A method, system, and medium for non-destructive field testing of a current transformer
By combining DR (Digital Radiography) testing and ultrasonic testing, the problem of inspecting the internal structure of current transformers has been solved, achieving rapid, non-destructive, and accurate testing results, thus ensuring the safe operation of current transformers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- STATE GRID HUNAN ELECTRIC POWER COMPANY LIMITED
- Filing Date
- 2022-09-22
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies lack effective methods for routine inspection of the internal structure and insulation layer distribution of current transformers, leading to problems such as eccentricity and uneven insulation layer thickness during operation, resulting in frequent faults such as discharge and explosion.
A combination of DR (radio frequency) and ultrasonic testing was used to inspect the front and sides of the current transformer. DR testing was used for imaging and dimensional inspection, while ultrasonic testing was used for measuring the eccentricity and insulation thickness. Defect identification was performed using standard test blocks and simulated test blocks.
It enables rapid, non-destructive, and accurate detection of the position and status of internal components of current transformers, improving detection efficiency, ensuring safe equipment operation, and reducing maintenance workload.
Smart Images
Figure CN116045863B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of transformer internal structure inspection, and more particularly to a field non-destructive testing method, system, and medium for current transformers. Background Technology
[0002] Transformer overcurrent, short-circuit, overload, and differential protection all require current signals from current transformers. Similarly, transformer load, current, and electricity meter readings also require current signals from current transformers. Since protection and measurement have different requirements for the accuracy and capacity of the transformers, the high-voltage side of a transformer typically has several current transformer secondary windings to meet different needs, making it a crucial high-voltage component for power grid operation.
[0003] Current transformers frequently encounter the following problems during operation:
[0004] 1) The insulation of current transformers is very thick, and some insulation wrapping is loose with wrinkles between insulation layers. In addition, poor vacuum treatment and incomplete impregnation can cause air-containing cavities, which can easily lead to partial discharge faults.
[0005] 2) If the size and arrangement do not meet the design requirements, the capacitor plates are not smooth or flat, or even misaligned or broken, their voltage equalization characteristics will be compromised. Therefore, when the electric field strength along the surface of the local solid insulation reaches a certain value, partial discharge will occur.
[0006] 3) Due to unclean or high moisture content of the insulating material, surface discharge may occur on its surface.
[0007] 4) Loose connections or floating potential of metal parts will cause spark discharge. For example, a loose support nut of primary winding 1 will cause the shielding aluminum foil of primary winding 1 to float. Poor contact or welding of the end screen lead or even a broken wire will cause this type of fault.
[0008] Currently, there is no effective method for routine inspection of the internal structure and insulation layer distribution of current transformers. Due to manufacturing processes and other factors, current transformers often suffer from issues such as eccentricity and uneven insulation layer thickness. After prolonged use, these uneven insulation layer distributions can lead to problems such as excessively short gaps between the primary winding 1 and secondary winding 2, or between the windings and the silicon steel sheets, causing discharge after a period of operation. This can result in frequent instances of transformer explosions and burnouts. Therefore, it is essential to develop a simple, non-destructive testing technique for current transformers. Summary of the Invention
[0009] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a safe and efficient on-site non-destructive testing method for current transformers.
[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0011] A method for on-site non-destructive testing of current transformers includes the following steps:
[0012] S1. Using the front and back sides of the current transformer as the DR detection surfaces respectively, perform DR detection on the current transformer and obtain the DR detection results.
[0013] S2. Compare the DR test results with the design requirements to determine whether the DR test pattern and the measured size parameters of the current transformer in the DR test results meet the design requirements. If they all meet the requirements, proceed to step S3; otherwise, the current transformer is unqualified.
[0014] S3. Using the two sides of the current transformer as ultrasonic testing surfaces, perform ultrasonic testing for defects and ultrasonic testing for winding eccentricity of the current transformer, and obtain the ultrasonic testing results.
