Temperature-controllable dielectric constant test equipment and use method thereof

Abstract

The invention discloses temperature-controllable dielectric constant test equipment and a use method thereof, and belongs to the technical field of electrical performance detection of insulating materials. The equipment comprises a high-precision high-voltage capacitance bridge, a temperature control shielding box and a test electrode, wherein the test electrode comprises a measuring electrode, a protection electrode, a grounding electrode, a thermocouple and an insulating sleeve; the temperature control shielding box comprises a shielding box and a temperature control module, the temperature control module comprises a heating resistor, a controller and a relay, and the controller is connected with the thermocouple of the test electrode. The temperature control over the dielectric constant room temperature can be achieved, the three electrodes are adopted for measuring the temperature at the same time, the temperature is more accurate, and distribution is more uniform. And a test system and a temperature control system of the test equipment are completely isolated, and a thermocouple is provided with an insulating sleeve, so that the influence on temperature control during high-voltage test is prevented, and the test accuracy is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical performance detection of insulating materials, and relates to a temperature-controllable dielectric constant test device and a use method thereof. Background Art

[0002] Ultra-high voltage direct current transmission technology has become a key means to solve the uneven distribution of energy and promote the efficient use of clean energy due to its significant advantages of long distance, large capacity and low loss. With the widespread construction of ultra-high voltage direct current transmission projects, the performance and reliability of the converter transformer, as the core equipment of the direct current transmission system, are directly related to the stable operation of the entire transmission system.

[0003] The converter transformer is different from the traditional AC transformer. It plays an important role in converting AC to DC (or vice versa) in the DC transmission system. This conversion process involves complex power electronic device control and a large amount of energy conversion, which makes the converter transformer face more severe working conditions during operation. In particular, a large amount of harmonic current and voltage fluctuations will be generated inside the converter transformer. These non-sinusoidal currents not only increase the loss of the transformer, but also may cause local overheating and accelerated aging of the insulation material. In addition, the converter transformer usually operates at a higher voltage level and capacity level, which makes the electric field distribution and temperature field distribution inside it extremely complex. The determination of the hot spot location and the highest temperature point becomes a major problem. In the face of these challenges, the insulation system design of the converter transformer is particularly important. As the first line of defense to protect the transformer from electrical breakdown and overheating damage, the electrical performance, thermal stability and long-term aging characteristics of the insulation material are directly related to the safe operation life of the transformer. In particular, under high temperature and high electric field strength, the dielectric properties of the insulation material (such as dielectric constant, dielectric loss, etc.) will change significantly, and these changes directly affect the insulation strength and energy loss of the transformer. The dielectric constant is a physical quantity that measures the material's ability to store electric field energy. Its change with temperature is one of the key parameters for studying the performance changes of insulating materials. However, the electrode part of the existing dielectric constant test equipment does not have the function of temperature regulation, which makes it difficult to meet the test requirements.

[0004] In summary, it is urgent to develop a dielectric constant testing equipment that can accurately control the test temperature, so as to accurately capture the changes in the dielectric properties of materials at different temperatures and provide scientific and effective testing equipment for the research and development of insulating materials for transformers. Summary of the invention

[0005] The purpose of the present invention is to provide a temperature-controllable dielectric constant test device and a method of using the same, so as to solve the technical problems that the dielectric constant test device in the prior art is difficult to meet the test requirements of insulating materials at different temperatures and the temperature is difficult to control.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a temperature-controllable dielectric constant testing device, comprising a capacitance bridge, a temperature-controlled shielding box and a test electrode; the test electrode is installed in the temperature-controlled shielding box, the test electrode is used to clamp the sample to be tested, and the temperature-controlled shielding box can control the test temperature; the capacitance bridge is electrically connected to the temperature-controlled shielding box and the test electrode, respectively.

[0007] Furthermore, the test electrode includes a measuring electrode, a guard electrode and a grounding electrode; the grounding electrode is located on one side of the sample to be tested, and the measuring electrode and the guard electrode are located on the other side of the sample to be tested; the measuring electrode and the grounding electrode are cylindrical structures, and the guard electrode is a circular ring structure; the guard electrode is sleeved outside the measuring electrode, leaving a gap between the guard electrode and the measuring electrode.

[0008] Furthermore, the guard electrode and the measuring electrode are coaxially arranged.

[0009] Furthermore, thermocouples are arranged on the measuring electrode, the protection electrode and the grounding electrode.

