Electric power fitting aging test device and test method

Abstract

The invention relates to the technical field of electric power fitting testing, in particular to an electric power fitting aging testing device and method, the stress state of an electric power fitting in actual use is simulated through the cooperation of a tensioning mechanism and a mechanical loading mechanism, environmental loads such as temperature change, humidity change and salt mist are applied through an environmental load simulation mechanism, and the aging test of the electric power fitting is achieved. And meanwhile, alternating current is applied to the electric power fitting through the power supply module, so that the actual load of the electric power fitting is comprehensively simulated, a test environment identical to an actual application environment is constructed, and the reliability of a test result is ensured. And meanwhile, an equivalent cable simulation load spectrum is deduced according to historical load data by using a fatigue damage model, and the tensioning mechanism, the mechanical loading mechanism and the environment simulation mechanism act cooperatively according to the cable simulation load spectrum to carry out aging test on the electric power fitting, so that the test time is shortened, and the accuracy of an aging test result is ensured.

Description

Technical Field

[0001] This invention relates to the field of power fitting testing technology, specifically to a power fitting aging testing device and testing method. Background Technology

[0002] Traditional life testing of power fittings often involves conducting individual experiments on different aging factors. For example, tensile testing machines are used to test the tensile strength of power fittings and analyze their tensile properties. Alternatively, high and low temperature chambers are used to test their electrical properties or corrosion resistance at different temperatures. However, in actual use, the aging process of power fittings often occurs under the combined influence of multiple factors. For instance, busbar fixing hardware and some clamps must withstand the complex and variable mechanical forces of cables, as well as high and low temperatures, moisture, and salt spray from the environment. The alternating current and salt spray simultaneously corrode their surfaces, so their actual service life often falls short of the design life. Therefore, a testing device capable of simultaneously applying multiple loads to power fittings is needed to simulate the actual usage environment. Summary of the Invention

[0003] To address the technical problem that existing aging test devices cannot effectively simulate the actual load-bearing state of power fittings, this application provides an aging test device and test method for power fittings, wherein the device includes: a frame, and a tensioning mechanism, a mechanical loading mechanism and an environmental load simulation mechanism connected to the frame; The tensioning mechanism is used to tension cables and / or fix power fittings; The mechanical loading mechanism is used to apply mechanical load to the power fittings according to the cable simulated load spectrum; The mechanical loads include a vertical load along the direction of gravity, a horizontal axial load along the cable axis, and a horizontal radial load perpendicular to the cable axis. The vertical load, horizontal axial load, and horizontal radial load meet the mechanical load ratio requirements. The environmental load simulation mechanism is used to apply environmental loads to the power fittings according to the cable simulated load spectrum. The environmental loads include temperature load, humidity load, salt spray load, and current load.

[0004] Specifically, the mechanical load ratio requirement is as follows: ;

[0005] In the formula, For vertical loads, For horizontal axial load, For horizontal radial load, The length of the cable. The height of the cable sag. This represents the cable swing angle.

[0006] Specifically, the simulated cable load spectrum is obtained through the following steps: Obtain historical load data for power fittings and the SN curves of the materials used in power fittings; A fatigue damage model is established by applying the fatigue damage law, and the total cumulative damage of power fittings throughout their entire life cycle is calculated based on historical load data and SN curves. Based on the principle of keeping the total cumulative damage constant, the equivalent load is calculated according to the cable fatigue damage model and the planned test duration, and the cable simulated load spectrum is established.

[0007] The present invention also provides an aging test method for power fittings, which uses the above-mentioned device to perform the aging test and includes the following steps: Fix the power fittings and preload them so that the ratio between the vertical preload and the horizontal axial preload on the power fittings meets the mechanical load ratio requirements. Mechanical loads and environmental loads are applied to the power fittings according to the cable simulated load spectrum. The mechanical loads include vertical loads, horizontal axial loads, and horizontal radial loads that meet the mechanical load ratio requirements. The environmental loads include temperature loads, humidity loads, salt spray loads, and current loads. The aging test is completed when the power fittings reach the failure criteria, or when all loads in the simulated load spectrum of the cable have been applied.

