A method and system for testing insulation performance of heating cable

Abstract

The present application relates to the technical field of electrical performance testing, and specifically to a method and system for testing the insulation performance of a heating cable. The method comprises: dividing the temperature rise stage according to the temperature change of the insulation layer between adjacent moments; obtaining the insulation coefficient according to the comparison of the insulation resistance values ​​at the beginning and end of each temperature rise stage; obtaining the insulation change parameter according to the insulation coefficient of the heating cable, the temperature rise rate change value at all moments, and the duration of the temperature rise stage; obtaining the current change degree value according to the numerical distribution of the characteristic current; obtaining the insulation performance attenuation parameter of the heating cable according to the duration of all temperature rise stages, the current change degree value, and the insulation change parameter; and obtaining the insulation performance test result of the heating cable according to the concentration degree of the numerical distribution of the insulation performance attenuation parameter of the heating cable under all insulation performance tests. The present application can improve the accuracy of the insulation performance test of the heating cable.

Description

Technical Field

[0001] The present application relates to the technical field of electrical performance testing, and in particular to a method and system for testing the insulation performance of a heating cable. Background Art

[0002] Heating cables are used to provide heat to surfaces such as pipes, containers, equipment, or building structures. They primarily use the heat generated by current passing through the cable to prevent icing and condensation on pipes and equipment, maintain stable temperatures, or heat objects that require a specific temperature. The insulation performance of these cables directly impacts the safety and stability of the system.

[0003] Traditional heating cable insulation performance tests are mainly conducted at room temperature. However, heating cables need to be in a high temperature environment for a long time during use. Testing the insulation performance of heating cables only at room temperature or a fixed temperature cannot represent the insulation performance status of heating cables under actual temperature changes, resulting in inaccurate insulation performance test results of heating cables. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a method and system for testing the insulation performance of heating cables. The technical solutions adopted are as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for testing the insulation performance of a heating cable, the method comprising the following steps:

[0006] S1, real-time acquisition of characteristic current, insulation layer temperature and insulation resistance value of the heating cable during each insulation performance test;

[0007] S2, obtaining the temperature rise rate change value at each moment according to the temperature change of the insulation layer between adjacent moments; dividing the temperature rise stage according to the numerical distribution of the temperature rise rate change values ​​at consecutive moments;

[0008] S3, based on the comparison of the insulation resistance values ​​at the beginning and end of each temperature rise stage, the insulation coefficient of the heating cable in each temperature rise stage is obtained; based on the insulation coefficient of the heating cable in each temperature rise stage, the temperature rise rate change value at all times and the duration of the temperature rise stage, the insulation change parameter of each temperature rise stage is obtained;

[0009] S4, according to the numerical distribution of the characteristic current in each temperature rise stage, the current variation value in each temperature rise stage is obtained; according to the time length of all temperature rise stages, the current variation value and the insulation variation parameter, the insulation performance attenuation parameter of the heating cable is obtained;

[0010] S5, obtaining insulation performance test results of the heating cable according to the concentration degree of the numerical distribution of the insulation performance attenuation parameters of the heating cable under all insulation performance tests.

[0011] Furthermore, obtaining the temperature rise rate change value at each moment according to the temperature change of the insulation layer between adjacent moments includes:

[0012] The temperature change rate at each moment is obtained based on the temperature difference of the insulation layer between adjacent moments; the difference in the temperature change rate at each moment and the next moment is used as the temperature rise rate change value at each moment.

[0013] Furthermore, the temperature change rate at each moment is obtained based on the temperature difference between adjacent moments, including: recording the temperature change rate at the i-th moment as v i , Where t is the time interval between adjacent moments; w i+1 、w i are the insulation layer temperatures at the i+1th and ith moments respectively.

[0014] Furthermore, the temperature rise stages are divided according to the numerical distribution of the temperature rise rate change values ​​at consecutive moments, including:

[0015] A time period consisting of consecutive moments in which the normalized value of the temperature rise rate change value is less than a preset threshold is recorded as a temperature rise stage.