[0015] S4. Compare the ultrasonic test results with the standard results to determine whether the winding eccentricity and defects in the ultrasonic test results meet the design requirements. If all meet the requirements, the current transformer is qualified; otherwise, the current transformer is unqualified.
[0016] As a further improvement to the above technical solution:
[0017] Preferably, in step S2, the measured size parameters are obtained based on DR detection maps;
[0018] The design requirements include a preset defect map and preset size parameters. The preset defect map is obtained through the following steps:
[0019] A1. A simulated test block is made according to the preset size parameters of the current transformer, and the simulated test block has a preset defect;
[0020] A2. Using the front side of the simulated test block as the DR inspection surface, perform DR inspection on the simulated test block to obtain a preset defect map.
[0021] The preset defects are burn-related defects, porosity defects, high-stress damage defects, and linear defects.
[0022] If a preset defect from the preset defect map appears in the DR inspection map, the DR inspection result is determined to be non-compliant with the design requirements; otherwise, it is compliant.
[0023] If the measured dimensional parameters are within the error range of the preset dimensional parameters, the DR test result is determined to meet the design requirements; otherwise, it does not meet the requirements.
[0024] Preferably, in step S3, the ultrasonic defect detection includes the following steps:
[0025] B1. Using the upper surface of a standard test block with multiple transverse through holes as the ultrasonic testing surface, the ultrasonic testing instrument is calibrated using the standard test block, and standard results are obtained. The standard results are standard distance amplitude curves. The parameters of the calibrated ultrasonic testing instrument are saved.
[0026] B2. Place the ultrasonic probe on the side of the current transformer and perform ultrasonic testing on the current transformer to obtain the ultrasonic test results, wherein the measured amplitude of the ultrasonic test results is obtained.
[0027] Preferably, the ultrasonic detection of the winding eccentricity specifically includes the following steps:
[0028] C1. Using a standard stepped test block and a stepped surface with a similar thickness to the insulation layer of the current transformer as the test surface, debug the ultrasonic testing system and save the parameters of the debugged ultrasonic testing instrument.
[0029] C2. Using both sides of the current transformer as ultrasonic testing surfaces, select multiple points on each side to test the insulation layer thickness, obtaining insulation layer thickness values at multiple points. Determine whether the deviation of the insulation layer thickness values at each point on the same ultrasonic testing surface exceeds the design requirements. If it does, the current transformer is unqualified. If it does not exceed the requirements, compare the average insulation layer thickness values at each point on the same ultrasonic testing surface with the average insulation layer thickness values at each point on the other side of the ultrasonic testing surface, and determine whether the deviation between the two average values exceeds the design requirements. If it does, the current transformer is unqualified. If it does not exceed the requirements, proceed to step C3.
[0030] C3. Using the two sides of the current transformer as ultrasonic testing surfaces, move the ultrasonic probe. When the peak height is the first preset height, the center of the ultrasonic probe is the initial reference point O. Move the ultrasonic probe to both sides in the horizontal direction of the initial reference point O. When the peak height drops to the second preset height, mark the center of the probe at point O' and point O”.
[0031] C4. Move the ultrasonic probe vertically along the initial reference point O, and take the position of the center of the ultrasonic probe when the peak height is the first preset height as the reference point O1. Replace the initial reference point O with the reference point O1 and repeat step C3 to obtain the marked probe center position point O1' and position point O2”.
[0032] C5. Repeat step C4 to obtain multiple reference points O. n And mark the location point O of the probe center. n Location point O n ”;
[0033] C6. Transfer the positions O' and O1' located on the same side of each reference point to O nConnect the points to obtain line l1, and then connect the points O” and O1” located on the other side of each reference point to O”. n "Connect to obtain line l2."
[0034] Preferably, when the measured amplitude is within the range of the standard amplitude curve spectrum, the defect in the ultrasonic test result in step S4 is determined to meet the design requirements; otherwise, it does not meet the requirements.
