A dry-type transformer winding coil material eddy current detection method and device

Abstract

The present invention relates to a method and device for eddy current testing of the winding coil material of a dry-type transformer. An eddy current analyzer is connected to an eddy current detection probe, which is used to receive the impedance signal of the induced magnetic field and transmit it back to the eddy current analyzer. A winding comparison test block includes a copper winding layer and a non-metallic layer with adjustable thickness coated on the outside of the copper winding layer. The copper winding layer has the same structure as the dry-type transformer winding to be tested. An aluminum winding comparison test block has the same structure as the copper winding comparison test block, except that the aluminum winding layer replaces the copper winding layer. The method is suitable for acceptance testing of dry-type transformer winding materials, and its sensitivity can effectively determine the winding coil material. The winding coil material inside the dry-type transformer can be directly tested without disassembling the dry-type transformer, effectively avoiding the waste of resources caused by acceptance testing. Automated, high-speed batch testing of dry-type transformer winding coil materials can be achieved.

Description

Technical Field

[0001] The invention relates to a method and a device for eddy current detection of winding coil material of a dry-type transformer, belonging to the technical field of power equipment detection. Background Art

[0002] Transformers are important power conversion devices manufactured based on the principle of electromagnetic induction, capable of transforming voltage, current, and impedance. They are widely used in power engineering. Dry-type transformers are transformers whose cores and windings are not immersed in insulating oil and rely on natural cooling through air convection or the addition of fans for cooling.

[0003] The conductive materials used in dry-type transformer windings are primarily copper or aluminum, which are used in large quantities. However, the two materials differ significantly in conductivity, resulting in varying power quality for users. Copper wire offers high conductivity and low power loss, while aluminum wire is inexpensive, costing only about 40% of copper per unit, reducing overall winding material costs by over 70%. Because dry-type transformer windings not only have an insulating surface layer on the conductor itself, but also undergo external insulation measures such as varnishing and epoxy encapsulation during production, the conductor's material cannot be determined from the outside. Consequently, the substitution of aluminum for copper is a common occurrence in dry-type transformer supply.

[0004] Currently, there are three methods for determining the material quality of transformer windings: the first is direct disassembly, which is a destructive test that is time-consuming, labor-intensive, and a waste of resources; the second is the temperature rise test, which is time-consuming and generally requires two cycles, each lasting about 8 hours, and is subject to interference from external factors, making the test implementation and result judgment very difficult; the third is the X-ray detection method, which produces ionizing radiation hazards and poses a greater operational risk. In addition, the detection equipment is complex to operate and places high demands on the detection personnel.

[0005] Chinese patent publication number CN107192738A, "A Method for Detecting the Material of Distribution Transformer Windings," discloses a method for detecting the material of distribution transformer windings based on the thermoelectric effect and inverse algorithm, taking into account the capacity and thermoelectric potential of the distribution transformer. This method avoids the inaccurate detection results caused by using a single detection method and can greatly improve the accuracy of distribution transformer winding material detection.

[0006] The Chinese patent publication number CN107748199A, "A Method for Identifying the Material of a Power Transformer Coil," can quickly and easily identify the material of a transformer coil without damaging the transformer. Summary of the Invention

[0007] The purpose of the present invention is to provide a method and device for eddy current detection of the material of dry-type transformer winding coils, so as to solve the application requirements of the detection technology for the acceptance of dry-type transformer winding materials proposed in the above background technology, and to achieve the problem of non-destructive, efficient, safe and convenient detection and identification of the material of dry-type transformer winding coils.

[0008] The technical solutions of the present invention are as follows:

[0009] A dry-type transformer winding coil material eddy current detection device, comprising:

[0010] Eddy current analyzer: the eddy current analyzer is connected to an eddy current detection probe, and the eddy current detection probe is used to receive the impedance signal of the induced magnetic field and transmit it back to the eddy current analyzer;

[0011] Copper winding comparison test block: The copper winding comparison test block includes a copper winding layer and a non-metallic layer with adjustable thickness coated on the outside of the copper winding layer. The copper winding layer structure is the same as the dry-type transformer winding to be tested;

[0012] Aluminum winding comparison test block: The aluminum winding comparison test block has the same structure as the copper winding comparison test block, except that the aluminum winding layer replaces the copper winding layer.

