Real-time monitoring device for electrical equipment partial discharge detection equipment

Abstract

The invention relates to the technical field of electrical equipment partial discharge detection, in particular to a real-time monitoring device for electrical equipment partial discharge detection equipment, which comprises a cabinet body, a door body is hinged to the cabinet body, a control panel is fixedly mounted on one side surface, far away from the cabinet body, of the door body, and an audible and visual alarm is fixedly mounted at the top of the cabinet body. The cabinet comprises a cabinet body and a contact leakage electricity-detecting structure installed in the cabinet body, the contact leakage electricity-detecting structure comprises an outer frame body installed in the cabinet body in a sliding mode, the outer frame body is connected with a reversing bearing part, and the reversing bearing part is connected with a plurality of groups of leakage electricity-detecting mechanisms. Through cooperation of the contact electricity leakage detection structure and the guide limiting structure, contact type electric leakage monitoring is carried out on an electric appliance installed in the cabinet body, the electricity leakage detection mechanism is prevented from pressing a switch of the electric appliance, and meanwhile, personnel can conveniently carry out disassembly and maintenance operation on the electricity leakage detection mechanism.

Description

Technical Field

[0001] The invention relates to the technical field of partial discharge detection of electrical equipment, in particular to a real-time monitoring device for partial discharge detection of electrical equipment. Background Art

[0002] Electrical equipment is a general term for generators, transformers, power lines, circuit breakers and other equipment in the power system. The important role that electricity plays in our lives and production cannot be ignored. It brings us great convenience and becomes an important energy source in our production and life. The most critical factor that enables the normal operation and transmission of electricity in power plants is electrical equipment.

[0003] During daily use, as the equipment ages, electrical equipment will age and be damaged. At this time, some lines or components of the electrical equipment will age and be damaged, causing partial discharge of the electrical equipment. At this time, if people directly touch the electrical equipment, they are likely to be injured by the current, causing safety hazards. Therefore, a real-time monitoring device for partial discharge detection equipment of electrical equipment is needed to monitor leakage of electrical appliances. Summary of the invention

[0004] The object of the present invention is to provide a real-time monitoring device for partial discharge detection equipment of electrical equipment to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A real-time monitoring device for partial discharge detection equipment of electrical equipment comprises a cabinet, a door body is hingedly connected to the cabinet, a control panel is fixedly installed on one side of the door body away from the cabinet, an audible and visual alarm is fixedly installed on the top of the cabinet, and further comprises:

[0007] A contact leakage detection structure installed in a cabinet, the contact leakage detection structure includes an outer frame slidably installed in the cabinet, the outer frame is connected to a reversing bearing part, the reversing bearing part is connected to multiple groups of leakage detection mechanisms, the leakage detection mechanism includes a locking connection part connected to the reversing bearing part, the locking connection part is fixedly connected to two groups of butt joints, the two groups of butt joints are fixedly connected to each other, the butt joints are fixedly connected to a guide block, the guide block is slidably connected to a slide bar, the slide bar is fixedly connected to a trapezoidal block, the trapezoidal block is slidably installed in the butt joint, a first spring is installed between the trapezoidal block and the guide block, the two groups of butt joints are commonly connected to a group of shells, the shells are slidably connected to a linkage frame, the linkage frame Both ends of the moving frame are fixedly installed with a step rod, the step rod is slidably connected to the shell, the step rod is fixedly connected to a second spring, the second spring is fixedly connected to the shell, the step rod is coaxially fixedly connected to a connecting rod, the connecting rod is fixedly connected to a hemispherical head, a double-bevel roller is slidably installed on the connecting rod, two groups of annular bevels are symmetrically arranged on the double-bevel roller, an inner groove matched with the annular bevel is arranged on the side of the hemispherical head close to the double-bevel roller, the hemispherical head is movably connected to the trapezoidal block, the shell is fixedly connected to a fixed frame, the fixed frame is fixedly connected to multiple groups of elastic telescopic frames, and the moving ends of the multiple groups of elastic telescopic frames are commonly fixedly connected to current sensors;

[0008] A guide and limit structure connected to the cabinet body, wherein the guide and limit structure is connected to the outer frame body.