[0010] Furthermore, the thermocouple is covered with an insulating sleeve.

[0011] Furthermore, the temperature-controlled shielding box comprises a shielding box, a heating resistor and a temperature control module; the heating resistor is located in the shielding box, and the temperature control module is electrically connected to the thermocouple and the heating resistor respectively.

[0012] Furthermore, the temperature control module includes a controller and a relay electrically connected to each other; the controller is electrically connected to the thermocouple, and the relay is electrically connected to the heating resistor.

[0013] Furthermore, the shielding box is composed of a double-layer metal structure, and the heating resistor is located between the double-layer metal structure.

[0014] Furthermore, an opening and closing door is installed on one side of the shielding box.

[0015] In a second aspect, the present invention provides a method for using the temperature-controllable dielectric constant test device, comprising the following steps: Sample handling: Place the sample to be tested on the ground electrode after pretreatment, and then press the sample to be tested with the measuring electrode and the guard electrode, and ensure that the guard electrode is coaxial with the measuring electrode; Temperature setting: The temperature is set by the controller, and the controller starts heating the heating resistor through the relay, so that the temperature inside the shielding box increases; the temperature of the test electrode is measured by the thermocouple, and when the difference between the various temperature values ​​is less than 0.5°C and the average temperature reaches the preset temperature, the controller stops heating the heating resistor through the relay and prepares to start the test; In the dielectric constant measurement test, the capacitor bridge is turned on and preheated. After the temperature-controlled shielding box reaches the preset test temperature, the test voltage and test material parameters are set, and the sensitivity is adjusted from low to high. The capacitor bridge is balanced at each sensitivity to measure the dielectric constant of the solid insulating material.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a temperature-controllable dielectric constant test equipment and a method for using the same. The test temperature can be accurately controlled as required by a temperature-controlled shielding box. The temperature-controlled shielding box can not only effectively control the temperature, but also play the role of electromagnetic shielding, protecting the test personnel and the test equipment from external electromagnetic interference, and ensuring the safety and stability of the test process. In addition, the present invention measures the temperature of the measuring electrode, the protective electrode, and the grounding electrode at the same time, and the temperature is more accurate and the distribution is more uniform. In addition, the test equipment test system of the present invention is completely isolated from the temperature control system, and the thermocouple is equipped with an insulating sleeve to prevent the high-voltage test from affecting the temperature control and ensure the accuracy of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 The figure is a schematic diagram of the overall structure of a temperature-controllable dielectric constant testing device of the present invention.

[0019] Among them: 1-capacitance bridge; 2-temperature control shielding box; 21-shielding box; 22-heating resistor; 23-controller; 24-relay; 31-measuring electrode; 32-protective electrode; 33-grounding electrode; 34-thermocouple; 35-insulating sleeve; 4-sample to be tested. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0023] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1The embodiment of the present invention discloses a temperature-controllable dielectric constant test device, including a capacitance bridge 1, a temperature-controlled shielding box 2 and a test electrode; the test electrode is installed in the temperature-controlled shielding box 2, the test electrode is used to clamp the sample 4 to be tested, and the temperature-controlled shielding box 2 can control the test temperature; the capacitance bridge 1 is electrically connected to the temperature-controlled shielding box 2 and the test electrode respectively. This embodiment can accurately control the test temperature as required through the temperature-controlled shielding box 2. The temperature-controlled shielding box 2 can not only effectively control the temperature to meet the test requirements of insulating materials at different temperatures, but also play the role of electromagnetic shielding, protecting the test personnel and test equipment from external electromagnetic interference, and ensuring the safety and stability of the test process.

[0027] In a feasible embodiment of the present invention, the test electrode includes a measuring electrode 31, a guard electrode 32 and a grounding electrode 33, and the test electrode includes the measuring electrode 31, the guard electrode 32 and the grounding electrode 33, which are all electrically connected to the capacitance bridge 1; the grounding electrode 33 is located on one side of the sample 4 to be tested, and the measuring electrode 31 and the guard electrode 32 are located on the other side of the sample 4 to be tested; the measuring electrode 31 and the grounding electrode 33 are cylindrical structures, and the guard electrode 32 is an annular structure; the guard electrode 32 is sleeved outside the measuring electrode 31, and a gap is left between the guard electrode 32 and the measuring electrode 31. And the guard electrode 32 is coaxially arranged with the measuring electrode 31.