[0035] When the difference between the distances of two points on the same horizontal direction on straight lines l1 and l2 and the central axis or edge of the ultrasonic testing surface is less than a preset value, it is determined that the winding eccentricity distance in the ultrasonic testing result in step S4 meets the design requirements; otherwise, it does not meet the requirements.
[0036] Preferably, the first preset height is 70%-80% of the highest peak height, and the second preset height is 10%-20% of the highest peak height; the preset value is 5mm.
[0037] As a general inventive concept, the present invention also provides a field non-destructive testing system for current transformers, comprising the following modules:
[0038] The first detection module is used to perform DR detection on the current transformer by using the front and back sides of the current transformer as DR detection surfaces respectively, and to obtain the DR detection results.
[0039] The second judgment module compares the DR test results with the design requirements and determines whether the DR test pattern and the measured size parameters of the current transformer in the DR test results meet the design requirements. If they all meet the requirements, the module jumps to the third test module; otherwise, the current transformer is unqualified.
[0040] The third detection module uses the two sides of the current transformer as ultrasonic detection surfaces to perform ultrasonic defect detection and ultrasonic winding eccentricity detection on the current transformer, and obtains the ultrasonic detection results.
[0041] The fourth judgment module compares the ultrasonic test results with the standard results to determine whether the winding eccentricity and defects in the ultrasonic test results meet the design requirements. If all meet the requirements, the current transformer is qualified; otherwise, the current transformer is unqualified.
[0042] As a general inventive concept, the present invention also provides a computer-readable medium storing a computer program programmed or configured to perform the aforementioned field non-destructive testing method for a current transformer.
[0043] Compared with the prior art, the advantages of the present invention are as follows:
[0044] The present invention provides a field non-destructive testing method for current transformers. Due to limitations in field testing locations and low calibration efficiency, this method does not employ phased array, eddy current, or traditional X-ray testing. Instead, it combines DR (radio frequency) testing and ultrasonic testing. First, DR testing is used to detect obvious defects and dimensional non-compliance in the current transformer. Then, ultrasonic testing is used to detect the eccentricity distance and obtain the insulation layer thickness. This method can quickly and effectively detect the positions of the primary and secondary windings of the current transformer and measure the winding eccentricity distance. Because the insulation material on the side of the current transformer is thick, DR testing cannot effectively image the side of the current transformer. Therefore, ultrasonic testing is used for subsequent eccentricity distance detection. Since DR testing offers higher visualization, accuracy, and efficiency compared to ultrasonic testing, it is used for the thinner front and back sides of the insulation material.
[0045] The present invention provides a field non-destructive testing method for current transformers based on DR (digital radiography) and ultrasonic testing. Depending on the insulation layer thickness of the different testing surfaces of the TA (transformer), DR rapid imaging technology is used to detect the left-right deviation between the primary and secondary windings on the side with thinner insulation (front). On the side with thicker insulation, ultrasonic rapid positioning of the primary winding is used to determine if there are any eccentricities. Simultaneously, ultrasonic and digital radiography are used to identify dangerous defects in the current transformer and to inspect for discharge points after operation. This method does not require disassembly of the TA equipment, allows for on-site testing, is convenient to operate, and has a fast testing speed.
[0046] The non-destructive testing method of this invention utilizes standard test blocks and simulated test blocks to detect and identify internal defects in current transformers during DR and ultrasonic testing, thereby ensuring the safe operation of current transformers. It can quickly and efficiently detect the location and condition of internal components of current transformers, greatly improving testing efficiency and reducing maintenance workload. It is simple, safe, and efficient. Attached Figure Description
[0047] Figure 1 This is a flowchart of the on-site non-destructive testing method of the present invention.
[0048] Figure 2 This is a structural diagram of the current transformer of the present invention (the left diagram shows the DR detection surface, and the right diagram shows the ultrasonic detection surface).
[0049] Figure 3 This is a diagram of the DR detection results of the present invention.
[0050] Figure 4 This is a schematic diagram of the defect structure of the simulated test block of the present invention.
