Cable insulation defect detection device suitable for string type photovoltaic system

Abstract

The invention relates to the field of cable insulation detection, in particular to a cable insulation defect detection device suitable for a string type photovoltaic system, which is characterized in that three groups of annularly distributed clamps are fixed on an insulation seat, each group of clamps corresponds to a group of telescopic electric pins fixed on the insulation seat, the insulation seat is rotatably connected with a phase cutting assembly used for phase line switching, and the phase cutting assembly is connected with a power supply. According to the invention, through the integrated structural design, connection and switching of three-phase cables are integrated in the same device, the wiring process of on-site detection is greatly simplified, through cooperation of the phase cutting assembly and the telescopic electric pins, the connection and switching of the three-phase cables can be realized, and the connection and switching of the three-phase cables can be realized. The high-efficiency operation mode of'one-time wiring, rotary switching and one-by-one detection 'is realized, time waste and misoperation risks caused by repeated disassembly and assembly of alligator clips in traditional detection are avoided, the frequency of an operator in contact with an electrified part is reduced, and the detection efficiency and the operation safety are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of cable insulation testing technology, and in particular to a cable insulation defect detection device suitable for string photovoltaic systems. Background Technology

[0002] Common methods for detecting cable insulation defects include insulation resistance testing, DC withstand voltage testing, AC withstand voltage testing, dielectric loss tangent (tanδ) testing, partial discharge detection, and infrared thermal imaging detection. For example, a megohmmeter applies a DC voltage to measure the insulation resistance between the cable core and the shielding layer, thus determining the magnitude of leakage current in the insulation layer. Acceptance standards: Low-voltage cables (≤1kV) ≥0.5MΩ; high-voltage cables must show no significant decrease compared to historical data.

[0003] When using a megohmmeter to test the insulation of three-phase cables, the three phases are divided into A, B, and C. When measuring phase A, BC is short-circuited; when measuring phase B, AC is short-circuited; and when measuring phase C, AB is short-circuited. Therefore, three measurements are required. This necessitates frequent switching of wiring and the L-terminal phase wire of the megohmmeter during the measurement process. Unlike traditional substations where only a small number of main cables need to be tested, photovoltaic power stations have a massive number of low-voltage AC and DC cables. The traditional "single-person, three-step method" is completely inadequate for the testing needs of such a large number of nodes, resulting in a consistently low sampling rate during maintenance and an inability to comprehensively identify insulation hazards. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a cable insulation defect detection device suitable for string photovoltaic systems.

[0005] A cable insulation defect detection device suitable for string photovoltaic systems, comprising an insulation base, characterized in that: The insulating base is fixed with three sets of clamps arranged in a ring. Each set of clamps corresponds to a set of retractable electrical contacts fixed on the insulating base. A phase-cutting assembly for phase switching is rotatably connected to the insulating base. The phase-cutting assembly includes a turntable with three retractable phase contacts arranged in a ring on the turntable. A drive unit for driving the phase contacts to extend and retract and for driving the turntable to rotate is located at the center of the turntable. Two of the three phase contacts are electrically connected.

[0006] Furthermore, in order to better realize the present invention, the driving unit includes an inverted frustum and a hexagonal shaft fixed to the bottom of the frustum, and an insulating handle is fixed to the top of the frustum. The turntable has multiple annularly distributed limiting grooves, and the phase wire pins are placed in the limiting grooves; The turntable has an operating port at its center that matches the maximum outer diameter of the cone, and a square hole that matches the hexagonal shaft. The turntable has three radial grooves that fit the phase wire pins. An insulating rod is fixed to one end of the phase wire pin near the operating port, and a spring is connected between the insulating rod and the groove.

[0007] Furthermore, in order to better realize the present invention, the insulating base includes a base plate, on the upper surface of which three circularly distributed upright plates are fixed. The electrical contact includes a fixed foot fixed to the upright plate and a movable foot slidably inserted into the fixed foot. The fixed foot and the movable foot are elastically connected by a spring.

[0008] Furthermore, in order to better realize the present invention, the base plate is provided with multiple annularly distributed mounting ports, and ground pins are installed in the mounting ports, with nuts threaded to the top of the ground pins; a limit opening is provided on the side of the base plate near the clamp.