[0028] In a feasible embodiment of the present invention, the measuring electrode 31, the protective electrode 32 and the grounding electrode 33 are all provided with a thermocouple 34. The thermocouple 34 is covered with an insulating sleeve 35. The present invention measures the temperature of the measuring electrode 31, the protective electrode 32 and the grounding electrode 33 at the same time, and the temperature is more accurate and the distribution is more uniform. The insulating sleeve 35 can reduce the heat exchange between the thermocouple 34 and the surrounding medium, prevent the influence on the temperature control during the high-voltage test, reduce the measurement error caused by environmental factors, and thus improve its measurement accuracy.

[0029] In a feasible embodiment of the present invention, the temperature-controlled shielding box 2 includes a shielding box 21, a heating resistor 22 and a temperature control module; the shielding box 21 is composed of a double-layer metal structure, the heating resistor 22 is located between the double-layer metal structure, and an opening and closing door is installed on one side of the shielding box 21. The temperature control module is electrically connected to the thermocouple 34 and the heating resistor 22 respectively.

[0030] The temperature control module includes a controller 23 and a relay 24 which are electrically connected to each other; the controller 23 is electrically connected to a thermocouple 34 , and the relay 24 is electrically connected to a heating resistor 22 .

[0031] The embodiment of the present invention discloses a method for using the temperature-controllable dielectric constant testing device, comprising the following steps: Step 1, sample handling: The sample 4 to be tested is placed on the ground electrode 33 after pretreatment, and then the sample 4 to be tested is pressed tightly by the measuring electrode 31 and the protective electrode 32 , and it is ensured that the protective electrode 32 is coaxially arranged with the measuring electrode 31 .

[0032] In this step, it can be ensured that the sample to be tested is clamped between the test electrodes evenly and stably, and the protection electrode 32 and the measuring electrode 31 are kept equidistant, which effectively reduces the influence of the edge effect on the test result, thereby improving the accuracy of the dielectric constant measurement.

[0033] Step 2, temperature setting: The temperature is set by the controller 23, and the controller 23 starts heating the heating resistor 22 through the relay 24, so that the temperature in the shielding box 21 increases; the temperature of the test electrode is measured by the thermocouple 34, and when the difference between the various temperature values ​​is less than 0.5°C and the temperature average reaches the preset temperature, the controller 23 stops heating the heating resistor 22 through the relay 24 and prepares to start the test; In this step, the temperature in the shielding box 21 is precisely controlled by the controller, and the test is started only after the temperature is stabilized, thereby further eliminating the interference of temperature fluctuations on the test results.

[0034] Step 3, dielectric constant measurement test: The capacitor bridge 1 is turned on and preheated. After the temperature-controlled shielding box 2 reaches the preset test temperature, the test voltage and test material parameters are set, and the sensitivity is adjusted from low to high. The capacitor bridge is balanced at each sensitivity to measure the dielectric constant of the solid insulating material.

[0035] The method of this embodiment allows the user to set different test temperatures according to actual needs, so that the material properties under different temperature environments can be simulated, providing researchers with a broader testing space. This flexibility enables the device to be applicable to the dielectric constant test of a variety of solid insulating materials, meeting the research needs of different fields. Accurate control and stable maintenance of temperature are achieved through automated control means (such as controller 23, relay 24, etc.), thereby reducing manual intervention during the test process and improving test efficiency. In addition, the method also allows real-time monitoring of temperature values ​​during the test process to ensure the consistency of test conditions and further improve test efficiency.

