An insulation property test platform

Abstract

The application belongs to the technical field of high-voltage insulation characteristic experiment, and particularly relates to an insulation characteristic test platform. When an insulation characteristic test experiment of an insulation material under multiple stresses is performed, there is a large deviation between an actual heating temperature of the material and a temperature control setting value, which influences the accuracy of the experimental result. The application provides a temperature control system of an insulation characteristic test platform, which comprises a pressure applying mechanism, a heating mechanism and a temperature measuring mechanism. The temperature measuring mechanism collects the surface temperature of the insulation material, obtains the surface temperature change of the insulation material with pressure, calculates a fitting formula of the contact thermal resistance change with pressure, and then calculates the correction amount of the temperature control system setting temperature according to the contact thermal resistance under a certain pressure, so as to correct the temperature control setting value and make the surface temperature of the insulation material reach the expected temperature. The application solves the problem that the material surface temperature is influenced by the contact thermal resistance change of the material caused by pressure in the insulation characteristic test experiment under multiple stresses.

Description

Technical Field

[0001] This application belongs to the field of high voltage insulation characteristic testing technology, and in particular relates to an insulation characteristic testing platform. Background Technology

[0002] Currently, insulation property testing experiments on insulating materials are conducted under single and multiple stress fields. For example, the changes in insulation properties under single stresses such as pressure and temperature are investigated, or the changes under the combined effects of pressure and temperature. However, when conducting experiments under multiple stresses, the effects of each stress cannot be simply superimposed; the coupling relationship between the stresses must be considered. For instance, the pressure applied by the pressure application module affects the contact thermal resistance between the material and the heat source. This is because the contact surface between the heat source and the insulating material is not smooth, and the magnitude of the applied pressure affects the actual contact area. A microscopic schematic diagram of the contact interface is attached. Figure 1 As shown, the two seemingly flat solid contact surfaces appear to fit perfectly together macroscopically. However, in reality, the surfaces are not perfectly smooth; the solid-solid contact occurs only at a series of discrete contact points. When current and heat pass through the contact surfaces, they do not travel through the entire interface but rather through these discrete, actual contact points, hindering the propagation of electrical energy and heat and creating additional contact thermal resistance R at the interface. th Contact thermal resistance affects the heating effect of the heat source, causing a deviation between the temperature control setpoint and the actual temperature of the insulating material. As pressure increases, the adhesion between the contact surfaces improves, and the contact thermal resistance tends to decrease with increasing pressure. In other words, the magnitude of the applied pressure affects the heating effect of the heat source, and the actual heating temperature of the material changes with the magnitude of the pressure.

[0003] Therefore, when conducting insulation characteristic tests on insulating materials under thermo-coupling conditions, it is necessary to consider the influence of the applied pressure on the material on the contact thermal resistance between the heat source and the experimental material, and to correct the temperature control setting value according to the applied pressure. However, current insulation characteristic tests on insulating materials under multi-stress conditions do not consider the influence of contact thermal resistance on the heating effect, resulting in a large deviation between the actual heating temperature of the insulating material and the temperature control setting value, which affects the accuracy of the experimental results. Summary of the Invention

[0004] 1. Technical problems to be solved

[0005] Current experimental studies investigating the effects of applying pressure and temperature separately on the insulation properties of insulating materials, such as breakdown voltage and conductivity, do not consider the coupling effect of pressure and temperature. To conduct coupled pressure and temperature experiments, it is necessary to consider the mutual influence between pressure and temperature. This is manifested in the fact that applying pressure affects the contact thermal resistance between the heat source and the insulating material, leading to a deviation between the actual heating temperature on the insulating material and the temperature control system setpoint, thus affecting the accuracy and reliability of the experiment. This application provides an insulation characteristic testing platform.

[0006] 2. Technical Solution

[0007] To achieve the above objectives, this application provides an insulation characteristic testing platform, which includes a universal testing machine connected to a smart terminal. The universal testing machine contains a pressure applying mechanism, a temperature measuring mechanism, and a heating mechanism connected in sequence. The temperature measuring mechanism is connected to the smart terminal. The pressure applying mechanism applies pressure to the insulating material, the heating mechanism heats the insulating material, and the temperature measuring mechanism collects the surface temperature of the insulating material to obtain the change in surface temperature with pressure. A fitting formula for the change in contact thermal resistance with pressure is calculated, and the magnitude of the contact thermal resistance under a certain pressure condition is obtained through the fitting formula. Then, the correction amount for the set temperature is calculated from the contact thermal resistance, and the temperature set value is corrected so that the surface temperature of the insulating material reaches the expected temperature.

