Secondary circuit insulation detection system

Abstract

The invention discloses a secondary circuit insulation detection system in the technical field of power detection, and the system comprises a detection supporting box body and a detection installation groove formed in the upper plane of the detection supporting box body, the detection installation groove is of a rectangular groove structure, and the side edge of the detection installation groove is provided with a tester storage groove. A fixed clamping seat is fixedly mounted on one side, far away from the tester accommodating groove, in the detection mounting groove, and a movable clamping seat is arranged on the other side in the detection mounting groove. The top surface of the detection support box body is provided with a detection mounting groove and a tester storage groove, an insulation resistance tester can be taken out in the detection process, and the insulation resistance tester is clamped and placed in the detection mounting groove through cooperation of a fixed clamping seat and a movable clamping seat. The upper end of the insulation electromagnetic tester is provided with a plugging connection hole and a crimping connection column which are connected with a detection line, thereby facilitating the connection of the detection line, and the insulation resistance tester is effectively fixed through a detection installation groove, so that one hand can be liberated.

Description

Technical Field

[0001] The invention belongs to the technical field of power detection, and in particular relates to a secondary circuit insulation detection system. Background Art

[0002] The electrical circuit formed by the interconnection of secondary devices to monitor, control, adjust and protect the primary equipment is called the secondary circuit. The secondary circuit is a circuit in the electrical system that is connected by the secondary winding of the mutual inductor, measuring and monitoring instruments, relays, automatic devices, etc. through control cables. It is used to control, protect, adjust, measure and monitor the working conditions of various parameters and components in the primary circuit. The circuits used to monitor measuring meters, control operation signals, relay protection and automatic devices are called secondary circuits. In order to ensure public safety and personal safety and extend the service life of equipment, it is necessary to conduct insulation inspections on the secondary circuits regularly. By checking the insulation status of electrical equipment and lines, faults caused by insulation damage can be effectively prevented, thereby ensuring the safe and stable operation of the power system.

[0003] The insulation test of the secondary circuit is usually carried out with an insulation resistance tester. During the test, the operator holds the tester in one hand and the test terminal of the test line in the other hand to test the position of the secondary circuit terminal in the distribution cabinet. The operator has to hold the tester for a long time, which is labor-intensive.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a secondary circuit insulation detection system. To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is: A secondary circuit insulation detection system comprises a detection support box and a detection installation slot provided on the upper plane thereof, wherein the detection installation slot is a rectangular slot structure, a tester storage slot is provided on the side of the detection installation slot, a fixed clamping seat is fixedly installed on one side of the detection installation slot away from the tester storage slot, a movable clamping seat is provided on the other side of the detection installation slot, the clamping end of the movable clamping seat is located in the detection installation slot, the other end of the movable clamping seat is located in a telescopic matching slot, a telescopic guide column is fixedly provided at the bottom position of the telescopic matching slot, a guide column matching hole is provided on the end surface of the movable clamping seat located at one end of the telescopic matching slot, and the telescopic matching slot is provided with a guide column matching hole. One end of the retractable guide post is located in the guide post matching hole, and a telescopic spring is installed in the section of the outer side of the telescopic guide post between the bottom of the telescopic matching groove and the end face of the movable clamping seat. A lower mounting seat is fixedly provided at the four corners of the bottom surface of the detection support box body, and an internal thread is provided in the lower mounting seat. A main support rod is installed in the lower mounting seat through a threaded connection, and an upper mounting seat is provided on the top surface of the detection support box body, and an internal thread of the same specification as that of the lower mounting seat is provided in the upper mounting seat. The main support rod can be installed in the upper mounting seat and the lower mounting seat through a threaded connection, and a pull rod is provided at the upper end of the main support rod installed at the upper mounting seat.

[0006] As a further solution of the present invention: an upper connecting stud is provided at the upper end of the main support rod, and a lower connecting threaded hole is provided at the lower end of the main support rod. The specifications of the upper connecting stud are compatible with the specifications of the lower connecting threaded hole, and the specifications of the lower connecting threaded hole are the same as the internal thread specifications of the upper mounting seat and the lower mounting seat, ensuring that the connection and assembly of the main support rod and the keyway support box can be achieved.