[0016] Furthermore, the method for obtaining the insulation coefficient of the heating cable at each temperature rise stage includes:

[0017] The ratio of the insulation resistance value at the last moment of the temperature rise stage to the insulation resistance value at the first moment of the temperature rise stage is calculated, and the normalized value of the ratio is used as the insulation coefficient of the heating cable in the temperature rise stage.

[0018] Furthermore, the method for obtaining the insulation change parameters in each temperature rise stage includes:

[0019]

[0020] Among them, g a is the insulation change parameter in the ath temperature rise stage; δ a is the insulation change parameter in the ath temperature rise stage; Δt a is the time length of the ath temperature rise stage; the time length is the time difference between the first and last moments of the temperature rise stage; v y ' is the temperature rise rate change value at the yth moment in the ath temperature rise stage; n is the number of moments included in the ath temperature rise stage.

[0021] Furthermore, the method for calculating the current variation value in each temperature rise stage includes:

[0022] Obtain the maximum value of the characteristic current at all times during the detection process; calculate the maximum mean value of the characteristic current at all times in the temperature rise stage; and use the difference between the maximum value and the maximum mean value as the current change degree value in the temperature rise stage.

[0023] Furthermore, the method for obtaining the insulation performance attenuation parameter of the heating cable specifically includes:

[0024]

[0025] Among them, R is the insulation performance attenuation parameter of the heating cable, m is the number of temperature rise stages, τ a is the current change value in the ath temperature rise stage, Δt a is the duration of the ath temperature rise stage, g a is the insulation change parameter during the temperature rise stage, and softsign() uses the derivative of the softsign function to normalize the result.

[0026] Furthermore, obtaining the insulation performance test result of the heating cable according to the concentration degree of the numerical distribution of the insulation performance attenuation parameter of the heating cable under all insulation performance tests includes:

[0027] The insulation performance attenuation parameter of the heating cable under each insulation performance test is normalized to obtain a normalized value; the standard deviation of the normalized value of the heating cable under all insulation performance tests is calculated; if the standard deviation is less than a preset fluctuation threshold, the insulation performance of the heating cable is good; otherwise, the insulation performance of the heating cable is unqualified.

[0028] In a second aspect, an embodiment of the present application also provides a heating cable insulation performance testing system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned heating cable insulation performance testing methods are implemented.

[0029] This application has at least the following beneficial effects:

[0030] This application analyzes the limitations of testing the insulation performance of heating cables at a fixed temperature. First, the temperature factor that has a significant impact on the insulation performance in the application scenarios of heating cables is analyzed. During the temperature rise process of the heating cable, the rate of change of the temperature rise of the heating cable varies at different stages. The temperature rise stages are divided according to the temperature change within a local time. The application further analyzes the influence of temperature changes on the resistance of the heating cable, which leads to the degradation of insulation performance, during the process of converting electrical energy into thermal energy. The insulation coefficient is obtained by comparing the insulation resistance values ​​of the insulation layer of the heating cable before and after the temperature rise stage, which reflects the degree to which the insulation performance of the heating cable is affected by temperature. The changes in temperature and insulation coefficient during the temperature rise stage are comprehensively analyzed to obtain insulation change parameters to represent the insulation performance of each stage. Finally, the insulation performance attenuation parameters of the heating cable are obtained by combining the time lengths of all temperature rise stages with the current change degree values ​​and insulation coefficient change parameters. Taking into account the insulation performance attenuation phenomenon of insulating materials during long-term use, the insulation performance attenuation parameters of the heating cable test samples are synthesized and the values ​​of the insulation performance attenuation parameters of multiple tests are combined to obtain the insulation performance test results of the heating cable, thereby improving the accuracy of the insulation performance test of the heating cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A flowchart of a method for testing the insulation performance of a heating cable provided in one embodiment of the present application;

[0033] Figure 2 A schematic diagram of a curve showing changes in insulation coefficient and characteristic current with temperature provided in one embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0036] The following describes in detail a method and system for testing the insulation performance of a heating cable provided by the present application with reference to the accompanying drawings.

[0037] See also Figure 1 , which shows a flowchart of a method for testing the insulation performance of a heating cable provided by an embodiment of the present application, the method comprising the following steps:

[0038] S1, real-time acquisition of characteristic current, insulation layer temperature and insulation resistance value of the heating cable during each insulation performance test.