[0008] The technical effects and advantages of this invention are as follows: This testing device can accurately simulate the complex environment faced by power fittings in actual use. Through the cooperation of the tensioning mechanism and the mechanical loading mechanism, it simulates the stress state of power fittings during actual use. An environmental load simulation mechanism applies environmental loads, such as temperature changes, humidity changes, and salt spray. Simultaneously, an alternating current is applied to the power fittings through the power module, thus comprehensively simulating the actual load on the power fittings and constructing a testing environment identical to the actual application environment, ensuring the reliability of the test results. Furthermore, by using a fatigue damage model to derive an equivalent cable simulated load spectrum based on historical load data, the tensioning mechanism, mechanical loading mechanism, and environmental simulation mechanism coordinate their actions according to the cable simulated load spectrum to perform aging tests on the power fittings, shortening the testing time and ensuring the accuracy of the aging test results. Attached Figure Description

[0009] Figure 1 This is a schematic front view of the testing device provided by the present invention.

[0010] Figure 2 This is a schematic side view of the structure of the testing device provided by the present invention.

[0011] Figure 3This is a schematic diagram of the testing device provided by the present invention when testing a tension clamp.

[0012] Figure 4 This is a flowchart of the testing method provided by the present invention.

[0013] Figure 5 This is a simplified diagram analyzing the stress state of a suspended cable.

[0014] Figure 6 This is a simplified diagram analyzing the force state of a cable when it is suspended and swinging.

[0015] Figure 7 This is a schematic diagram of the cable simulated load spectrum in this invention.

[0016] The attached figures are labeled as follows: 1. Frame; 2. Tensioning mechanism; 21. Tensioning actuator; 22. First insulating clamp; 23. Second insulating clamp; 3. Mechanical loading mechanism; 31. Horizontal loading element; 32. Vertical loading element; 33. Third insulating clamp; 4. Environmental load simulation mechanism; 41. Sealed enclosure; 42. Temperature control module; 43. Humidity control module; 44. Power supply module; 100. Power fittings; 101. Cable. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] refer to Figure 1 and Figure 2 This invention provides an aging test device for power fittings, comprising: Rack 1; Tensioning mechanism 2 is used to fix cable 101 or power fitting 100 to tension cable 101. Tensioning mechanism 2 includes tensioning actuator 21, first insulating clamp 22, and second insulating clamp 23. One end of tensioning actuator 21 is hinged to frame 1, and the other end is fixedly connected to first insulating clamp 22. Second insulating clamp 23 is hinged to frame 1. Tensioning actuator 21 drives first insulating clamp 22 to cooperate with second insulating clamp 23 to achieve tensioning of cable 101.

[0019] The mechanical loading mechanism 3 includes a horizontal loading element 31, a vertical loading element 32, and a third insulating clamp 33. One end of the vertical loading element 32 is hinged to the frame 1, and the other end is fixedly connected to the third insulating clamp 33. It is used to apply a vertical load along the direction of gravity and a horizontal axial load along the axis of the cable 101 to the cable 101, simulating the sag of the cable 101 due to its own weight. One end of the horizontal loading element 31 is hinged to the frame 1, and the other end is hinged to the third insulating clamp 33 or the vertical loading element 32. The third insulating clamp 33 is used to fix the power fitting 100 or to make insulating contact with the cable 101. The horizontal loading element 31 is used to drive the vertical loading element 32 to swing around the axis of the cable 101, thereby simulating the swing of the cable 101 caused by wind under actual working conditions, so as to apply a horizontal radial load perpendicular to the axis of the cable 101 to the power fitting 100. The vertical loading element 32 and the horizontal loading element 31 can also vibrate at a preset frequency to simulate wind vibration and electromagnetic vibration. With the cooperation of the vertical loading element 32 and the horizontal loading element 31, the mechanical loading mechanism 3 can apply mechanical stress load to the power fitting 100 according to the cable simulated load spectrum.