[0007] As a further solution of the present invention: an extended support rod is installed on the lower end of the main support rod via a threaded connection, and a movable wheel is installed on the lower end of the extended support rod via a threaded connection, and a connecting mounting column is provided at the upper end of the movable wheel, and the connecting mounting column is a stud structure, and the specifications of the connecting mounting column are consistent with the specifications of the upper connecting stud, and the movable wheel can be directly installed in the lower mounting seat, the lower end of the main support rod, and the lower end of the extended support rod.

[0008] As a further solution of the present invention: a storage drawer is arranged at the lower position of the detection support box body, and a drawer locking screw is arranged at the middle position of the upper outer side of the storage drawer through a threaded connection, and the drawer locking screw is used to lock the relative position of the storage drawer and the detection support box body, and the storage drawer is used to store the main support rod, the extended support rod, the movable wheel, and the pull rod.

[0009] As a further solution of the present invention: an insulation resistance tester is placed in the detection installation groove, and a plug-in connection hole and a crimping connection column are arranged on the top surface of the insulation resistance tester. The plug-in connection hole and the crimping connection column are correspondingly connected with a detection line for realizing insulation detection of the secondary circuit.

[0010] As a further solution of the present invention: a cover plate recess is provided on the outer edge of the detection installation groove, and cover plate fixing holes are processed at the four corners of the cover plate recess, and the cover plate fixing holes are threaded holes. A protective cover plate is provided at the cover plate recess. When no detection is performed, the protective cover plate is installed at the cover plate recess position to protect the detection installation groove.

[0011] As a further solution of the present invention: a sealing cover plate is rotatably connected and installed on one side of the tester storage slot close to the upper mounting seat, a cover plate locking screw is installed on the outer side of the sealing cover plate away from the rotating end, and a cover plate locking hole is provided on the outer side of the tester storage slot at a position corresponding to the cover plate locking screw. The cover plate locking hole is a threaded hole, and the specification of the cover plate locking hole is compatible with the specification of the cover plate locking screw, and the sealing cover plate is locked and fixed by using the cover plate locking screw.

[0012] As a further solution of the present invention: the pull rod is a U-shaped structure, and the end of the pull rod that cooperates with the main support rod is a cylindrical end, the diameter of the cylinder is smaller than the inner diameter of the lower connecting threaded hole of the main support rod, and a fixing screw is provided at the outer position of the connection between the main support rod and the pull rod, which is used to fix the relative position of the pull rod and the main support rod.

[0013] As a further solution of the present invention: the main support rod and the extended support rod are set with different length specifications to meet diverse usage requirements, the clamping surfaces of the movable clamping seat and the fixed clamping seat are both provided with protective pads, and the movable clamping seat is provided with a limiting block at the outer position near one end of the telescopic spring.

[0014] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0015] The top surface of the detection support box of the present invention is provided with a detection installation groove and a tester storage groove. During the detection process, the insulation resistance tester can be taken out, and the insulation resistance tester is clamped and placed in the detection installation groove by cooperating with the fixed clamping seat and the movable clamping seat. The upper end of the insulation electromagnetic tester is provided with a plug-in connection hole and a crimping connection column connected to the detection line, which is convenient for connecting the detection line. The insulation resistance tester is effectively fixed by using the detection installation groove, so that one hand can be freed. Insulation detection in the secondary circuit can be realized by simply holding the detection end of the detection line to contact different positions of the secondary circuit, thereby effectively reducing the labor intensity of the secondary circuit insulation detection process.

[0016] The bottom of the detection support box of the present invention is provided with a lower mounting seat, which can be matched with the mounting column support rod. The lower end of the main support rod can be installed with movable wheels or lengthened support rods to support the height position of the detection support box to meet the use requirements of different distribution cabinet detection heights. The main support rod, the lengthened support rod and the movable wheels are all detachable structures, which are convenient for disassembly, assembly and storage. An upper mounting seat is provided on the top surface of the detection support box. The upper mounting seat is used for installing the main support rod and the pull rod. When not in the detection state, the detection support box is a pull rod box type structure, which is convenient for carrying and moving.

