Transformer oil paper insulation aging test device based on pressure stress

Abstract

The utility model relates to a transformer oil paper insulation aging test device based on pressure stress, which comprises a test box, a base is arranged on the inner bottom surface of the test box, movable pressure heads are arranged above the base at intervals, and the movable pressure heads move towards the base under the action of driving power; the first copper wire and the second copper wire are arranged between the movable pressure head and the base at intervals up and down and are connected to a current control loop in series; the surfaces of the first copper wire and the second copper wire are uniformly wound with oiled paper, and an insulating cushion block is clamped between the first copper wire and the second copper wire; on the basis of conventional oil paper thermal aging, mechanical pressure is introduced for testing, so that the actual working condition of oil paper aging can be simulated more truly, and the accuracy of an oil paper aging characteristic test research result is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, and in particular to a transformer oil paper insulation aging test device based on compressive stress. Background Technology

[0002] Oil-paper insulation is the primary insulation form for large oil-immersed power transformers. During long-term operation, the oil-paper gradually ages due to factors such as electrical, thermal, and mechanical stress. Although minor aging reduces the breakdown strength of the insulation paper, it significantly weakens its mechanical strength and reduces its resistance to impact short circuits. Furthermore, the detachment of aged fibers from the insulation paper into the insulating oil weakens the electrical strength of the oil-paper insulation, threatening the operational safety of the equipment. The aging process of the winding insulation paper is irreversible, and the oil-paper itself cannot be replaced; therefore, the lifespan of the insulation paper determines the actual technical lifespan of the oil-immersed transformer.

[0003] Since the aging process of insulating paper is greatly affected by various physical and chemical factors in the actual operating environment, conducting research on the insulation aging characteristics of transformer oil paper under different factors is of great engineering significance for the insulation design and remaining life assessment of oil-immersed transformers.

[0004] Most current research on oil paper aging only involves the influence of single or combined factors among conventional factors such as electric field, heat, moisture, and oxygen concentration. For example, patent document CN 117538709A, published on 20240209, discloses a multi-factor combined aging test device and method for transformer oil paper insulation, involving the study of the influence of multiple factors such as electricity, heat, and ambient oxygen concentration on insulation aging; patent document CN 117907764 A, published on 20240419, discloses an oil paper insulation thermal aging test device and a method for constructing an oil paper insulation thermal life model, involving the aging study of insulating oil paper at various temperatures, and constructing a thermal life model of insulating oil paper based on a series of test results.

[0005] In actual operation, besides electrical aging, thermal aging, and environmental aging, the impact of mechanical stress, which also plays a crucial role in the aging process of oil-paper insulation, is rarely considered. In fact, the oil-paper insulation material in transformers bears various forms of mechanical stress, including the electromagnetic force generated by the combined action of constant winding clamping force, alternating winding current, and leakage flux. When subjected to continuous mechanical stress, the rate and process of the internal fibers of the oil-paper shedding into the insulating oil due to aging are significantly affected. Cracks appear in the molecular structure of the oil-paper material, gradually increasing in size over time. When these quantitative changes accumulate to a certain extent, a qualitative change occurs, and the oil-paper material structure completely breaks down and loses its insulating function.

[0006] Therefore, the results and conclusions derived from the aging study of oil-paper insulation without considering the objective factor of mechanical stress are inaccurate and deviate significantly from the actual situation. To address this problem, this application provides a transformer oil-paper insulation aging test device based on compressive stress, to solve the aforementioned issues. Utility Model Content

[0007] To address the aforementioned issues, this application provides a reasonably structured transformer oil-paper insulation aging test device based on compressive stress, which can more realistically simulate the actual working conditions of oil-paper aging and effectively improve the accuracy of the test results of oil-paper aging characteristics.

[0008] The technical solution adopted in this utility model is as follows:

[0009] A transformer oil-paper insulation aging test device based on compressive stress includes a test box, a base installed on the bottom surface of the test box, and movable pressure heads spaced apart above the base. The movable pressure heads move toward the base under the action of driving power. It also includes a first copper wire and a second copper wire spaced apart vertically between the movable pressure heads and the base. The first copper wire and the second copper wire are connected in series to a current control circuit. The surfaces of the first copper wire and the second copper wire are uniformly wrapped with oil paper, and an insulating pad is placed between the first copper wire and the second copper wire.

[0010] As a further improvement of the above technical solution:

[0011] The first copper wire and the second copper wire are connected in series at one end via a short wire, and the other end is connected to the corresponding terminal block via a wire. The terminal block is installed on the top cover of the test box, and the two terminal blocks are connected to an external power source to form a current control circuit.