[0009] Furthermore, to better realize the present invention, the two phase wires of the electrical connection are connected by a spiral cable, and the spiral cable is electrically connected to a grounding wire with an alligator clip; an opening is provided on one side of the top of the turntable, and a clamp for connecting a test instrument is fixedly connected to the third phase wire that is not connected to the spiral cable.

[0010] Furthermore, in order to better realize the present invention, the turntable includes two insulating plates that are stacked and fixed on top of each other. The opposite sides of the two insulating plates are provided with wire grooves and multiple slots placed in the sliding groove. One end of the second spring is fixed to the insulating rod, and the other end is fixed to the ring plate. The ring plate is adapted to be inserted into the slot.

[0011] Furthermore, in order to better realize the present invention, the clamp includes a quick clamp fixed on the base plate, and the clamping end of the quick clamp is fixed with an insulating rubber sleeve.

[0012] Furthermore, in order to better realize the present invention, the end of the fixing foot near the insulating rubber sleeve protrudes from the upright plate.

[0013] A cable insulation defect detection system includes a hand-cranked megohmmeter and the aforementioned cable insulation defect detection device suitable for string photovoltaic systems.

[0014] The beneficial effects of this invention are: This application integrates the connection and switching of three-phase cables into a single device through an integrated structural design, which greatly simplifies the wiring process for on-site testing. By utilizing the phase-cutting component and the telescopic electrical connector, it achieves a highly efficient operation mode of "one-time wiring, rotational switching, and sequential testing". This avoids the time waste and risk of misoperation caused by repeated disassembly and assembly of alligator clips in traditional testing, while also reducing the frequency of operators' contact with live parts, significantly improving testing efficiency and operational safety. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the phase-cutting component structure of the present invention; Figure 3 This is a schematic diagram of the ground needle structure of the present invention; Figure 4 This is a schematic diagram of the fixture structure of the present invention; Figure 5 This is a schematic diagram of the driving unit structure of the present invention; Figure 6 This is a schematic diagram of the phase lead structure of the present invention; Figure 7 This is a schematic diagram of the upper half of the turntable structure of the present invention; Figure 8 This is a schematic diagram of the lower half of the turntable structure of the present invention; Figure 9 This is a schematic diagram of the electrical connector structure of the present invention.

[0016] In the picture, 10. Insulating base; 11. Base plate; 111. Mounting port; 112. Limiting port; 12. Vertical plate; 13. Ground pin; 131. Nut; 20. Electrical contact pin; 21. Fixed pin; 22. Movable pin; 23. Spring 1; 30. Clamps; 31. Quick clamps; 32. Insulating sleeves; 40. Phase cutting assembly; 41. Turntable; 411. Cable groove; 412. Limiting groove; 413. Operating port; 414. Square hole; 415. Slot; 42. Phase wire lead; 421. Clamping rod; 43. Insulating rod; 44. Spring II; 45. Ring plate; 46. Spiral cable; 47. Grounding wire; 48. Drive unit; 481. Insulating handle; 482. Frustum; 483. Hexagonal shaft; 50. Hand-cranked megohmmeter. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] Figures 1-9This invention provides a specific embodiment of a cable insulation defect detection device suitable for string photovoltaic systems. The device includes an insulating base 10, on which three sets of ring-shaped clamps 30 are fixed. Each set of clamps 30 corresponds to a set of retractable electrical contacts 20 fixed to the insulating base 10. The electrical contacts 20 are used to connect to the copper terminals of the phase wires, and the clamps 30 hold the terminals on the contacts 20. A phase-switching assembly 40 for phase switching is rotatably connected to the insulating base 10. The phase-switching assembly 40 includes a turntable 41, and the turntable 41 is ring-shaped. The circuit has three retractable phase wire pins 42, which are coplanar with the electrical contact pins 20. The retraction directions of the phase wire pins 42 and the electrical contact pins 20 are collinear. The retraction and extension of the electrical contact pins 20 are adjusted to ensure contact between the phase wire pins 42 and the electrical contact pins 20. A drive unit 48 for driving the phase wire pins 42 to extend and the turntable 41 to rotate is slidably mounted in the center of the turntable 41. Two phase wire pins 42 are electrically connected. Normally, the two phase wire pins 42 are in an electrically connected state. Therefore, when the two phase wire pins 42 contact the two electrical contact pins 20, the two electrical contact pins 20 are short-circuited. The device is connected to the grounding wire 47. Then, the L-end alligator clip of the hand-cranked megohmmeter 50 is clamped onto the third electrical contact pin 20 to perform cable insulation testing on the phase wire connected to the L end. After the test is completed, simply press down on the drive unit 48 to extend the phase wire pin 42 and retract the electrical contact pin 20. At the same time, rotate the drive unit 48 to make the phase wire pin 42 with the L end connection contact the next electrical contact pin 20 to perform insulation testing on the second phase wire. This eliminates the need for frequent back-and-forth removal and removal of the alligator clips on the phase wires, allowing for quick insulation testing of all three phase wires one by one. Through the integrated structural design, the connection and switching of the three-phase cable are integrated into the same device, greatly simplifying the wiring process for on-site testing. By utilizing the cooperation of the phase-cutting component 40 and the telescopic electrical contact pin 20, a highly efficient operation mode of "one-time wiring, rotational switching, and one-by-one testing" is achieved. This avoids the time waste and risk of misoperation caused by repeated removal and installation of alligator clips in traditional testing, while also reducing the frequency of operators contacting live parts, significantly improving testing efficiency and operational safety.

