A pressure test device and method for overhead insulated cables

Abstract

This invention relates to a withstand voltage testing device and method for overhead insulated cables, belonging to the field of power equipment testing technology. It includes a cable under test, with a grounding wire connected to one end. A terminal block is located at the end of the grounding wire, and a test connector is connected to the terminal block. An adjustable fixing component is mounted on the test connector, and an insulating protection component is located around the adjustable fixing component. A timing test component is also mounted on the test connector. The adjustable fixing component is used to adapt to and clamp terminals of different diameters. This invention, through its integrated design of adaptive clamping, timing interlocking, and insulating protection, solves the problems of poor contact, poor versatility, lack of safety interlocking, and susceptibility to misoperation found in traditional devices. It has advantages such as wide applicability, simple operation, high safety, and stable and reliable operation, and is suitable for on-site withstand voltage testing of overhead insulated cables of various diameters.

Description

Technical Field

[0001] This invention relates to the field of power equipment testing technology, and in particular to a withstand voltage test device and method for overhead insulated cables. Background Technology

[0002] As a core component of power transmission systems, the insulation performance of overhead insulated cables directly determines the safe and stable operation of the power supply system. Withstand voltage testing is a crucial method for detecting defects in cable insulation and verifying electrical safety indicators, and it is widely used in cable manufacturing, project completion acceptance, and on-site maintenance. By applying a high-voltage test to the cable for a specified duration, potential hazards such as insulation damage, cracks, and air gaps can be effectively detected, making it an essential testing procedure to ensure reliable cable operation.

[0003] Because single-core overhead insulated cables lack a negative pole, traditional methods require immersion in a water tank to create a negative pressure circuit using water as a grounding medium for withstand voltage and water resistance tests. This approach is cumbersome, involves bulky equipment, is limited by site constraints, has high waterproofing requirements, and is inefficient. Furthermore, current withstand voltage tests for overhead insulated cables generally lack mechanically enforced timing constraints for high-voltage wiring and safety protection. Test wiring often relies on simple clamps for manual completion, leading to unreliable contact and high risk of high-voltage exposure. Traditional devices operate cable clamping, protective isolation, and high-voltage switching independently, lacking a safety linkage logic. This can result in violations such as energizing before clamping or pressurizing before sealing, posing safety hazards like discharge and electric shock. Additionally, existing devices often use electrical sensors and microswitches for status detection, which are susceptible to environmental interference and lack reliability, failing to fundamentally guarantee the safe test sequence of clamping, then protection, and finally energizing.

[0004] Therefore, this application provides a withstand voltage testing apparatus and method for overhead insulated cables to meet the requirements. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a withstand voltage test device and method for overhead insulated cables, so as to solve the problems of lack of mechanical forced timing interlocking in high voltage testing and lack of safety constraints on clamping protection energized action.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A withstand voltage testing device for overhead insulated cables includes a cable under test. A grounding wire is connected to the non-test end of the cable under test via a metal clamp. A terminal block is provided at the test end of the cable under test, and a test connector is connected to the terminal block. An adjustable fixing component is provided on the test connector, and an insulating protective component is provided around the adjustable fixing component. A timing test component is provided on the test connector. A portable withstand voltage testing device is installed on the side of the cable under test. The portable withstand voltage testing device has a built-in simulated grounding negative voltage module. The grounding wire is connected to the portable withstand voltage testing device... The grounding terminal of the step-up transformer on the right is connected; the adjustable fixing component is used to adapt to and clamp terminals of different diameters; the insulation protection component is used to close the high-voltage wiring area in the test state; the timing test component works in conjunction with the adjustable fixing component and the insulation protection component to complete the clamping, fixing and protective sealing in sequence according to a preset time sequence through a single-axis multi-phase eccentric cam, and allows high voltage to be connected for testing after sealing, so as to avoid starting high voltage when the terminals are not clamped, which would lead to poor contact discharge, and starting high voltage when the protective cover is not closed, which would lead to electric shock risk.

[0007] Optionally, the adjustable fixing component includes two symmetrically distributed adjustable clamps, each adjustable clamp having a V-shaped gripper inside, and a disc spring assembly between the V-shaped gripper and the adjustable clamp. The inner surface of the V-shaped gripper is inlaid with a conductive elastic contact piece, which is made of silver-plated beryllium copper alloy.

[0008] Optionally, a connecting rod is fixedly connected to the bottom of the adjustable clamp, a return spring is fixedly installed at the bottom of the connecting rod, the return spring is installed on the test connector, and a guide protrusion is fixedly connected to the outer surface of the adjustable clamp.