[0020] The environmental load simulation mechanism 4 includes a sealed enclosure 41, and a temperature control module 42, a humidity control module 43, and a power supply module 44 disposed within the sealed enclosure 41. The sealed enclosure 41 is used to form a closed test environment around the electrical fitting 100 under test. The temperature control module 42 is used to change the ambient temperature inside the sealed enclosure 41. The humidity control module 43 is used to change the ambient humidity and salt spray concentration inside the sealed enclosure 41. The power supply module 44 is used to apply alternating current to the electrical fitting 100 under test.

[0021] During testing, a cable 101 is used to connect and fix the power fitting 100. Vertical and horizontal axial loads are applied to the power fitting 100 via the vertical loading element 32, while the horizontal loading element 31 drives the cable 101 to swing, applying a horizontal radial load to the power fitting 100. This simulates the various complex mechanical stresses experienced by the power fitting 100 during actual operation. At the start of the test, the vertical and horizontal loading elements 32 and 31 vibrate continuously at a preset frequency to further simulate the effects of wind and electromagnetic vibrations on the power fitting 100. Simultaneously, the environmental load simulation mechanism 4 activates. The temperature control module 42 adjusts the temperature inside the sealed enclosure 41 according to a preset cable simulation load spectrum to simulate the impact of temperature changes in different regions and seasons on the power fitting 100. The humidity control module 43 precisely controls the humidity and salt spray concentration inside the enclosure based on the cable simulation load spectrum to simulate special environmental conditions such as humid and coastal environments. The power supply module 44 applies alternating current to the power fitting 100 under test to simulate its electrical operating conditions during actual operation. This multi-factor comprehensive simulation makes the test environment as close as possible to the actual operating environment of the power fitting 100, thereby more accurately assessing the aging condition and service life of the power fitting 100.

[0022] Specifically, the tensioning actuator 21, the horizontal loading element 31, and the vertical loading element 32 can be linear motion devices such as pneumatic cylinders or hydraulic cylinders. Considering that the power fittings 100 used in some high-voltage applications need to bear a large load on the cable 101, hydraulic cylinders are preferred, which can provide greater tension force and load, and better simulate the stress state of the power fittings 100.

[0023] The connection between the tensioning actuator 21 and the frame 1 is preferably a ball joint connection. When the horizontal loading element 31 and the vertical loading element 32 apply vertical and horizontal loads, the tensioning actuator 21 can swing with the movement of the cable 101, so that the tensioning mechanism 2 only bears axial force, improves the stress state of the cylinder or hydraulic cylinder, and increases its service life.

[0024] The specific shapes of the first insulating clamp 22, the second insulating clamp 23, and the third insulating clamp 33 vary depending on the form of the power fitting 100 being tested. When used to connect the power fitting 100, they are fixed according to the fixing method of the power fitting 100 in actual application. For example... Figure 1As shown, when testing the suspension clamp, the first insulating clamp 22 and the second insulating clamp 23 are used to fix the two ends of the cable 101, respectively. Therefore, the first insulating clamp 22 and the second insulating clamp 23 can use the same clamp, for example, both can be insulators used in conjunction with tension clamps to fix the cable 101, or ceramic clamps can be used directly to fix the cable 101. The third insulating clamp 33 is connected to the suspension clamp through the pin hole on the suspension clamp, and the fixing method is the same as that of the suspension clamp in actual application. However, when testing the tension clamp, such as Figure 3 As shown, the first insulating clamp 22 is connected via the pin hole of the tension clamp, which fixes one end of the cable 101. The second insulating clamp 23 fixes the other end of the cable 101. At this point, the first insulating clamp 22 and the second insulating clamp 23 need to have different structures. Since a load needs to be applied to the cable 101 via the third insulating clamp 33, the third insulating clamp 33 needs to have a structure that maintains good contact with the cable 101 and does not abrade the cable 101. For example… Figure 3 As shown, it adopts the same shape as the suspension clamp.