[0012] Temperature and pressure sensor modules are respectively arranged on the sides of the first copper wire and the second copper wire facing each other. The temperature and pressure sensor modules are arranged facing each other and are respectively wrapped inside the oil paper.

[0013] The first and second copper wires, placed one above the other, are of the same size and their projections overlap. The projection centers of the first and second copper wires, the temperature and pressure sensor modules, and the insulating pad are located on the same vertical line. The two temperature and pressure sensor modules are located on the upper and lower sides of the insulating pad, respectively.

[0014] The temperature and pressure sensor module is a modular sheet structure composed of a temperature sensor and a pressure sensor integrated together. The area of ​​the temperature and pressure sensor module is smaller than the area of ​​the insulating pad.

[0015] It also includes a temperature and pressure detection module installed on the top cover of the test box, and the temperature and pressure sensor module is electrically connected to the temperature and pressure detection module.

[0016] The test box is a metal sealed box, and the current control circuit, driving power, and temperature and pressure detection module are all installed insulated relative to the test box.

[0017] A drive shaft is connected to the top of the movable pressure head. The drive shaft extends upwards out of the test box and connects to the output end of the pressure driving power, which constitutes the driving power for the movable pressure head to move up and down. A through plate is installed between the drive shaft and the top cover of the test box.

[0018] The second copper wire located below is fixed to the base by a positioning component.

[0019] The test chamber is filled with transformer oil. A top cover is detachably installed on the upper part of the test chamber, and an oil drain valve is installed on the lower part of the side wall of the test chamber.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention introduces mechanical pressure into the conventional thermal aging test of oil paper, thereby more realistically simulating the actual working conditions of oil paper aging and effectively improving the accuracy of the test results of oil paper aging characteristics.

[0022] This utility model also has the following advantages:

[0023] By clamping an insulating pad between the first and second copper conductors, and applying force through the movable pressure head above, combined with a current control circuit, a "sandwich" structure is used to simulate the contact and compression conditions at the locations where support bars or pads are placed between turns or layers of a real power transformer winding. This simulates the aging conditions of oil-paper under normal transformer operation and voltage impact, helping to ensure the accuracy of the test results. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of this utility model.

[0025] Figure 2 This is a schematic diagram of the winding of the oil paper on the side of the first copper conductor of this utility model.

[0026] Figure 3 This is a schematic diagram showing the limiting position of the second copper wire on the base according to this utility model.

[0027] The components include: 1. Test box; 2. Wiring terminal; 3. Movable pressure head; 4. Temperature and pressure sensor module; 5. Insulating pad; 6. Base; 7. Second copper wire; 8. First copper wire; 9. Oil paper; 10. Oil drain valve.

[0028] 11. Top cover;

[0029] 31. Drive shaft; 32. Through disc; 33. Pressure-driven power;

[0030] 40. Temperature and pressure detection module;

[0031] 60. Positioning components. Detailed Implementation

[0032] The specific embodiments of this utility model are described below with reference to the accompanying drawings.

[0033] like Figure 1 As shown, this embodiment of a transformer oil-paper insulation aging test device based on compressive stress includes a test box 1, a base 6 mounted on the bottom surface of the test box 1, and movable pressure heads 3 spaced apart above the base 6. The movable pressure heads 3 move toward the base 6 under the action of driving force. It also includes a first copper wire 8 and a second copper wire 7 spaced apart vertically between the movable pressure heads 3 and the base 6, and the first copper wire 8 and the second copper wire 7 are connected in series to a current control circuit. The surfaces of the first copper wire 8 and the second copper wire 7 are uniformly wound with oil paper 9, such as... Figure 2 As shown, an insulating pad 5 is placed between the first copper wire 8 and the second copper wire 7.

[0034] In this embodiment, mechanical pressure is introduced into the test based on conventional thermal aging of oil paper, so as to more realistically simulate the actual working conditions of oil paper aging.

[0035] In this embodiment, an insulating pad 5 is sandwiched between the first copper wire 8 and the second copper wire 7. The force applied by the movable pressure head 3 above, combined with the heating by the current control circuit, is used to simulate the contact and compression conditions at the positions where the support bars or pads are placed between the turns or layers of the winding of a real power transformer. This can simulate the aging conditions of oil paper under normal operation and voltage impact of the transformer, which helps to ensure the accuracy of the test results.

[0036] The first copper wire 8 and the second copper wire 7 are connected in series at one end via a short wire, and the other end is connected to the corresponding terminal 2 via a wire. The terminal 2 is installed on the top cover 11 of the test box 1. The two terminal 2 are connected to the external power supply to form a current control circuit.

