Copper bar contact resistance testing method

Abstract

The invention belongs to the technical field of production and manufacturing of transformers, converter transformers, reactors and the like, and relates to a copper bar contact resistance testing method, which comprises the following steps: assembling a testing platform comprising a supporting platform, and installing an axial force applying system and a direct current resistance tester on the side of the supporting platform, connecting the copper bar sample, the wiring terminal and the fastening nut to a direct-current resistance tester through a resistance test clamp and a test line; the direct-current resistance tester and the axial force applying system are started, the axial force applying system is used for tightening the fastening nut to apply axial force to the copper bar sample step by step, and the axial force on the copper bar sample is transmitted to the axial force sensor through the supporting plate for axial force measurement; the direct-current resistance tester measures insulation resistance along with the axial force loading process, copper bar contact resistance is obtained through calculation, and an axial force-contact resistance curve is drawn. According to the invention, the copper bar connection condition in the transformer can be accurately simulated through the copper bar sample, and the contact resistance of the copper bar sample is measured by applying an axial force.

Description

Technical Field

[0001] This invention belongs to the technical field of manufacturing transformers, converter transformers and reactors, and specifically relates to a method for testing the contact resistance of copper busbars. Background Technology

[0002] Copper busbar connections are crucial in transformer structures. Both the copper busbar and connecting components such as terminals have through holes. Axial force is applied using bolts to ensure contact between the copper busbar and terminals, providing the structure with mechanical strength and enabling current conduction. Under normal circumstances, the resistance of the copper busbar, the terminals, and the contact resistance between them are low. The losses and heat generated by the current flowing through the copper busbar do not affect transformer operation. However, when the axial force is insufficient or the contact between the terminals and the copper busbar is poor, the contact resistance increases sharply, leading to localized heating and even equipment meltdown. This type of risk is currently prevalent in the transformer industry.

[0003] Therefore, testing the change in contact resistance of copper busbars under different axial forces is of great significance. However, existing copper busbar resistance testing platforms usually only focus on the resistance of the copper busbar itself, and lack test platforms for testing the contact resistance between the copper busbar and the terminal block under different axial forces. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a design scheme for testing the contact resistance of copper busbars. The technical solution adopted by this invention is as follows: A method for testing the contact resistance of copper busbars includes the following steps: Assembly and testing platform: The support platform is a hollow box with an opening on the front side. A circular through hole is opened in the center of the upper panel of the support platform. The upper diameter of the circular through hole is larger than the lower diameter, forming a stepped structure. The circular plate support plate is clamped onto the stepped structure and fixedly connected to the support platform. A shaft force sensor and a bolt anti-rotation support plate are arranged in sequence below the support plate from top to bottom. A square groove is opened in the center of the lower surface of the bolt anti-rotation support plate. A copper busbar sample, a terminal block and a flat washer are arranged in sequence above the support plate from bottom to top. The flat washer, terminal block, copper busbar sample, support plate, shaft force sensor and bolt anti-rotation support plate are fixedly connected as a whole by bolts or screws. An axial force application system is fixedly installed on the rear side of the support platform, and a DC resistance tester is fixedly installed on the left side of the support platform. The copper busbar sample, terminals, and fastening nuts at the upper end of bolts or screws are connected to the DC resistance tester using resistance test fixtures and test leads. Start the DC resistance tester and axial force application system. Tighten the bolts or the fastening nuts at the upper end of the screws through the axial force application system to apply axial force to the copper busbar sample in steps. The axial force on the copper busbar sample is transmitted to the axial force sensor through the support plate for axial force measurement. The DC resistance tester measures the insulation resistance during the axial force loading process, and calculates the copper busbar contact resistance to obtain the axial force-contact resistance curve.

[0005] Preferably, the lower base plate of the support platform has a sliding groove 1 and a sliding groove 2. The sliding bracket 1 and the sliding bracket 2 with an inverted U-shaped structure are slidably installed inside the support platform through the sliding groove 1 and the sliding groove 2. The sliding bracket 2 is fitted into the sliding bracket 1. The upper panel of the sliding bracket 1 has a circular through hole 2 corresponding to the circular through hole 1. The upper panel of the sliding bracket 1 with the circular through hole 2 is fixedly installed with a bolt anti-rotation support plate mounting plate. The bolt anti-rotation support plate mounting plate is a rectangular plate with a U-shaped opening processed along its length. The lower surface of the bolt anti-rotation support plate mounting plate has a sliding groove corresponding to the U-shaped opening. The bolt anti-rotation support plate has a circular plate structure. The bolt anti-rotation support plate is slidably inserted into the sliding groove. The flat washer, the terminal block, the copper busbar sample, the support plate, the axial force sensor and the bolt anti-rotation support plate are fixedly connected as a whole by bolts. The bolt head is located in the square groove, and the threaded end of the bolt is screwed with a nut.