[0009] Optionally, the insulating protective assembly includes two symmetrically distributed insulating protective covers, with a hinge rod hingedly connected inside the insulating protective cover via a hinge seat, and a roller rotatably connected to the bottom of the hinge rod via a rotating shaft.

[0010] Optionally, the timing test component includes a rotary handle, which is fixedly connected to a rotary shaft. An eccentric cam one, an eccentric cam two, and an eccentric cam three are sleeved on the rotary shaft, with two eccentric cams one and two eccentric cams two respectively.

[0011] Optionally, the eccentric cam one is correspondingly engaged with the guide protrusion, and the guide protrusion can slide along the contour of the eccentric cam one to achieve clamping and holding of the gripper.

[0012] Optionally, the eccentric cam has an arc-shaped sliding groove, and the roller at the bottom of the hinge rod slides in cooperation with the sliding groove to achieve the closing and retention of the protective cover.

[0013] Optionally, the timing test assembly further includes an insulating rod with an internal conductive wire and a second reset spring fixedly installed at the bottom of the insulating rod, the second reset spring being mounted on the test connector.

[0014] Optionally, the eccentric cam three corresponds to and cooperates with the insulating rod to drive the insulating rod to move, thereby connecting and disconnecting the high-voltage circuit. The energized wires are respectively connected to the high-voltage output terminal and the simulated ground negative voltage terminal to form a complete waterless withstand voltage circuit of the cable under test.

[0015] The present invention also provides another technical solution: a method for using a withstand voltage testing device for overhead insulated cables, the method comprising the following steps: S1. Clamp the grounding wire to the outside of the non-test end of the cable under test with a metal clamp. Connect the other end of the grounding wire to the grounding terminal of the step-up transformer in the portable withstand voltage test equipment. Then, place the terminal of the test end of the cable under test between the V-shaped clamps of the adjustable fixing component to complete the docking preparation between the cable under test and the test device. There is no need to immerse the cable under test in a water tank. The clamping can be completed directly in the field air environment. S2. In the first stage, rotating the handle drives the V-shaped jaws to close and clamp the terminal block via the eccentric cam, so that the conductive elastic contact piece and the terminal block form a stable conductive connection, providing a reliable wiring basis for high voltage testing. S3. In the second stage, continue to rotate the handle, and drive the eccentric cam to close the insulating protective cover along the arc trajectory, completely sealing the high-voltage wiring area, isolating the high voltage and the exposed parts of the grounding wire, and forming the insulating protective environment required for the withstand voltage test. S4. In the third stage, continue to rotate the handle, and move the insulating rod through the eccentric cam to make reliable contact between the internal energized wire and the conductive elastic contact piece, so that the high voltage test circuit is officially connected. At the same time, the grounding wire is connected to the grounding terminal of the step-up transformer to form a simulated grounding negative pressure circuit, thus creating a waterless withstand voltage electrical condition for the cable under test. S5. Start the portable withstand voltage test equipment. The built-in simulated grounding negative pressure module, combined with the grounding wire on the outside of the cable, automatically generates a stable negative pressure. Apply the test voltage to the cable under test and complete the withstand voltage and water resistance equivalent test of the single-core overhead insulated cable in a waterless environment. After the test is completed, disconnect the high-voltage power supply to ensure that the device is out of the energized state. S6. Rotate the handle in the opposite direction to disconnect the high-voltage circuit, open the insulating protective cover, and release the V-shaped clamps in reverse sequence. Finally, remove the metal clamp and grounding wire on the outside of the cable, remove the cable to be tested, and complete the entire waterless, portable withstand voltage test process.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: In the above solution, by setting an adjustable fixing component and adopting a symmetrical V-shaped gripper and disc spring assembly structure, adaptive centering and constant force clamping of cable terminals of different wire diameters are achieved. This solves the problems of uneven clamping force, easy damage to conductors, and narrow applicability of traditional clamps. The V-shaped gripper can automatically center conductors of different diameters, and the disc spring assembly provides a constant clamping force, ensuring stable contact without damaging the copper core, greatly improving the versatility of the device. The inner side of the gripper is inlaid with silver-plated beryllium copper alloy conductive elastic contact pieces, which significantly increases the contact area and reduces the contact resistance, avoiding phenomena such as overheating, arcing, and poor contact during the test, thus improving the test accuracy and reliability. The bottom connecting rod and return spring ensure that the gripper always fits the cam profile, and the guide protrusion achieves precise timing action, maintaining a clamped state without loosening throughout the entire process of protective cover closing and high voltage connection. The overall pure mechanical structure requires no electrical control, is highly durable, and easy to maintain. It truly achieves universal use of one clamp for multiple specifications of cables, greatly improving the efficiency of on-site withstand voltage testing, and has outstanding structural innovation and practical value.