[0013] Preferably, the non-metallic layer includes a fixed layer and a movable layer, and a sealed space for accommodating non-metallic powder is formed between the fixed layer and the movable layer. The distance between the fixed layer and the movable layer is adjustable, and a retractable pressing plate for compacting the non-metallic powder is provided in the sealed space.

[0014] Preferably, the movable layer and the fixed layer are linearly slidably fitted together via an adjusting screw.

[0015] Preferably, an elastic bag is provided around the outer wall of the lower portion of the adjusting screw, and the inner cavity of the elastic bag is expanded or shrunk by inflation or deflation.

[0016] Preferably, an air passage is provided in the adjusting screw extending from its upper surface toward the elastic bag, and an inflation valve is installed at the upper end of the air passage.

[0017] Preferably, the telescopic pressing plate includes an upper pressing plate and a lower pressing plate, which are tightly fitted and linearly slidably matched. The upper pressing plate linearly slides inside the movable layer, and the lower pressing plate linearly slides inside the fixed layer.

[0018] Preferably, a clamping screw for driving the lower pressing plate to slide is installed on the fixing layer.

[0019] Preferably, the eddy current detection probe is a low-frequency placement type absolute eddy current probe, which includes several linearly packaged eddy current detection units, which can send and receive electromagnetic signals in the low frequency band of 1kHz to 100kHz, the end of which is a detection surface, and a positioning mark is set on the eddy current detection probe.

[0020] Preferably, the eddy current detection unit is a cylinder, the outer diameter / width of the bottom surface of the cylinder is smaller than the winding coil width of the dry-type transformer winding to be inspected, and an excitation coil and a receiving coil parallel to the bottom surface of the cylinder are arranged from top to bottom, and its lower bottom surface is coplanar with the detection surface of the eddy current detection probe, and the excitation coil and the receiving coil are arranged parallel to the detection surface.

[0021] Preferably, the eddy current analyzer includes a signal module and a display module. The signal module is used to send, receive, and process electromagnetic signals, and set and adjust signal parameters; the display module is used to graphically display received signal information.

[0022] A method for eddy current detection of the winding coil material of a dry-type transformer comprises the following steps:

[0023] S1. Connect the eddy current detection probe to the eddy current analyzer and preset the electromagnetic signal related parameters of the eddy current analyzer;

[0024] S2. Place the detection surface of the eddy current detection probe flat on the detection points of the outer wall of the copper winding comparison test block and the aluminum winding comparison test block in sequence. The eddy current analyzer sends an alternating current to the excitation coil of the eddy current detection probe. The excitation coil generates an alternating magnetic field, thereby generating an alternating eddy current in the copper winding layer and the aluminum winding layer. The induced magnetic field of the alternating eddy current is received by the receiving coil of the eddy current detection probe and transmitted back to the eddy current analyzer.

[0025] S3. Fine-tune the electromagnetic signal parameters of frequency, pre-gain, drive, correction, phase angle, and amplitude using an eddy current analyzer, and repeat step S4 so that the induced magnetic field impedance information obtained by the copper winding layer and the aluminum winding layer can be clearly distinguished;

[0026] S4. Place the detection surface of the eddy current detection probe flat on several detection points on the outer surface of the dry-type transformer winding coil to be inspected (the operation method for determining the detection points is the same as step S3), obtain induced magnetic field impedance information, and compare it with the induced magnetic field impedance information of the copper winding comparison test block and the aluminum winding comparison test block to confirm whether the material of the dry-type transformer winding coil to be inspected is aluminum or copper.

