Method and system for testing resistivity of shield in cable

Abstract

The invention relates to the technical field of material detection, and provides a cable inner shield resistivity test method and system. The method comprises the following steps: generating initial diagnosis signal data based on power transmission signal data of a cable, and injecting an initial diagnosis signal into the cable at a sending end of the cable based on the initial diagnosis signal data; after the initial diagnosis signal is injected into the cable, multiple pieces of composite signal data within a preset time period are obtained at the receiving end of the cable; for each sampling moment, determining target diagnosis signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining internal shielding resistivity corresponding to the sampling moment based on the initial diagnosis signal data and the target diagnosis signal data; and determining whether the inner shield of the cable is in a healthy state based on each inner shield resistivity. According to the method, real-time testing of the internal shielding resistivity in the cable operation process is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of material detection, and in particular to a method and system for testing the resistivity of inner shielding of a cable. Background Art

[0002] The inner shielding layer of the cable is usually made of metal materials, and its main function is to shield electromagnetic interference and stabilize the electrical performance of the cable. However, the inner shielding layer may experience oxidation, corrosion, mechanical damage and other problems during long-term use, causing its resistivity to change. If the resistivity of the inner shielding layer is too low, it will easily cause a lot of heat to be generated, accelerating the aging of the cable. If the resistivity of the inner shielding layer is too high, the shielding effect will be reduced, which will in turn cause increased electromagnetic interference, affect the transmission quality of the cable signal, and may even cause safety accidents. Therefore, testing the resistivity of the inner shielding layer is the key to ensuring the normal operation of the cable. However, the existing cable inner shielding test method cannot realize the test of the inner shielding resistivity during the operation of the cable. Summary of the invention

[0003] The present application provides a cable inner shield resistivity testing method and system to solve the problems raised by the above background technology.

[0004] In a first aspect, the present application provides a method for testing the inner shield resistivity of a cable, comprising: Acquiring power transmission signal data of the cable, generating initial diagnostic signal data based on the power transmission signal data, and injecting an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data; After injecting an initial diagnostic signal into the cable, acquiring a plurality of composite signal data within a preset time period at a preset sampling frequency at a receiving end of the cable; For each sampling moment, determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data; Whether the inner shield of the cable is in a healthy state is determined based on the resistivity of each inner shield.

[0005] In a possible implementation, determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment includes: Inputting the composite signal data into a preset fast Fourier transform algorithm to obtain spectrum data; constructing a bandpass filter having a center frequency equal to the frequency of the initial diagnostic signal; Performing filtering processing on the spectrum data based on the bandpass filter to obtain a target spectrum; The target frequency spectrum is processed by inverse fast Fourier transform to obtain the target diagnostic signal data.

[0006] In a possible implementation, determining the inner shield resistivity corresponding to the sampling time based on the initial diagnostic signal data and the target diagnostic signal data includes: Generate signal characteristic information based on the initial diagnostic signal data and the target diagnostic signal data; wherein the signal characteristic information includes an amplitude attenuation coefficient and a phase change coefficient; Acquire the total resistance of the cable based on the signal characteristic information; The inner shield resistivity is obtained based on the total resistance of the cable.

[0007] In a possible implementation manner, the generating signal characteristic information based on the initial diagnostic signal data and the target diagnostic signal data includes: Acquire a first amplitude and a first phase based on the initial diagnostic signal data, and acquire a second amplitude and a second phase based on the target diagnostic signal data; The amplitude attenuation coefficient is obtained by formula (1); wherein, is the amplitude attenuation coefficient, is the second amplitude, is the first amplitude, L is the length between the transmitting end and the receiving end of the cable; (1); The phase change coefficient is obtained by formula (2); wherein, is the phase variation coefficient, is the second phase, is the first phase; (2).

[0008] In a possible implementation manner, the acquiring the total cable resistance based on the signal characteristic information includes: The propagation coefficient of the cable is obtained by formula (3); wherein, is the propagation coefficient, j represents the imaginary unit; (3); Acquire electrical parameter information of the cable; wherein the electrical parameter information includes the inductance and capacitance of the cable; The total resistance of the cable is obtained by formula (4); wherein, is the total resistance of the cable, is the frequency of the initial diagnostic signal, is the inductance, is the capacitor; (4).