[0039] A specific implementation scenario of the present application is the scenario of performing insulation performance testing on heating cables. During the insulation performance testing of heating cables, temperature changes have a certain impact on the insulation performance of the insulating material of the insulation layer, and there are errors in the test results of the insulation performance of the heating cables under a single temperature environment.

[0040] In the above-mentioned heating cable insulation performance test, only the current state test results are analyzed, without considering the changes in insulation performance caused by temperature changes, resulting in inaccurate insulation performance test results. This embodiment simulates the scenario in which the insulation layer temperature rises due to cable heating during operation, performs the test, and monitors the cable data in real time. The actual insulation performance of the heating cable is then obtained based on the monitoring data, thereby improving the effectiveness and accuracy of the heating cable insulation performance test.

[0041] Therefore, this embodiment uses AC superposition technology to test the insulation performance of the heating cable; first, ensure that the heating cable to be tested is in a power-off state, use a connecting wire to connect the output end of the signal generator to the shielding layer of the heating cable, and connect the input end of the current sensor to the cable to measure the characteristic current.

[0042] The heating cable is placed in a heating device to simulate the temperature environment in which the heating cable operates. The temperature is gradually increased to cause the heating cable to heat up, and the insulation layer temperature is recorded. Simultaneously, a megohmmeter is used to measure the insulation resistance of the heating cable in real time during the AC superposition test to compare the effect of voltage on the cable insulation layer.

[0043] The heating cable is tested, and the monitored characteristic current I is recorded according to the test time. The heating cable to be tested is tested multiple times. In this embodiment, a total of 10 tests are performed.

[0044] S2, obtaining the temperature rise rate change value at each moment according to the temperature change of the insulation layer between adjacent moments; dividing the temperature rise stage according to the numerical distribution of the temperature rise rate change values ​​at consecutive moments.

[0045] The conductive properties of insulating materials are primarily ionic. In ionic conduction, current is generated by the directed movement of ions, which originate from the insulator's crystalline lattice. At room temperature, the small number of ions indicates poor conductivity and high insulation resistance. As temperature rises, the thermal vibrations of the insulator's molecules increase, causing more ions to detach from the lattice, resulting in increased conductivity and a decrease in insulation resistance.

[0046] Heating cables utilize electrical energy to replenish heat lost by the heated medium in the surrounding environment, maintaining the medium within a certain temperature range. This results in the insulation layer of the heating cable being exposed to high temperatures for extended periods of time. Therefore, as the ambient temperature of the heating cable rises during use, the insulation performance of the heating cable decreases. Therefore, we further analyzed the temperature changes of the insulation layer of heating cables in elevated temperatures.

[0047] As the ambient temperature of the heating cable increases, the temperature of the heating cable insulation layer also increases, the characteristic current increases, and the insulation performance decreases. To determine the degree to which the insulation performance of the heating cable is affected by temperature, the characteristic current at adjacent moments is compared to analyze the changes in insulation performance.

[0048] As temperature rises, the insulation properties of the insulation material change, causing the characteristic current monitored by the current sensor to increase as the insulation properties decrease. Because the insulation efficiency of the insulation layer is affected by temperature, as the temperature of the heating cable rises, the insulation properties of the heating cable decrease, increasing the current flowing through the insulation layer and further exacerbating the temperature rise. Therefore, during the heating cable's temperature rise, the rate of change varies at different stages: the faster the temperature rise, the worse the insulation properties.

[0049] For the analysis of the temperature change state of the heating cable during the temperature rise process, the temperature rise process is divided into different stages according to the difference in temperature change rate, and the temperature insulation state parameters of different temperature rise stages are obtained according to the temperature rise time and temperature rise amplitude in each stage:

[0050] First, the temperature change rate at each moment is obtained based on the temperature change between different moments. The calculation formula for the temperature change rate at the i-th moment is: t is the time interval between adjacent moments; w i+1 、w i are the insulation layer temperatures at the i+1th and ith moments respectively.