[0008] Another embodiment provided in this application is as follows: the universal testing machine includes a crossbeam and a press, the crossbeam is disposed at one end of the universal testing machine, the press is disposed at the other end of the universal testing machine, and the pressure applying mechanism includes a pressure sensor, a pressure plate and a grooved epoxy gasket connected in sequence, and the pressure sensor is disposed on the crossbeam.

[0009] Another embodiment provided in this application is as follows: the temperature measuring mechanism includes an electrode, a thermocouple is disposed on the electrode, the thermocouple is connected to a second temperature controller, and the electrode is disposed inside the slotted epoxy gasket.

[0010] Another embodiment provided in this application is as follows: the temperature measuring mechanism includes a heating plate, the heating plate is connected to an oil circulation machine, the oil circulation machine is connected to a first temperature controller, and the insulating material is placed on the heating plate.

[0011] Another embodiment provided in this application is that the electrode is a cylindrical brass electrode.

[0012] Another embodiment provided in this application is: the electrode is provided with a groove, and the thermocouple is disposed in the groove.

[0013] Another embodiment provided in this application is: the thermocouple includes a probe end and a data transmission end, and the data transmission end is connected to the second temperature controller.

[0014] Another embodiment provided in this application is: an insulating epoxy pad is provided below the heating plate.

[0015] Another embodiment provided in this application is that the insulating material is a BOPP film.

[0016] 3. Beneficial effects

[0017] Compared with the prior art, the beneficial effects of the insulation characteristic testing platform provided in this application are as follows:

[0018] The insulation characteristic testing platform provided in this application is a multi-stress insulation characteristic testing platform that takes into account the influence of contact thermal resistance, so as to obtain the temperature setpoint of the temperature control system after considering the influence of pressure on contact thermal resistance under electrothermal coupling experimental conditions.

[0019] The insulation characteristic testing platform provided in this application is used for insulation characteristic experiments of insulating materials under multiple stress conditions. Attached Figure Description

[0020] Figure 1 This is a microscopic schematic diagram of the material contact surface;

[0021] Figure 2 This is a schematic diagram of the insulation characteristic testing platform structure of this application;

[0022] Figure 3 This is a partial structural schematic diagram of the insulation characteristic testing platform of this application;

[0023] Figure 4 This is a schematic diagram of the temperature measurement mechanism structure of this application;

[0024] Figure 5 This is a schematic diagram of the thermal coupling process of this application;

[0025] Figure 6 This is a schematic diagram showing how the surface temperature of the material changes with pressure. Detailed Implementation

[0026] In the following, specific embodiments of this application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand and implement this application. Without departing from the principles of this application, features from various embodiments can be combined to obtain new implementations, or certain features from some embodiments can be substituted to obtain other preferred implementations.

[0027] See Figures 1-6 This application provides an insulation characteristic testing platform, which includes a universal testing machine 1 connected to a smart terminal. The universal testing machine 1 is equipped with a pressure applying mechanism, a temperature measuring mechanism, and a heating mechanism connected in sequence. The temperature measuring mechanism is connected to the smart terminal. The pressure applying mechanism applies pressure to an insulating material 12, and the heating mechanism heats the insulating material 12. The temperature measuring mechanism collects the surface temperature of the insulating material 12, obtaining a curve showing the change in surface temperature of the insulating material 12 with pressure. A fitting formula for the change in contact thermal resistance with pressure is calculated. The magnitude of the contact thermal resistance under a certain pressure condition is obtained through the fitting formula. The correction amount for the temperature setpoint is then calculated from the contact thermal resistance, and the temperature control setpoint is corrected so that the surface temperature of the insulating material 12 reaches the expected temperature.

[0028] The smart terminal here can be a computer, mobile phone, or tablet. The smart terminal processes the data collected by the temperature measurement device.

[0029] Furthermore, the universal testing machine 1 includes a crossbeam and a press. The crossbeam is located at one end of the universal testing machine, and the press is located at the other end of the universal testing machine. The pressure application mechanism includes a pressure sensor 2, a pressure plate 3, and a slotted epoxy gasket 4 connected in sequence. The pressure sensor 2 is located on the lower surface of the crossbeam.

[0030] Furthermore, the temperature measuring mechanism includes a brass column electrode 9, on which a thermocouple 10 is disposed. The thermocouple 10 is connected to a second temperature controller 11, and the electrode 9 is placed inside the slotted epoxy gasket 4.

[0031] Furthermore, the temperature measuring mechanism includes a heating plate 7, which is connected to an oil circulation machine 6. The oil circulation machine 6 is connected to a first temperature controller 5, and the insulating material is placed on the heating plate 7.

[0032] Place the insulating material 12 on the heating plate 7, set a certain temperature through the second temperature controller 5, turn on the heating and circulation buttons of the constant temperature oil circulation machine 6, wait for the temperature of the circulating oil in the constant temperature oil circulation machine 6 to stabilize, and read the temperature shown by the second temperature controller 5.