[0037] Temperature and pressure sensor modules 4 are respectively arranged on the sides of the first copper wire 8 and the second copper wire 7 facing each other. The temperature and pressure sensor modules 4 are arranged vertically and directly opposite each other and are respectively wrapped inside the oil paper 9, so that the copper wire, the corresponding temperature and pressure sensor module 4, and the oil paper 9 form an integral structure.

[0038] The first copper wire 8 and the second copper wire 7, placed vertically, are the same size and their vertical projections overlap. The projection centers of the first copper wire 8, the second copper wire 7, the temperature and pressure sensor module 4, and the insulating pad 5 are located on the same vertical line. The two temperature and pressure sensor modules 4 are located on the upper and lower sides of the insulating pad 5, respectively.

[0039] In this embodiment, based on the pressure information fed back by the temperature and pressure sensor module 4, pressure is applied to the first copper wire 8 and the second copper wire 7 through the movable pressure head 3, thereby simulating the compressive stress condition of the winding during operation.

[0040] In this embodiment, based on the temperature information fed back by the temperature and pressure sensor module 4, a current is generated through a current control loop for heating.

[0041] The temperature and pressure sensor module 4 is a modular sheet structure composed of a temperature sensor and a pressure sensor. The area of ​​the temperature and pressure sensor module 4 is smaller than the area of ​​the insulating pad 5.

[0042] It also includes a temperature and pressure detection module 40 installed on the top cover 11 of the test box 1. The temperature and pressure sensor module 4 is electrically connected to the temperature and pressure detection module 40, so as to monitor the real-time environmental pressure and temperature of the oil paper 9 during the test in a timely and effective manner.

[0043] Test box 1 is a metal sealed box, and the current control circuit, driving power, and temperature and pressure detection module 40 are all installed insulated relative to test box 1.

[0044] A drive shaft 31 is connected to the top of the movable pressure head 3. The drive shaft 31 extends upward from the test box 1 and is connected to the output end of the pressure driving power 33, which constitutes the driving power for the movable pressure head 3 to move up and down. A through plate 32 is installed between the drive shaft 31 and the top cover 11 of the test box 1.

[0045] In this embodiment, a drive shaft 31 and a through plate 32 are used to place the pressure driving power 33 outside the test box 1 and transmit the power of the pressure driving power 33 to the movable pressure head 3 located inside the test box 1; the through plate 32 effectively ensures the installation between the drive shaft 31 and the top cover 11 of the test box 1.

[0046] In this embodiment, the pressure driving power 33 can be a hydraulic power system or other power sources such as electric cylinders, oil cylinders, and pneumatic cylinders, depending on the actual test requirements.

[0047] like Figure 3 As shown, the second copper wire 7 located below is fixed to the base 6 by a positioning piece 60.

[0048] In this embodiment, a positioning element 60 can be pre-installed on the base 6 outside the second copper wire 7. The positioning element 60 restricts the position of the second copper wire 7, effectively preventing the second copper wire 7 from slipping during the test pressure process.

[0049] In this embodiment, the positioning element 60 can be a positioning pin or a positioning block, as long as it can limit the position of the second copper wire 7.

[0050] The test box 1 is filled with transformer oil. The top cover 11 is detachably installed on the upper part of the test box 1, and the oil drain valve 10 is installed on the lower part of the side wall of the test box 1.

[0051] In this embodiment, the body of the test box 1 and the top cover 11 can be connected by bolts and stepped limiters, which are conventional structural forms that facilitate test operation.

[0052] In this embodiment, two copper wires, namely the first copper wire 8 and the second copper wire 7, are used to form the test winding. The copper wires can be flat copper wires.

[0053] In actual tests, three, four, or more sections of copper wire can be set as test windings according to actual test requirements.

[0054] In actual testing, the pressure-driven power unit 33 operates, applying a specific pressure from directly above the first copper conductor 8 via the movable pressure head 3. The pressure value is adjusted according to the test requirements, taking into account the actual operating conditions of the transformer: considering that the clamping force during manufacturing and assembly is less than 10MPa, the alternating impact stress generated by a sudden short circuit is generally 50-100MPa, and the alternating electromagnetic force during normal operation is generally less than 1MPa; therefore, the pressure adjustment range can be set to 10-100MPa during the test.

[0055] During the pressurization process, the pressure value output by the temperature and pressure detection module 40 is observed in real time to ensure that the output pressure value is consistent with the preset pressurization value. At the same time, during the pressurization process, the projection centers of the first copper wire 8, the temperature and pressure sensor module 4, the insulating pad 5, the temperature and pressure sensor module 4, and the second copper wire 7 in the vertical direction are always coincided to effectively ensure that the pressure value at each pressurized point is relatively uniform and accurate during the pressurization process.