[0009] In a possible implementation manner, acquiring the inner shield resistivity based on the total resistance of the cable includes: The inner shielding resistance is obtained by subtracting the conductor resistance of the cable from the total resistance of the cable; The inner shield resistivity is obtained by formula (5); wherein, is the inner shield resistivity, is the inner shield resistance, is the outer radius of the inner shielding layer of the cable, is the inner radius of the inner shielding layer of the cable; (5).

[0010] In a possible implementation, judging whether the inner shield of the cable is in a healthy state based on the resistivity of each inner shield includes: Determining whether each of the inner shielding resistivities is within a preset inner shielding resistivity threshold range; If any of the inner shield resistivity is not within the inner shield resistivity threshold range, it is determined that the inner shield of the cable is in an unhealthy state; If the inner shielding resistivities of each of the inner shielding resistivities are within the inner shielding resistivity threshold range, obtaining the standard deviation between the inner shielding resistivities of each of the inner shielding resistivities; comparing the standard deviation with a preset standard deviation threshold; If the standard deviation is greater than the standard deviation threshold, it is determined that the inner shield of the cable is in an unhealthy state; If the standard deviation is not greater than the standard deviation threshold, it is determined that the inner shielding of the cable is in a healthy state.

[0011] In a second aspect, the present application provides a cable inner shield resistivity testing system, comprising: A first acquisition module, configured to acquire power transmission signal data of a cable, generate initial diagnostic signal data based on the power transmission signal data, and inject an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data; A second acquisition module, configured to acquire a plurality of composite signal data within a preset time period at a preset sampling frequency at a receiving end of the cable after injecting an initial diagnostic signal into the cable; A determination module, for determining, for each sampling moment, target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data; A judging module is used to judge whether the inner shield of the cable is in a healthy state based on the resistivity of each inner shield.

[0012] The present application provides a method and system for testing the resistivity of the inner shield of a cable, the method comprising: obtaining the power transmission signal data of the cable, generating initial diagnostic signal data based on the power transmission signal data, and injecting the initial diagnostic signal into the cable at the transmitting end of the cable based on the initial diagnostic signal data; after injecting the initial diagnostic signal into the cable, obtaining multiple composite signal data within a preset time period at the receiving end of the cable at a preset sampling frequency; for each sampling moment, determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining the inner shield resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data; judging whether the inner shield of the cable is in a healthy state based on each inner shield resistivity. The method realizes real-time, non-invasive testing of the inner shield resistivity during the operation of the cable, avoids the inconvenience caused by power outages, disassembly or sampling detection in traditional methods, helps to timely warn and handle abnormal conditions of the inner shielding layer, prevent potential safety hazards, and ensure the safe operation of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0014] Figure 1 A schematic diagram of a process for testing the inner shield resistivity of a cable provided in an embodiment of the present application; Figure 2 A schematic block diagram of the structure of a cable inner shield resistivity testing system provided in an embodiment of the present application; Figure 3 A schematic block diagram of the structure of a terminal device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments 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.

[0016] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may also be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0017] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0018] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0019] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] See also Figure 1 , Figure 1 A schematic diagram of a method for testing the inner shield resistivity of a cable provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the cable inner shield resistivity testing method provided in the embodiment of the present application includes steps S1 to S4.

[0021] Step S1, acquiring power transmission signal data of a cable, generating initial diagnostic signal data based on the power transmission signal data, and injecting an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data.

[0022] Specifically, the power transmission signal data includes the frequency and amplitude of the power transmission signal, and the initial diagnostic signal data includes the frequency and amplitude of the initial diagnostic signal. The frequency of the initial diagnostic signal is much greater than the frequency of the power transmission signal, and the amplitude of the initial diagnostic signal is much smaller than the amplitude of the power transmission signal. Based on the initial diagnostic signal data, the diagnostic signal source at the transmitting end of the cable is controlled to generate the initial diagnostic signal, and the initial diagnostic signal is injected into the transmitting end of the cable through a coupler between the diagnostic signal source and the cable.

[0023] Step S2: After injecting an initial diagnostic signal into the cable, a plurality of composite signal data within a preset time period is acquired at a preset sampling frequency at a receiving end of the cable.