[0006] Preferably, an upper and lower support with an inverted U-shaped structure are fixedly installed on the lower base plate of the support platform. The lower support is located inside the upper support. The upper panel of the upper support has a circular through hole three corresponding to the circular through hole one. A bolt anti-rotation support plate mounting plate is fixedly installed on the upper panel of the upper support around the circular through hole three. The bolt anti-rotation support plate mounting plate is a rectangular plate with a U-shaped opening machined along its length. The lower surface of the bolt anti-rotation support plate mounting plate has a groove corresponding to the U-shaped opening. The bolt anti-rotation support plate is a circular plate structure. The bolt anti-rotation support plate slides into the groove. The flat washer, wiring terminal, copper busbar sample, support plate, axial force sensor and bolt anti-rotation support plate are fixedly connected as a whole by a screw. The lower nut is located in the square groove and screwed onto the lower end of the screw. The upper end of the screw is screwed onto the nut.

[0007] Preferably, bolt through holes 1 are opened on the support plates on both sides of the copper busbar sample, and bolt through holes 2 corresponding to bolt through holes 1 are opened on the stepped structure 1 of the support platform. The support plate fixing bolts are screwed into bolt through holes 1 and bolt through holes 2 to fix the support plate and the support platform into one piece.

[0008] Preferably, the upper diameter of the bolt anti-rotation support plate is larger than the lower diameter to form a stepped structure, and the upper diameter of the bolt anti-rotation support plate is adapted to the arc of the end of the slide groove.

[0009] Preferably, the resistance test fixture uses alligator clips.

[0010] Preferably, before starting the test, the fastening bolts and flat washers at the upper end of the bolt or screw are cleaned and dried, and the terminals and copper busbar sample surfaces are cleaned.

[0011] Preferably, the axial force application system is equipped with a tightening sleeve assembly.

[0012] The beneficial effects of this invention are: The copper busbar contact resistance testing method of the present invention can accurately simulate the copper busbar connection in a transformer using a copper busbar sample, and measure the contact resistance of the copper busbar sample by applying axial force. The measurement data can be used to judge the contact quality of the copper busbar sample, avoid transformer failures caused by insufficient axial force or poor contact, reduce costs and improve production efficiency. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a front view of the test platform, DC resistance tester, and axial force application system according to Embodiment 1 of the present invention; Figure 2 This is an assembly diagram of the copper busbar sample according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the bolt anti-rotation support plate mounting plate according to Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the bolt anti-rotation support plate according to Embodiment 1 of the present invention, wherein part 4a is a top view and part 4b is a bottom view; Figure 5 This is a schematic diagram of the tightening sleeve assembly according to Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the axial force application mechanism according to Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the contact resistance test wiring according to Embodiment 1 of the present invention; Figure 8 This is a flowchart of the contact resistance testing steps according to Embodiment 1 of the present invention; In the figure, 1 is a DC resistance tester, 2 is a resistance test fixture, 3 is an axial force application system, 4 is a support plate, 5 is an axial force sensor, 6 is a bolt anti-rotation support plate, 7 is a support platform, 8 is a support plate fixing bolt, 9 is a copper busbar sample, 10 is a terminal block, 11 is a flat washer, 12 is a nut, 13 is a sliding groove, 14 is a through hole one, 15 is a square groove, 16 is a tightening sleeve assembly, 17 is a sliding bracket one, 18 is a sliding bracket two, and 19 is a bolt anti-rotation support plate mounting plate. Detailed Implementation

[0014] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0015] Example 1:

[0016] like Figure 1-4 As shown, a copper busbar contact resistance testing platform includes a support platform 7, which is a hollow box. The front side opening of the support platform 7 is used to push in sliding bracket 17, sliding bracket 2 18, and bolt anti-rotation support plate 6. Sliding bracket 17 and sliding bracket 2 18 are both inverted U-shaped structures. The upper surface of the lower bottom plate inside the support platform 7 is provided with sliding groove 1 and sliding groove 2. Sliding bracket 17 and sliding bracket 2 18 are slidably installed inside the support platform 7 through sliding groove 1 and sliding groove 2, with sliding bracket 2 18 fitted inside sliding bracket 17.