[0056] In practice, a transparent observation hole can be made on the test box 1, such as the top cover 11, to allow real-time observation of the test conditions inside the test box 1.

[0057] An external power supply is connected to the first copper wire 8 and the second copper wire 7 via terminal 2 for heating. During the heating process, the temperature value output by the temperature and pressure detection module 40 is referenced in real time to ensure that the output temperature value is consistent with the preset test temperature value. When the output temperature value is higher than the preset temperature value, the current control circuit is disconnected and the test winding is no longer heated. When the output temperature value is lower than the preset temperature value, the current control circuit is connected to continuously heat the test winding, maintaining the temperature of the external insulating oil paper of the winding within the range of ±1℃ of the preset temperature value.

[0058] During actual testing, the pressure, ambient temperature, and duration are determined according to the testing requirements; after the aging test is completed, the [equipment / mechanism] is opened. Figure 1 The test box 1 shown has a top cover 11. The test winding, oil paper 9, and transformer oil sample are taken out and tested and analyzed according to relevant standards for specific properties such as tensile strength, degree of polymerization, electrical strength, breakdown voltage, acid value, dielectric loss factor, and furfural.

[0059] This invention combines thermal and mechanical pressure in the experiment, which can more realistically simulate the actual aging conditions of oil paper and effectively improve the accuracy of the test results of oil paper aging characteristics.

[0060] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0061] The above description is an explanation of the present utility model and not a limitation thereof. The scope of the present utility model is defined by the claims. Within the protection scope of the present utility model, any form of modification may be made.

Claims

1. A transformer oil-paper insulation aging test device based on compressive stress, comprising a test box (1), characterized in that: The test box (1) is equipped with a base (6) on its inner bottom surface. Movable pressure heads (3) are arranged at intervals above the base (6). The movable pressure heads (3) move toward the base (6) under the action of driving power. It also includes a first copper wire (8) and a second copper wire (7) arranged at intervals between the movable pressure head (3) and the base (6). The first copper wire (8) and the second copper wire (7) are connected in series to the current control circuit. The surfaces of the first copper wire (8) and the second copper wire (7) are evenly wrapped with oil paper (9). An insulating pad (5) is placed between the first copper wire (8) and the second copper wire (7).

2. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 1, characterized in that: The first copper wire (8) and the second copper wire (7) are connected in series at one end via a short wire, and the other end is connected to the corresponding terminal (2) via a wire. The terminal (2) is installed on the top cover (11) of the test box (1), and the two terminals (2) are connected to the external power supply to form a current control circuit.

3. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 1, characterized in that: Temperature and pressure sensor modules (4) are respectively arranged on the sides of the first copper wire (8) and the second copper wire (7), and the temperature and pressure sensor modules (4) are arranged facing each other and respectively wrapped inside the oil paper (9).

4. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 3, characterized in that: The first copper wire (8) and the second copper wire (7) placed vertically are the same size and their vertical projections overlap. The projection centers of the first copper wire (8), the second copper wire (7), the temperature and pressure sensor module (4), and the insulating pad (5) are located on the same vertical line. The two temperature and pressure sensor modules (4) are located on the upper and lower sides of the insulating pad (5) respectively.

5. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 3, characterized in that: The temperature and pressure sensor module (4) is a modular sheet structure composed of a temperature sensor and a pressure sensor. The area of ​​the temperature and pressure sensor module (4) is smaller than the area of ​​the insulating pad (5).

6. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 3, characterized in that: It also includes a temperature and pressure detection module (40) installed on the top cover (11) of the test box (1), and the temperature and pressure sensor module (4) is electrically connected to the temperature and pressure detection module (40).

7. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 6, characterized in that: The test box (1) is a metal sealed box, and the current control circuit, driving power, and temperature and pressure detection module (40) are all installed insulated relative to the test box (1).

8. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 1, characterized in that: The top of the movable pressure head (3) is connected to a drive shaft (31). The drive shaft (31) extends upward from the test box (1) and is connected to the output end of the pressure driving power (33), which constitutes the driving power for the movable pressure head (3) to move up and down. A through plate (32) is installed between the drive shaft (31) and the top cover (11) of the test box (1).

9. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 1, characterized in that: The second copper wire (7) located below is fixed to the base (6) by a positioning element (60).

10. The transformer oil-paper insulation aging test device based on compressive stress as described in claim 1, characterized in that: The test box (1) is filled with transformer oil. A top cover (11) is detachably installed on the upper part of the test box (1), and an oil drain valve (10) is installed on the lower part of the side wall of the test box (1).

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