Electrical equipment safety test device
By setting arc plates, lever, resistant assembly and pull assembly in the electrical equipment safety test device, the problem of large jaw spacing is solved, resulting in the inability to accurately center the wire, and the test effect and tightness are improved.
Patent Information
- Application Number
- CN202411602552.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2025-02-28
AI Technical Summary
When conducting safety tests on high-altitude electrical equipment, the high-voltage jaws are spacing large, which makes it impossible to accurately ensure that the wires are located in the center of the jaws, affecting the test effect.
By setting up a combination of structures such as arc plates and levers, ensure that the wires are always located in the center area of the jaw, and the tightening force of the jaw is increased by setting up a resisting assembly and pulling assembly.
Effectively improve the test effect, ensure that the wires are in full contact with the contact surface and maintain tightness during long-term use or shelving.
Smart Images
Figure CN119535033A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of safety testing equipment, in particular to a safety testing device for electrical equipment. Background Art
[0002] Electrical equipment safety testing is an important part of ensuring the safety of electrical equipment and systems. It aims to check whether the equipment meets safety standards and whether there are potential safety hazards. When conducting safety tests on electrical equipment located at high altitudes, it is necessary to use high-voltage clamps to clamp the wire installed above the transformer so that the wire is located in the center area of the clamps to ensure that the wire is in full contact with the contact surface during the clamping process, thereby improving the quality and reliability of the electrical connection. When using a tester for testing, it is necessary to manually hold the bottom of the insulating rod and forcefully prop up the tester connected to the insulating rod so that the jaws are located below the wire. After aligning the position, the jaws are opened so that the wire is located in the middle area of the jaws, and then the bottom ends of the high-voltage clamps are held toward each other and the jaws are closed through the hinge at the upper end of the clamp rod to clamp the wire. However, the distance between the jaws is generally large. Due to the obstructed field of view in actual use, it is impossible to accurately ensure that the wire is located in the center area of the jaws, and then it is impossible to ensure that the wire is in full contact with the contact surface, affecting the subsequent test results. Therefore, in summary, it needs to be improved. Summary of the invention
[0003] In order to solve the problem mentioned in the above background technology that the distance between the jaws is generally large, the field of vision is obstructed in actual use, and it is impossible to accurately ensure that the wire is located in the central area of the jaws, and thus it is impossible to ensure that the wire is fully in contact with the contact surface, thereby affecting the subsequent test results, the present invention provides an electrical equipment safety testing device, which ensures that the wire of the tested electrical equipment is always located in the central area of the jaws by setting up structures such as arc plates and resisting rods, thereby improving the subsequent test results; and improves the tightening force of the jaws by setting up structures such as resistance components and pulling components, thereby avoiding poor tightening of the device during long-term outdoor use or long-term storage.
[0004] To achieve the above object, the present invention provides the following technical solution: an electrical equipment safety test device, comprising a high-voltage clamp, and further comprising: A connecting piece, wherein the connecting piece is movably sleeved on the outside of the hinge of the high-voltage clamp; A movable component, which is installed on the outside of the high-voltage clamp and abuts against the connecting piece; A pulling assembly, wherein the pulling assembly is fixedly connected to the connecting piece, and the outer wall of the pulling assembly is sleeved with a limiting assembly located outside the high-voltage clamp; The connecting part includes an extrusion frame and a rotating shaft, and the two sides of the outer wall of the extrusion frame are fixedly connected to the pulling component; the movable component includes an arc plate and a resistance rod, the arc plate is slidably engaged with the outer wall of the high-voltage clamp, and the resistance rod is hinged in the inner wall of the high-voltage clamp; the pulling component includes a U-shaped pull rod, the bottom end of the U-shaped pull rod passes through the limit assembly and extends to the bottom of the limit assembly, and the lower end of the U-shaped pull rod is fixedly connected to the resistance assembly.
[0005] Preferably, the high-voltage pliers include a first pliers rod and a second pliers rod, the middle ends of the first pliers rod and the second pliers rod are hinged via a rotating shaft, and the inner walls of the first pliers rod and the second pliers rod are both provided with movable components.