[0017] By incorporating an insulating protective component and employing a symmetrical insulating protective cover and roller slide linkage structure, an innovative mechanical timing interlock with the clamping action is achieved. This fundamentally avoids the safety hazards of closing without clamping or energizing without closing. The protective cover is made of high-insulation-strength material, which can completely seal the high-voltage wiring area, forming a reliable physical protective barrier and effectively preventing risks such as accidental contact, surface discharge, and external interference. The hinge rod and roller, in conjunction with the arc-shaped slide of the eccentric cam, achieve a smooth and jam-free arc-shaped closing motion with stable movement trajectory and good sealing performance. The component does not operate in the first timing sequence, completes the closure in the second timing sequence, and remains locked in the third timing sequence. It can only be opened when the handle is reversed, possessing forced protection and fail-safe characteristics. Compared with traditional independent protective covers, this component does not require manual switching or sensor detection. The pure mechanical linkage is more reliable, the response is more direct, and the safety level is higher. It is particularly suitable for high-voltage testing scenarios and has significant safety innovations and structural advantages.

[0018] By setting up a timing test component, with a single-axis three-phase eccentric cam as the core, it innovatively achieves forced timing linkage of clamping, protection, and energization in three steps. The same rotating axis drives the first, second, and third eccentric cams to move sequentially. The action sequence is physically locked by the phase difference, which prevents skipping steps, reversal, and bypassing, eliminating the risk of misoperation. Eccentric cam one controls clamping, eccentric cam two controls protection, and eccentric cam three controls high voltage switching. The three work together precisely and coordinately. The insulating rod has a built-in energized wire, and the high voltage end is completely insulated and not exposed. It only conducts when clamped in the third phase, and immediately separates when reversed, achieving a fail-safe design. The entire mechanism eliminates vulnerable electrical components such as microswitches and grounding switches, making the structure simpler, the operation more stable, and the anti-interference stronger. All test preparations can be completed by rotating the handle. The operation is extremely simple, efficient, and safe. It deeply integrates mechanical linkage with high voltage safety logic and has significant originality and industrial application value. Attached Figure Description

[0019] Figure 1 A three-dimensional structural diagram of a withstand voltage testing device for overhead insulated cables; Figure 2 This is a schematic diagram of the three-dimensional structure of the test connector; Figure 3 This is a schematic diagram of the three-dimensional structure of the adjustable fixing component; Figure 4 Exploded view of adjustable fixed components; Figure 5 This is a schematic diagram of the three-dimensional structure of the insulation and protection component; Figure 6 This is a schematic diagram of the three-dimensional structure of the timing test component; Figure 7 A three-dimensional structural diagram of the adjustable fixed component and the timing test component; Figure 8 This is a schematic diagram showing the changes in the adjustable clamp and eccentric cam at each stage of the adjustable fixed component. Figure 9 A three-dimensional structural diagram of the insulation protection component and the timing test component; Figure 10 A schematic diagram showing the changes in the insulating protective cover and eccentric cam II at each stage of the insulating protective assembly; Figure 11 A three-dimensional structural diagram of the insulating rod and timing test assembly; Figure 12 This is a schematic diagram showing the changes in the energized conductor and eccentric cam three at each stage of the insulating rod.

[0020] Figure label: 1. Cable under test; 2. Grounding wire; 201. Terminal block; 3. Test connector; 4. Adjustable fixing assembly; 401. Adjustable clamp; 402. V-shaped gripper; 403. Disc spring assembly; 404. Conductive elastic contact; 405. Connecting rod; 406. Return spring one; 407. Guide protrusion; 5. Insulation protection assembly; 501. Insulation protective cover; 502. Hinge rod; 503. Roller; 6. Timing test assembly; 601. Rotary handle; 602. Rotary shaft; 603. Eccentric cam one; 604. Eccentric cam two; 605. Slide groove; 606. Eccentric cam three; 607. Insulating rod; 608. Current-carrying wire; 609. Return spring two; 7. Portable withstand voltage test equipment. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the following detailed description is provided in conjunction with the accompanying drawings and preferred embodiments, based on the specific implementation methods, structures, features and effects of the present invention.