[0033] The universal testing machine 1 is used to apply different pressures to the insulating material. The temperature data table measured by the second thermometer 11 is read, and the contact thermal resistance under different pressures is calculated. Based on the obtained contact thermal resistance under different pressures, the data is fitted to obtain the fitting formula of contact thermal resistance with pressure F. The dependent variable of the formula is the contact thermal resistance and the independent variable is the pressure.

[0034] Based on the definition of contact thermal resistance, the correction amount ΔT for the set value of the first temperature controller 5 is obtained as follows: ΔT = R th *P,R th To determine the contact thermal resistance, the above-obtained fitting formula can be used in conjunction with the pressure and temperature values ​​at this time for calculation. P is the heating power of heating plate 7. Finally, the fitting formula for the temperature correction amount ΔT at this set temperature as a function of pressure F is obtained.

[0035] Based on the fitting formula of the temperature correction amount ΔT changing with pressure F, the correction amount of the oil bath machine temperature controller setting value is obtained when a certain pressure value is applied. In the actual insulation characteristic test experiment of the insulation material 12, the setting value of the first temperature controller 5 should be set to the expected heating temperature plus the obtained correction amount, so that the setting temperature of the first temperature controller 5 changes with the pressure. That is, the actual heating temperature on the insulation material 12 takes into account the influence of contact thermal resistance, so that the actual temperature of the insulation material 12 is consistent with the expected heating temperature.

[0036] Furthermore, the electrode 9 is a cylindrical brass electrode.

[0037] Furthermore, the electrode 9 is provided with a groove, and the thermocouple 10 is placed in the groove.

[0038] Furthermore, the thermocouple 10 includes a probe end and a data transmission end, the probe end being in close contact with the insulating material, and the data transmission end being connected to the second temperature controller 11.

[0039] Furthermore, an insulating epoxy gasket 8 is provided below the heating plate 7.

[0040] Furthermore, the insulating material 12 is a BOPP film. The insulating material here includes all materials whose insulation properties need to be tested, whether in film or sheet form.

[0041] The heating temperature of the constant temperature oil circulation machine 6 is set by the first temperature controller 5, and the insulating material 12 is heated by the heating plate 7. The universal testing machine 1 is responsible for applying pressure to the insulating material 12, and the thermocouple 10 is responsible for collecting the actual surface temperature of the insulating material 12. The curve of the actual surface temperature of the insulating material 12 changing with pressure is measured, and the fitting formula of the change of the contact thermal resistance between the insulating material 12 and the heating plate with pressure is further calculated. The magnitude of the contact thermal resistance under a certain pressure condition can be obtained through the obtained fitting formula. Then, the correction amount of the temperature set by the first temperature controller 5 is calculated from the contact thermal resistance, which solves the problem of the deviation between the temperature control set temperature and the actual temperature of the material, so that the surface temperature of the material reaches the expected heating temperature. This solves the problem of the influence of the change of material contact thermal resistance caused by pressure on the surface temperature of the material in the insulation characteristic test experiment under multiple stress.

[0042] Example

[0043] The electronic universal testing machine 1 is connected to a computer via a data cable, allowing the computer to control the machine to apply the required pressure with an accuracy of ±0.5%. The universal testing machine 1 has a horizontal beam that can move up and down, applying pressure to the test area. A pressure sensor is connected to the lower surface of the beam, reading the pressure applied to the test area and transmitting it to the computer. A pressure plate 3 is connected to the lower surface of the pressure sensor 2; its larger area allows for more even pressure application to the testing area. A slotted epoxy gasket 4 is connected to the lower surface of the pressure plate 3; the epoxy resin provides excellent insulation, preventing heat from the heating mechanism from being transferred upwards. A brass electrode 9 is placed inside the slotted epoxy gasket, and the slotted design facilitates the fixation of the brass electrode 9.

[0044] The first temperature controller 5 can be manually set to the target heating temperature of the oil circulation machine 6. The oil circulation machine 6 contains heating oil, which circulates between the oil circulation machine 6 and the heating plate 7, so that the temperature of the heating plate 7 is consistent with the temperature set by the first temperature controller 5. Insulating material 12 is placed on the heating plate 7, and the heating plate 7 heats the insulating material 12. An insulating epoxy gasket 8 is placed under the heating plate 7 to provide insulation and ensure that the temperature of the heating plate 7 is not transferred downwards.