[0006] Preferably, the inner cavity of the extrusion frame is movably connected to the rotating shaft, the outer wall of the extrusion frame is fixedly connected to the U-shaped pull rod, and the top surface and the bottom surface of the extrusion frame are respectively in contact with the first clamp rod and the second clamp rod. When the U-shaped pull rod is pulled up, the U-shaped pull rod will contact the outer walls of the first clamp rod and the second clamp rod through the extrusion frame, so that the first clamp rod and the second clamp rod rotate around the rotating shaft, resulting in the top ends of the first clamp rod and the second clamp rod being fitted together, and then subsequent testing of the wire can be performed.
[0007] Preferably, a spur gear is fixedly connected to the outer end of the support rod and the first clamp rod hinge shaft, and an arc-shaped toothed plate is fixedly connected to the end of the arc plate close to the support rod. The spur gear is meshingly connected to the arc-shaped toothed plate. When the arc plate moves, the spur gear is driven to rotate through the arc-shaped toothed plate. When the spur gear rotates, the support rod is synchronously driven to flip over on the inner wall of the first clamp rod. At this time, the two support rods will be engaged with each other, thereby limiting the wire located in the inner cavity of the first clamp rod and the second clamp rod, so that the wire is always located at the center position of the inner cavity of the first clamp rod and the second clamp rod.
[0008] Preferably, mutually staggered notches are provided at the ends of the two push rods that are in contact with each other, and the two push rods are both made of rubber.
[0009] Preferably, the outer wall of the U-shaped pull rod is smooth and made of rubber material. The outer wall of the upper end of the U-shaped pull rod is sleeved with a first spring. The top of the first spring is fixedly connected to the limit assembly, and the bottom end of the first spring is fixedly connected to one side of the outer wall of the U-shaped pull rod. Pulling the U-shaped pull rod will drive the extrusion frame to compress the first clamp rod and the second clamp rod, so that the first clamp rod and the second clamp rod rotate, and the first spring has a resetting effect on the movement of the U-shaped pull rod.
[0010] Preferably, the limit assembly includes a limit frame, which is sleeved on the outer walls of the first clamp rod and the second clamp rod, and movable cavities for allowing the first clamp rod and the second clamp rod to move are provided on both sides of the inner cavity of the limit frame, and first limit grooves for limiting the movement of the first clamp rod and the second clamp rod are provided on both sides of the inner wall of the movable cavity.
[0011] Preferably, a second spring is disposed in the inner cavity of the first limiting groove, one end of the second spring is fixedly connected to the inner wall of the first limiting groove, and the other end of the second spring is fixedly connected to the first clamp rod.
[0012] Preferably, a second limiting groove is provided on both sides of the first clamp rod and the second clamp rod, the interior of the second limiting groove is slidably engaged with the arc plate, a third spring is placed inside the second limiting groove, one end of the third spring is fixedly connected to the inner wall of the second limiting groove, and the other end of the third spring is fixedly connected to the arc plate.
[0013] Preferably, the abutment assembly comprises an abutment plate, the abutment plate is fixedly sleeved on the outer wall of the U-shaped pull rod, rubber pads are installed on both sides of the lower end of the U-shaped pull rod, and the outer walls of the two rubber pads are respectively abutted against the first clamp rod and the second clamp rod; The outer shape of the abutment plate is trapezoidal.
[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention ensures that the wire of the tested electrical equipment is always located in the central area of the jaws by arranging the coordination of structures such as the arc plate and the push rod, so as to improve the subsequent test effect. During the upward movement of the extrusion frame, the top surface will resist the bottom end of the arc plate, so that the arc plate can slide upward synchronously on the outer walls of the first clamp rod and the second clamp rod, and drive the spur gear to rotate through the arc-shaped tooth plate. When the spur gear rotates, the push rod is driven to flip downward in the inner walls of the first clamp rod and the second clamp rod. The two push rods press the wire downward in a cross shape, so as to ensure that the wire is located in the middle area of the first clamp rod and the second clamp rod, thereby improving the subsequent test effect on the electrical equipment.
