe connected to receiver E should be equipped with a shielding sleeve; Step 302: The signal generation structure applies a verification signal to the transmitting circuit within the set test frequency range. In the low frequency band, test frequency points are selected every set frequency. In the mid frequency band, a set number of test frequency points are selected per octave. The control signal is at a fixed amplitude to keep the current of the transmitting circuit constant at each frequency. It is confirmed that the deviation between the measured values ​​of receiver E and receiver F is within ±3dB. The test system verification specifically includes low-frequency band test system verification and mid-frequency band test system verification; verifying whether the measurement result error of the measurement receiver is within the acceptable range at each frequency point in the low-frequency and mid-frequency bands respectively.

8. The cable coupling interference effect test method as described in claim 6, characterized in that, Prior to step 201, a simulated cable transfer impedance test is performed; The simulated cable transfer impedance test specifically involves: for a cable of the same type or with similar structural characteristics as the simulated cable under test, a transfer impedance test is conducted under laboratory conditions according to the method specified in the national standard, and a transfer impedance curve is obtained within the set test frequency range, which is then used as the transfer impedance data.

Images