[0017] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are part of this application and are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 This is a schematic diagram of the structure of the detection device of the present invention in a heightened use state; Figure 2 This is a schematic diagram of the structure of the detection device of the present invention in a normal use state; Figure 3 This is a schematic diagram of the semi-storage state structure of the present invention; Figure 4 It is a front view of the storage state of the present invention; Figure 5 This is a front view of the detection device of the present invention in a heightened state of use; Figure 6 This is a schematic diagram of the connection between the main support rod and the moving wheel of the present invention; Figure 7 A top view of the present invention; Figure 8 It is a schematic diagram of the installation of the movable clamping seat of the present invention.

[0019] In the figure: 1. detection support box; 2. storage drawer; 3. drawer locking screw; 4. main support rod; 5. extension support rod; 6. moving wheel; 7. detection installation slot; 8. cover plate sink slot; 9. insulation resistance tester; 10. tester storage slot; 11. sealing cover plate; 12. cover plate locking screw; 13. cover plate fixing hole; 14. plug-in connection hole; 15. crimping connection column; 16. detection line; 17. lower mounting seat; 18. upper mounting seat; 19. pull rod; 20. fixing screw; 21. upper connection stud; 22. lower connection threaded hole; 23. connection installation column; 24. fixed clamping seat; 25. movable clamping seat; 26. cover plate locking hole; 27. protective pad; 28. telescopic matching slot; 29. ​​telescopic guide column; 30. guide column matching hole; 31. limit block; 32. telescopic spring.

[0020] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0022] like Figures 1 to 8As shown, a secondary circuit insulation detection system comprises a detection support box 1 and a detection installation slot 7 provided on the upper plane thereof, wherein the detection installation slot 7 is a rectangular slot structure, a tester receiving slot 10 is provided on the side of the detection installation slot 7, a fixed clamping seat 24 is fixedly installed on one side of the detection installation slot 7 away from the tester receiving slot 10, a movable clamping seat 25 is provided on the other side of the detection installation slot 7, a clamping end of the movable clamping seat 25 is located in the detection installation slot 7, and the other end of the movable clamping seat 25 is located in a telescopic matching slot 28, a telescopic guide column 29 is fixedly provided at the bottom of the telescopic matching slot 28, and a guide column matching hole 30 is provided on the end surface of the movable clamping seat 25 located at one end of the telescopic matching slot 28, One end of the telescopic guide column 29 is located in the guide column matching hole 30, and the outer side of the telescopic guide column 29 is located in the section between the bottom of the telescopic matching groove 28 and the end face of the movable clamping seat 25, and a telescopic spring 32 is installed. The four corners of the bottom surface of the detection support box 1 are fixedly provided with a lower mounting seat 17, and an internal thread is provided in the lower mounting seat 17. The main support rod 4 is installed in the lower mounting seat 17 through a threaded connection. An upper mounting seat 18 is provided on the top surface of the detection support box 1, and an internal thread of the same specification as that in the lower mounting seat 17 is provided in the upper mounting seat 18. The main support rod 4 can be installed in the upper mounting seat 18 and the lower mounting seat 17 through a threaded connection, and the upper end of the main support rod 4 installed at the upper mounting seat 18 is matched with a pull rod 19.

[0023] Among them, an upper connecting stud 21 is provided at the upper end of the main support rod 4, and a lower connecting threaded hole 22 is provided at the lower end of the main support rod 4. The specifications of the upper connecting stud 21 are compatible with the specifications of the lower connecting threaded hole 22, and the specifications of the lower connecting threaded hole 22 are the same as the internal thread specifications of the upper mounting seat 18 and the lower mounting seat 17, ensuring that the main support rod 4 can be connected and assembled with the keyway support box.