[0051] Figure 5 This is a schematic diagram of the transverse through-hole test block for ultrasonic testing according to the present invention.
[0052] Figure 6 This is a schematic diagram of the standard stepped test block for ultrasonic testing according to the present invention.
[0053] Figure 7 This is a schematic diagram of the ultrasonic detection of eccentric distance according to the present invention.
[0054] The labels in the diagram represent: 1. Primary winding; 2. Secondary winding. Detailed Implementation
[0055] The present invention will be further described in detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.
[0056] Example 1:
[0057] The on-site non-destructive testing method for current transformers of the present invention is further described in detail using the current transformer on the upper part of phase A of a 350kV transformer as an example.
[0058] The on-site non-destructive testing method for current transformers in this embodiment includes the following steps:
[0059] Before undergoing a DR (Digital Radiography) examination, necessary preparations should be made, including the following steps:
[0060] (1) Consult as follows Figure 2 Using the current transformer winding design diagram and other data shown, the specific distribution and main dimensions of the primary winding 1 and the secondary winding 2 are determined, and the preset dimension parameters are obtained.
[0061] (2) Take the front view of the current transformer (main view of primary winding 1, such as...) Figure 2 The direction perpendicular to the paper shown in the left figure is the DR detection surface. Place the pulse X-ray machine on the main viewing surface, 600-800mm away from the TA (transformer). Its height should be consistent with the height of the center part of the primary winding 1 of the TA. Place the imaging plate parallel to the back of the TA detection surface and take necessary measures (such as fixing) to prevent the imaging plate from slipping.
[0062] In this embodiment, since the current transformer drawings are missing, a lead marker block with a length of 5mm is specially made and placed on the upper center plane of the current transformer (to prevent the lower part of the current transformer from being photographed on the center plane of the side of the current transformer). The lead marker block is used as a ruler for subsequent dimensional measurements.
[0063] S1. Using the front or back of the current transformer as the DR testing surface, perform DR testing on the current transformer and obtain the DR testing results; specifically including the following steps:
[0064] (3) Installation of DR testing equipment
[0065] ① Connect the imaging panel wireless transmission system and turn on the imaging panel and DR pulse X-ray machine;
[0066] ② Open the remote control program on the computer and check the connection status of the wireless transmission system;
[0067] ③ After the connection is established, start the remote control program and set the relevant detection parameters (time, location, etc.);
[0068] ④ Select a monitoring pulse count of no more than 20, and the detection time should not exceed the instrument's set time;
[0069] ⑤ Observe and monitor the surrounding situation. After confirming that personnel have been evacuated to a safe area, start the detection procedure.
[0070] (4) Data Reading and Measurement: Under normal circumstances, the detection time is generally 3-5 seconds, and the data reading time is about 10 seconds. After data reading, the built-in software is used to optimize the image for clear identification. After the image is clearly modulated, the DR detection map is obtained as follows: Figure 3 As shown, a 5mm lead standard block is used to calibrate its dimensions. After calibration, relevant dimensions can be measured, defects can be located, and the actual dimensional parameters of the current transformer can be obtained. Figure 3 As can be seen from the diagram, the minimum distance from the left side of the secondary winding 2 to the primary winding 1 is S1, and the minimum distance from the right side of the secondary winding 2 to the primary winding 1 is S2. The deviation distance is S1-S2, and neither S1 nor S2 shall be less than the design value.
[0071] S2. Compare the DR test results with the design requirements to determine whether the DR test pattern and the measured size parameters of the current transformer in the DR test results meet the design requirements. If they all meet the requirements, proceed to step S3; otherwise, the current transformer is unqualified.
[0072] The design requirements include a preset defect map and preset size parameters. The preset defect map is obtained through the following steps:
[0073] A1. A simulated test block is made according to the preset size parameters of the current transformer, and the simulated test block has a preset defect;
[0074] A2. Using the front side of the simulated test block as the DR inspection surface, perform DR inspection on the simulated test block to obtain a preset defect map.