[0017] A circular through-hole with a stepped structure is formed at the center of the upper panel of the support platform 7. The upper diameter of the circular through-hole is larger than the lower diameter, forming the stepped structure. The circular plate support plate 4 is fitted onto the stepped structure of the circular through-hole on the upper part of the support platform 7. A square copper busbar sample 9 is installed in the middle of the upper surface of the support plate 4. Bolt through holes are formed on the support plate 4 on both sides of the copper busbar sample 9. Bolt through holes corresponding to bolt through holes are formed on the stepped structure of the support platform 7. The support plate fixing bolts 8 are screwed into bolt through holes one and bolt through holes two, fixing the support plate 4 and the support platform 7 together.

[0018] The upper panel of the sliding bracket 17 has a second circular through hole corresponding to the first circular through hole. A bolt anti-rotation support plate mounting plate 19 is fixedly installed on the upper surface of the sliding bracket 17 around the second circular through hole. The bolt anti-rotation support plate mounting plate 19 is a rectangular plate with a U-shaped opening. The lower surface of the bolt anti-rotation support plate mounting plate 19 has a groove 13 corresponding to the U-shaped opening. The bolt anti-rotation support plate 6 is slidably inserted into the groove 13. The axial force sensor 5 is installed between the support plate 4 and the bolt anti-rotation support plate 6. The axial force sensor 5 passes through the second circular through hole on the sliding bracket 17 and the end circular hole on the groove 13 of the bolt anti-rotation support plate mounting plate 19.

[0019] The bolt anti-rotation support plate 6 is a circular thick plate. The lower surface of the bolt anti-rotation support plate 6 has a stepped structure II, with the upper diameter of the bolt anti-rotation support plate 6 being larger than the lower diameter, forming the stepped structure II. The upper diameter of the bolt anti-rotation support plate 6 is adapted to the end arc of the sliding groove 13. A through hole 14 is opened at the center of the bolt anti-rotation support plate 6. A square groove 15 is machined on the lower surface of the bolt anti-rotation support plate 6 around the through hole 14 to accommodate the bolt head. The center positions of the axial force sensor 5, the support plate 4, and the copper busbar sample 9 are respectively provided with through holes 2, 3, and 4 corresponding to through hole 14. The bolt passes through the bolt anti-rotation support plate 6, the axial force sensor 5, the support plate 4, and the copper busbar sample 9 in sequence from bottom to top. The upper end of the bolt above the copper busbar sample 9 is fitted with the terminal block 10 and the flat washer 11 in sequence from bottom to top. Finally, the nut 12 is screwed on the top of the copper busbar sample 9. Tightening the nut 12 fixes the bolt anti-rotation support plate 6, the axial force sensor 5, the support plate 4, the copper busbar sample 9, the terminal block 10, and the flat washer 11 into a whole.

[0020] The axial force sensor 5 is an existing product, and a hollow ring-shaped axial force sensor with model number Messitechnik-300kN can be selected.

[0021] Different specifications of matching support plates 4 and bolt anti-rotation support plates 6 can be designed. For example, three support plates 4 of commonly used specifications are designed. They are discs with the same outer diameter and three through holes of different diameters in the center. The through holes three can pass through bolts of M8, M10, and M12 specifications respectively. The contact surface between the support plate 4 and the copper busbar sample 9 is made of insulating material to ensure accurate contact resistance measurement. There are also three bolt anti-rotation support plates 6. Their dimensions match the slide groove 13. The through holes 14 of the bolt anti-rotation support plate 6 can pass through bolts of M8, M10, and M12 specifications respectively. The width of the square groove 15 of the bolt anti-rotation support plate 6 is consistent with the width of the parallel side of the hexagonal head of the M8, M10, and M12 specifications respectively. After the bolt is inserted, the square groove 15 locks the bolt head and prevents it from rotating.