[0027] Preferably, in order to avoid interference from the coil gap, the positioning mark of the eddy current detection probe is used to keep the arrangement direction of the eddy current detection unit inside the eddy current detection probe parallel to the length direction of the winding coil, and the eddy current detection probe is scanned in a direction perpendicular to the arrangement direction of the eddy current detection unit. Due to the influence of the eddy current detection unit constantly crossing the coil gap, the induced magnetic field signal obtained during the scanning process changes alternately in strength, and the position where the induced magnetic field signal is the strongest is determined as the detection point (at this time, the eddy current detection unit does not cross the coil gap and is directly above a single winding coil as a whole).

[0028] Preferably, the method of using the eddy current detection probe to detect the copper material winding comparison test block and the aluminum material winding comparison test block is the same as that of detecting the dry-type transformer to be tested.

[0029] The present invention has the following beneficial effects:

[0030] 1. Suitable for acceptance inspection of dry-type transformer winding materials, avoiding interference from winding coil gaps, with high detection sensitivity, and can effectively determine the winding coil material.

[0031] 2. The eddy current testing method used is a non-destructive test. It can directly test the winding coil material inside the dry-type transformer without disassembling it, effectively avoiding the waste of resources caused by acceptance testing.

[0032] 3. Compared with X-ray detection, the eddy current detection method does not produce any ionizing radiation hazards during the entire detection process of the dry-type transformer winding coil material, and has lower requirements for operators and the surrounding environment. The test results are not easily affected by the level of the testers.

[0033] 4. After debugging the detection parameters, the average time for a single inspected component is only a few seconds, which can realize the automated high-speed batch detection of dry-type transformer winding coil materials;

[0034] 5. The thickness of the non-metallic layer can be adjusted to meet the requirements of epoxy resin layer thickness of different dry-type transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic structural diagram of the first use scenario of the present invention;

[0036] Figure 2 This is a schematic structural diagram of the second usage scenario of the present invention;

[0037] Figure 3 This is a schematic diagram of the induced magnetic field impedance information of the copper winding comparison test block of the present invention;

[0038] Figure 4 This is a schematic diagram of the induced magnetic field impedance information of the aluminum winding comparison test block of the present invention;

[0039] Figure 5 This is a schematic diagram of the induced magnetic field impedance information of the winding of the first dry-type transformer to be inspected in the present invention;

[0040] Figure 6 This is a schematic diagram of the induced magnetic field impedance information of the winding of the second dry-type transformer to be inspected according to the present invention;

[0041] Figure 7 This is a schematic diagram of the structure of a copper winding comparison test block of the present invention;

[0042] Figure 8 This is a schematic diagram of the telescopic pressing plate and the clamping screw structure of the present invention;

[0043] Figure 9 This is a schematic structural diagram of the adjusting screw and its matching components of the present invention;

[0044] Figure 10 This is a schematic diagram of the adjusting screw structure of the present invention;

[0045] Figure 11 This is a schematic diagram of the structure of an eddy current detection probe composed of multiple groups of eddy current detection units in the present invention;

[0046] Figure 12 for Figure 11 A schematic diagram of the structure of an application scenario.

[0047] The reference numerals in the figures are as follows:

[0048] 1. Eddy current analyzer; 11. Signal module; 12. Display module; 200. Eddy current detection probe; 2. Eddy current detection unit; 21. Excitation coil; 22. Receiving coil; 23. Detection surface; 3. Copper winding comparison test block; 31. Copper winding layer; 32. Non-metallic layer; 321. Fixed layer; 322. Movable layer; 323. Non-metallic powder; 33. Scanning surface; 34. Adjusting screw; 341. Air channel; 35. Telescopic pressure plate; 351. Lower pressure plate; 352. Upper pressure plate; 36. Clamping screw; 37. Elastic bag; 38. Inflation valve; 4. Aluminum winding comparison test block; 41. Aluminum winding layer; 5. Dry-type transformer winding to be inspected; 51. Winding coil. DETAILED DESCRIPTION