[0025] Specifically, the sealed enclosure 41 is preferably made of metal and is insulated and fixedly connected to the frame 1. The sealed enclosure 41 is grounded to shield the cable 101 from external discharge when the power module 44 supplies power to the cable 101, ensuring the safety of the entire equipment and the testing personnel. Through holes are provided on the sealed enclosure 41 at positions corresponding to the first insulating clamp 22, the second insulating clamp 23, and the third insulating clamp 33. During testing, a portion of the first insulating clamp 22, the second insulating clamp 23, and the third insulating clamp 33 extends into the sealed enclosure 41 through the through holes, while the other portion remains exposed. Sealing elements are provided on the through holes to prevent moisture inside the sealed enclosure 41 from flowing to the outside along the surfaces of the first insulating clamp 22, the second insulating clamp 23, and the third insulating clamp 33, thereby preventing leakage caused by connecting the power module 44 to the outside.

[0026] Based on the above-mentioned testing apparatus, this application provides a testing method, with reference to... Figure 4 This includes the following steps: S1. Fixing the power fittings 100: Different power fittings 100 are fixed in different ways, which have been described above and will not be repeated here; S2, Preload: The tensioning actuator 21 tensions the cable 101, and at the same time, the vertical loading element 32 cooperates with the tensioning actuator 21 to make the tension force of the cable 101 (i.e., the horizontal axial preload of the power fitting 100) and the output force of the vertical loading element 32 (i.e., the vertical preload of the power fitting 100) meet the mechanical load ratio requirements. Specifically, the stress state of the power fitting 100 differs from that of components in other scenarios. For the power fitting 100 used to fix or connect the cable 101, the load it experiences mainly comes from the self-weight of the cable 101, wind loads, and vibrations generated by the high-voltage alternating current. Therefore, the simulation of the power fitting 100 should be based on the fundamental characteristics of the cable 101.

[0027] For example, tension clamps and suspension clamps, because they are fixedly connected to cable 101, not only bear the self-weight load of cable 101, but also the internal tension of cable 101. Their stress state is as follows: Figure 5 As shown.

[0028] When the two hanging points of cable 101 are at the same height, the curve formed by cable 101 under gravity conforms to the catenary equation. The self-weight load of cable 101 is evenly distributed by the power fittings 100 at both ends. The internal tension of cable 101 under gravity can be calculated according to the following formula: ;

[0029] In the formula, This refers to the weight per unit length of the cable. The length of the cable between the two hanging points. The height of the cable sag is generally determined by the construction site environment based on the safe distance to the ground.

[0030] The cable's self-weight load is evenly distributed between the power fittings at both ends, constituting the vertical load on the power fittings, which is: ;

[0031] The above analysis shows that the horizontal axial load and vertical load borne by power fittings have a certain proportional relationship: ;

[0032] It can be seen that for a cable with one end fixed, the ratio of horizontal axial load to vertical load of the power fittings is fixed.

[0033] When cables sway under wind force, the horizontal axial load and vertical load on the power fittings change, similar to a pendulum. The calculation is as follows: ;

[0034] In the formula, This refers to the inherent tension of the cable after it swings, i.e., the horizontal axial load when the swing occurs. This represents the swing angle of the cable.

[0035] At this time, the stress state of the power fittings is as follows: Figure 6As shown, after the cable swings, the vertical load generates a component force in the horizontal radial direction of the cable, causing the power fitting to be under triaxial stress. The magnitude of the horizontal radial load on the power fitting at this time is: ;

[0036] Therefore, when the cable swings, the proportional relationship (i.e., the mechanical load ratio requirement) between the horizontal axial load, vertical load, and horizontal radial load is: ;

[0037] The above analysis shows that there is a certain proportional relationship between the horizontal axial load, vertical load and horizontal radial load actually borne by power fittings.

[0038] During the aging test of the power fitting 100, because the cable 101 used to fix the power fitting 100 is relatively short, the shape formed when bent by the vertical loading element 32 is different from the shape formed by the cable 101 under its own weight. Therefore, the resulting tension force is not entirely consistent with the tension force generated by the cable 101's own weight. This leads to the ratio between the horizontal axial load and the vertical load not always satisfying the above formula. Furthermore, when the horizontal loading element 31 drives the cable 101 to swing, the center of the swing of the cable 101 may not coincide with the center of the swing of the horizontal loading element 31 (specific details need to be determined). (This needs to be determined based on the design details of the equipment). This results in the swing angle applied to the cable 101 during the test being inconsistent with the actual swing angle, causing the ratio between the applied horizontal radial load and the vertical load and the horizontal axial load to be inconsistent with the above formula. Therefore, when conducting aging tests, the tensioning actuator 21, the vertical loading element 32 and the horizontal loading element 31 need to cooperate with each other to ensure that the stress state of the tested power fitting 100 meets the above mechanical load ratio requirements. Therefore, the tensioning actuator 21, the vertical loading element 32 and the horizontal loading element 31 should adopt a control method with the output force as the control target.