[0022] The copper busbar contact resistance testing method provided in this embodiment of the invention has good scalability. If it is necessary to measure the copper busbar sample 9 using larger specification bolts, it is only necessary to make a support plate 4 and a bolt anti-rotation support plate 6 of the corresponding specifications.

[0023] The assembly steps for the transformer copper busbar contact resistance testing platform are as follows: Place the support platform 7 stably on the ground, and push the sliding bracket 17 into the hollow structural box of the support platform 7; push the bolt anti-rotation support plate 6 into the sliding groove 13 of the bolt anti-rotation support plate mounting plate 19, and pass the bolt through the through hole 14 of the bolt anti-rotation support plate 6, with the bolt head falling into the square groove 15 of the bolt anti-rotation support plate 6; push the sliding bracket 2 18 into the sliding bracket 17, and the sliding bracket 2 18 provides temporary support for the bolt anti-rotation support plate 6; place the axial force sensor 5 above the bolt anti-rotation support plate 6, with the bolt passing through the axial force sensor 5. A support plate 4 is placed above the axial force sensor 5, and bolts are inserted through the support plate 4. The support plate 4 and the support platform 7 are fixedly connected as one unit by a pair of support plate fixing bolts 8. A copper busbar sample 9 is placed above the support plate 4, and bolts are inserted through the copper busbar sample 9. A terminal block 10 is placed above the copper busbar sample 9, and bolts are inserted through the terminal block 10. A flat washer 11 is placed above the terminal block 10, and bolts are inserted through the flat washer 11. Finally, a nut 12 is screwed on and tightened at the upper end of the bolt. After tightening the nut 12, the lower bolt anti-rotation support plate 6 is removed from the upper surface of the sliding bracket 18.

[0024] like Figure 5-8 As shown, the test steps for the contact resistance of transformer copper busbars are as follows: An axial force application system 3 is fixedly installed on the ground behind the support platform 7, and a DC resistance tester 1 is fixedly installed on the ground to the left of the support platform 7. The copper busbar sample 9, terminal block 10, and nut 12 are connected to the DC resistance tester 1 via the resistance test fixture 2 and test leads. The resistance test fixture 2 can be a low-resistance alligator clip, which can be easily fixed at the designated position of the copper busbar sample 9 to be tested.

[0025] Start the DC resistance tester 1 and the axial force application system 3. Tighten the nut 12 through the axial force application system 3 to apply axial force to the copper busbar sample 9 in steps. The axial force on the copper busbar sample 9 is accurately transmitted to the axial force sensor 5 through the support plate 4 for measurement. The DC resistance tester 1 measures the insulation resistance during the axial force loading process, and calculates the copper busbar contact resistance to obtain the axial force-contact resistance curve.

[0026] The axial force application system 3 is a mature existing product, mainly including the following functions: setting loading (forward rotation), unloading (reverse rotation), and automatically loading to the required value after setting the axial force. Multiple loading points can be set, and the axial force and corresponding contact resistance are measured sequentially. The axial force application system 3 includes a support frame installed on the ground and a balance beam installed on the support frame. The end of the balance beam is located above the support platform 7. An axial force application mechanism and sensor are installed on the balance beam. The axial force application mechanism is used to tighten the nut 12 and apply axial force. The height of the balance beam must meet the requirements of the axial force application system 3 for tightening bolts. The core component of the axial force application mechanism is a Panasonic MDMF202L1G6M servo motor, with a tightening sleeve assembly 16 connected to the lower part of the servo motor. The axial force control range can reach 0~300kN, with an accuracy better than ±2%, which can meet the testing requirements of all commonly used copper busbar specifications. The axial force is applied to the set value step by step through the axial force application system 3, and the insulation resistance is measured by the DC resistance tester 1 during the axial force loading process.

[0027] The tightening sleeve assembly 16 includes a standard 1 / 2" adapter and a universal torque sleeve for various bolt sizes, which can be easily replaced and also allows users to customize the tightening sleeve assembly 16 according to their testing needs. The servo motor and the tightening sleeve assembly 16 are mounted together on the balance beam, which allows users to easily move the tightening sleeve assembly 16 up and down and back and forth to tighten the bolts.

[0028] The DC resistance tester 1 is an existing product used to measure the contact resistance of the copper busbar sample 9. The test range is 0.01uΩ to 300Ω, the accuracy class is better than 0.05, and the minimum test accuracy (0.01uΩ) can reach 1 / 1000 of the conventional copper busbar resistance.