[0049] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1-10 As shown:

[0051] The device includes an eddy current analyzer 1, an eddy current detection probe 200, a copper winding comparison test block 3, and an aluminum winding comparison test block 4. The eddy current analyzer 1 is connected to the eddy current detection probe 200. When the eddy current analyzer 1 generates an alternating current to the eddy current detection probe 200, the eddy current detection probe 200 generates an alternating magnetic field. When the detection surface 23 of the eddy current detection probe 200 is placed flat on the corresponding scanning surface 33 of the copper winding comparison test block 3 or the aluminum winding comparison test block 4, eddy currents are generated in the copper winding comparison test block 3 or the aluminum winding comparison test block 4, thereby forming an induced magnetic field. The eddy current detection probe 200 receives the impedance signal of the induced magnetic field and transmits it back to the eddy current analyzer 1.

[0052] The eddy current analyzer 1 includes a signal module 11 and a display module 12. The signal module 11 can send, receive, and process electromagnetic signals, and set and adjust signal parameters (frequency, pre-gain, drive, correction, phase angle, amplitude, etc.); the display module 12 is a graphical display of the received signal information.

[0053] The eddy current detection probe 200 is a low-frequency placement type absolute eddy current probe, which is composed of several eddy current detection units 2 and is packaged in a linear manner inside a cylindrical mounting shell. It can send and receive electromagnetic signals in the low frequency band of 1kHz to 100kHz. Its end is the detection surface, and a positioning mark is set on the outer wall of the eddy current detection probe 200.

[0054] The copper winding comparison test block 3 is a rectangular sandwich structure, with the inner layer being a copper winding layer 31 and the outer layer being a fused non-metallic layer 32 (such as epoxy resin). The upper surface of the rectangular block is set as a scanning surface 33, and the thickness of the non-metallic layer 32 from the scanning surface 33 to the upper surface of the inner layer is consistent with the thickness of the epoxy resin layer of the dry-type transformer.

[0055] The copper winding layer 31 is composed of several layers of windings, each layer of which is composed of copper wires arranged side by side into a single layer winding of a certain width. The width is sufficiently larger than the detection surface 23 of the eddy current detection probe 200 (to avoid edge effects). The specifications, structure, shape, material, etc. of the copper winding layer are consistent with the dry-type transformer winding 5 under inspection.

[0056] The only difference between the aluminum winding comparison test block 4 and the copper winding comparison test block 3 is that the inner layer is an aluminum winding layer 41 .

[0057] like Figure 7As shown, the non-metallic layer 32 includes a fixed layer 321 and a movable layer 322. A sealing ring is provided between the movable layer 322 and the fixed layer 321 to improve the sealing effect. A sealed space of a rectangular structure is formed between the fixed layer 321 and the movable layer 322. The lower end of the adjusting screw 34 is rotatably connected to the fixed layer 321, and the adjusting screw 34 is threadedly connected to the movable layer 322. Rotating the adjusting screw 34 drives the movable layer 322 to slide linearly relative to the fixed layer 321, thereby adjusting the thickness of the sealed space of the rectangular structure.

[0058] like Figure 7-8 As shown, the telescopic pressing plate 35 is relatively placed in the sealed space of the rectangular structure, and the height of the telescopic pressing plate 35 is adapted to the thickness of the sealed space of the rectangular structure and changes synchronously with it. The telescopic pressing plate 35 divides the sealed space into a working chamber and a non-working chamber that are independent of each other, and non-metallic powder (epoxy resin powder) is filled in the working chamber of the sealed space; the telescopic pressing plate 35 includes a lower pressing plate 351 and an upper pressing plate 352, the lower pressing plate 351 slides horizontally and linearly in the fixed layer 321 (perpendicular to its height direction), and the upper pressing plate 352 slides horizontally and linearly in the movable layer 322 slides linearly in a horizontal direction (perpendicular to its height direction), and the upper pressing plate 352 slides linearly in a vertical direction (height direction) relative to the lower pressing plate 351, thereby realizing the height adjustment of the upper pressing plate 352 and the lower pressing plate 351; the side wall of the fixed layer 321 is threadedly connected with a clamping screw 36, and one end of the clamping screw 36 rotates with the lower pressing plate 351, so that the rotating clamping screw 36 drives the lower pressing plate 351 to slide linearly in a horizontal direction in the fixed layer 321. During this process, the upper pressing plate 352 follows the inner side wall of the movable layer 322 and slides linearly in a horizontal direction;