[0015] The present invention improves the tightening force of the jaws by arranging the cooperation of structures such as the resistance component and the pulling component. The upward movement of the U-shaped pull rod synchronously drives the resistance plate to move upward, so that the resistance plate resists the side walls of the first clamp rod and the second clamp rod through the rubber pad, thereby increasing the friction force, so that the clamping effect of the jaws of the first clamp rod and the second clamp rod on the wire is tighter, thereby avoiding poor tightening of the device when it is used outdoors for a long time or is shelved for a long time. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the structural matching relationship between the first clamp rod and the second clamp rod of the present invention; Figure 3 It is a schematic diagram of the subdivided structure of the conflicting components of the present invention; Figure 4 It is a schematic diagram of the subdivided structure of the limit assembly of the present invention; Figure 5 It is a schematic diagram of the subdivision structure of the active components of the present invention; Figure 6 for Figure 5 A schematic diagram of the partially enlarged structure at center A; Figure 7 It is a schematic diagram of the structural matching relationship between the limit frame and the movable cavity of the present invention; Figure 8 for Figure 7 Schematic diagram of the local enlarged structure at point B in the middle.
[0017] In the figure: 1. high-voltage pliers; 11. first pliers rod; 12. second pliers rod; 2. connecting piece; 21. extrusion frame; 22. rotating shaft; 3. movable assembly; 31. arc plate; 32. arc tooth plate; 33. spur gear; 34. push rod; 4. pulling assembly; 41. U-shaped pull rod; 42. first spring; 5. limiting assembly; 51. limiting frame; 52. first limiting groove; 53. second spring; 54. movable cavity; 6. abutting assembly; 61. push plate; 62. rubber pad; 7. second limiting groove; 8. third spring. DETAILED DESCRIPTION
[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0019] like Figures 1 to 8 As shown, the present invention provides an electrical equipment safety test device, including a high-voltage clamp 1, and also including: A connecting piece 2, which is movably sleeved on the outer side of the hinge of the high-voltage clamp 1; A movable component 3, which is installed on the outside of the high-voltage clamp 1 and abuts against the connecting piece 2; A pulling assembly 4, the pulling assembly 4 is fixedly connected to the connecting piece 2, and the outer wall of the pulling assembly 4 is sleeved with a limiting assembly 5 located outside the high-voltage clamp 1; The connecting member 2 includes an extrusion frame 21 and a rotating shaft 22, and the two sides of the outer wall of the extrusion frame 21 are fixedly connected to the pulling component 4; the movable component 3 includes an arc plate 31 and a push rod 34, the arc plate 31 is slidably engaged with the outer wall of the high-voltage clamp 1, and the push rod 34 is hinged in the inner wall of the high-voltage clamp 1; the pulling component 4 includes a U-shaped pull rod 41, the bottom end of the U-shaped pull rod 41 passes through the limit assembly 5 and extends to the bottom of the limit assembly 5, and the lower end of the U-shaped pull rod 41 is fixedly connected to the resistance assembly 6.
[0020] like Figure 2 and Figure 3As shown, the high-voltage pliers 1 include a first pliers rod 11 and a second pliers rod 12 . The middle ends of the first pliers rod 11 and the second pliers rod 12 are hinged via a rotating shaft 22 . The inner walls of the first pliers rod 11 and the second pliers rod 12 are both provided with movable components 3 .
[0021] By adopting the above solution, pressing the two first tongs rods 11 and the second tongs rods 12 toward each other will enlarge the openings at the top ends of the first tongs rods 11 and the second tongs rods 12, otherwise they will be closed, and the contact surfaces at the top ends of the first tongs rods 11 and the second tongs rods 12 will fit completely.
[0022] like Figure 5 and Figure 7 As shown, the inner cavity of the extrusion frame 21 is movably connected to the rotating shaft 22, the outer wall of the extrusion frame 21 is fixedly connected to the U-shaped pull rod 41, and the top surface and the bottom surface of the extrusion frame 21 are respectively in contact with the first clamp rod 11 and the second clamp rod 12.