[0024] The lower end of the main support rod 4 is installed with an extended support rod 5 through a threaded connection, and the lower end of the extended support rod 5 is installed with a moving wheel 6 through a threaded connection. The upper end of the moving wheel 6 is provided with a connecting mounting column 23, and the connecting mounting column 23 is a stud structure. The specifications of the connecting mounting column 23 are consistent with the specifications of the upper connecting stud 21. The moving wheel 6 can be directly installed in the lower mounting seat 17, the lower end of the main support rod 4, and the lower end of the extended support rod 5.

[0025] A storage drawer 2 is provided at the lower position of the detection support box 1, and a drawer locking screw 3 is provided at the middle position of the upper outer side of the storage drawer 2 through a threaded connection. The drawer locking screw 3 is used to lock the relative position of the storage drawer 2 and the detection support box 1. The storage drawer 2 is used to store the main support rod 4, the extended support rod 5, the moving wheel 6, and the pull rod 19.

[0026] An insulation resistance tester 9 is placed in the detection installation groove 7. A plug-in connection hole 14 and a crimping connection column 15 are provided on the top surface of the insulation resistance tester 9. The plug-in connection hole 14 and the crimping connection column 15 are correspondingly connected with a detection line 16 for realizing insulation detection of the secondary circuit.

[0027] A cover plate recess 8 is provided on the outer edge of the detection installation groove 7, and cover plate fixing holes 13 are processed at the four corners of the cover plate recess 8. The cover plate fixing holes 13 are threaded holes. A protective cover plate is provided at the cover plate recess 8. When no detection is performed, the protective cover plate is installed at the position of the cover plate recess 8 to protect the detection installation groove 7.

[0028] A sealing cover plate 11 is rotatably connected and installed on one side of the tester storage slot 10 close to the upper mounting seat 18, and a cover plate locking screw 12 is installed on the outer side of the sealing cover plate 11 away from the rotating end. A cover plate locking hole 26 is provided on the outer side of the tester storage slot 10 at a position corresponding to the cover plate locking screw 12. The cover plate locking hole 26 is a threaded hole, and the specifications of the cover plate locking hole 26 are compatible with the specifications of the cover plate locking screw 12. The sealing cover plate 11 is locked and fixed by using the cover plate locking screw 12.

[0029] The pull rod 19 is a U-shaped structure, and the end of the pull rod 19 that cooperates with the main support rod 4 is a cylindrical end. The diameter of the cylinder is smaller than the inner diameter of the lower connecting threaded hole 22 of the main support rod 4. A fixing screw 20 is provided at the outer position of the connection between the main support rod 4 and the pull rod 19, which is used to fix the relative position of the pull rod 19 and the main support rod 4.

[0030] The main support rod 4 and the extended support rod 5 are provided with different length specifications to meet diverse usage requirements. Protective pads 27 are provided at the clamping surfaces of the movable clamping seat 25 and the fixed clamping seat 24. A limiting block 31 is provided at the outer position of the movable clamping seat 25 near one end of the telescopic spring 32.