[0051] Furthermore, by comparing the temperature rise rates at adjacent moments, the temperature rise rate change value v is obtained. i '=|v i -v i+1 |. The larger the value, the worse the insulation performance.

[0052] All acquired temperature-rise rate change values, v', are recorded and normalized using the MAX-MIN function, with a threshold of 0.6. A temperature-rise phase is defined as a period of time consisting of consecutive moments in which the normalized temperature-rise rate change value is less than the preset threshold. For example, if the normalized temperature-rise rate change values ​​are 0.3, 0.5, 0.6, 0.7, 0.4, 0.3, and 0.4, there are two temperature-rise phases: 0.3, 0.5, and 0.4, 0.3, and 0.4.

[0053] S3, based on the comparison of the insulation resistance values ​​at the beginning and end of each temperature rise stage, the insulation coefficient of the heating cable in each temperature rise stage is obtained; based on the insulation coefficient of the heating cable in each temperature rise stage, the temperature rise rate change value at all times and the duration of the temperature rise stage, the insulation change parameter of each temperature rise stage is obtained.

[0054] During use, the heating cable will continuously convert electrical energy into heat energy and release it to achieve the effect of clearing snow and removing ice. However, during the heating process, the outer material of the heating cable will gradually lose its insulation performance due to the temperature increase. Figure 2 Figure 2 shows a schematic diagram of the variation of insulation coefficient and characteristic current with temperature, illustrating the gradual decline in insulation performance and increase in characteristic current as temperature rises. Therefore, we first analyze the test data of the heating cable under elevated temperature conditions. When the heating cable is connected to power, current flows from one core through the conductive PTC material to the other, forming a loop. Since the insulation resistance of the heating cable's insulation layer varies with voltage, the higher the voltage, the lower the insulation resistance. Insulation resistance is a key parameter for measuring insulation performance.

[0055] Therefore, by comparing the insulation resistance values ​​of the heating cable insulation layer before and after the temperature rise stage, the insulation coefficient of the heating cable can be obtained:

[0056]

[0057] Among them, δ is the insulation coefficient of the heating cable, Ω z ,Ω o The insulation resistance values ​​at the last and first moments of the temperature rise phase, respectively, are represented by norm(), which is a linear normalization function. The smaller the insulation resistance value of the heating cable after the temperature rise phase is compared to that before the temperature rise phase, the poorer the insulation effect.

[0058] Furthermore, the state parameters of temperature rise changes in different stages are different, which leads to changes in the insulation coefficient of the heating cable at different times and decreases with the actual temperature rise. Therefore, when analyzing the insulation state change parameters of the heating, it is necessary to analyze the changes in the insulation coefficient during the temperature rise stage. Based on the insulation coefficient and temperature rise rate change values ​​of the heating cable during the temperature rise stage, the insulation change parameter g during the temperature rise stage is obtained:

[0059]

[0060] Among them, g a is the insulation change parameter in the ath temperature rise stage; δ a is the insulation change parameter in the ath temperature rise stage; Δt a is the duration of the ath temperature rise stage; specifically, it is the time difference between the first and last moments of the temperature rise stage; v y ' is the temperature rise rate change value at the yth moment in the ath temperature rise stage; n is the number of moments included in the ath temperature rise stage. It is the average change of the insulation coefficient of the heating cable during the temperature rise stage. Its product with the change value of the temperature rise rate represents the changing relationship between the insulation state and temperature. The larger the value is, the greater the insulation change parameter is during the temperature rise stage, and the worse the insulation performance is.

[0061] S4, according to the numerical distribution of the characteristic current in each temperature rise stage, the current change degree value in each temperature rise stage is obtained; according to the time length of all temperature rise stages, the current change degree value and the insulation change parameter, the insulation performance attenuation parameter of the heating cable is obtained.

[0062] During the operation of the heating cable, when the power reaches the rated power, the temperature of the heating cable no longer increases, and the insulation layer is in a relatively stable temperature range. At this time, the maximum characteristic current I detected by the current sensor is max .