[0029] The main unit of the DC resistance tester 1 is equipped with a Pt1000 temperature sensor and long test leads. The sensor can be arranged around the copper busbar sample 9 to accurately measure the ambient temperature with a temperature resolution of 0.1℃. Based on the measured temperature, the measured resistance is converted into a standard resistance at 20℃ or other temperatures.

[0030] The yield axial force is calculated based on the bolt specifications and material, serving as the target axial force for the test. The axial force is gradually increased from zero, with each force value and corresponding insulation resistance recorded until the yield axial force is reached. An axial force-contact resistance curve is then plotted. The copper busbar sample 9 is replaced, and the above test procedure is repeated. Insulation resistance = resistance of terminal 10 itself + resistance of copper busbar sample 9 itself + contact resistance. During measurement, the actual measured value is the insulation resistance, which reflects the change in contact resistance.

[0031] The contact resistance stability value can be compared based on the axial force-contact resistance curve to determine whether the contact resistance of copper busbar sample 9 and terminal 10 is qualified; the minimum applied axial force under the contact resistance qualification requirement can be determined, which is used to detect the copper busbar connection quality during the production process; the contact resistance stability point can be determined, and the recommended value of axial force loading can be determined to prevent excessive axial force during the production process from causing bolt breakage.

[0032] Before starting the test, the bolts and flat washers 11 were cleaned and dried, and the terminals 10 and the copper busbar sample 9 were cleaned.

[0033] Example 2:

[0034] Implementation Two improves the structure of the support platform 7 in Implementation One by omitting the sliding bracket 17 and sliding bracket 18, transforming the support platform 7 into a multi-layered, integrated structure. Simultaneously, the bolts in Implementation One are replaced with threaded rods, with nuts and upper nuts screwed onto both ends of the threaded rods. Inside the hollow box-shaped housing of the support platform 7, an upper bracket and a lower bracket are fixedly installed on the bottom plate. Both the upper and lower brackets are inverted U-shaped structures, with the lower bracket located inside the upper bracket. An opening is located in the center of the upper surface of the upper bracket, where a bolt anti-rotation support plate mounting plate 19 is fixedly installed. An opening on the front side is used to push in the bolt anti-rotation support plate 6.

[0035] When assembling the test platform, first place the lower nut into the square groove 15 of the bolt anti-rotation support plate 6. Push the bolt anti-rotation support plate 6 together with the lower nut into the gap between the upper and lower supports, where the lower support provides temporary support. After pushing the bolt anti-rotation support plate 6 into the sliding groove 13 of the bolt anti-rotation support plate mounting plate 19, screw the lower end of the screw into the lower nut. The other assembly steps are the same as in Example 1. Finally, tighten the upper nut at the upper end of the screw.

[0036] In the embodiments of the present invention, all technical features not described in detail are existing technologies or conventional technical means, and will not be repeated here.

[0037] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A method for testing the contact resistance of a copper busbar, characterized in that, Includes the following steps: Assembly and testing platform: The support platform (7) is a box with a hollow internal structure. The front side of the support platform (7) is open. A circular through hole is opened at the center of the upper panel of the support platform (7). The upper diameter of the circular through hole is larger than the lower diameter to form a step structure. The circular plate support plate (4) is clamped on the step structure and fixedly connected to the support platform (7). The axial force sensor (5) and the bolt anti-rotation support plate (6) are arranged from top to bottom below the support plate (4). A square groove (15) is opened at the center of the lower surface of the bolt anti-rotation support plate (6). The copper busbar sample (9), the wiring terminal (10) and the flat washer (11) are arranged from bottom to top above the support plate (4). The flat washer (11), the wiring terminal (10), the copper busbar sample (9), the support plate (4), the axial force sensor (5) and the bolt anti-rotation support plate (6) are fixedly connected as a whole by bolts or screws. An axial force application system (3) is fixedly installed on the rear side of the support platform (7), and a DC resistance tester (1) is fixedly installed on the left side of the support platform (7). The copper busbar sample (9), the terminal block (10), and the fastening nut at the upper end of the bolt or screw are connected to the DC resistance tester (1) through the resistance test fixture (2) and the test leads. Start the DC resistance tester (1) and the axial force application system (3). Tighten the bolt or the fastening nut at the upper end of the screw through the axial force application system (3) to apply axial force to the copper busbar sample (9) in steps. The axial force on the copper busbar sample (9) is transmitted to the axial force sensor (5) through the support plate (4) for axial force measurement. The DC resistance tester (1) measures the insulation resistance during the axial force loading process, and calculates the copper busbar contact resistance to obtain the axial force-contact resistance curve.