[0031] The working principle of the present invention is: when performing insulation testing on the secondary circuit in the distribution cabinet, according to the height of the distribution cabinet, the main support rod 4 is installed in the lower mounting seat 17 of the detection support box 1, and the height position of the detection support box 1 is raised by the support of the main support rod 4. The lower end of the main support rod 4 can be equipped with a moving wheel 6 (such as the attached Figure 2As shown), it is convenient for the device to move to a certain position, then loosen the cover locking screw 12 on the sealing cover 11, open the sealing cover 11, take out the insulation resistance tester 9 from the tester storage slot 10, and place it vertically in the detection installation slot 7, make one side of the insulation resistance tester 9 contact with the movable clamping seat 25, compress the movable clamping seat 25 toward the side of the telescopic matching slot 28, and the telescopic spring 32 is compressed. The lower end of the insulation resistance tester 9 is clamped and fixed by the fixed clamping seat 24 and the movable clamping seat 25, so that the insulation electromagnetic tester is in a stable state, and then the detection line 16 is connected to the connection end of the insulation resistance tester 9, and the other end of the detection line 16 is used to contact the tested position of the secondary circuit to perform insulation detection. During the detection process, the operator needs to wear insulating gloves and pay attention to safety protection; If the height position of the power distribution cabinet is relatively high, an extended support rod 5 can be installed at the lower end of the main support rod 4, and the moving wheel 6 can be installed at the lower end of the extended support rod 5 to further increase the height position of the detection support box 1 for insulation detection. The insulation resistance tester 9 can use DT-6605. It should be noted that this embodiment mainly optimizes and improves the detection operation process using the insulation resistance tester 9 for the existing secondary circuit to reduce the problem of high labor intensity in the continuous hand-held state during the detection operation process. The specific structure and working principle of the secondary circuit insulation resistance tester are not repeated here. After the detection is completed, the main support rod 4, the extended support rod 5 and the moving wheel 6 are disassembled, the moving wheel 6 is installed on the lower mounting seat 17, the extended support rod 5 is stored in the storage drawer 2, the main support rod 4 is installed on the upper mounting seat 18, the pull rod 19 is installed on the upper end of the main support rod 4, and the installation of the pull rod 19 is locked by the fixing screw 20, the insulation resistance tester 9 is taken out from the detection installation groove 7, put back into the tester storage groove 10, and the sealing cover plate 11 is closed, and locked by the cover plate locking screw 12, and the sinking groove cover plate is installed at the cover plate sinking groove 8 of the detection installation groove 7 to protect the detection installation groove 7. At this time, the detection device as a whole is a box-type structure with a pull rod 19 (as shown in the attached Figure 4 As shown), easy to carry; The top surface of the detection support box 1 of the present invention is provided with a detection installation groove 7 and a tester storage groove 10. During the detection process, the insulation resistance tester 9 can be taken out, and the insulation resistance tester 9 is clamped and placed in the detection installation groove 7 by the cooperation of the fixed clamping seat 24 and the movable clamping seat 25. The upper end of the insulation electromagnetic tester is provided with a plug-in connection hole 14 and a crimping connection column 15 connected to the detection line 16, which is convenient for connecting the detection line 16. The insulation resistance tester 9 is effectively fixed by using the detection installation groove 7, so that one hand can be freed. Only the detection end of the detection line 16 needs to be held to contact different positions of the secondary circuit to realize the insulation detection in the secondary circuit, which effectively reduces The labor intensity of the secondary circuit insulation detection process is low; a lower mounting seat 17 is provided at the bottom of the detection support box 1, which can be used in conjunction with the installation column support rod. The lower end of the main support rod 4 can be installed with a movable wheel 6 or an extended support rod 5 to support the height position of the detection support box 1 to meet the use requirements of different distribution cabinet detection heights. The main support rod 4, the extended support rod 5, and the movable wheel 6 are all detachable structures, which are convenient for disassembly and storage. An upper mounting seat 18 is provided on the top surface of the detection support box 1. The upper mounting seat 18 is used to install the main support rod 4 and the pull rod 19. When not in the detection state, the detection support box 1 is a box-type structure with a pull rod 19, which is convenient for carrying and moving.

[0032] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A secondary circuit insulation detection system, comprising a detection support box (1) and a detection installation groove (7) provided on an upper plane thereof, characterized in that: The detection installation groove (7) is a rectangular groove structure. A tester storage groove (10) is arranged on the side of the detection installation groove (7). A fixed clamping seat (24) is fixedly installed on the side of the detection installation groove (7) away from the tester storage groove (10). A movable clamping seat (25) is arranged on the other side of the detection installation groove (7). The clamping end of the movable clamping seat (25) is located in the detection installation groove (7). The other end of the movable clamping seat (25) is located in the telescopic matching groove (28). A telescopic guide column (29) is fixedly arranged at the bottom of the telescopic matching groove (28). A guide column matching hole (30) is opened on the end surface of the movable clamping seat (25) located at one end of the telescopic matching groove (28). One end of the telescopic guide column (29) is located in the guide column matching hole (30). A telescopic spring (32) is installed on the outer side of the telescopic guide column (29) in a section between the bottom of the telescopic matching groove (28) and the end surface of the movable clamping seat (25); a lower mounting seat (17) is fixedly provided at the four corners of the bottom surface of the detection support box (1); an internal thread is provided in the lower mounting seat (17); a main support rod (4) is installed in the lower mounting seat (17) through a threaded connection; an upper mounting seat (18) is provided on the top surface of the detection support box (1); an internal thread of the same specification as that of the lower mounting seat (17) is provided in the upper mounting seat (18); the main support rod (4) can be installed in both the upper mounting seat (18) and the lower mounting seat (17) through a threaded connection; and a pull rod (19) is provided at the upper end of the main support rod (4) installed at the upper mounting seat (18).