[0009] As a further improvement scheme of the present invention: the reversing bearing part includes a longitudinal frame fixedly connected to the outer frame, the longitudinal frame is slidably connected to a sleeve frame, the sleeve frame is movably connected to two groups of first support rods, the two groups of first support rods are commonly fixedly connected to an inner frame, the inner frame is rotatably connected to the longitudinal frame, the inner frame is rotatably connected to the outer frame, the inner frame is fixedly connected to a plurality of groups of horizontal plates arranged along the longitudinal direction, and the locking connection part is connected to the horizontal plates.

[0010] As a further improvement of the present invention: the locking connection portion includes two groups of recessed frames connected to the transverse plate, the two groups of recessed frames are fixedly connected to two groups of butt joints, the recessed frames are slidably connected to friction plates, the friction frames abut against the transverse plate, the recessed frames are threadedly connected to multiple groups of threaded parts, the threaded parts abut against the friction plates, and one group of recessed frames is fixedly connected to one group of butt joints.

[0011] As a further improvement scheme of the present invention: the guide and limiting structure includes an active telescopic rod fixedly connected to the cabinet body, the movable end of the active telescopic rod extends into the outer frame, the cabinet body is fixedly connected to an L-shaped frame, the L-shaped frame is provided with a straight groove, the L-shaped frame is slidably connected to a J-shaped groove, a group of second support rods are slidably installed in the straight groove and the J-shaped groove, and the two groups of second support rods are fixedly installed on the top of the outer frame.

[0012] As a further improvement of the present invention: an inner cavity adapted to the hemispherical head is provided in the docking joint, and a plurality of groups of ventilation holes are provided in the docking joint.

[0013] As a further improvement of the present invention: the door body is hinged with a fastener, the fastener is provided with an arc groove, and the cabinet body is fixedly connected with a protruding shaft matching the arc groove.

[0014] As a further improvement of the present invention: an electromagnet is fixedly mounted on the top of the longitudinal frame, and the sleeve frame has ferromagnetism.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] When in use, the electrical appliance is installed in the cabinet, and then multiple sets of locking connections are installed on the reversing bearing part according to the distribution of the electrical appliances, and then the shell is docked with the two sets of docking joints, so that the extruded trapezoidal block of the hemispherical head moved into the docking joint, the slide rod and the guide block slide relatively, and then under the push of the first spring on the trapezoidal block, the trapezoidal block is pressed on the step rod and the trapezoidal block abuts against the annular end face of the hemispherical head to limit the movement of the hemispherical head. Since the shell is connected to an elastic telescopic frame through a fixed frame, and the elastic telescopic frame is connected to a current sensor, the installation of the current sensor is completed at this time. As the outer frame moves toward the electrical appliance and the reversing bearing part rotates toward the electrical appliance, the current sensor is pressed against the surface of the electrical appliance. During this period, the elastic telescopic frame is compressed, and the guide limit structure limits the movement of the outer frame. When the current sensor senses that the electrical appliance has a leakage, the control panel controls the sound and light alarm to sound an alarm, and the current sensor needs to be disassembled for During maintenance, the guide limit structure releases the limit on the outer frame and provides a moving guide for the moving outer frame, and then the reversing bearing part drives the locking connection part installed on the reversing bearing part to rotate, so that the current sensor faces the personnel. At this time, the personnel manually presses the linkage frame, and the linkage frame drives the step rod to compress the second spring, and the step rod drives the connecting rod to move toward the docking head. At this time, the step rod presses the double-bevel roller block, and under the extrusion of the annular bevel on the double-bevel roller block, the trapezoidal block is pressed, and as the personnel releases the linkage frame, the second spring presses the step rod to reset, and the step rod drives the hemispherical head to move toward the shell through the connecting rod. At this time, under the top movement of the trapezoidal block on the double-bevel roller, the double-bevel roller is stuck in the inner groove, and then under the extrusion of a group of annular bevels on the trapezoidal block, the trapezoidal block compresses the first spring and the trapezoidal block slides across the surface of the annular bevel and the hemispherical head, so as to separate the docking head from the shell and remove the current sensor. The present invention cooperates with the contact leakage detection structure and the guide limit structure to perform contact leakage monitoring on the electrical appliance installed in the cabinet, and avoids the leakage detection mechanism from pressing on the switch of the electrical appliance, while facilitating personnel to disassemble and maintain the leakage detection mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0018] Figure 2 A schematic diagram of a three-dimensional structure from another viewing angle of the present invention;