[0020] like Figure 2 , Figure 5 , Figure 8 As shown, the turntable 41 is rotatably mounted on the insulating seat 10 via bearings. The drive unit 48 includes an inverted truncated cone 482 and a hexagonal shaft 483 fixed to the bottom of the truncated cone 482. An insulating handle 481 is fixed to the top of the truncated cone 482. The turntable 41 has three annularly distributed limiting grooves 412, and the phase wire pins 42 are placed in the limiting grooves 412. The turntable 41 has an operating port 413 at its center that is adapted to the maximum outer diameter of the truncated cone 482, and the turntable 41 also has a square hole 414 at its center that is adapted to the hexagonal shaft 483. The turntable 41 has three radially formed grooves that fit the phase wire pins 42. An insulating rod 43 is fixed to one end of the phase wire pin 42 near the operating port 413. The insulating rod 43 is connected to the grooves via a second spring 44. When the insulating handle 481 slides downwards along the square hole 414, the slope of the cone 482 gradually presses against the insulating rod 43, causing the second spring 44 to be elastically compressed. Simultaneously, the insulating rod 43 pushes the electrical contact pin 20 to retract and disengage from the limiting groove 412. Rotating the insulating handle 481 then aligns the electrical contact pin 20 with the next limiting groove 412. Releasing the insulating handle 481 then triggers the spring 44 to spring back. The insulated handle 481 is lowered to reset upwards, and the electrical contact 20 is engaged in the limiting groove 412 and contacts the phase wire 42. At this time, the limiting groove 412 limits the electrical contact 20, thereby preventing the phase wire 42 from disengaging from the electrical contact 20 due to the rotation of the turntable 41. The engaging engagement of the limiting groove 412 and the electrical contact 20 constitutes a reliable mechanical self-locking mechanism, which can effectively prevent the turntable 41 from shifting due to vibration or accidental contact during the megohmmeter test, ensuring the stability of the contact between the phase wire 42 and the electrical contact 20, thereby ensuring the accuracy of the insulation resistance reading and avoiding misjudgment due to poor contact.

[0021] like Figure 2 , Figure 6 , Figure 9 As shown, the insulating base 10 includes a base plate 11, and three annularly distributed vertical plates 12 are fixed on the upper surface of the base plate 11. The electrical contact 20 includes a fixed foot 21 fixed on the vertical plate 12 and a movable foot 22 slidably inserted into the fixed foot 21. The movable foot 22 is in electrical contact with the fixed foot 21. The fixed foot 21 and the movable foot 22 are elastically connected by a spring 23. When the movable foot 22 is pushed by the phase line foot 42, the movable foot 22 slides into the fixed foot 21 and compresses the spring 23 to store force, so as to push the movable foot 22 out of the limiting groove 412. The elastic floating connection structure between the movable foot 22 and the fixed foot 21 can not only compensate for manufacturing tolerances and wear after long-term use, but also ensure that the phase line foot 42 and the electrical contact 20 always maintain a constant contact pressure and reduce contact resistance. Meanwhile, the energy storage function of spring 23 provides active power for the electrical contact 20 to disengage from and reset from the limiting groove 412, making the mechanical switching action more crisp and sensitive, avoiding jamming, and extending the service life of the device.