[0075] If a preset defect from the preset defect map appears in the DR inspection map, the DR inspection result is determined to be non-compliant with the design requirements; otherwise, it is compliant.
[0076] If the measured dimensional parameters are within the error range of the preset dimensional parameters, the DR test result is determined to meet the design requirements; otherwise, it does not meet the requirements.
[0077] In this embodiment, the defect points on the DR detection spectrum image are compared with the preset defect spectrum (obtained by DR detection) on the simulated test block to identify the dangerous preset defects in the current transformer. These preset defects include burn-off defects, porosity defects, high-stress damage defects, and linear defects. Figure 4 As shown.
[0078] S3. Use any side of the current transformer as the ultrasonic testing surface (e.g., Figure 2 The ultrasonic testing of defects and winding eccentricity of the current transformer is performed on the plane shown in the right figure (perpendicular to the paper), and the ultrasonic testing results are obtained.
[0079] In step S3, the defect ultrasonic detection includes the following steps:
[0080] B1. Using a standard test block with multiple transverse through holes (such as...) Figure 5 The upper surface of the instrument (as shown) is used as the ultrasonic testing surface. The ultrasonic testing instrument is calibrated using a standard test block, and standard results are obtained. The standard results are standard distance amplitude curves. The parameters of the calibrated ultrasonic testing instrument are saved.
[0081] B2. Place the ultrasonic probe on the side of the current transformer and perform ultrasonic defect detection on the current transformer to obtain the ultrasonic detection result, which is the measured amplitude.
[0082] In this embodiment, the ultrasonic defect detection includes the following steps:
[0083] ① After completing the DR test, select the side of the current transformer as the ultrasonic test surface, clean its surface to meet the ultrasonic test requirements;
[0084] ② Select a 5MHz straight probe as the detection probe. The probe diameter should be less than 10mm. After calibrating the probe and ultrasonic system as required, the corresponding positioning test can be performed.
[0085] ③ On-site inspection requires not only checking the position of winding 1 once, but also searching for the thickness of the insulation layer and dangerous defects between layers.
[0086] ④ Adjust the ultrasonic instrument. Utilize, for example... Figure 5 The standard test block shown is used to create a distance amplitude curve based on a horizontal through-hole test block with a diameter of 1 mm (the purpose is to improve the sensitivity of the system). The simulated test block is used as the defect judgment test block (the non-standard test block simulates the current breakdown morphology and defects such as dense pores and shrinkage cavities).
[0087] ⑤ Defect scanning: After completing the winding positioning inspection, the insulation material on both sides is scanned using the distance amplitude curve. Defect points with problems are marked. After marking, the image information is compared with the image information of the comparison test block to determine the defect type.
[0088] In this invention, the ultrasonic testing of the insulation layer thickness and winding eccentricity specifically includes the following steps:
[0089] C1. Using standard stepped test blocks (such as...) Figure 6 As shown, a step with a thickness similar to (the same or equivalent) to the insulation layer of the current transformer under test is used as the test surface. The ultrasonic testing system is debugged and the parameters of the debugged ultrasonic testing instrument (ultrasonic velocity of the current transformer insulation material) are saved.
[0090] C2. Using both sides of the current transformer as ultrasonic testing surfaces, select multiple points (5 in this embodiment) to test the insulation layer thickness and obtain the insulation layer thickness values at multiple points.
[0091] Determine whether the deviation of the insulation layer thickness at each point on the same ultrasonic testing surface exceeds the design requirements. If it does, the current transformer is unqualified. If it does not, take the average value of the insulation layer thickness at each point on the same ultrasonic testing surface and compare it with the average value of the insulation layer thickness at each point on the other side of the ultrasonic testing surface. Determine whether the deviation of the two average values exceeds the design requirements. If it does, the current transformer is unqualified. If it does not, proceed to step C3.