[0019] Figure 3 It is a schematic diagram of the three-dimensional structure of the outer frame, the reversing bearing part and the leakage detection mechanism of the present invention;

[0020] Figure 4 It is a three-dimensional structural schematic diagram of another perspective of the outer frame, the reversing bearing part, and the leakage detection mechanism of the present invention cooperating with each other;

[0021] Figure 5 It is a schematic diagram of the three-dimensional structure of the leakage detection mechanism of the present invention cooperating with the horizontal plate;

[0022] Figure 6 It is a structural schematic diagram of the cooperation between the leakage detection mechanism and the horizontal plate of the present invention;

[0023] Figure 7 It is a schematic diagram of the three-dimensional structure of the inner concave frame, the friction plate and the threaded member cooperating with each other in the present invention;

[0024] Figure 8 It is a partial structural schematic diagram of the leakage detection mechanism of the present invention;

[0025] Fig. 9 It is a partial three-dimensional structural schematic diagram of the leakage detection mechanism of the present invention;

[0026] Fig.10 It is a schematic diagram of a three-dimensional structure in which the outer frame, the reversing bearing part, and the guide and limiting structure cooperate with each other in the present invention;

[0027] Fig.11 It is a schematic diagram of the internal three-dimensional structure of the sleeve frame and the first support rod of the present invention.

[0028] In the figure: 1, cabinet; 2, door; 3, electromagnet; 4, control panel; 5, sound and light alarm; 6, contact leakage detection structure; 7, outer frame; 8, reversing bearing part; 9, leakage detection mechanism; 10, locking connection part; 11, vent hole; 12, docking joint; 13, guide block; 14, slide bar; 15, trapezoidal block; 16, housing; 17, linkage frame; 18, step rod; 19, connecting rod; 20, hemispherical head; 21, double inclined roller block; 2 2. Annular inclined surface; 23. Inner groove; 24. Fixed frame; 25. Elastic telescopic frame; 26. Current sensor; 27. Guide limit structure; 28. Longitudinal frame; 29. ​​Sleeve frame; 30. First support rod; 31. Inner frame; 32. Transverse plate; 33. Inner recessed frame; 34. Friction plate; 35. Threaded part; 36. Active telescopic rod; 37. L-shaped frame; 38. Straight groove; 39. J-shaped groove; 40. Second support rod; 41. Fastener; 42. Protruding shaft. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below in conjunction with specific implementation methods.

[0030] Example 1, see Figures 1 to 11 As shown, a real-time monitoring device for partial discharge detection equipment of electrical equipment includes a cabinet 1, the cabinet 1 is hinged with a door 2, a control panel 4 is fixedly installed on a side surface of the door 2 away from the cabinet 1, and an audible and visual alarm 5 is fixedly installed on the top of the cabinet 1, and also includes:

[0031] A contact leakage detection structure 6 installed in the cabinet 1, the contact leakage detection structure 6 includes an outer frame 7 slidably installed in the cabinet 1, the outer frame 7 is connected to a reversing bearing part 8, the reversing bearing part 8 is connected to multiple groups of leakage detection mechanisms 9, the leakage detection mechanism 9 includes a locking connection part 10 connected to the reversing bearing part 8, one group of locking connection parts 10 is fixedly connected to two groups of docking joints 12, the two groups of docking joints 12 are fixedly connected to each other, the docking joints 12 are fixedly connected to a guide block 13, the guide block 13 is slidably connected to a slide bar 14, the slide bar 14 is fixedly connected to a trapezoidal block 15, the trapezoidal block 15 is slidably installed in the docking joint 12, a first spring is installed between the trapezoidal block 15 and the guide block 13, the two groups of docking joints 12 are commonly connected to a group of shells 16, the shells 16 are slidably connected to a linkage frame 17, the linkage frame Both ends of 17 are fixedly installed with a step rod 18, the step rod 18 is slidably connected to the housing 16, the step rod 18 is fixedly connected to a second spring, the second spring is fixedly connected to the housing 16, the step rod 18 is coaxially fixedly connected to a connecting rod 19, the connecting rod 19 is fixedly connected to a hemispherical head 20, a double-bevel roller 21 is slidably installed on the connecting rod 19, two groups of annular bevels 22 are symmetrically arranged on the double-bevel roller 21, an inner groove 23 adapted to the annular bevel 22 is arranged on the side of the hemispherical head 20 close to the double-bevel roller 21, the hemispherical head 20 is movably connected to the trapezoidal block 15, the housing 16 is fixedly connected to a fixing frame 24, the fixing frame 24 is fixedly connected to a plurality of groups of elastic telescopic frames 25, and the moving ends of the plurality of groups of the elastic telescopic frames 25 are commonly fixedly connected to a current sensor 26;