[0022] like Figure 2 , Figure 3 , Figure 6As shown, the base plate 11 has multiple annularly distributed mounting openings 111. A ground pin 13 is installed in the mounting opening 111. A nut 131 is threaded to the top of the ground pin 13. The upper half of the ground pin 13 is fixed with a limiting flange. The top of the ground pin 13 is inserted into the mounting opening 111, and with the cooperation of the nut 131, the ground pin 13 can be assembled onto the base plate 11. Inserting the ground pin 13 into the soil serves two purposes: first, to ground the ground, and second, to support the base plate 11. At the same time, the assembly and disassembly of the ground pin 13 from the base plate 11 facilitates the overall disassembly and transport. Meanwhile, by opening a limiting port 112 on the side of the base plate 11 near the clamp 30, the cable can be inserted into the limiting port 112, which can prevent shaking when testing the cable. The dual-function design of the grounding pin 13 not only solves the grounding problem during field operations and provides a reliable reference potential for insulation testing, but also stabilizes the base of the device and prevents the device from tipping over during operation.

[0023] like Figure 2 , Figure 6 , Figure 8 As shown, two phase wires 42 are electrically connected by a spiral cable 46, which is electrically connected to a grounding wire 47 with an alligator clip. A movable opening is provided on one side of the top of the turntable 41. A clamp rod 421 is fixedly connected to the phase wire 42 (that is, the third phase wire 42) on the movable opening side. The cable with the clamp rod 421 is the cable to be tested. The remaining two phase cables are short-circuited by the spiral cable 46 and then grounded by the grounding wire 47 through the alligator clip.

[0024] like Figure 7 , Figure 8 As shown, the turntable 41 consists of two stacked and fixed insulating plates. Each of the two insulating plates has a wire groove 411 and multiple slots 415 placed in the sliding groove on opposite sides. The spiral cable 46 is placed in the wire groove 411. The phase wire 42 and the insulating rod 43 slide along the sliding groove. One end of the second spring 44 is fixed to the insulating rod 43, and the other end is fixed to the ring plate 45. The ring plate 45 is adapted to the slots 415. During assembly, the ring plate 45 is inserted into the corresponding slots 415, and then the two insulating plates are bolted together. At this time, the end of the second spring 44 away from the phase wire 42 can be fixed to the turntable 41.

[0025] like Figure 4 As shown, the clamp 30 includes a quick clamp 31 fixed on the base plate 11. The clamping end of the quick clamp 31 is fixed with an insulating sleeve 32. The quick clamp 31 is used to quickly clamp and fix the copper terminal of the cable onto the upright plate 12. The insulating sleeve 32 provides buffering and insulation. The insulating sleeve 32 not only provides the necessary electrical insulation to prevent leakage, but also acts as a soft contact medium to protect the copper terminal of the photovoltaic cable, avoiding terminal deformation or plating damage due to excessive clamping force.

[0026] like Figure 4 , Figure 6 As shown, the end of the fixing foot 21 near the insulating sleeve 32 protrudes from the upright plate 12. At the same time, the insulating sleeve 32 has a recess that matches the fixing foot 21. The mounting hole of the fixing foot 21 is then inserted into the protruding end of the fixing foot 21, thereby preventing the copper terminal from falling off the fixing foot 21.