2. The method for testing the contact resistance of a copper busbar according to claim 1, characterized in that, The bottom plate of the support platform (7) is provided with a sliding groove 1 and a sliding groove 2. The sliding bracket 1 (17) and the sliding bracket 2 (18) with the inverted U-shaped structure are slidably installed inside the support platform (7) through the sliding groove 1 and the sliding groove 2. The sliding bracket 2 (18) is fitted into the sliding bracket 1 (17). The upper panel of the sliding bracket 1 (17) is provided with a circular through hole 2 corresponding to the circular through hole 1. The upper panel of the sliding bracket 1 (17) on the outer periphery of the circular through hole 2 is fixedly installed with a bolt anti-rotation support plate mounting plate (19). The bolt anti-rotation support plate mounting plate (19) is a rectangular plate. The support plate mounting plate (19) has a U-shaped opening along its length. The lower surface of the bolt anti-rotation support plate mounting plate (19) has a groove (13) corresponding to the U-shaped opening. The bolt anti-rotation support plate (6) is a circular plate structure. The bolt anti-rotation support plate (6) is slidably inserted into the groove (13). The flat washer (11), the terminal block (10), the copper busbar sample (9), the support plate (4), the axial force sensor (5), and the bolt anti-rotation support plate (6) are fixedly connected as a whole by bolts. The bolt head is located in the square groove (15), and the threaded end of the bolt is screwed with a nut (12).

3. The method for testing the contact resistance of a copper busbar according to claim 1, characterized in that, The lower base plate of the support platform (7) is fixedly installed with an upper and lower support of an inverted U-shape structure. The lower support is located inside the upper support. The upper panel of the upper support has a circular through hole three corresponding to the circular through hole one. The upper panel of the upper support is fixedly installed with a bolt anti-rotation support plate mounting plate (19) around the circular through hole three. The bolt anti-rotation support plate mounting plate (19) is a rectangular plate. The bolt anti-rotation support plate mounting plate (19) has a U-shaped opening processed along its length. The lower surface of 19) is machined with a groove (13) corresponding to the U-shaped opening. The bolt anti-rotation support plate (6) is a circular plate structure. The bolt anti-rotation support plate (6) is slidably inserted into the groove (13). The flat washer (11), terminal block (10), copper busbar sample (9), support plate (4), axial force sensor (5) and bolt anti-rotation support plate (6) are fixedly connected as a whole by a screw. The lower nut is located in the square groove (15) and screwed on the lower end of the screw. The upper end of the screw is screwed on with a nut.

4. A method for testing the contact resistance of a copper busbar according to claim 2 or 3, characterized in that, Bolt through holes 1 are opened on the support plates (4) on both sides of the copper busbar sample (9), and bolt through holes 2 corresponding to bolt through holes 1 are opened on the step structure 1 of the support platform (7). The support plate fixing bolts (8) are screwed into bolt through holes 1 and bolt through holes 2 to fix the support plate (4) and the support platform (7) into one piece.

5. A method for testing the contact resistance of a copper busbar according to claim 2 or 3, characterized in that, The upper diameter of the bolt anti-rotation support plate (6) is larger than the lower diameter to form a stepped structure. The upper diameter of the bolt anti-rotation support plate (6) is adapted to the arc at the end of the slide groove (13).

6. The method for testing the contact resistance of a copper busbar according to claim 1, characterized in that, The resistance test fixture (2) uses alligator clips.

7. The method for testing the contact resistance of a copper busbar according to claim 1, characterized in that, Before starting the test, clean and dry the fastening bolts and flat washers (11) at the upper end of the bolt or screw, and clean the surface of the terminal block (10) and the copper busbar sample (9).

8. The method for testing the contact resistance of a copper busbar according to claim 1, characterized in that, The axial force application system (3) is equipped with a tightening sleeve assembly (16).

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