[0022] like Figures 1 to 12 As shown, an embodiment of the present invention provides a withstand voltage testing device for overhead insulated cables, including a cable under test 1. A grounding wire 2 is installed at the non-test end of the cable under test 1 via a metal clamp. A terminal block 201 is installed at the test end of the cable under test 1, and a test connector 3 is connected to the terminal block 201. An adjustable fixing component 4 is installed on the test connector 3, and an insulating protection component 5 is installed around the adjustable fixing component 4. A timing test component 6 is installed on the test connector 3. A portable withstand voltage testing device 7 is installed on the side of the cable under test 1, and the portable withstand voltage testing device 7 has a built-in simulated grounding. The negative pressure module can construct a stable negative pressure test circuit for single-core overhead insulated cables without immersion in a water tank. Grounding wire 2 is connected to the grounding terminal of the step-up transformer on the right side of the portable withstand voltage test equipment 7. Adjustable fixing component 4 is used to adapt to and clamp terminals 201 of different diameters. Insulation protection component 5 is used to seal the high-voltage wiring area during testing, preventing high voltage activation without clamping terminals 201, which could lead to poor contact and discharge, and preventing electric shock risk from activation without closing the protective cover. The timing test component 6, along with the adjustable fixing component 4 and insulation protection... Component 5 works in conjunction with other components to sequentially clamp, fix, and protect the cable using a single-axis, multi-phase eccentric cam according to a preset time sequence. After sealing, high-voltage connection testing is permitted. The adjustable fixing component 4 can adapt to and clamp terminals 201 of different diameters, meeting the universal clamping requirements of overhead insulated cables of different diameters. This eliminates the need to change clamps for different cross-sections, significantly improving on-site testing efficiency. The insulation protection component 5 can completely seal the high-voltage wiring area during testing, forming a high-strength physical insulation barrier to prevent operators from accidentally touching live high-voltage parts, eliminating safety hazards such as electric shock and discharge. The timing test component 6 works in conjunction with the adjustable fixing component 4 and the insulation protection component 5. Through a single-axis multi-phase eccentric cam mechanism, the actions are executed sequentially according to a preset timing sequence: clamping and fixing, then protection and sealing, and finally allowing high voltage access. The cam phase difference and the equal radius maintain the contour to achieve a natural locking of the action sequence. Without the need for electrical components such as sensors and microswitches, the mechanical structure ensures that there is no skipping, no reversibility, and no premature pressure application. This fundamentally eliminates the violation of applying high voltage without clamping or sealing the protection, and significantly improves the inherent safety and operational stability of the withstand voltage test.

[0023] like Figures 3 to 4As shown, the adjustable fixing assembly 4 includes two symmetrically distributed adjustable clamps 401. V-shaped grippers 402 are provided inside each adjustable clamp 401. A disc spring assembly 403 is provided between the V-shaped grippers 402 and the adjustable clamp 401. A conductive elastic contact 404 is embedded on the inner surface of the V-shaped grippers 402. The conductive elastic contact 404 is made of silver-plated beryllium copper alloy. A connecting rod 405 is fixedly connected to the bottom of the adjustable clamp 401. A return spring 406 is fixedly installed at the bottom of the connecting rod 405 and is mounted on the test connector 3. A guide protrusion 407 is fixedly connected to the outer surface of the adjustable clamp 401. The V-shaped grippers 402 allow terminals 201 of different diameters to be automatically centered and positioned, cooperating with the disc spring assembly 403. It provides a constant and moderate clamping force, ensuring reliable contact without damaging the cable conductor. It is compatible with a wide range of wire diameters. The conductive elastic contact 404, plated with silver-beryllium copper alloy, can significantly increase the contact area with the terminal 201, significantly reducing contact resistance and avoiding problems such as overheating, arcing, and poor contact under high current, thus improving the accuracy of test data. The reset spring 406 provides a reset driving force for the gripper, ensuring that the gripper always fits the cam profile. The guide protrusion 407 and the eccentric cam 603 cooperate precisely to realize the sequential action of clamping in the first stage and maintaining clamping in the second and third stages. Throughout the subsequent process of closing the protective cover and connecting the high voltage, the clamping state remains stable and does not loosen, ensuring the continuous and reliable test process.