[0027] Working principle: First, insert the three phase wires into the limit slots 112 and hang them on the protruding ends of the fixing feet 21. Then, use the quick clamps 31 to fix the copper terminals on the fixing feet 21. The hand-cranked megohmmeter 50 was calibrated using conventional technical means. After calibration, the E terminal of the hand-cranked megohmmeter 50 was grounded. The hand-cranked megohmmeter 50 was then cranked until its pointer pointed to infinity. The alligator clip with the L terminal was then clamped onto the clamp rod 421. The pointer of the hand-cranked megohmmeter 50 was observed. When the pointer pointed to infinity, the tested cable had good grounding insulation to the other two cables. The tested cable was then discharged using a discharge rod. Then, by pressing the insulating handle 481 downwards, the slope of the cone 482 squeezes the insulating rod 43, and the movable foot 22 is pushed outwards through the phase wire foot 42, disengaging from the limiting groove 412. At this time, rotate the insulating handle 481 so that the phase wire foot 42 with the clamping rod 421 corresponds to the electrical contact foot 20 of the next phase wire cable. Then repeat the above test to perform insulation test on the second phase wire. Finally, operate the insulating handle 481 again to quickly perform insulation test on the third phase wire.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A cable insulation defect detection device suitable for string photovoltaic systems, comprising an insulation base (10), characterized in that: The insulating base (10) is fixed with three sets of clamps (30) arranged in a ring. Each set of clamps (30) corresponds to a set of retractable electrical contacts (20) fixed on the insulating base (10). The insulating base (10) is rotatably connected with a phase-cutting assembly (40) for phase switching. The phase-cutting assembly (40) includes a turntable (41). The turntable (41) is provided with three retractable phase wire contacts (42) arranged in a ring. The center of the turntable (41) is provided with a drive unit (48) for driving the phase wire contacts (42) to extend and retract and for driving the turntable (41) to rotate. Among the three phase wire contacts (42), two phase wire contacts (42) are electrically connected.

2. The cable insulation defect detection device for string photovoltaic systems according to claim 1, characterized in that: The drive unit (48) includes an inverted truncated cone (482) and a hexagonal shaft (483) fixed to the bottom of the truncated cone (482). An insulating handle (481) is fixed to the top of the truncated cone (482). The turntable (41) has multiple annularly distributed limiting grooves (412), and the phase wire (42) is placed in the limiting groove (412); The turntable (41) has an operating port (413) at its center that is adapted to the maximum outer diameter of the cone (482) and a square hole (414) that is adapted to the hexagonal shaft (483). The turntable (41) has three radial grooves that are adapted to the phase wire pins (42). An insulating rod (43) is fixed to one end of the phase wire pin (42) near the operating port (413). A spring (44) is connected between the insulating rod (43) and the groove.

3. The cable insulation defect detection device for string photovoltaic systems according to claim 1, characterized in that: The insulating base (10) includes a base plate (11), and three circularly distributed upright plates (12) are fixed on the upper surface of the base plate (11). The electrical contact (20) includes a fixed foot (21) fixed on the upright plate (12) and a movable foot (22) slidably inserted on the fixed foot (21). The fixed foot (21) and the movable foot (22) are elastically connected by a spring (23).

4. The cable insulation defect detection device for string photovoltaic systems according to claim 3, characterized in that: The base plate (11) has multiple annularly distributed mounting ports (111), and a ground pin (13) is installed in the mounting port (111). A nut (131) is threaded onto the top of the ground pin (13). A limit port (112) is opened on the side of the base plate (11) near the clamp (30).

5. The cable insulation defect detection device for string photovoltaic systems according to claim 1, characterized in that: The two phase wires (42) of the electrical connection are connected by a spiral cable (46), which is electrically connected to a grounding wire (47) with an alligator clip; an opening is provided on one side of the top of the turntable (41), and a clamp (421) for connecting test instruments is fixedly connected to the third phase wire (42) that is not connected to the spiral cable (46).

6. The cable insulation defect detection device for string photovoltaic systems according to claim 2, characterized in that: The turntable (41) includes two insulating plates that are stacked and fixed on top of each other. The two insulating plates are provided with wire grooves (411) and multiple slots (415) placed in the sliding groove on opposite sides. One end of the second spring (44) is fixed to the insulating rod (43), and the other end is fixed to the ring plate (45). The ring plate (45) is adapted to be inserted into the slot (415).

7. The cable insulation defect detection device for string photovoltaic systems according to claim 1, characterized in that: The clamp (30) includes a quick clamp (31) fixed on the base plate (11), and the clamping end of the quick clamp (31) is fixed with an insulating rubber sleeve (32).

8. The cable insulation defect detection device for string photovoltaic systems according to claim 3, characterized in that: The fixed foot (21) protrudes from the upright plate (12) at one end near the insulating sleeve (32).

9. A cable insulation defect detection system, characterized in that: Includes a hand-cranked megohmmeter (50) and a cable insulation defect detection device suitable for string photovoltaic systems as described in any one of claims 1-8.

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