[0059] According to the thickness of the epoxy resin layer of the dry-type transformer winding 5 to be inspected, the spacing between the movable layer 322 and the fixed layer 321 is adjusted to be the same. At this time, the height of the sealed space of the rectangular structure changes, and the retractable pressure plate 35 is pushed by the clamping screw 36 to compact the non-metallic powder in the working chamber.

[0060] like Figure 7 As shown, the adjusting screw 34 is relatively placed in the working chamber of the sealed space. The presence of the adjusting screw 34 will affect the compaction of the non-metallic powder 323 by the telescopic pressing plate 35. There is a dead angle on the side of the adjusting screw 34 facing away from the telescopic pressing plate 35, and it is inconvenient for the non-metallic powder 323 to fill the dead angle area.

[0061] like Figure 9-10As shown, an elastic bag 37 is provided on the lower outer wall of the working chamber of the adjusting screw 34. The elastic bag 37 can be deformed at will. The elastic bag 37 is inflated and expanded by an external air source through the inflation valve 38 and the air channel 341. The inflation of the elastic bag 37 fills the dead corner area near the adjusting screw 34 where the metal powder 323 is inconvenient to fill, thereby avoiding the hollowing out of the dead corner area and causing the flow of the compacted non-metallic powder 323. The free flow of the non-metallic powder 323 without compaction will cause thickness changes and make the measurement results inaccurate.

[0062] Before adjusting the distance between the movable layer 322 and the fixed layer 321 , the inflation valve 38 is opened to discharge the air in the elastic bag 37 through the air channel 341 .

[0063] The scanning surface 33 is arranged on the upper surface of the movable layer 322 away from the adjusting screw 34 and the non-working cavity position. The distance between the movable layer 322 and the fixed layer 321 can be changed arbitrarily, and the non-metallic powder in the working cavity is in a compacted state.

[0064] like Figure 11 As shown, five groups of eddy current detection units 2 are packaged in a linear manner inside a cylindrical mounting shell to form an eddy current detection probe 200. The outer diameter / width of the eddy current detection unit 2 is smaller than the width of a single winding coil 51 (or the aluminum winding layer 41 / copper winding layer 31) of the dry-type transformer winding 5 to be inspected;

[0065] The eddy current detection unit 2 is a low-frequency placement type absolute eddy current probe that can send and receive low-frequency (1kHz~100kHz) electromagnetic signals. The eddy current detection unit 2 is equipped with an excitation coil 21 and a receiving coil 22 from top to bottom. The excitation coil 21 and the receiving coil 22 are arranged parallel to the detection surface 23.

[0066] The outer wall of the eddy current detection probe 200 is provided with a positioning mark indicating the arrangement direction of the five groups of eddy current detection units 2 inside. When a person skilled in the art sees the dry-type transformer winding 5 to be inspected, he can determine its model. The model can be used to understand information such as the arrangement direction and width of the winding coil 51 inside it, thereby adjusting the direction of the eddy current detection probe 200 so that the arrangement direction of the five groups of eddy current detection units 2 therein is consistent with the length direction of the single winding coil 51 / copper winding layer 31 / aluminum winding layer 41. During scanning, the mounting shell is pushed to move according to the graphical display on the display module 12 to avoid the gap. When the eddy current signal amplitude is maximum, the eddy current detection unit 2 is just above a winding coil 51, thus avoiding the gap.