[0039] Meanwhile, when testing different power fittings 100, the direction of movement of the vertical loading element 32 is different. For example, when testing the suspension clamp, refer to... Figure 1 The third insulating clamp 33 is connected to the suspension clamp via the pin hole of the suspension clamp. The suspension clamp is positioned in the middle of the cable 101. The vertical loading element 32 should lift the suspension clamp upwards, pulling the cable 101 upwards to simulate the state when the suspension clamp suspends the cable 101. When testing the tension clamp, if... Figure 3As shown, the tension clamp to be tested is hinged to the first insulating clamp 22 through the pin hole on it. The tension clamp fixes one end of the cable 101, and the second insulating clamp 23 fixes the other end of the cable 101. The vertical loading element 32 should drive the third insulating clamp 33 to press down and bend the cable 101, thereby simulating the situation where the tension clamp fixes the end of the cable 101.

[0040] Although the mechanical load borne by the power fitting 100 will fluctuate at a certain frequency, the fluctuation range is not large relative to the absolute value of the load. Therefore, by preloading, the stress state of the power fitting 100 is adjusted to the initial state. During the subsequent loading process, the mechanical load borne by the power fitting 100 can be kept within this range, thereby reducing the control difficulty of the tensioning actuator 21, the vertical loading element 32 and the horizontal loading element 31 and improving the control accuracy.

[0041] S3. Control the tensioning actuator 21, mechanical loading mechanism 3, and environmental load simulation mechanism 4 to apply mechanical load and environmental load to the power fitting 100 according to the cable simulated load spectrum. Specifically, such as Figure 7 As shown, the cable simulation load spectrum includes a mechanical load spectrum and an environmental load spectrum. The mechanical load spectrum includes multiple mechanical loads of different load levels and their corresponding load cycle numbers. The mechanical loads include vertical loads along the direction of gravity, horizontal axial loads along the axis of cable 101, and horizontal radial loads perpendicular to the axis of cable 101. The ratio between these three loads should meet the above-mentioned mechanical load ratio requirements.

[0042] The environmental load spectrum includes multiple environmental loads of different load levels and their corresponding load cycle numbers. Environmental loads include temperature load, humidity load, salt spray load, and current load.

[0043] Specifically, the cable simulated load spectrum is obtained through the following steps: S31. Obtain historical load data of the power fitting 100 and the SN curve of the materials used in the power fitting 100; Specifically, the historical load data of the power fitting 100 should include historical mechanical load data and historical environmental load data experienced by the power fitting 100 throughout its entire life cycle.

[0044] Historical mechanical load data should include historical vertical load, historical horizontal axial load, and historical horizontal radial load. Considering that power fittings 100 are mostly used in high-voltage power transmission, it is difficult to obtain the actual mechanical load borne by power fittings 100 through conventional methods such as strain gauges. Therefore, the average vertical load and average horizontal axial load of power fittings 100 can be calculated by statistically analyzing the weight of the cables 101 suspended by power fittings 100, the spacing between cable 101 suspension points, and the height difference. The specific calculation can refer to the aforementioned calculation formula. At the same time, local annual wind data, including wind speed distribution data and wind direction distribution data, should be collected. Based on the annual wind data and the aerodynamic model of cable 101, the swing pattern of cable 101 (i.e., the number of cycles and amplitude of the swing angle) should be analyzed. Thus, the number of cycles and amplitude of the horizontal radial load of power fittings 100 can be calculated based on the average vertical load.