[0036] The working principle of the present invention is as follows: The temperature controllable capacitance bridge test equipment of the present invention comprises a high-precision and high-voltage capacitance bridge 1, a temperature control shielding box 2, and a test electrode, wherein the test electrode comprises a measuring electrode 31, a protective electrode 32, a grounding electrode 33, a thermocouple 34, and an insulating sleeve 35; the temperature control shielding box 2 comprises a shielding box 21 and a temperature control module, wherein the shielding box 21 is a double-layer metal structure, and an opening and closing door is arranged in the front; the temperature control module comprises a heating resistor 22, a controller 23, and a relay 24. The high-precision capacitance bridge 1 is connected to the three electrodes of the test electrode, provides a high-voltage test voltage, adjusts the bridge balance, and reads the test result; the test electrode is placed in the temperature control shielding box 2, and the three electrodes are equipped with a thermocouple 34 to measure the temperature of the three electrodes; the thermocouple 34 measures the temperature and feeds it back to the controller 23 of the temperature control module, and the controller 23 can set the test temperature. When the measured temperature is lower than the set temperature, the controller 23 controls the relay 24 to close, and the heating resistor 22 starts heating, otherwise the heating stops, and the controller 23 has a temperature display. When the temperature reaches the set temperature, the controller sends a signal to remind the start of the test. The present invention can realize temperature control above room temperature of dielectric constant, and adopts three electrodes to measure temperature simultaneously, so that the temperature is more accurate and the distribution is more uniform. In addition, the test equipment test system and the temperature control system are completely isolated, and the thermocouple 34 is equipped with an insulating sleeve 35 to prevent the high voltage test from affecting the temperature control and ensure the accuracy of the test.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A temperature-controllable dielectric constant test device, characterized in that: The invention comprises a capacitance bridge (1), a temperature-controlled shielding box (2) and a test electrode; the test electrode is installed in the temperature-controlled shielding box (2), the test electrode is used to clamp a sample to be tested (4), and the temperature-controlled shielding box (2) can control the test temperature; the capacitance bridge (1) is electrically connected to the temperature-controlled shielding box (2) and the test electrode respectively.

2. A temperature-controllable dielectric constant testing device according to claim 1, characterized in that: The test electrode comprises a measuring electrode (31), a protective electrode (32) and a grounding electrode (33); the grounding electrode (33) is located on one side of the sample to be tested (4), and the measuring electrode (31) and the protective electrode (32) are located on the other side of the sample to be tested (4); the measuring electrode (31) and the grounding electrode (33) are cylindrical structures, and the protective electrode (32) is an annular structure; the protective electrode (32) is sleeved outside the measuring electrode (31), with a gap between the protective electrode (32) and the measuring electrode (31).

3. A temperature-controllable dielectric constant testing device according to claim 2, characterized in that: The protection electrode (32) is coaxially arranged with the measuring electrode (31).

4. The temperature-controllable dielectric constant testing device according to claim 2, characterized in that: The measuring electrode (31), the protection electrode (32) and the grounding electrode (33) are all provided with thermocouples (34).

5. The temperature-controllable dielectric constant testing device according to claim 4, characterized in that: The thermocouple (34) is provided with an insulating sleeve (35) on its outer casing.

6. The temperature-controllable dielectric constant testing device according to claim 4, characterized in that: The temperature-controlled shielding box (2) comprises a shielding box (21), a heating resistor (22) and a temperature control module; the heating resistor (22) is located in the shielding box (21), and the temperature control module is electrically connected to the thermocouple (34) and the heating resistor (22) respectively.

7. The temperature-controllable dielectric constant testing device according to claim 6, characterized in that: The temperature control module comprises a controller (23) and a relay (24) which are electrically connected to each other; the controller (23) is electrically connected to a thermocouple (34), and the relay (24) is electrically connected to a heating resistor (22).

8. The temperature-controllable dielectric constant testing device according to claim 7, characterized in that: The shielding box (21) is composed of a double-layer metal structure, and the heating resistor (22) is located between the double-layer metal structure.

9. The temperature-controllable dielectric constant testing device according to claim 8, characterized in that: An opening and closing door is installed on one side of the shielding box (21).

10. A method for using the temperature-controllable dielectric constant testing device according to any one of claims 1 to 9, characterized in that: The following steps are involved: Sample handling: placing the sample to be tested (4) on the ground electrode (33) after pretreatment, and then pressing the sample to be tested (4) with the measuring electrode (31) and the guard electrode (32), and ensuring that the guard electrode (32) and the measuring electrode (31) are coaxially arranged; Temperature setting, setting the temperature through the controller (23), the controller (23) starts heating the heating resistor (22) through the relay (24), thereby increasing the temperature inside the shielding box (21); measuring the temperature of the test electrode through the thermocouple (34), and when the difference between the temperature values ​​is less than 0.5°C and the temperature average reaches a preset temperature, the controller (23) stops heating the heating resistor (22) through the relay (24), and prepares to start the test; In the dielectric constant measurement test, the capacitor bridge (1) is turned on and preheated. After the temperature-controlled shielding box (2) reaches the preset test temperature, the test voltage and test material parameters are set, and the sensitivity is adjusted from low to high. At each sensitivity, the capacitor bridge is balanced to measure the dielectric constant of the solid insulating material.

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