[0024] Specifically, after the initial diagnostic signal is injected into the cable, a plurality of composite signal data within a preset time period is acquired at a preset sampling frequency through a sensor at the receiving end of the cable. It can be understood that one sampling moment corresponds to one composite signal data.

[0025] Step S3: for each sampling moment, determine the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determine the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data.

[0026] Specifically, the determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment comprises the following steps: Inputting the composite signal data into a preset fast Fourier transform algorithm to obtain spectrum data; constructing a bandpass filter having a center frequency equal to the frequency of the initial diagnostic signal; Performing filtering processing on the spectrum data based on the bandpass filter to obtain a target spectrum; The target frequency spectrum is processed by inverse fast Fourier transform to obtain the target diagnostic signal data.

[0027] The method of determining the inner shield resistivity corresponding to the sampling time based on the initial diagnostic signal data and the target diagnostic signal data comprises the following steps: Generate signal characteristic information based on the initial diagnostic signal data and the target diagnostic signal data; wherein the signal characteristic information includes an amplitude attenuation coefficient and a phase change coefficient; Acquire the total resistance of the cable based on the signal characteristic information; The inner shield resistivity is obtained based on the total resistance of the cable.

[0028] The step of generating signal characteristic information based on the initial diagnostic signal data and the target diagnostic signal data comprises the following steps: A first amplitude and a first phase are obtained based on the initial diagnostic signal data, and a second amplitude and a second phase are obtained based on the target diagnostic signal data; specifically, a first amplitude is directly obtained from the initial diagnostic signal, and an initial diagnostic signal corresponding to the initial diagnostic signal data is compared with a reference signal to obtain the first phase; a second amplitude is directly obtained from the target diagnostic signal, and a target diagnostic signal corresponding to the target diagnostic signal data is compared with the reference signal to obtain the second phase; The amplitude attenuation coefficient is obtained by formula (1); wherein, is the amplitude attenuation coefficient, is the second amplitude, is the first amplitude, L is the length between the transmitting end and the receiving end of the cable; (1); The phase change coefficient is obtained by formula (2); wherein, is the phase variation coefficient, is the second phase, is the first phase; (2).

[0029] Wherein, obtaining the total cable resistance based on the signal characteristic information comprises the following steps: The propagation coefficient of the cable is obtained by formula (3); wherein, is the propagation coefficient, j represents the imaginary unit; (3); Acquire electrical parameter information of the cable; wherein the electrical parameter information includes the inductance and capacitance of the cable; The total resistance of the cable is obtained by formula (4); wherein, is the total resistance of the cable, is the frequency of the initial diagnostic signal, is the inductance, is the capacitor; (4).

[0030] Wherein, obtaining the inner shield resistivity based on the total resistance of the cable comprises the following steps: The inner shielding resistance is obtained by subtracting the conductor resistance of the cable from the total resistance of the cable; wherein the conductor resistance refers to the resistance of the center conductor in the cable; The inner shield resistivity is obtained by formula (5); wherein, is the inner shield resistivity, is the inner shield resistance, is the outer radius of the inner shielding layer of the cable, is the inner radius of the inner shielding layer of the cable; (5) .

[0031] Step S4: judging whether the inner shield of the cable is in a healthy state based on the resistivity of each inner shield.

[0032] Specifically, step S4 includes the following steps: Determining whether each of the inner shielding resistivities is within a preset inner shielding resistivity threshold range; If any of the inner shield resistivity is not within the inner shield resistivity threshold range, it is determined that the inner shield of the cable is in an unhealthy state; If the inner shielding resistivities of each of the inner shielding resistivities are within the inner shielding resistivity threshold range, obtaining the standard deviation between the inner shielding resistivities of each of the inner shielding resistivities; comparing the standard deviation with a preset standard deviation threshold; If the standard deviation is greater than the standard deviation threshold, it is determined that the inner shield of the cable is in an unhealthy state; If the standard deviation is not greater than the standard deviation threshold, it is determined that the inner shielding of the cable is in a healthy state.

[0033] It can be understood that step S4 of this embodiment achieves accurate judgment on the health status of the inner shield of the cable by performing multi-level analysis on the resistivity of each inner shield, which helps to improve the safety and reliability of cable operation.