[0092] C3. Using the two sides of the current transformer as ultrasonic testing surfaces, detect the eccentricity distance between the primary winding 1 and the secondary winding 2. Move the ultrasonic probe. When the peak height is the first preset height, the position of the center of the ultrasonic probe is the initial reference point O. Move the ultrasonic probe to both sides in the horizontal direction of the initial reference point O. When the peak height drops to the second preset height, mark the position point O' and position point O” of the probe center.
[0093] C4. Move the ultrasonic probe vertically along the initial reference point O, and take the position of the center of the ultrasonic probe when the peak height is the first preset height as the reference point O1. Replace the initial reference point O with the reference point O1 and repeat step C3 to obtain the marked probe center position point O1' and position point O2”.
[0094] C5. Repeat step C4 to obtain multiple reference points O. n And mark the location point O of the probe center. n Location point O n ”;
[0095] C6. Transfer the positions O' and O1' located on the same side of each reference point to O nConnect the points to obtain line l1, and then connect the points O” and O1” located on the other side of each reference point to O”. n "Connect to obtain line l2."
[0096] In this embodiment, ultrasonic testing is used to detect the thickness deviation of the insulation layer. In other embodiments, DR (dielectric transducer) testing can also be used to detect the thickness deviation of the insulation layer. The general steps are the same as those for ultrasonic testing of the insulation layer thickness deviation, and the specific steps are as follows:
[0097] D1. Using the front and back sides of the current transformer as the detection surfaces, select multiple points (5 in this embodiment) to detect the insulation layer thickness and obtain the insulation layer thickness values at multiple points.
[0098] D2. Determine whether the thickness deviation of the insulation layer at each point on the same test surface exceeds the design requirements (known dimensional parameters). If it does, the current transformer is unqualified; if it does not, proceed to step D3.
[0099] D3. Compare the average value of the insulation layer thickness at each point on the same testing surface with the average value of the insulation layer thickness at each point on the other testing surface, and determine whether the deviation between the two average values exceeds the design requirements. If it does, the current transformer is unqualified; if it does not exceed the requirements, proceed to step C3.
[0100] In this embodiment, the ultrasonic detection of the eccentricity distance of the primary winding 1 specifically includes the following steps:
[0101] ⑥ After the probe and ultrasonic system are debugged, select the highest peak of the reflected wave to modulate 80% of the full screen. Slowly move the ultrasonic probe to both sides until the peak drops to 10% of the full screen height, and mark the center position of the probe on site.
[0102] ⑦ After marking, slowly move the probe to the other side. When the peak drops to 10% of the full screen height, mark the center position of the probe. At this time, the distance between the two marked positions is the width of the primary winding 1.
[0103] The ultrasonic testing procedure for the eccentricity of secondary winding 1 is the same as that for the ultrasonic testing procedure for the eccentricity of primary winding 1.
[0104] S4. Compare the ultrasonic test results with the standard results to determine whether the winding eccentricity and defects in the ultrasonic test results meet the design requirements. If all meet the requirements, the current transformer is qualified; otherwise, the current transformer is unqualified.
[0105] In this invention, the judgment criteria are as follows:
[0106] When the measured amplitude is within the range of the standard amplitude curve spectrum, it is determined that the defect in the ultrasonic test result in step S4 meets the design requirements; otherwise, it does not meet the requirements.
[0107] When the difference between the distances of two points on the same horizontal direction on curves l1 and l2 and the central axis or edge of the ultrasonic testing surface is less than a preset value, it is determined that the winding eccentricity distance in the ultrasonic testing result in step S4 meets the design requirements; otherwise, it does not meet the requirements.
[0108] In this invention, the first preset height is 70%-80% of the highest peak height, and the second preset height is 10%-20% of the highest peak height; the preset value is 5mm.