[0023] By adopting the above scheme: when the U-shaped pull rod 41 is pulled up, the U-shaped pull rod 41 will contact the outer walls of the first clamp rod 11 and the second clamp rod 12 through the extrusion frame 21, so that the first clamp rod 11 and the second clamp rod 12 rotate around the rotating shaft 22, resulting in the top ends of the first clamp rod 11 and the second clamp rod 12 being fitted together, thereby performing subsequent tests on the wire.
[0024] like Figure 5 and Figure 6 As shown, a spur gear 33 is fixedly connected to the outer end of the hinge shaft between the push rod 34 and the first clamp rod 11 , and an arc-shaped toothed plate 32 is fixedly connected to one end of the arc plate 31 close to the push rod 34 , and the spur gear 33 is meshingly connected with the arc-shaped toothed plate 32 .
[0025] The above scheme is adopted: when the arc plate 31 moves, the spur gear 33 will be driven to rotate through the arc-shaped tooth plate 32. While the spur gear 33 rotates, the push rod 34 will be synchronously driven to flip over on the inner wall of the first clamp rod 11. At this time, the two push rods 34 will be engaged with each other, thereby limiting the wire located in the inner cavity of the first clamp rod 11 and the second clamp rod 12, so that the wire is always located at the center position of the inner cavity of the first clamp rod 11 and the second clamp rod 12.
[0026] like Figure 5 As shown, the ends of the two push rods 34 that are in contact with each other are provided with interlaced notches, and the two push rods 34 are both made of rubber.
[0027] With the above solution, when the top ends of the two abutting rods 34 are engaged with each other, the notches provided at the top ends thereof effectively prevent the two from interfering with each other, thereby avoiding the phenomenon that the two cannot move downward.
[0028] like Figure 1 , Figure 3 and Figure 4As shown, the outer wall of the U-shaped pull rod 41 is smooth and made of rubber material. The outer wall of the upper end of the U-shaped pull rod 41 is sleeved with a first spring 42. The top of the first spring 42 is fixedly connected to the limit assembly 5, and the bottom end of the first spring 42 is fixedly connected to one side of the outer wall of the U-shaped pull rod 41.
[0029] By adopting the above solution, pulling the U-shaped pull rod 41 will drive the extrusion frame 21 to press the first clamp rod 11 and the second clamp rod 12, so that the first clamp rod 11 and the second clamp rod 12 rotate, and the first spring 42 has a reset effect on the movement of the U-shaped pull rod 41.
[0030] like Figure 4 As shown, the limit assembly 5 includes a limit frame 51, which is sleeved on the outer walls of the first clamp rod 11 and the second clamp rod 12. Both sides of the inner cavity of the limit frame 51 are provided with movable cavities 54 for allowing the first clamp rod 11 and the second clamp rod 12 to move. Both sides of the inner wall of the movable cavity 54 are provided with first limit grooves 52 for limiting the movement of the first clamp rod 11 and the second clamp rod 12.
[0031] By adopting the above solution, the movable cavity 54 and the first limiting groove 52 ensure the stable movement of the first clamp rod 11 and the second clamp rod 12, so that the movement of the first clamp rod 11 and the second clamp rod 12 will not be offset, thereby ensuring the subsequent stable clamping and testing of the wire by the first clamp rod 11 and the second clamp rod 12.
[0032] like Figure 4 As shown, a second spring 53 is disposed in the inner cavity of the first limiting groove 52 , one end of the second spring 53 is fixedly connected to the inner wall of the first limiting groove 52 , and the other end of the second spring 53 is fixedly connected to the first clamp rod 11 .
[0033] Adopt the above solution: Combine Figure 4 It can be known that four second springs 53 are provided, and the four second springs 53 will respectively restrict the first clamp rod 11 and the second clamp rod 12 so that the first clamp rod 11 and the second clamp rod 12 can perform a subsequent reset effect.