[0045] Specifically, for the high-frequency vibration generated by the alternating current in cable 101, the interaction force between two adjacent conductors can be calculated according to the Biot-Savart law. Combining this with the sinusoidal variation characteristics of the alternating current, the electromagnetic excitation force of cable 101's vibration can be obtained. The final amplitude and frequency of cable 101 need to be determined by considering the dynamic characteristics of cable 101 and its fixed end. A simplified calculation method is to simplify cable 101 between the two suspension points as a tensioned string with hinged ends, establishing a dynamic mathematical model of cable 101. The dynamic response of this model under electromagnetic excitation force can then be calculated using forced vibration theory. This part can be implemented in professional analysis software, such as the dynamic analysis module of finite element software like ANSYS and ABAQUS, and will not be elaborated upon here. The dynamic analysis results can provide the amplitude and frequency of the vertical load and horizontal axial load of the power fitting 100 under electromagnetic excitation force. Combined with the mechanical load ratio requirements given by the above formula, the amplitude and frequency of the horizontal radial load can be determined. In this way, complete historical mechanical load data can be obtained, that is, the amplitude and number of cycles of the vertical load, horizontal axial load, and horizontal radial load that the power fitting 100 bears during its complete life cycle.

[0046] Historical environmental load data includes typical environmental characteristics of the operating environment of the power fittings 100, such as minimum temperature, maximum temperature, annual average temperature, and annual average rainfall. Based on this historical environmental load data, it can be determined how to set the temperature, humidity, and salt spray conditions inside the sealed chamber 41 during testing.

[0047] The SN curve is a concept of fatigue life curve proposed by the German scientist Waller in 1847, which suggests that the fatigue life of a material is related to the stress level it withstands. SN curves are usually obtained through material sample experiments, and for some commonly used metallic materials, corresponding SN curves can be found in some design manuals.

[0048] S32. Establish a fatigue damage model by applying the fatigue damage principle; There are various fatigue damage rules, such as Miner's linear cumulative damage criterion, nonlinear cumulative damage rule, bilinear cumulative damage rule, etc. There are also some theories that evaluate the fatigue life of metal parts based on the fatigue crack propagation rate, such as the Paris formula and the Forman formula. These are all existing technologies and will not be elaborated here.

[0049] Taking Miner's damage law as an example, and combining it with the material's SN curve, the total damage of the power fitting 100 under multiple load cycles of different load levels is: ;

[0050] In the formula, Let i be the number of load cycles for the i-th load level. The number of load cycles in the entire life cycle corresponding to the i-th load level in the SN curve.

[0051] The historical mechanical load data obtained in step S31 can be statistically analyzed using the rainflow counting method. The data is then categorized into load levels based on load amplitude, and the number of load cycles under different load levels is counted to form a historical mechanical load spectrum. The total damage generated under the historical mechanical load spectrum is calculated using the above formula.

[0052] In particular, since the mechanical load is divided into vertical load, horizontal axial load, and horizontal radial load, and according to the fourth strength theory of mechanics of materials, the fatigue life of metallic materials is related to the comprehensive equivalent stress, it is necessary to synthesize the vertical load, horizontal axial load, and horizontal radial load into forces, and then calculate the total damage based on the resultant force.

[0053] Furthermore, the above calculation only considers the total damage caused by historical mechanical load data and does not consider the influence of environmental loads on fatigue life. Therefore, the above formula is improved as follows to further correct the calculated total damage, resulting in the fatigue damage model: For each environmental load, a life correction factor is assigned to represent the impact of different environmental loads on fatigue life, as follows: ;

[0054] In the formula, This represents the total cumulative damage over the entire lifespan after environmental load correction. The total mechanical damage is calculated based on the historical mechanical load spectrum. This is the temperature load weighting factor. Humidity load weighting factor This is the salt spray load weighting coefficient. This is the current load weighting coefficient.

[0055] , , , Experiments using the controlled variable method can be conducted, for example, fatigue tests on a certain type of power fittings are performed, applying the same mechanical load as different environmental loads. By changing the type of environmental load, the influence of different environmental loads on the lifespan of the power fittings can be analyzed, and the weighting coefficients of each environmental load can be determined based on the changes in lifespan under different environmental loads.