[0109] In this embodiment, after multiple measurements, connecting the measurement points with a line allows observation of the eccentricity of the primary winding 1. If the eccentricity is small (less than a preset value), the center position needs to be marked on the TA side, and then the distance from the center position to the central axis of the ultrasonic testing surface or the edge of the primary winding 1 (in this embodiment, the central axis) is measured. The two distances (e.g., ...) Figure 7 Subtracting S1 and S2 from each other gives the eccentricity distance S. Figure 7 As shown. From Figure 7 As can be seen from the diagram, l1 and l2 are two straight lines parallel to the center line. The eccentricity can be shown on this diagram. For example, l1 is farther from the center line (distance S1), while the width of the primary winding 1 remains unchanged. Therefore, l2 is closer to the center line (distance S2). The difference between the two distances from the center line (S1-S2) is the eccentricity S.
[0110] A field non-destructive testing system for current transformers includes the following modules:
[0111] The first detection module is used to perform DR detection on the current transformer by using the front and back sides of the current transformer as DR detection surfaces, and to obtain the DR detection results.
[0112] The second judgment module compares the DR test results with the design requirements and determines whether the DR test pattern and the measured size parameters of the current transformer in the DR test results meet the design requirements. If they all meet the requirements, the module jumps to the third test module; otherwise, the current transformer is unqualified.
[0113] The third detection module uses the two sides of the current transformer as ultrasonic detection surfaces to perform ultrasonic defect detection and ultrasonic winding eccentricity detection on the current transformer, and obtains the ultrasonic detection results.
[0114] The fourth judgment module compares the ultrasonic test results with the standard results to determine whether the winding eccentricity and defects in the ultrasonic test results meet the design requirements. If all meet the requirements, the current transformer is qualified; otherwise, the current transformer is unqualified.
[0115] A computer-readable medium storing a computer program programmed or configured to perform the aforementioned field non-destructive testing method for a current transformer.
[0116] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD / ROM, optical storage, etc.) containing computer-usable program code. This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0117] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.
Claims
1. A method for on-site non-destructive testing of current transformers, characterized in that: Includes the following steps: S1. Using the front and back sides of the current transformer as the DR detection surfaces respectively, perform DR detection on the current transformer and obtain the DR detection results. S2. Compare the DR test results with the design requirements to determine whether the DR test pattern and the measured size parameters of the current transformer in the DR test results meet the design requirements. If they all meet the requirements, proceed to step S3; otherwise, the current transformer is unqualified. S3. Using the two sides of the current transformer as ultrasonic testing surfaces, perform ultrasonic testing for defects and ultrasonic testing for winding eccentricity of the current transformer, and obtain the ultrasonic testing results. The ultrasonic defect detection includes the following steps: B1. Using the upper surface of a standard test block with multiple transverse through holes as the ultrasonic testing surface, the ultrasonic testing instrument is calibrated using the standard test block, and standard results are obtained. The standard results are standard distance amplitude curves. The parameters of the calibrated ultrasonic testing instrument are saved. B2. Place the ultrasonic probe on the side of the current transformer and perform ultrasonic testing on the current transformer to obtain the ultrasonic test results, which are the measured amplitudes. The ultrasonic detection of the winding eccentricity distance specifically includes the following steps: C1. Using a standard stepped test block and a stepped surface with a similar thickness to the insulation layer of the current transformer as the test surface, debug the ultrasonic testing system and save the parameters of the debugged ultrasonic testing instrument. C2. Using both sides of the current transformer as ultrasonic testing surfaces, select multiple points on each side to test the insulation layer thickness, obtaining insulation layer thickness values at multiple points. Determine whether the deviation of the insulation layer thickness values at each point on the same ultrasonic testing surface exceeds the design requirements. If it does, the current transformer is unqualified. If it does not exceed the requirements, compare the average insulation layer thickness values at each point on the same ultrasonic testing surface with the average insulation layer thickness values at each point on the other side of the ultrasonic testing surface, and determine whether the deviation between the two average values exceeds the design requirements. If it does, the current transformer is unqualified. If it does not