[0063] Furthermore, there is a maximum value of characteristic current in each temperature rise stage. Therefore, when analyzing the insulation performance parameters of the cable, it is necessary to obtain the current change value of each temperature rise stage. The current change value τ of the ath temperature rise stage is a =I max -I' a ; Among them, I max is the maximum value of the characteristic current at all times during the detection process; I' a is the average of the maximum values ​​of the characteristic current at all moments in the ath temperature rise stage.

[0064] Furthermore, during use, heating cables output power at a rated or fixed voltage. Over time, the insulation performance of the heating cable's insulation layer degrades, resulting in additional current losses during transmission and increasing the heating cable's temperature rise efficiency. The insulation performance degradation parameter, R, of the heating cable is calculated based on the duration of the temperature rise phase, combined with the current variation and insulation coefficient variation parameters.

[0065]

[0066] Among them, m is the number of temperature rise stages, τ a is the current change value in the ath temperature rise stage, Δt a is the duration of the ath temperature rise stage, g a is the insulation change parameter during the temperature rise stage, and softsign() uses the derivative of the softsign function to normalize the result. The rate of change of the current change degree in the temperature rise stage. The larger the value, the more the insulation performance is affected by temperature. At this time, the larger the insulation change parameter in the temperature rise stage, the larger the insulation performance attenuation parameter is, and the worse the insulation performance is.

[0067] S5, obtaining insulation performance test results of the heating cable according to the concentration degree of the numerical distribution of the insulation performance attenuation parameters of the heating cable under all insulation performance tests.

[0068] Over long-term use, the insulation performance of insulating materials will gradually degrade, affecting the safety of heating cables. Therefore, when testing and evaluating the insulation performance of heating cables, it is necessary to consider the insulation performance degradation of insulating materials during long-term use. To do this, multiple tests were conducted on heating cable test samples, and the insulation performance degradation parameters of the heating cables were obtained using the above method for each test.

[0069] Finally, the insulation performance of a heating cable reflects the extent to which it damages electrical energy. If the insulation performance of a heating cable is stable, the insulation performance attenuation parameters across multiple tests should be relatively consistent and fluctuate within a small range. Therefore, this embodiment normalizes the insulation performance attenuation parameters of the heating cable during each insulation performance test to obtain a normalized value. The standard deviation of these normalized values ​​for all insulation performance tests is then calculated. If the standard deviation ε' is less than 0.1, the insulation performance of the heating cable is good; otherwise, the insulation performance of the heating cable is unqualified. To ensure the accuracy of the insulation performance of the heating cable, a preset fluctuation threshold of 0.1 is used. When the standard deviation is less than the fluctuation threshold, the insulation performance attenuation parameters across multiple tests are relatively uniform, indicating that the insulation performance of the heating cable is good.

[0070] This application uses AC superposition detection technology to obtain characteristic current, and then analyzes the monitoring data of the heating cable under different temperature parameters during the heating process, simulates the heating environment of the heating cable during operation, detects the insulation performance parameters of the heating cable, and analyzes the insulation performance status parameters of the heating cable based on the obtained parameters. The application also obtains the changes in the insulation performance status parameters through multiple tests to judge the insulation performance of the heating cable, and then obtains the real insulation performance evaluation results of the heating cable, thereby improving the test effect and accuracy of the insulation performance of the heating cable.

[0071] Based on the same inventive concept as the above method, an embodiment of the present application also provides a heating cable insulation performance testing system, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned heating cable insulation performance testing methods are implemented.

[0072] Through the above description of the implementation method in combination with the accompanying drawings, technical personnel in the relevant field can understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0073] The above content is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, and they should all be covered by the protection scope of the present application.

Claims

1. A method for testing the insulation performance of a heating cable, characterized in that: The method comprises the following steps: S1, real-time acquisition of characteristic current, insulation layer temperature and insulation resistance value of the heating cable during each insulation performance test; S2, obtaining the temperature rise rate change value at each moment according to the temperature change of the insulation layer between adjacent moments; dividing the temperature rise stage according to the numerical distribution of the temperature rise rate change values ​​at consecutive moments; S3, based on the comparison of the insulation resistance values ​​at the beginning and end of each temperature rise stage, the insulation coefficient of the heating cable in each temperature rise stage is obtained; based on the insulation coefficient of the heating cable in each temperature rise stage, the temperature rise rate change value at all times and the duration of the temperature rise stage, the insulation change parameter of each temperature rise stage is obtained; S4, according to the numerical distribution of the characteristic current in each temperature rise stage, the current variation value in each temperature rise stage is obtained; according to the time length of all temperature rise stages, the current variation value and the insulation variation parameter, the insulation performance attenuation parameter of the heating cable is obtained; S5, obtaining insulation performance test results of the heating cable according to the concentration degree of the numerical distribution of the insulation performance attenuation parameters of the heating cable under all insulation performance tests.