[0032] A guide and limit structure 27 connected to the cabinet 1 , wherein the guide and limit structure 27 is connected to the outer frame 7 .

[0033] When in use, the electrical appliance is installed in the cabinet 1, and then multiple sets of locking connection parts 10 are installed on the reversing bearing part 8 according to the distribution of the electrical appliances, and then the housing 16 is docked with the two sets of docking joints 12, so that the hemispherical head 20 that moves into the docking joint 12 squeezes the trapezoidal block 15, the slide bar 14 and the guide block 13 slide relative to each other, and then under the push of the first spring on the trapezoidal block 15, the trapezoidal block 15 is pressed on the step rod 18 and the trapezoidal block 15 abuts against the annular end face of the hemispherical head 20 to limit the movement of the hemispherical head 20. 24 is connected to an elastic telescopic frame 25, and the elastic telescopic frame 25 is connected to a current sensor 26. At this time, the installation of the current sensor 26 is completed. As the outer frame 7 moves toward the electrical appliance and the reversing bearing portion 8 rotates toward the electrical appliance, the current sensor 26 is pressed against the surface of the electrical appliance. During this period, the elastic telescopic frame 25 is compressed, and the guide limit structure 27 limits the movement of the outer frame 7. When the current sensor 26 senses that the electrical appliance has a leakage, the control panel 4 controls the sound and light alarm 5 to sound an alarm. When the current sensor 26 needs to be disassembled for maintenance, the guide limit structure 27 controls the sound and light alarm 5 to sound an alarm. The structure 27 releases the limit on the outer frame 7 and the guide limit structure 27 provides movement guidance for the moving outer frame 7, and then the reversing bearing part 8 drives the locking connection part 10 installed on the reversing bearing part 8 to rotate, so that the current sensor 26 faces the personnel. At this time, the personnel manually presses the linkage frame 17, and the linkage frame 17 drives the step rod 18 to compress the second spring. The step rod 18 drives the connecting rod 19 to move toward the docking head 12. At this time, the step rod 18 presses the double-bevel roller block 21. Under the extrusion of the annular bevel 22 on the double-bevel roller block 21, the trapezoidal block 1 5 is pressed, and as the personnel release the linkage frame 17, the second spring presses the step rod 18 to reset, and the step rod 18 drives the hemispherical head 20 to move toward the housing 16 through the connecting rod 19. At this time, under the push of the trapezoidal block 15 on the double-bevel roller 21, the double-bevel roller 21 is stuck in the inner groove 23, and then under the pressure of a group of annular bevels 22 on the trapezoidal block 15, the trapezoidal block 15 compresses the first spring and the trapezoidal block 15 passes through the surface of the annular bevel 22 and the hemispherical head 20, which is convenient for separating the joint 12 from the housing 16 to remove the current sensor 26. The present invention performs contact leakage monitoring on the electrical appliances installed in the cabinet 1 through the cooperation of the contact leakage detection structure 6 and the guide limit structure 27, and avoids the leakage detection mechanism 9 from pressing on the switch of the electrical appliances, while facilitating the personnel to disassemble and maintain the leakage detection mechanism 9.