[0045] like Figure 5 As shown, this patent considers the mechanism of pressure's influence on the temperature of the thin film sample. First, without applying voltage and considering the effect of voltage on temperature, an initial experiment is conducted without pressure to obtain the relationship between the actual temperature of the BOPP film and the set value under the initial condition. At this point, the contact thermal resistance is relatively high, and there is a significant deviation between the set value and the actual film temperature. Second, the pressure device is turned on, and different pressures are applied. Under constant temperature, the actual temperatures of the BOPP film under different pressures are obtained to verify the effect of pressure application on contact thermal resistance. A fitting formula for the change of contact thermal resistance with pressure is calculated. Next, the one-dimensional heat conduction function relationship is calculated, and numerical simulations under thermo-mechanical coupling are performed. The experimental data fitting formula is combined with theoretical calculations and numerical simulations for analysis, giving the relationship between pressure and BOPP film temperature. Based on this relationship, the temperature correction amount under a certain pressure can be calculated to correct the temperature controller set value.

[0046] To ensure that the heat transfer effect of the experimental platform in this application is consistent with that of the actual insulation test experimental platform, and considering that the national standard for insulation performance testing adopts cylindrical brass electrodes, this application also uses cylindrical brass electrodes to directly apply pressure to the insulating material; the bottom surface of the brass electrode is grooved, and the width and depth of the groove are determined according to the diameter of the thermocouple; a thermocouple probe with a diameter smaller than the groove width is placed in the groove of the brass electrode; the lower surface of the brass electrode is pressed against the upper surface of the insulating material 12, so that the thermocouple probe is in close contact with the insulating material 12; the data transmission end of the thermocouple 10 is connected to the second temperature controller 11, which can collect and display the probe temperature in real time, and the probe temperature is the surface temperature of the insulating material 12.

[0047] Figure 6 The vertical axis of the curve represents the temperature value, and the horizontal axis represents the position of the material surface. It is a simulation calculation of the experimental device to extract the actual surface temperature of the thin film material at different positions. The horizontal axis represents the different positions on the surface of the thin film material, with the pressure value gradually increasing from bottom to top, from 0 to 1250 N, with a step size of 250 N. The cluster of curves indicates that as the pressure increases, the surface temperature of the tested sample tends to rise, while the rate of increase gradually decreases.

[0048] Although this application has been described above with reference to specific embodiments, those skilled in the art will understand that many modifications can be made to the configurations and details disclosed in this application within the principles and scope of the disclosure. The scope of protection of this application is determined by the appended claims, and the claims are intended to cover all modifications included in the literal meaning or scope of equivalents of the technical features in the claims.

Claims

1. An insulation characteristic testing platform, the testing platform comprising a universal testing machine, the universal testing machine being connected to a smart terminal, characterized in that: The universal testing machine is equipped with a pressure applying mechanism, a temperature measuring mechanism, and a heating mechanism connected in sequence. The temperature measuring mechanism is connected to the smart terminal. The pressure applying mechanism applies pressure to the insulating material, the heating mechanism heats the insulating material, and the temperature measuring mechanism collects the surface temperature of the insulating material to obtain a curve showing the change of the surface temperature of the insulating material with pressure. A fitting formula for the change of contact thermal resistance with pressure is calculated. A second fitting formula for the change of temperature correction amount with pressure at a set temperature is obtained through the fitting formula. The correction amount for the set temperature is calculated based on the second fitting formula, and the temperature set value is corrected using the correction amount so that the surface temperature of the insulating material reaches the expected temperature.

2. The insulation characteristic testing platform as described in claim 1, characterized in that: The universal testing machine includes a crossbeam and a press. The crossbeam is located at one end of the universal testing machine, and the press is located at the other end of the universal testing machine. The pressure application mechanism includes a pressure sensor, a pressure plate, and a slotted epoxy gasket connected in sequence. The pressure sensor is located on the crossbeam.

3. The insulation characteristic testing platform as described in claim 2, characterized in that: The temperature measuring mechanism includes an electrode, on which a thermocouple is mounted. The thermocouple is connected to a second temperature controller, and the electrode is located within the slotted epoxy gasket.

4. The insulation characteristic testing platform as described in claim 3, characterized in that: The temperature measuring mechanism includes a heating plate, which is connected to an oil circulation machine, which is connected to a first temperature controller, and the insulating material is placed on the heating plate.

5. The insulation characteristic testing platform as described in claim 3, characterized in that: The electrode is a cylindrical brass electrode.

6. The insulation characteristic testing platform as described in claim 5, characterized in that: The electrode has a groove, and the thermocouple is disposed in the groove.

7. The insulation characteristic testing platform as described in claim 6, characterized in that: The thermocouple includes a probe end and a data transmission end, and the data transmission end is connected to the second temperature controller.

8. The insulation characteristic testing platform as described in claim 4, characterized in that: An insulating epoxy pad is provided below the heating plate.

9. The insulation characteristic testing platform according to any one of claims 1 to 8, characterized in that: The insulating material is BOPP film.

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