[0024] like Figure 5 As shown, the insulation protection component 5 includes two symmetrically distributed insulation protective covers 501. A hinge rod 502 is hinged inside each insulation protective cover 501 via a hinged seat. A roller 503 is rotatably connected to the bottom of the hinge rod 502 via a rotating shaft. The insulation protective cover 501 is made of high-insulation-strength material, capable of completely covering the high-voltage wiring area, forming a reliable withstand voltage protection barrier to prevent risks such as surface discharge and accidental contact during testing. The hinge rod and roller 503 form a flexible follow-up transmission structure. The roller 503 and the arc-shaped sliding groove 605 on the eccentric cam 604 form a sliding fit. In the first stage, the cover does not move; in the second stage, it drives the protective cover to close smoothly along a set trajectory; and in the third stage, it remains completely closed and stationary. This achieves strict timing linkage with the clamping action. The protective cover only begins to close after the cable is reliably clamped. After closing, it remains locked until the handle is reversed to allow opening. This ensures adequate protection while avoiding motion interference with the clamping mechanism. The overall transmission is smooth, without jamming or offset, with good sealing performance and a high level of safety protection.

[0025] like Figures 6 to 12As shown, the timing test assembly 6 includes a rotary handle 601, which is fixedly connected to a rotary shaft 602. An eccentric cam 603, an eccentric cam 604, and an eccentric cam 606 are mounted on the rotary shaft 602. Two eccentric cams 603 and 604 are symmetrically arranged. The eccentric cam 603 corresponds to and engages with a guide protrusion 407, which can slide along the contour of the eccentric cam 603 to clamp and hold the gripper. The eccentric cam 604 has an arc-shaped groove 605, and the roller 503 at the bottom of the hinge rod 502 slides in conjunction with the groove 605 to close and hold the protective cover. The timing test assembly 6 also includes an insulating rod 607, which contains a current-carrying wire 608. A return spring 609 is fixedly installed at the bottom of the insulating rod 607 and mounted on the test connector 3. The eccentric cam 606 and the insulating rod 607 are aligned... The device is designed to drive the insulating rod 607 to move, thereby connecting and disconnecting the high-voltage circuit. The energized wire 608 is connected to the high-voltage output terminal and the simulated grounding negative voltage terminal, forming a complete waterless withstand voltage circuit for the cable under test 1. The entire assembly uses the same rotating shaft 602 as the sole power input. Through the phase difference design of three sets of cams, strict timing control is achieved. The first stage completes cable clamping, the second stage completes the sealing of the protective cover, and the third stage drives the insulating rod 607 to move and connect the high-voltage circuit. When the handle is reversed, the high voltage is disconnected, the protective cover is opened, and the clamps are released in the reverse order. The insulating rod 607 encloses the high-voltage energized wire 608, so the high-voltage end is not exposed and there is no risk of discharge. The reset spring 609 ensures reliable separation action and achieves fail-safe operation. The overall structure has no micro switch or grounding switch, which simplifies the structure and improves reliability. All preparation operations can be completed by rotating the handle. The operation is simple, efficient, and safe.

[0026] The present invention also provides another technical solution: a method for using a withstand voltage testing device for overhead insulated cables, the method comprising the following steps: S1. Clamp the grounding wire 2 to the outside of the non-test end of the cable under test 1 with a metal clamp. The other end of the grounding wire 2 is pre-connected to the grounding terminal of the step-up transformer in the portable withstand voltage test equipment 7. Then, place the terminal 201 of the test end of the cable under test 1 between the V-shaped claws 402 of the adjustable fixing component 4 to complete the docking preparation of the cable under test 1 and the test device. There is no need to put the cable into the water tank for immersion. The clamping is completed directly in the field air environment. S2. In the first stage, rotating the handle 601 drives the V-shaped gripper 402 to close and clamp the terminal 201 via the eccentric cam 603, so that the conductive elastic contact 404 and the terminal 201 form a stable conductive connection, providing a reliable wiring basis for the high voltage test. S3. In the second stage, continue to rotate the rotary handle 601, and drive the insulating protective cover 501 to close along the arc trajectory through the eccentric cam 604, completely sealing the high-voltage wiring area, isolating the high voltage from the exposed part of the grounding wire 2, and forming the insulating protective environment required for the withstand voltage test. S4. In the third stage, continue to rotate the rotary handle 601, and push the insulating rod 607 to move through the eccentric cam 606, so that the internal energized wire 608 can reliably contact the conductive elastic contact piece 404, and connect the high voltage circuit. At the same time, the grounding wire 2 is connected to the grounding terminal of the step-up transformer to form a simulated grounding negative pressure circuit, and construct a waterless withstand voltage electrical condition for the cable under test 1. S5. Start the portable withstand voltage test equipment 7. The built-in simulated grounding negative pressure module, combined with the cable outer grounding wire 2, automatically generates a stable negative pressure. Apply the test voltage to the cable under test 1 and complete the withstand voltage and water resistance equivalent test of the single-core overhead insulated cable in a waterless environment. After the test is completed, disconnect the high voltage power supply to ensure that the device is out of the energized state. S6. Rotate the handle 601 in the reverse direction to disconnect the high-voltage circuit, open the insulating protective cover 501, and loosen the V-shaped clamp 402 in reverse sequence. Finally, remove the metal clamp and grounding wire 2 on the outside of the cable, and take off the cable to be tested 1 to complete the entire waterless, portable withstand voltage test process.