2. A method for testing the insulation performance of a heating cable according to claim 1, characterized in that: The step of obtaining the temperature rise rate change value at each moment based on the temperature change of the insulation layer between adjacent moments includes: The temperature change rate at each moment is obtained based on the temperature difference of the insulation layer between adjacent moments; the difference in the temperature change rate at each moment and the next moment is used as the temperature rise rate change value at each moment.

3. A method for testing the insulation performance of a heating cable according to claim 2, characterized in that: The method of obtaining the temperature change rate at each moment according to the temperature difference between adjacent moments includes: recording the temperature change rate at the i-th moment as v i , Where t is the time interval between adjacent moments; w i+1 、w i are the insulation layer temperatures at the i+1th and ith moments respectively.

4. A method for testing the insulation performance of a heating cable according to claim 1, characterized in that: The temperature rise stages are divided according to the numerical distribution of the temperature rise rate change values ​​at consecutive moments, including: A time period consisting of consecutive moments in which the normalized value of the temperature rise rate change value is less than a preset threshold is recorded as a temperature rise stage.

5. A method for testing insulation performance of a heating cable according to claim 1, characterized in that: The method for obtaining the insulation coefficient of the heating cable at each temperature rise stage includes: The ratio of the insulation resistance value at the last moment of the temperature rise stage to the insulation resistance value at the first moment of the temperature rise stage is calculated, and the normalized value of the ratio is used as the insulation coefficient of the heating cable in the temperature rise stage.

6. A method for testing the insulation performance of a heating cable according to claim 1, characterized in that: The method for obtaining the insulation change parameters in each temperature rise stage includes: Among them, g a is the insulation change parameter in the ath temperature rise stage; δ a is the insulation change parameter in the ath temperature rise stage; Δt a is the time length of the ath temperature rise stage; the time length is the time difference between the first and last moments of the temperature rise stage; v y ' is the temperature rise rate change value at the yth moment in the ath temperature rise stage; n is the number of moments included in the ath temperature rise stage.

7. A method for testing insulation performance of a heating cable according to claim 1, characterized in that: The method for calculating the current variation value in each temperature rise stage includes: Obtain the maximum value of the characteristic current at all times during the detection process; calculate the maximum mean value of the characteristic current at all times in the temperature rise stage; and use the difference between the maximum value and the maximum mean value as the current change degree value in the temperature rise stage.

8. A method for testing insulation performance of a heating cable according to claim 1, characterized in that: The method for obtaining the insulation performance attenuation parameter of the heating cable specifically includes: Among them, R is the insulation performance attenuation parameter of the heating cable, m is the number of temperature rise stages, τ a is the current change value in the ath temperature rise stage, Δt a is the duration of the ath temperature rise stage, g a is the insulation change parameter during the temperature rise stage, and softsign() uses the derivative of the softsign function to normalize the result.

9. A method for testing insulation performance of a heating cable according to claim 1, characterized in that: The method of obtaining the insulation performance test result of the heating cable according to the concentration degree of the numerical distribution of the insulation performance attenuation parameter of the heating cable under all insulation performance tests includes: The insulation performance attenuation parameter of the heating cable under each insulation performance test is normalized to obtain a normalized value; the standard deviation of the normalized value of the heating cable under all insulation performance tests is calculated; if the standard deviation is less than a preset fluctuation threshold, the insulation performance of the heating cable is good; otherwise, the insulation performance of the heating cable is unqualified.

10. A heating cable insulation performance testing system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for testing the insulation performance of a heating cable as described in any one of claims 1 to 9 are implemented.

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