[0067] like Figure 12 As shown, there is a gap between two adjacent winding coils 51. If the eddy current detection unit 2 spans the gap, it will affect the detection result.

[0068] On the contrary, if the width / outer diameter of the eddy current detection unit 2 is more than several times the width of a single winding coil 51 (or the aluminum winding layer 41 / copper winding layer 31); the following situations may occur, for example, when the eddy current detection probe 200 detects the dry-type transformer winding 5 to be inspected, it spans one gap, and when the eddy current detection unit 2 detects the copper winding comparison test block 3 / aluminum winding comparison test block 4, it spans two gaps.

[0069] A dry-type transformer winding coil material eddy current detection method is implemented according to the following steps:

[0070] (1) Connect the eddy current detection probe 200 to the eddy current analyzer 1, start the eddy current analyzer 1 and preset electromagnetic signal parameters such as frequency, pre-gain, drive, correction, phase angle, amplitude, etc.

[0071] (2) The detection surface 23 of the eddy current detection probe 200 is slowly placed flat on the central position of the scanning surface 33 of the copper winding comparison test block 3. The eddy current analyzer 1 sends an alternating current to the excitation coil 21 of the eddy current detection probe 200. The excitation coil 21 generates an alternating magnetic field, thereby generating an alternating eddy current in the copper winding 31 in the copper winding comparison test block 3. The induced magnetic field of the alternating eddy current is received by the receiving coil 22 of the eddy current detection probe 200 and transmitted back to the eddy current analyzer 1, and the induced magnetic field impedance information (impedance amplitude, impedance phase angle, etc.) is obtained and graphically displayed on the display module 12 of the eddy current analyzer 1.

[0072] (3) The eddy current detection probe detection surface 23 is slowly placed flat on the central position of the scanning surface 33 of the aluminum winding comparison test block. The eddy current analyzer 1 sends an alternating current to the excitation coil 21 of the eddy current detection probe 200. The excitation coil 21 generates an alternating magnetic field, thereby generating an alternating eddy current in the aluminum winding 41 in the aluminum winding comparison test block 4. The induced magnetic field of the alternating eddy current is received by the receiving coil 22 of the eddy current detection probe 200 and transmitted back to the eddy current analyzer 1, and the induced magnetic field impedance information (impedance amplitude, impedance phase angle, etc.) is obtained and graphically displayed on the display module 12 of the eddy current analyzer 1.

[0073] (4) Fine-tune the electromagnetic signal parameters such as frequency, preamplifier gain, drive, correction, phase angle, and amplitude through the eddy current analyzer 1, and repeat steps (2) and (3), so that the induced magnetic field impedance information obtained by the two can be clearly distinguished.

[0074] (5) The detection surface 23 of the eddy current detection probe 200 is slowly placed flat on the outer surface of the coil of the dry-type transformer winding 5 to be inspected. The positioning mark of the eddy current detection probe 200 is used to keep the arrangement direction of the eddy current detection unit 2 inside the eddy current detection probe 200 parallel to the length direction of the winding coil 51. The eddy current detection probe 200 is scanned in a direction perpendicular to the arrangement direction of the eddy current detection unit 2. The induced magnetic field signal obtained during the scanning process changes alternately in strength, and the position where the induced magnetic field signal is the strongest is determined as the detection point.

[0075] The detection surface 23 of the eddy current detection probe 200 is placed at the detection point on the outer surface of the coil of the dry-type transformer winding 5 to be inspected, and the induced magnetic field impedance information is obtained and compared with the induced magnetic field impedance information of the copper winding comparison test block 3 and the aluminum winding comparison test block 4 to confirm whether the coil material of the dry-type transformer winding 5 to be inspected is aluminum or copper.