[0034] In one case of the present embodiment, the reversing bearing part 8 includes a longitudinal frame 28 fixedly connected to the outer frame 7, the longitudinal frame 28 is slidably connected to a sleeve frame 29, the sleeve frame 29 is movably connected to two groups of first support rods 30, the two groups of first support rods 30 are commonly fixedly connected to an inner frame 31, the inner frame 31 is rotatably connected to the longitudinal frame 28, the inner frame 31 is rotatably connected to the outer frame 7, the inner frame 31 is fixedly connected to a plurality of groups of transverse plates 32 arranged in the longitudinal direction, and the locking connection part 10 is connected to the transverse plates 32. The sleeve frame 29 is lifted to release the limit of the sleeve frame 29 on the first support rod 30. At this time, the personnel manually rotate the inner frame 31, the inner frame 31 drives the transverse plate 32 to rotate, and the transverse plate 32 drives the leakage detection mechanism 9 to rotate, so that the leakage detection mechanism 9 faces the personnel, and then the housing 16 is disassembled.

[0035] In one case of the present embodiment, the locking connection part 10 includes two groups of inner recessed frames 33 connected to the transverse plate 32, the inner recessed frames 33 are slidably connected with friction plates 34, the two groups of inner recessed frames 33 are fixedly connected to two groups of butt joints 12, the friction plates 34 abut against the transverse plate 32, the inner recessed frames 33 are threadedly connected with multiple groups of threaded members 35, the surface of the threaded members 35 is provided with threads, the threaded members 35 abut against the friction plates 34, and one group of inner recessed frames 33 is fixedly connected to one group of butt joints 12. When in use, the notch of the inner recessed frame 33 is hung on the transverse plate 32 and the relative position of the inner recessed frame 33 and the transverse plate 32 is adjusted, and then the threaded member 35 is manually rotated, and the threaded member 35 presses the friction plate 34 toward the transverse plate 32 to adjust the friction between the friction plate 34 and the transverse plate 32, so that the locking connection part 10 is installed on the transverse plate 32.

[0036] In one case of the present embodiment, the guide and limiting structure 27 includes an active telescopic rod 36 fixedly connected to the cabinet body 1, the movable end of the active telescopic rod 36 extends into the outer frame body 7, the cabinet body 1 is fixedly connected with an L-shaped frame 37, a straight groove 38 is provided on the L-shaped frame 37, the L-shaped frame 37 is slidably connected with a J-shaped groove 39, a group of second support rods 40 are slidably installed in the straight groove 38 and the J-shaped groove 39, and the two groups of second support rods 40 are fixedly installed on the top of the outer frame body 7. As the active telescopic rod 36 contracts, the active telescopic rod 36 and the outer frame 7 are separated from each other to release the limit of the active telescopic rod 36 on the outer frame 7, and then the outer frame 7 is pulled, so that the two groups of second support rods 40 slide along the straight groove 38 and the J-shaped groove 39 respectively, and the second support rod 40 in the straight groove 38 moves to one end in the straight groove 38, and the other group of second support rods 40 rotates into the arc groove section of the J-shaped groove 39, the outer frame 7 rotates, and the outer frame 7 drives the reversing bearing part 8 to rotate, so that personnel can operate the electrical appliances in the cabinet 1.

[0037] In one case of this embodiment, the butt joint 12 is provided with an inner cavity adapted to the hemispherical head 20, and the butt joint 12 is provided with multiple groups of vents 11. The vents 11 are provided to reduce the resistance of the hemispherical head 20 moving in the butt joint 12.

[0038] In one case of this embodiment, the door body 2 is hinged with a fastener 41, and an arc groove is formed on the fastener 41, and a protruding shaft 42 matching the arc groove is fixedly connected to the cabinet body 1. As the fastener 41 rotates and hangs on the protruding shaft 42, the rotation of the door body 2 is restricted, so that the door body 2 covers the opening of the cabinet body 1.

[0039] Embodiment 2, based on embodiment 1, refer to Figure 3 and Fig.10 The top of the longitudinal frame 28 is fixedly provided with an electromagnet 3, and the sleeve frame 29 has ferromagnetism. The sleeve frame 29 is magnetically attracted by the electromagnet 3 so that the sleeve frame 29 rises along the longitudinal frame 28.

[0040] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention.