[0034] The method provided in this embodiment realizes real-time, non-invasive testing of the inner shield resistivity during cable operation, avoiding the inconvenience caused by power outages, disassembly or sampling inspection in traditional methods, and helps to timely warn and deal with abnormal conditions of the inner shielding layer, prevent potential safety hazards, and ensure the safe operation of the cable.

[0035] See also Figure 2 , Figure 2 The structure schematic block diagram of the cable inner shield resistivity testing system 100 provided in the embodiment of the present application is as follows: Figure 2 As shown, the cable inner shield resistivity testing system 100 provided in the embodiment of the present application includes: The first acquisition module 110 is used to acquire power transmission signal data of the cable, generate initial diagnostic signal data based on the power transmission signal data, and inject an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data.

[0036] The second acquisition module 120 is used to acquire a plurality of composite signal data within a preset time period at a preset sampling frequency at a receiving end of the cable after injecting an initial diagnostic signal into the cable.

[0037] The determination module 130 is used to determine, for each sampling moment, the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determine the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data.

[0038] The judging module 140 is configured to judge whether the inner shield of the cable is in a healthy state based on the resistivity of each inner shield.

[0039] It should be noted that technicians in the relevant technical field can clearly understand that for the convenience and simplicity of description, the specific working process of the system and each module described above can refer to the corresponding process in the aforementioned cable inner shield resistivity test method embodiment, and will not be repeated here.

[0040] The cable inner shield resistivity testing system 100 provided in the above embodiment can be implemented in the form of a computer program. The computer program can be used in Figure 3 The system is run on the terminal device 200 shown.

[0041] See also Figure 3 , Figure 3 The present invention provides a schematic block diagram of the structure of a terminal device 200 according to an embodiment of the present application. The terminal device 200 includes a processor 201 and a memory 202. The processor 201 and the memory 202 are connected via a device bus 203, wherein the memory 202 may include a non-volatile storage medium and an internal memory.

[0042] The non-volatile storage medium can store a computer program. The computer program includes program instructions, and when the program instructions are executed by the processor 201, the processor 201 can execute any of the above-mentioned cable inner shield resistivity testing methods.

[0043] The processor 201 is used to provide computing and control capabilities to support the operation of the entire terminal device 200.

[0044] The internal memory provides an environment for the operation of the computer program in the non-volatile storage medium. When the computer program is executed by the processor 201, the processor 201 can execute any of the above-mentioned cable inner shield resistivity testing methods.

[0045] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the terminal device 200 involved in the scheme of the present application. The specific terminal device 200 may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0046] It should be understood that the processor 201 may be a central processing unit (CPU), and the processor 201 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0047] In some embodiments, the processor 201 is used to run a computer program stored in the memory to implement the following steps: Acquiring power transmission signal data of the cable, generating initial diagnostic signal data based on the power transmission signal data, and injecting an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data; After injecting an initial diagnostic signal into the cable, acquiring a plurality of composite signal data within a preset time period at a preset sampling frequency at a receiving end of the cable; For each sampling moment, determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data; Whether the inner shield of the cable is in a healthy state is determined based on the resistivity of each inner shield.

[0048] It should be noted that technicians in the relevant field can clearly understand that for the convenience and simplicity of description, the specific working process of the terminal device 200 described above can refer to the corresponding process of the aforementioned cable inner shield resistivity test method, and will not be repeated here.

[0049] An embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by one or more processors, the one or more processors implement the cable inner shield resistivity testing method provided in the embodiment of the present application.

[0050] The computer-readable storage medium may be an internal storage unit of the terminal device 200 in the aforementioned embodiment, such as a hard disk or memory of the terminal device 200. The computer-readable storage medium may also be an external storage system of the terminal device 200, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped with the terminal device 200.

[0051] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for testing the inner shield resistivity of a cable, characterized in that: include: Acquiring power transmission signal data of the cable, generating initial diagnostic signal data based on the power transmission signal data, and injecting an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data; After injecting an initial diagnostic signal into the cable, acquiring a plurality of composite signal data within a preset time period at a preset sampling frequency at a receiving end of the cable; For each sampling moment, determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data; Whether the inner shield of the cable is in a healthy state is determined based on the resistivity of each inner shield.