2. A secondary circuit insulation detection system according to claim 1, characterized in that: An upper connecting stud (21) is provided at the upper end of the main support rod (4), and a lower connecting threaded hole (22) is provided at the lower end of the main support rod (4); the specification of the upper connecting stud (21) matches the specification of the lower connecting threaded hole (22); and the specification of the lower connecting threaded hole (22) is the same as the specification of the internal threads of the upper mounting seat (18) and the lower mounting seat (17).

3. A secondary circuit insulation detection system according to claim 2, characterized in that: The lower end of the main support rod (4) is installed with an extended support rod (5) through a threaded connection, and the lower end of the extended support rod (5) is installed with a moving wheel (6) through a threaded connection. The upper end of the moving wheel (6) is provided with a connecting mounting column (23), and the connecting mounting column (23) is a stud structure. The specifications of the connecting mounting column (23) are consistent with the specifications of the upper connecting stud (21).

4. A secondary circuit insulation detection system according to claim 3, characterized in that: A storage drawer (2) is provided at the lower position of the detection support box (1), and a drawer locking screw (3) is provided at the middle position of the upper outer portion of the storage drawer (2) through a threaded connection.

5. A secondary circuit insulation detection system according to claim 4, characterized in that: An insulation resistance tester (9) is placed in the detection installation groove (7), and a plug-in connection hole (14) and a crimping connection column (15) are provided on the top surface of the insulation resistance tester (9), and detection wires (16) are correspondingly connected to the plug-in connection hole (14) and the crimping connection column (15).

6. A secondary circuit insulation detection system according to claim 5, characterized in that: The outer edge of the detection installation groove (7) is provided with a cover plate recess (8), and the four corners of the cover plate recess (8) are processed with cover plate fixing holes (13), the cover plate fixing holes (13) are threaded holes, and the cover plate recess (8) is matched with a protective cover plate.

7. A secondary circuit insulation detection system according to claim 6, characterized in that: A sealing cover plate (11) is rotatably connected and mounted on one side of the tester storage slot (10) close to the upper mounting seat (18); a cover plate locking screw (12) is mounted on the outer side of the sealing cover plate (11) away from the rotating end; a cover plate locking hole (26) is provided on the outer side of the tester storage slot (10) at a position corresponding to the cover plate locking screw (12); the cover plate locking hole (26) is a threaded hole; and the specification of the cover plate locking hole (26) is compatible with the specification of the cover plate locking screw (12).

8. A secondary circuit insulation detection system according to claim 7, characterized in that: The pull rod (19) is a U-shaped structure, and the end of the pull rod (19) that cooperates with the main support rod (4) is a cylindrical end, the diameter of the cylinder is smaller than the inner diameter of the lower connecting threaded hole (22) of the main support rod (4), and a fixing screw (20) is provided at the outer position where the main support rod (4) and the pull rod (19) are connected and cooperated.

9. A secondary circuit insulation detection system according to claim 8, characterized in that: The main support rod (4) and the extended support rod (5) are provided with different length specifications, the clamping surfaces of the movable clamping seat (25) and the fixed clamping seat (24) are both provided with protective pads (27), and the movable clamping seat (25) is provided with a limiting block (31) at an outer position close to one end of the telescopic spring (32).

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