Claims

1. A real-time monitoring device for partial discharge detection equipment of electrical equipment, comprising a cabinet, a door body hingedly connected to the cabinet, a control panel fixedly mounted on a side of the door body away from the cabinet, and an audible and visual alarm fixedly mounted on the top of the cabinet, characterized in that: Also includes: A contact leakage detection structure installed in a cabinet, the contact leakage detection structure includes an outer frame slidably installed in the cabinet, the outer frame is connected to a reversing bearing part, the reversing bearing part is connected to multiple groups of leakage detection mechanisms, the leakage detection mechanism includes a locking connection part connected to the reversing bearing part, the locking connection part is fixedly connected to two groups of butt joints, the two groups of butt joints are fixedly connected to each other, the butt joints are fixedly connected to a guide block, the guide block is slidably connected to a slide bar, the slide bar is fixedly connected to a trapezoidal block, the trapezoidal block is slidably installed in the butt joint, a first spring is installed between the trapezoidal block and the guide block, the two groups of butt joints are commonly connected to a group of shells, the shells are slidably connected to a linkage frame, the linkage frame Both ends of the moving frame are fixedly installed with a step rod, the step rod is slidably connected to the shell, the step rod is fixedly connected to a second spring, the second spring is fixedly connected to the shell, the step rod is coaxially fixedly connected to a connecting rod, the connecting rod is fixedly connected to a hemispherical head, a double-bevel roller is slidably installed on the connecting rod, two groups of annular bevels are symmetrically arranged on the double-bevel roller, an inner groove matched with the annular bevel is arranged on the side of the hemispherical head close to the double-bevel roller, the hemispherical head is movably connected to the trapezoidal block, the shell is fixedly connected to a fixed frame, the fixed frame is fixedly connected to multiple groups of elastic telescopic frames, and the moving ends of the multiple groups of elastic telescopic frames are commonly fixedly connected to current sensors; A guide and limit structure connected to the cabinet body, wherein the guide and limit structure is connected to the outer frame body.

2. A real-time monitoring device for partial discharge detection equipment of electrical equipment according to claim 1, characterized in that: The reversing bearing part includes a longitudinal frame fixedly connected to the outer frame, the longitudinal frame is slidably connected to a sleeve frame, the sleeve frame is movably connected to two groups of first support rods, the two groups of first support rods are commonly fixedly connected to an inner frame, the inner frame is rotatably connected to the longitudinal frame, the inner frame is rotatably connected to the outer frame, the inner frame is fixedly connected to a plurality of groups of horizontal plates arranged in the longitudinal direction, and the locking connection part is connected to the horizontal plates.

3. A real-time monitoring device for partial discharge detection equipment of electrical equipment according to claim 2, characterized in that: The locking connection part includes two groups of inner recessed frames connected to the transverse plate, the two groups of inner recessed frames are fixedly connected to two groups of butt joints, the inner recessed frames are slidably connected with friction plates, the friction frames abut against the transverse plate, the inner recessed frames are threadedly connected with multiple groups of threaded parts, the threaded parts abut against the friction plates, and one group of inner recessed frames is fixedly connected to one group of butt joints.

4. The real-time monitoring device for partial discharge detection equipment of electrical equipment according to claim 1, characterized in that: The guide and limiting structure includes an active telescopic rod fixedly connected to the cabinet body, the movable end of the active telescopic rod extends into the outer frame body, the cabinet body is fixedly connected to an L-shaped frame, the L-shaped frame is provided with a straight groove, the L-shaped frame is slidably connected to a J-shaped groove, a group of second support rods are slidably installed in the straight groove and the J-shaped groove, and the two groups of second support rods are fixedly installed on the top of the outer frame body.

5. The real-time monitoring device for partial discharge detection equipment of electrical equipment according to claim 1, characterized in that: An inner cavity matched with the hemispherical head is provided in the butt joint, and a plurality of groups of vent holes are provided in the butt joint.

6. A real-time monitoring device for partial discharge detection equipment of electrical equipment according to claim 1, characterized in that: The door body is hinged with a fastener, an arc groove is provided on the fastener, and a protruding shaft matching the arc groove is fixedly connected to the cabinet body.

7. A real-time monitoring device for partial discharge detection equipment of electrical equipment according to claim 2, characterized in that: An electromagnet is fixedly installed on the top of the longitudinal frame, and the sleeve frame has ferromagnetism.

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