[0056] The fatigue damage model established by the above formula is only one form of the fatigue damage model provided in this application. When the fatigue damage model is established based on other theories, the fatigue damage model can have different forms.

[0057] S33. Based on the principle of keeping the total cumulative damage constant, calculate the equivalent load according to the fatigue damage model and the planned test duration, and establish the cable simulated load spectrum to ensure that the test duration is controllable. Specifically, according to the SN curve, while keeping the total cumulative damage constant, increasing the load level can reduce the number of load cycles, thereby shortening the aging test duration. Therefore, when establishing the cable simulated load spectrum, the load level classification method in the historical load data processing can be kept unchanged. This way, the calculated cable simulated load spectrum will have more cycles for high-amplitude load levels and fewer cycles for low-amplitude load levels.

[0058] If maintaining the load class classification method results in the inability to obtain an equivalent load that meets the planned test duration, the load class classification can be changed. For example, the electrical fitting 100 being tested has a design life of 10 years. According to the statistical results of historical load data, it needs to undergo 10^10 load cycles of different load classes. If the testing device applies load cycles at a frequency of 50Hz, the entire test duration will reach 15 years. However, according to the load class classification method of historical mechanical load spectrum, even if all load cycles are the highest level load cycles, the entire test duration will still require 1 year, which undoubtedly cannot meet the needs of enterprises.

[0059] Therefore, when calculating the cable simulated load spectrum, the equivalent load is calculated based on the planned test duration, which ensures the controllability of the test duration and reduces the time cost of aging tests. The planned test duration can be based on the number of mechanical load cycles, which is the sum of the number of load cycles corresponding to each load level in the cable simulated load spectrum.

[0060] For environmental loads, the number of cycles corresponding to the planned test duration is calculated based on the design life and the statistical characteristics of various loads in historical environmental load data.

[0061] The cable simulation load spectrum obtained through the above steps not only considers the different types of loads on the power fittings 100 and the influence of environmental factors on their fatigue damage, but also establishes an equivalent load in conjunction with the fatigue damage model. This ensures that the number of load cycles required for aging tests is reduced under the same damage conditions, thereby achieving the goal of ensuring test accuracy while shortening the aging test time.

[0062] S4. When the power fitting 100 reaches the failure standard, or when all the loads in the cable simulated load spectrum have been applied, the aging test is completed.

[0063] Since the quality condition of the tested electrical fittings 100 cannot be predicted in advance during the testing process, a flexible test termination mechanism is required.

[0064] Specifically, the failure criteria for power fittings 100 generally include complete fracture or cracks reaching a specified crack length, excessive wear, and a sharp increase in contact resistance. These indicators can be determined by periodically or continuously checking the power fittings 100 during the testing process.

[0065] If the power fitting 100 does not reach the failure standard after the test according to the cable simulated load spectrum is completed, it means that the test life of the power fitting 100 has reached the design life. However, if the power fitting 100 fails before the cable simulated load spectrum is fully applied during the aging test, the test life of the power fitting 100 can be deduced from the fatigue damage model based on the number of load cycles already applied.

[0066] In summary, the aging test method provided in this application controls the coordination between the tensioning actuator 21, the vertical loading element 32, and the horizontal loading element 31 to ensure that the stress state of the tested power fitting 100 meets the mechanical load ratio requirements. This guarantees that the load state experienced by the power fitting 100 during the test is consistent with the actual application situation, thus ensuring the accuracy of the test results. Simultaneously, by adopting the principle of constant total cumulative damage and targeting the planned test duration, an equivalent cable simulated load spectrum is derived from historical load data using a fatigue damage model. This ensures the accuracy of the aging experiment while achieving controllable test duration, thereby shortening the aging test cycle and reducing the time cost of aging testing.

[0067] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An aging test device for electrical fittings, characterized in that, include: The frame, and the tensioning mechanism, mechanical loading mechanism and environmental load simulation mechanism connected to the frame; The tensioning mechanism is used to tension cables and / or fix power fittings; The mechanical loading mechanism is used to apply mechanical load to the power fittings according to the cable simulated load spectrum; The mechanical loads include a vertical load along the direction of gravity, a horizontal axial load along the cable axis, and a horizontal radial load perpendicular to the cable axis. The vertical load, horizontal axial load, and horizontal radial load meet the mechanical load ratio requirements. The environmental load simulation mechanism is used to apply environmental loads to the power fittings according to the cable simulated load spectrum. The environmental loads include temperature load, humidity load, salt spray load, and current load.