[0034] like Figure 7 As shown, a second limiting groove 7 is provided on both sides of the first clamp rod 11 and the second clamp rod 12. The interior of the second limiting groove 7 is slidably engaged with the arc plate 31. A third spring 8 is placed inside the second limiting groove 7. One end of the third spring 8 is fixedly connected to the inner wall of the second limiting groove 7, and the other end of the third spring 8 is fixedly connected to the arc plate 31.
[0035] With the above solution, when the arc plate 31 moves upward on the outer side of the first clamp rod 11, one end of the arc plate 31 will slide upward inside the second limiting groove 7 and compress the third spring 8. Conversely, the third spring 8 will provide elastic force to the arc plate 31 to achieve a reset effect.
[0036] like Figure 3 As shown, the abutment assembly 6 includes an abutment plate 61, which is fixedly sleeved on the outer wall of the U-shaped pull rod 41, and rubber pads 62 are installed on both sides of the lower end of the U-shaped pull rod 41. The outer walls of the two rubber pads 62 are respectively abutted against the first clamp rod 11 and the second clamp rod 12; The outer shape of the butt plate 61 is trapezoidal.
[0037] The above scheme is adopted: when the support plate 61 moves upward through the U-shaped pull rod 41, the outer wall of the support plate 61 will respectively contact the first clamp rod 11 and the second clamp rod 12 through the rubber pad 62, and the friction force with the first clamp rod 11 and the second clamp rod 12 is increased through the rubber pad 62, thereby improving the clamping and tightening effect of the first clamp rod 11 and the second clamp rod 12.
[0038] The working principle and use process of the present invention: First, the extrusion frame 21 is located outside the hinged area of the first clamp rod 11 and the second clamp rod 12, that is, outside the rotating shaft 22. At this time, the top ends of the first clamp rod 11 and the second clamp rod 12 will be in an open and closed state. Hold the bottom ends of the first clamp rod 11 and the second clamp rod 12 and the bottom of the U-shaped pull rod 41, and move up to place the wire between the first clamp rod 11 and the second clamp rod 12. When the wire is clamped, the U-shaped pull rod 41 is pushed upward, and the top of the U-shaped pull rod 41 drives the extrusion frame 21 to contact the outer wall of the first clamp rod 11 and the second clamp rod 12, so that the top of the first clamp rod 11 and the second clamp rod 12 are closed again. At the same time, during the upward movement of the extrusion frame 21, the top surface will contact the bottom end of the arc plate 31, so that the arc plate 31 will slide upward synchronously on the outer wall of the first clamp rod 11 and the second clamp rod 12. During the upward movement of the arc plate 31, the spur gear 33 will be driven to rotate through the arc tooth plate 32. When the spur gear 33 rotates, it will drive the push rod 34 to flip downward in the inner wall of the first clamp rod 11 and the second clamp rod 12. The two push rods 34 will press the wire downward in a cross shape, so that the wire is located in the middle area of the first clamp rod 11 and the second clamp rod 12. Subsequently, during the upward movement of the U-shaped pull rod 41, the support plate 61 will be driven upward synchronously, and the support plate 61 will contact the side walls of the first clamp rod 11 and the second clamp rod 12 through the rubber pad 62, thereby increasing the friction force to enhance the clamping effect of the jaws of the first clamp rod 11 and the second clamp rod 12 on the wire, thereby avoiding poor tightness of the device during long-term outdoor use or long-term storage.
[0039] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.
[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. An electrical equipment safety test device, comprising a high voltage clamp (1), characterized in that: A connecting piece (2), the connecting piece (2) being movably sleeved on the outside of a hinged portion of the high-voltage clamp (1); A movable component (3), the movable component (3) being mounted on the outside of the high-voltage clamp (1) and abutting against the connecting piece (2); A pulling assembly (4), wherein the pulling assembly (4) is fixedly connected to the connecting piece (2), and an outer wall of the pulling assembly (4) is provided with a limiting assembly (5) located outside the high-voltage clamp (1); The connecting member (2) comprises an extrusion frame (21) and a rotating shaft (22), and the two sides of the outer wall of the extrusion frame (21) are fixedly connected to the pulling component (4); the movable component (3) comprises an arc plate (31) and a resisting rod (34), and the arc plate (31) is slidably engaged with the outer wall of the high-voltage clamp (1), and the resisting rod (34) is hinged in the inner wall of the high-voltage clamp (1); the pulling component (4) comprises a U-shaped pull rod (41), and the bottom end of the U-shaped pull rod (41) passes through the limit assembly (5) and extends to the bottom of the limit assembly (5), and the lower end of the U-shaped pull rod (41) is fixedly connected to the resisting component (6).