[0076] Example 1

[0077] like Figure 1 As shown in FIG, in this embodiment, the frequency is set to 1kHz, the pre-gain is 35, the drive level is 7, the deviation correction is -4, the phase angle is 241°, and the amplitude is 25dB to obtain the induced magnetic field impedance information. Figure 3 As shown in the figure, the impedance phase angle of the copper winding comparison test block is 222° and the impedance amplitude is 266dB. Figure 4 As shown in the figure, the impedance phase angle of the aluminum winding comparison test block is 184° and the impedance amplitude is 441dB. Figure 5 As shown in the figure, the impedance phase angle of the tested dry-type transformer winding material is 181° and the impedance amplitude is 361dB.

[0078] The induced magnetic field impedance information of the dry-type transformer winding 5 under test matched that of the aluminum winding comparison test block 4, confirming that the dry-type transformer winding 5 under test was made of aluminum. Disassembly of the dry-type transformer winding 5 confirmed that the winding material was aluminum, confirming that the eddy current test results for the coil material of the dry-type transformer winding 5 were accurate.

[0079] Example 2

[0080] like Figure 1 As shown, the device and method provided by the present invention are used to detect the winding material of a dry-type transformer. In this embodiment, the frequency is set to 1kHz, the pre-gain is 35, the drive level is 7, the deviation correction is -4, the phase angle is 241°, and the amplitude is 25dB to obtain the induced magnetic field impedance information. Figure 3 As shown in the figure, the impedance phase angle of the copper winding comparison test block is 222° and the impedance amplitude is 266dB. Figure 4 As shown in the figure, the impedance phase angle of the aluminum winding comparison test block is 184° and the impedance amplitude is 441dB. Figure 6As shown, the impedance phase angle of the material of the dry-type transformer winding 5 to be inspected is 216°, and the impedance amplitude is 182 dB.

[0081] The induced magnetic field impedance information of the dry-type transformer winding 5 under test matched that of the copper winding comparison block 3, confirming that the dry-type transformer winding 5 under test was made of copper. Disassembly of the dry-type transformer winding 5 revealed that it was made of red copper, confirming that the eddy current test results for the coil material of the dry-type transformer winding 5 were accurate.

[0082] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A dry-type transformer winding coil material eddy current detection device, characterized by: include: Eddy current analyzer (1): the eddy current analyzer (1) is connected to an eddy current detection probe (200), and the eddy current detection probe (200) is used to receive an impedance signal of the induced magnetic field and transmit it back to the eddy current analyzer (1); Copper material winding comparison test block (3): the copper material winding comparison test block (3) comprises a copper material winding layer (31) and a non-metallic layer (32) with adjustable thickness coated on the outside of the copper material winding layer (31), and the structure of the copper material winding layer (31) is the same as that of the dry-type transformer winding (5) to be tested; Aluminum winding comparison test block (4): The aluminum winding comparison test block (4) has the same structure as the copper winding comparison test block (3), except that the aluminum winding layer (41) replaces the copper winding layer (31); The non-metallic layer (32) includes a fixed layer (321) and a movable layer (322); a sealed space for accommodating non-metallic powder (323) is formed between the fixed layer (321) and the movable layer (322); the distance between the fixed layer (321) and the movable layer (322) is adjustable; and a retractable pressing plate (35) for compacting the non-metallic powder (323) is provided in the sealed space; The movable layer (322) and the fixed layer (321) are linearly slidably engaged with each other via an adjusting screw (34); The telescopic pressing plate (35) comprises an upper pressing plate (352) and a lower pressing plate (351), wherein the upper pressing plate (352) and the lower pressing plate (351) are tightly fitted and linearly slidably matched, wherein the upper pressing plate (352) linearly slidably matches the inner side of the movable layer (322), and the lower pressing plate (351) linearly slidably matches the inner side of the fixed layer (321); A clamping screw (36) for driving the lower pressing plate (351) to slide is installed on the fixed layer (321).

2. The eddy current detection device for dry-type transformer winding coil material according to claim 1, characterized in that: An elastic bag (37) is provided around the outer wall of the lower portion of the adjusting screw (34), and the inner cavity of the elastic bag (37) is expanded or deflated by air.