[0027] The working principle of the technical solution provided by this invention is as follows: This invention uses a single-axis, multi-phase eccentric cam mechanical timing linkage as its core, integrating cable clamping, high-voltage protection, and high-voltage switching into a single rotary drive mechanism. By forcibly locking the action sequence through phase difference, it achieves an irreversible safety logic of clamping first, then sealing off protection, and finally connecting the high voltage. From the mechanical structure level, it completely solves the technical defects of traditional devices such as unreliable contact, inadequate protection, lack of interlocking operation, and easy misoperation. Combined with a portable withstand voltage testing device 7, it completes the automated and safe withstand voltage testing of overhead insulated cables.

[0028] Before the test begins, the device is in its initial state. The V-shaped gripper 402 of the adjustable fixing component 4 is in the open position, the insulating protective cover 501 is in the open state, the insulating rod 607 is separated from the conductive elastic contact 404, the high voltage circuit is kept disconnected to ensure that the initial state is safe and without power, and the portable withstand voltage test equipment 7 is in the standby power-off state to ensure that the initial state is safe and without power.

[0029] During test preparation, the operator places the terminal 201 of the cable under test 1 between the symmetrically arranged V-shaped clamps 402. In the first stage, the operator rotates the rotating handle 601, and the rotating shaft 602 drives the eccentric cam 603 to rotate synchronously. The contour of the eccentric cam 603 pushes the guide protrusion 407 on the outside of the adjustable clamp 401, causing the adjustable clamp 401 to close inward. Under the constant force of the disc spring assembly 403, the V-shaped clamps 402 automatically center and clamp the terminal 201. The silver-plated beryllium copper alloy conductive elastic contact 404 embedded in the inner side of the V-shaped clamps 402 fully adheres to the surface of the terminal 201, forming a large-area, low-resistance conductive connection. In the second and third stages, the eccentric cam 603 enters the equal radius holding section. With the cooperation of the return spring 406, the V-shaped clamps 402 remain in a clamped state, providing a stable wiring foundation for subsequent timing actions and the stable output of the portable withstand voltage test equipment 7.

[0030] In the second stage, the rotary handle 601 continues to rotate. Eccentric cam 1 603 enters the holding section and no longer drives the gripper. Eccentric cam 2 604 enters the driving section. The arc-shaped groove 605 on eccentric cam 2 604 pushes the roller 503 at the bottom of the hinge rod, causing the insulating protective cover 501 to smoothly close towards the center along a preset arc trajectory until it completely covers the entire high-voltage wiring area, forming a fully enclosed insulating protection. After the second stage, eccentric cam 2 604 enters the equal radius holding section, keeping the protective cover in a closed and locked state, preventing further displacement. This provides a safe and isolated environment for applying high voltage to the portable withstand voltage test equipment 7, ensuring that personnel cannot contact the high-voltage parts during the test, while also avoiding external interference affecting the test.

[0031] In the third stage, the rotary handle 601 continues to rotate. Eccentric cam 1 (603) and eccentric cam 2 (604) are both in the holding section, and the gripper and protective cover remain unchanged. Eccentric cam 3 (606) enters the driving section, pushing the insulating rod 607 towards the inside of the adjustable clamp 401, compressing the return spring 2 (609). This ensures precise contact between the energized wire 608 inside the insulating rod 607 and the conductive elastic contact 404 on the V-shaped gripper 402, reliably connecting the high-voltage circuit. At this point, the portable withstand voltage tester 7 is ready to start, and the operator can then apply the test voltage to the cable 1 under test, officially commencing the withstand voltage test. Throughout the entire test, the holding section structure of the three cams ensures that the clamping, protection, and conduction states remain stable, guaranteeing stable output and reliable test data from the portable withstand voltage tester 7.