2. The electrical equipment safety testing device according to claim 1, characterized in that: The high-voltage pliers (1) comprise a first pliers rod (11) and a second pliers rod (12); the middle ends of the first pliers rod (11) and the second pliers rod (12) are hinged via a rotating shaft (22); and the inner walls of the first pliers rod (11) and the second pliers rod (12) are both provided with movable components (3).
3. The electrical equipment safety testing device according to claim 1, characterized in that: The inner cavity of the extrusion frame (21) is movably connected to the rotating shaft (22), the outer wall of the extrusion frame (21) is fixedly connected to the U-shaped pull rod (41), and the top surface and bottom surface of the extrusion frame (21) are respectively in contact with the first clamp rod (11) and the second clamp rod (12).
4. The electrical equipment safety testing device according to claim 1, characterized in that: A spur gear (33) is fixedly connected to the outer end of the hinge shaft of the support rod (34) and the first clamp rod (11), an arc-shaped toothed plate (32) is fixedly connected to one end of the arc plate (31) close to the support rod (34), and the spur gear (33) is meshingly connected to the arc-shaped toothed plate (32).
5. The electrical equipment safety testing device according to claim 4, characterized in that: One end of the two abutting rods (34) is provided with mutually staggered notches, and the two abutting rods (34) are both made of rubber.
6. The electrical equipment safety testing device according to claim 1, characterized in that: The outer wall of the U-shaped pull rod (41) is smooth and made of rubber material. The outer wall of the upper end of the U-shaped pull rod (41) is sleeved with a first spring (42). The top of the first spring (42) is fixedly connected to the limit assembly (5), and the bottom of the first spring (42) is fixedly connected to one side of the outer wall of the U-shaped pull rod (41).
7. The electrical equipment safety testing device according to claim 1, characterized in that: The limiting assembly (5) comprises a limiting frame (51), the limiting frame (51) being sleeved on the outer walls of the first clamp rod (11) and the second clamp rod (12), and movable cavities (54) for enabling the first clamp rod (11) and the second clamp rod (12) to move are provided on both sides of the inner cavity of the limiting frame (51), and first limiting grooves (52) for limiting the movement of the first clamp rod (11) and the second clamp rod (12) are provided on both sides of the inner wall of the movable cavity (54).
8. The electrical equipment safety testing device according to claim 7, characterized in that: A second spring (53) is disposed in the inner cavity of the first limiting groove (52), one end of the second spring (53) is fixedly connected to the inner wall of the first limiting groove (52), and the other end of the second spring (53) is fixedly connected to the first clamp rod (11).
9. The electrical equipment safety testing device according to claim 8, characterized in that: A second limiting groove (7) is provided on both sides of the first clamp rod (11) and the second clamp rod (12), the interior of the second limiting groove (7) is slidably engaged with the arc plate (31), a third spring (8) is placed inside the second limiting groove (7), one end of the third spring (8) is fixedly connected to the inner wall of the second limiting groove (7), and the other end of the third spring (8) is fixedly connected to the arc plate (31).
10. The electrical equipment safety testing device according to claim 1, characterized in that: The abutment assembly (6) comprises an abutment plate (61), the abutment plate (61) being fixedly sleeved on the outer wall of the U-shaped pull rod (41), and rubber pads (62) being installed on both sides of the lower end of the U-shaped pull rod (41), and the outer walls of the two rubber pads (62) are respectively in abutment with the first clamp rod (11) and the second clamp rod (12); The outer shape of the abutment plate (61) is trapezoidal.