3. The eddy current detection device for dry-type transformer winding coil material according to claim 2, characterized in that: An air passage (341) is provided in the adjusting screw (34) extending from its upper surface toward the elastic bag (37), and an inflation valve (38) is installed at the upper end of the air passage (341).

4. The eddy current detection device for dry-type transformer winding coil material according to claim 1, characterized in that: The eddy current detection probe (200) is a low-frequency placement type absolute eddy current probe, comprising a plurality of linearly packaged eddy current detection units (2), capable of transmitting and receiving electromagnetic signals in the low frequency range of 1kHz to 100kHz, the end of which is a detection surface (23), and a positioning mark is provided on the eddy current detection probe (200).

5. The eddy current detection device for dry-type transformer winding coil material according to claim 4, characterized in that: The eddy current detection unit (2) is a column, the outer diameter / width of the bottom surface of the column is smaller than the width of the winding coil (51) of the dry-type transformer winding (5) to be detected, and an excitation coil (21) and a receiving coil (22) are arranged from top to bottom in parallel with the bottom surface of the column, and the bottom surface thereof is coplanar with the detection surface (23) of the eddy current detection probe (200), and the excitation coil (21) and the receiving coil (22) are arranged in parallel with the detection surface (23).

6. The eddy current detection device for dry-type transformer winding coil material according to claim 1, characterized in that: The eddy current analyzer (1) comprises a signal module (11) and a display module (12). The signal module (11) is used to send, receive, and process electromagnetic signals, and to set and adjust signal parameters; and the display module (12) is used to graphically display received signal information.

7. A method for eddy current testing of the winding material of a dry-type transformer, characterized by: The eddy current detection device for the material of the winding coil of a dry-type transformer according to claim 1 comprises the following steps: S1, connecting the eddy current detection probe (200) to the eddy current analyzer (1), and presetting the electromagnetic signal related parameters of the eddy current analyzer (1); S2, placing the detection surface (23) of the eddy current detection probe (200) flat on the detection points of the outer wall of the copper material winding comparison test block (3) and the aluminum material winding comparison test block (4) in sequence, the eddy current analyzer (1) sends an alternating current to the excitation coil (21) of the eddy current detection probe (200), the excitation coil (21) generates an alternating magnetic field, thereby generating an alternating eddy current in the copper material winding layer (31) and the aluminum material winding layer (41), and the induced magnetic field of the alternating eddy current is received by the receiving coil (22) of the eddy current detection probe (200) and transmitted back to the eddy current analyzer (1); S3, fine-tuning the electromagnetic signal parameters of frequency, pre-gain, drive, correction, phase angle, and amplitude by using the eddy current analyzer (1), and repeating step S2, so that the induced magnetic field impedance information obtained by the copper material winding layer (31) and the aluminum material winding layer (41) can be clearly distinguished; S4. Place the detection surface (23) of the eddy current detection probe (200) flatly on several detection points on the outer surface of the coil of the dry-type transformer winding (5) to be inspected, obtain induced magnetic field impedance information, and compare it with the induced magnetic field impedance information of the copper material winding comparison test block (3) and the aluminum material winding comparison test block (4), so as to confirm that the material of the coil of the dry-type transformer winding (5) to be inspected is aluminum or copper.

8. The eddy current testing method for dry-type transformer winding coil material according to claim 7, characterized in that: In order to avoid interference from the coil gap, the positioning mark of the eddy current detection probe (200) is used to keep the arrangement direction of the eddy current detection unit (2) inside the eddy current detection probe (200) parallel to the length direction of the winding coil (51), and the eddy current detection probe (200) is scanned in a direction perpendicular to the arrangement direction of the eddy current detection unit (2). Due to the influence of the eddy current detection unit (2) constantly crossing the coil gap, the induced magnetic field signal obtained during the scanning process changes alternately in strength, and the position where the induced magnetic field signal is the strongest is determined as the detection point.

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