2. The cable inner shield resistivity testing method according to claim 1, characterized in that: The determining the target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment comprises: Inputting the composite signal data into a preset fast Fourier transform algorithm to obtain spectrum data; constructing a bandpass filter having a center frequency equal to the frequency of the initial diagnostic signal; Performing filtering processing on the spectrum data based on the bandpass filter to obtain a target spectrum; The target frequency spectrum is processed by inverse fast Fourier transform to obtain the target diagnostic signal data.

3. The cable inner shield resistivity testing method according to claim 1, characterized in that: The determining the inner shield resistivity corresponding to the sampling time based on the initial diagnostic signal data and the target diagnostic signal data comprises: Generate signal characteristic information based on the initial diagnostic signal data and the target diagnostic signal data; wherein the signal characteristic information includes an amplitude attenuation coefficient and a phase change coefficient; Acquire the total resistance of the cable based on the signal characteristic information; The inner shield resistivity is obtained based on the total resistance of the cable.

4. The cable inner shield resistivity testing method according to claim 3, characterized in that: The generating signal characteristic information based on the initial diagnostic signal data and the target diagnostic signal data comprises: Acquire a first amplitude and a first phase based on the initial diagnostic signal data, and acquire a second amplitude and a second phase based on the target diagnostic signal data; The amplitude attenuation coefficient is obtained by formula (1); wherein, is the amplitude attenuation coefficient, is the second amplitude, is the first amplitude, L is the length between the transmitting end and the receiving end of the cable; （1）； The phase change coefficient is obtained by formula (2); wherein, is the phase variation coefficient, is the second phase, is the first phase; （2）。 5. The cable inner shield resistivity testing method according to claim 3, characterized in that: The acquiring the total cable resistance based on the signal characteristic information includes: The propagation coefficient of the cable is obtained by formula (3); wherein, is the propagation coefficient, j represents the imaginary unit; （3）； Acquire electrical parameter information of the cable; wherein the electrical parameter information includes the inductance and capacitance of the cable; The total resistance of the cable is obtained by formula (4); wherein, is the total resistance of the cable, is the frequency of the initial diagnostic signal, is the inductance, is the capacitor; （4）。 6. The cable inner shield resistivity testing method according to claim 3, characterized in that: The obtaining the inner shield resistivity based on the total resistance of the cable comprises: The inner shielding resistance is obtained by subtracting the conductor resistance of the cable from the total resistance of the cable; The inner shield resistivity is obtained by formula (5); wherein, is the inner shield resistivity, is the inner shield resistance, is the outer radius of the inner shielding layer of the cable, is the inner radius of the inner shielding layer of the cable; （5）。 7. The cable inner shield resistivity testing method according to claim 1, characterized in that: The step of judging whether the inner shield of the cable is in a healthy state based on the resistivity of each inner shield comprises: Determining whether each of the inner shielding resistivities is within a preset inner shielding resistivity threshold range; If any of the inner shield resistivity is not within the inner shield resistivity threshold range, it is determined that the inner shield of the cable is in an unhealthy state; If the inner shielding resistivities of each of the inner shielding resistivities are within the inner shielding resistivity threshold range, obtaining the standard deviation between the inner shielding resistivities of each of the inner shielding resistivities; comparing the standard deviation with a preset standard deviation threshold; If the standard deviation is greater than the standard deviation threshold, it is determined that the inner shield of the cable is in an unhealthy state; If the standard deviation is not greater than the standard deviation threshold, it is determined that the inner shielding of the cable is in a healthy state.

8. A cable inner shield resistivity testing system, characterized in that: include: A first acquisition module, configured to acquire power transmission signal data of a cable, generate initial diagnostic signal data based on the power transmission signal data, and inject an initial diagnostic signal into the cable at a transmitting end of the cable based on the initial diagnostic signal data; A second acquisition module, configured to acquire a plurality of composite signal data within a preset time period at a preset sampling frequency at a receiving end of the cable after injecting an initial diagnostic signal into the cable; A determination module, for determining, for each sampling moment, target diagnostic signal data corresponding to the sampling moment based on the composite signal data corresponding to the sampling moment, and determining the inner shielding resistivity corresponding to the sampling moment based on the initial diagnostic signal data and the target diagnostic signal data; A judging module is used to judge whether the inner shield of the cable is in a healthy state based on the resistivity of each inner shield.

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