2. The apparatus according to claim 1, characterized in that, The tensioning mechanism includes: The tensioning actuator is hinged to the frame; The first insulating clamp is fixedly connected to the tensioning actuator or hinged to the frame; The second insulating clamp is fixedly connected to the tensioning actuator or hinged to the frame; The tensioning actuator works in conjunction with the first insulating clamp and the second insulating clamp to tension the cable and / or fix the power fittings.

3. The apparatus according to claim 1, characterized in that, The mechanical loading mechanism includes a vertical loading element, a horizontal loading element, and a third insulating clamp; One end of the vertical loading element is hinged to the frame, and the other end is fixedly connected to the third insulating clamp; One end of the horizontal loading element is hinged to the frame, and the other end is hinged to the third insulating clamp or the vertical loading element; The third insulating clamp is used to fix power fittings or to make insulating contact with cables.

4. The apparatus according to claim 1, characterized in that, The environmental load simulation mechanism includes a sealed enclosure, and a temperature control module, a humidity control module, and a power supply module disposed within the sealed enclosure. The sealed enclosure is used to create a closed testing environment around the electrical fittings being tested. The temperature control module is used to change the ambient temperature inside the sealed box. The humidity control module is used to change the ambient humidity and salt spray concentration inside the sealed box. The power module is used to apply alternating current to the electrical fittings being tested.

5. The apparatus according to claim 1, characterized in that, The mechanical load ratio requirement is as follows: 、 In the formula, For vertical loads, For horizontal axial load, For horizontal radial load, The length of the cable. The height of the cable sag. This represents the cable swing angle.

6. The apparatus according to claim 1, characterized in that, The simulated cable load spectrum was obtained through the following steps: Obtain historical load data for power fittings and the SN curves of the materials used in power fittings; A fatigue damage model is established by applying the fatigue damage law, and the total cumulative damage of power fittings throughout their entire life cycle is calculated based on historical load data and SN curves. Based on the principle of keeping the total cumulative damage constant, the equivalent load is calculated according to the cable fatigue damage model and the planned test duration, and the cable simulated load spectrum is established.

7. The apparatus according to claim 6, characterized in that, The fatigue damage model is as follows: ； In the formula, This refers to the total cumulative damage to power fittings over their entire lifespan. The total mechanical damage is calculated based on the historical mechanical load spectrum. This is the temperature load weighting factor. Humidity load weighting factor This is the salt spray load weighting coefficient. This is the current load weighting coefficient.

8. The apparatus according to claim 7, characterized in that, The total mechanical damage was obtained through the following steps: Statistical analysis is performed on the historical mechanical load data in the historical load data, load levels are divided according to load amplitude, the number of load cycles under different load levels is counted, and a historical mechanical load spectrum is established. The total mechanical damage is calculated based on the fatigue damage rule and the historical mechanical load spectrum.

9. A method for testing the aging of electrical fittings, using the apparatus described in any one of claims 1-8, characterized in that, Includes the following steps: Fix the power fittings and preload them so that the ratio between the vertical preload and the horizontal axial preload on the power fittings meets the mechanical load ratio requirements. Mechanical loads and environmental loads are applied to the power fittings according to the cable simulated load spectrum. The mechanical loads include vertical loads, horizontal axial loads, and horizontal radial loads that meet the mechanical load ratio requirements. The environmental loads include temperature loads, humidity loads, salt spray loads, and current loads. The aging test is completed when the power fittings reach the failure criteria, or when all loads in the simulated load spectrum of the cable have been applied.

10. The method according to claim 9, characterized in that, The mechanical load ratio requirement is as follows: ； In the formula, For vertical loads, For horizontal axial load, For horizontal radial load, The length of the cable. The height of the cable sag. This represents the cable swing angle.

Images