[0032] After the test is completed, first manually stop the output of the portable withstand voltage test equipment 7, disconnect the high voltage power supply, and then the operator rotates the rotary handle 601 in the reverse direction. The mechanism resets in reverse sequence. The eccentric cam 3 606 retracts first, and the insulating rod 607 moves to the outside of the adjustable clamp 401 under the action of the reset spring 2 609. The energized wire 608 separates from the conductive elastic contact 404, and the high voltage circuit is completely disconnected. Continue to reverse, the eccentric cam 2 604 retracts, the insulating protective cover 501 opens, and continue to reverse, the eccentric cam 1 603 retracts. When the V-shaped gripper 402 opens under the action of the return spring 406, it releases the terminal 201, allowing the operator to safely remove the cable under test 1 and complete the entire test process. During the entire test, the portable withstand voltage tester 7 outputs a standard high voltage test voltage after voltage regulation and isolation boosting of the low voltage power frequency electricity, which is applied between the cable under test 1 and the terminal 201 to perform withstand voltage assessment on the main insulation and monitor leakage current in real time. When insulation is abnormal, breaks down, or leaks, the high voltage is quickly cut off to complete the insulation performance judgment.

[0033] To address the testing requirements of single-core overhead insulated cables that lack a negative pole and require immersion in water to create negative pressure, a simulated grounding negative pressure electrical circuit is used to replace the water-medium grounding method. Through the simulated grounding negative pressure module inside the portable withstand voltage test equipment 7, a stable potential difference equivalent to that of the immersion test is established outside the insulation layer of the cable under test 1. A virtual negative pressure circuit is formed through electric field coupling, ensuring that the electrical conditions required for withstand voltage testing are met between the single-core cable conductor and the simulated negative pressure. The insulation withstand voltage test can be completed without relying on water for conductivity. At the same time, the device adopts an integrated mechanical structure, concentrating clamping, protection, switching, and negative pressure access functions inside the miniaturized test connector 3. There is no external water tank or complex pipeline. The entire process is achieved through the mechanical linkage of the single-axis cam of the timing test component 6. The device is lightweight and compact, and can be operated by hand on-site. Thus, it achieves the unification of waterless equivalent testing and portable on-site operation at the principle level.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A withstand voltage testing device for overhead insulated cables, characterized in that, The test cable (1) is included. The non-test end of the test cable (1) is provided with a grounding wire (2) through a metal clamp. The test end of the test cable (1) is provided with a terminal block (201). The terminal block (201) is connected to a test connector (3). The test connector (3) is provided with an adjustable fixing component (4). The adjustable fixing component (4) is provided with an insulating protection component (5) on its outer periphery. The test connector (3) is provided with a timing test component (6). The side of the test cable (1) is provided with a portable withstand voltage test device (7). The portable withstand voltage test device (7) has a built-in simulated grounding negative voltage module. The grounding wire (2) is connected to the grounding terminal of the step-up transformer on the right side of the portable withstand voltage test device (7). The adjustable fixing component (4) is used to adapt to and clamp terminals (201) of different diameters. The insulation protection component (5) is used to seal the high-voltage wiring area under test conditions; The timing test component (6) works in conjunction with the adjustable fixing component (4) and the insulation protection component (5) to complete the clamping, fixing and protective sealing in sequence according to the preset timing through the single-axis multi-phase eccentric cam, and allow high voltage to be connected for testing after sealing, so as to avoid starting high voltage when the terminal (201) is not clamped, which would lead to poor contact discharge, and starting high voltage when the protective cover is not closed, which would lead to electric shock risk.

2. The withstand voltage testing device for overhead insulated cables according to claim 1, characterized in that, The adjustable fixing component (4) includes two symmetrically distributed adjustable clamps (401). The adjustable clamps (401) are provided with V-shaped claws (402) inside. A disc spring assembly (403) is provided between the V-shaped claws (402) and the adjustable clamps (401). The inner surface of the V-shaped claws (402) is inlaid with conductive elastic contact pieces (404). The conductive elastic contact pieces (404) are made of silver-plated beryllium copper alloy.

3. The withstand voltage testing device for overhead insulated cables according to claim 2, characterized in that, The adjustable clamp (401) is fixedly connected to a connecting rod (405) at its bottom. A reset spring (406) is fixedly installed at the bottom of the connecting rod (405). The reset spring (406) is installed on the test connector (3). A guide protrusion (407) is fixedly connected to the outer surface of the adjustable clamp (401).