exceed the requirements, proceed to step C3. C3. Using the two sides of the current transformer as ultrasonic testing surfaces, move the ultrasonic probe. When the peak height is the first preset height, the center of the ultrasonic probe is located at the initial reference point O. Move the ultrasonic probe to both sides in the horizontal direction of the initial reference point O. When the peak height drops to the second preset height, mark the probe center location point O' and location point O''. C4. Move the ultrasonic probe vertically along the initial reference point O, and take the position of the center of the ultrasonic probe when the peak height is the first preset height as the reference point O1. Replace the initial reference point O with the reference point O1 and repeat step C3 to obtain the marked probe center position point O1' and position point O1''. C5. Repeat step C4 to obtain multiple reference points O. n And mark the location point O of the probe center. n Location point O n ''; C6. Transfer the positions O' and O1' located on the same side of each reference point to O n Connect the points to obtain line l1, and then connect the points O'' and O1'' located on the other side of each reference point to O. n Connecting them yields line l2; S4. Compare the ultrasonic test results with the standard results to determine whether the winding eccentricity and defects in the ultrasonic test results meet the design requirements. If all meet the requirements, the current transformer is qualified; otherwise, the current transformer is unqualified. When the measured amplitude is within the range of the standard amplitude curve spectrum, it is determined that the defect in the ultrasonic test result in step S4 meets the design requirements; otherwise, it does not meet the requirements. When the difference between the distances of two points on the same horizontal direction on straight lines l1 and l2 and the central axis or edge of the ultrasonic testing surface is less than a preset value, it is determined that the winding eccentricity distance in the ultrasonic testing result in step S4 meets the design requirements; otherwise, it does not meet the requirements.
2. The on-site non-destructive testing method according to claim 1, characterized in that: In step S2, the measured size parameters are obtained based on the DR detection spectrum. The design requirements include a preset defect map and preset size parameters. The preset defect map is obtained through the following steps: A1. A simulated test block is made according to the preset size parameters of the current transformer, and the simulated test block has a preset defect; A2. Using the front side of the simulated test block as the DR inspection surface, perform DR inspection on the simulated test block to obtain a preset defect map.
3. The on-site non-destructive testing method according to claim 2, characterized in that: The preset defects are burn-related defects, porosity defects, high-stress damage defects, and linear defects.
4. The on-site non-destructive testing method according to claim 2, characterized in that: If a preset defect from the preset defect map appears in the DR inspection map, the DR inspection result is determined to be non-compliant with the design requirements; otherwise, it is compliant. If the measured dimensional parameters are within the error range of the preset dimensional parameters, the DR test result is determined to meet the design requirements; otherwise, it does not meet the requirements.
5. The on-site non-destructive testing method according to any one of claims 1 to 4, characterized in that: The first preset height is 70%-80% of the highest peak height, and the second preset height is 10%-20% of the highest peak height; the preset value is 5mm.
6. A field non-destructive testing system for a current transformer used to perform the field non-destructive testing method for a current transformer according to any one of claims 1 to 5, characterized in that: Includes the following modules: The first detection module is used to perform DR detection on the current transformer by using the front and back sides of the current transformer as DR detection surfaces respectively, and to obtain the DR detection results. The second judgment module compares the DR test results with the design requirements and determines whether the DR test pattern and the measured size parameters of the current transformer in the DR test results meet the design requirements. If they all meet the requirements, the module jumps to the third test module; otherwise, the current transformer is unqualified. The third detection module uses the two sides of the current transformer as ultrasonic detection surfaces to perform ultrasonic defect detection and ultrasonic winding eccentricity detection on the current transformer, and obtains the ultrasonic detection results. The fourth judgment module compares the ultrasonic test results with the standard results to determine whether the winding eccentricity and defects in the ultrasonic test results meet the design requirements. If all meet the requirements, the current transformer is qualified; otherwise, the current transformer is unqualified.
7. A computer-readable medium, characterized in that: The computer-readable storage medium stores a computer program that is programmed or configured to perform the field non-destructive testing method for the current transformer according to any one of claims 1 to 5.