4. The withstand voltage testing device for overhead insulated cables according to claim 3, characterized in that, The insulating protective assembly (5) includes two symmetrically distributed insulating protective covers (501). The interior of the insulating protective cover (501) is hinged to a hinge rod (502) via a hinge seat. The bottom of the hinge rod (502) is rotatably connected to a roller (503) via a rotating shaft.

5. The withstand voltage testing apparatus for overhead insulated cables according to claim 4, characterized in that, The timing test component (6) includes a rotary handle (601), which is fixedly connected to a rotary shaft (602). An eccentric cam one (603), an eccentric cam two (604), and an eccentric cam three (606) are sleeved on the rotary shaft (602). Two eccentric cams one (603) and two eccentric cams two (604) are symmetrically arranged.

6. The withstand voltage testing apparatus for overhead insulated cables according to claim 5, characterized in that, The eccentric cam (603) and the guide protrusion (407) are correspondingly engaged. The guide protrusion (407) can slide along the contour of the eccentric cam (603) to achieve clamping and holding of the gripper.

7. The withstand voltage testing apparatus for overhead insulated cables according to claim 6, characterized in that, The eccentric cam (604) has an arc-shaped groove (605), and the roller (503) at the bottom of the hinge rod (502) slides in cooperation with the groove (605) to achieve the closing and retention of the protective cover.

8. The withstand voltage testing apparatus for overhead insulated cables according to claim 7, characterized in that, The timing test assembly (6) also includes an insulating rod (607), which has an internal conductive wire (608) and a reset spring (609) fixedly installed at the bottom of the insulating rod (607). The reset spring (609) is installed on the test connector (3).

9. The withstand voltage testing apparatus for overhead insulated cables according to claim 8, characterized in that, The eccentric cam (606) and the insulating rod (607) are correspondingly matched to drive the insulating rod (607) to move, thereby realizing the connection and disconnection of the high voltage circuit. The energized wire (608) is connected to the high voltage output terminal and the simulated ground negative voltage terminal respectively, forming a complete waterless withstand voltage circuit of the cable under test (1).

10. A method of using a withstand voltage testing device for overhead insulated cables, applicable to the withstand voltage testing device for overhead insulated cables as described in claim 9, characterized in that, The method includes the following steps: S1. Clamp the grounding wire (2) on the outside of the non-test end of the cable to be tested (1) with a metal clamp. Connect the other end of the grounding wire (2) to the grounding terminal of the step-up transformer in the portable withstand voltage test equipment (7). Then place the terminal (201) of the test end of the cable to be tested (1) between the V-shaped claws (402) of the adjustable fixing component (4) to complete the docking preparation between the cable to be tested (1) and the test device. There is no need to put the cable to be tested (1) into the water tank for immersion. The clamping is completed directly in the field air environment. S2. In the first stage, rotating the handle (601) drives the V-shaped jaws (402) to close and clamp the terminal (201) through the eccentric cam (603), so that the conductive elastic contact (404) and the terminal (201) form a stable conductive connection, providing a reliable wiring basis for high voltage test; S3. In the second stage, continue to rotate the rotary handle (601), and drive the insulating protective cover (501) to close along the arc trajectory through the eccentric cam (604), completely sealing the high voltage wiring area, isolating the high voltage and the exposed part of the grounding wire (2), and forming the insulating protective environment required for the withstand voltage test. S4. In the third stage, continue to rotate the rotary handle (601) to push the insulating rod (607) to move through the eccentric cam (606), so that the internal energized wire (608) can reliably contact the conductive elastic contact piece (404) to connect the high voltage circuit. At the same time, the grounding wire (2) is connected to the grounding terminal of the step-up transformer to form a simulated grounding negative pressure circuit, thus constructing a waterless withstand voltage electrical condition for the cable under test (1). S5. Start the portable withstand voltage test equipment (7). The built-in simulated grounding negative pressure module, combined with the cable outer grounding wire (2), automatically generates a stable negative pressure. Apply the test voltage to the cable under test (1) and complete the withstand voltage and water resistance equivalent test of the single-core overhead insulated cable in a waterless environment. After the test is completed, disconnect the high voltage power supply to ensure that the device is out of the energized state. S6. Rotate the handle in the opposite direction (601) to disconnect the high voltage circuit, open the insulating protective cover (501), and loosen the V-shaped clamp (402) in reverse order. Finally, remove the metal clamp and grounding wire (2) on the outside of the cable and take off the cable to be tested (1) to complete the entire waterless and portable withstand voltage test process.

Images