阅读说明：本技术 一种嵌入式电缆用空间电荷检测装置及方法 (Space charge detection device and method for embedded cable ) 是由 吴锴 王世杰 陈嘉欣 于 2021-07-26 设计创作，主要内容包括：一种嵌入式电缆用空间电荷检测装置及方法,装置包括接地金属屏蔽盒,接地金属屏蔽盒的内腔当中设置有弹簧,弹簧上方支撑设置声波吸收层,声波吸收层的上表面贴合设置压电薄膜,压电薄膜的上表面贴合设置下电极；下电极与待测电缆接触,通过固定组件将待测电缆进行固定。下电极采用炭黑半导体材料制成,声波吸收层采用有机玻璃制成。固定组件采用绑带。安装方法包括先对待测电缆的表层进行剥离,使其绝缘层露出,并保证被剥离的表层有足够长的距离以防止加压过程中发生沿面放电；再使待测电缆露出的绝缘层与下电极相接触,通过固定组件将待测电缆进行固定。本发明能够对不同厚度和结构的电力电缆进行测量,装置使用方便,易于拆卸和安装。(A space charge detection device and method for an embedded cable comprises a grounding metal shielding box, wherein a spring is arranged in an inner cavity of the grounding metal shielding box, a sound wave absorption layer is supported and arranged above the spring, a piezoelectric film is arranged on the upper surface of the sound wave absorption layer in a pasting mode, and a lower electrode is arranged on the upper surface of the piezoelectric film in a pasting mode; the lower electrode is contacted with the cable to be tested, and the cable to be tested is fixed through the fixing component. The lower electrode is made of carbon black semiconductor material, and the sound wave absorption layer is made of organic glass. The fixing component adopts a binding band. The installation method comprises peeling the surface layer of the cable to be tested to expose the insulating layer, and ensuring that the peeled surface layer has a long enough distance to prevent creeping discharge in the pressurizing process; and then the exposed insulating layer of the cable to be tested is contacted with the lower electrode, and the cable to be tested is fixed through the fixing component. The device can measure the power cables with different thicknesses and structures, is convenient to use and is easy to disassemble and assemble.)

1. The utility model provides an embedded space charge detection device for cable which characterized in that: the piezoelectric acoustic wave sensor comprises a grounding metal shielding box (7), wherein a spring (6) is arranged in the inner cavity of the grounding metal shielding box (7), a sound wave absorption layer (5) is supported above the spring (6), a piezoelectric film (4) is attached to the upper surface of the sound wave absorption layer (5), and a lower electrode (3) is attached to the upper surface of the piezoelectric film (4); the lower electrode (3) is in contact with the cable (1) to be tested, and the cable (1) to be tested is fixed through the fixing component.

2. The space charge detecting device for an embedded cable according to claim 1, wherein: the lower electrode (3) is made of carbon black semiconductor material, and the thickness of the lower electrode (3) is 2mm-3 mm.

3. The space charge detecting device for an embedded cable according to claim 1, wherein: the sound wave absorption layer (5) is made of organic glass.

4. The space charge detecting device for an embedded cable according to claim 1, wherein: the fixing component adopts a binding band (2), the upper surface of the grounding metal shielding box (7) extends to be provided with an outer edge, and a through hole (8) for the binding band (2) to pass through is formed in the outer edge of the grounding metal shielding box (7).

5. The space charge detecting device for an embedded cable according to claim 4, wherein: the grounding metal shielding box (7) is cylindrical, and the outer edge of the upper surface of the grounding metal shielding box is circular; the inner cavity of the grounding metal shielding box (7) is of a cube structure; the diameter of the grounding metal shielding box (7) is 25mm, the height of the grounding metal shielding box is 20mm, the diameter of a circle formed by the outer edge of the grounding metal shielding box is 40mm, and the height of the outer edge is 2 mm.

6. The space charge detecting device for an embedded cable according to claim 1, wherein: the lower electrode (3) is flush with the upper surface of the grounding metal shielding box (7) in an initial state.

7. A method for installing a space charge detecting device for an embedded cable according to any one of claims 1 to 6, comprising the steps of:

stripping the surface layer of the cable (1) to be tested to expose the insulating layer of the cable, and ensuring that the stripped surface layer has a sufficient distance to prevent creeping discharge in the pressurizing process;

the exposed insulating layer of the cable (1) to be tested is contacted with the lower electrode (3), and the cable (1) to be tested is fixed through the fixing component.

8. The mounting method according to claim 7, wherein: and silicone oil is dripped between the exposed insulating layer of the cable (1) to be tested and the lower electrode (3) to improve the contact effect.

9. The mounting method according to claim 7, wherein: and winding an aluminum foil at the measured position of the cable (1) to be measured to form a closed structure together with the grounding metal shielding box (7).

Technical Field

The invention belongs to the field of space charge detection, and particularly relates to a space charge detection device and method for an embedded cable.

Background

Space charge is a description of the phenomenon that an insulating material internally accumulates charges under the action of high field strength, high temperature and the like. The coulomb field formed by these space charges and the applied electric field are superposed, so that the electric field inside the material is seriously distorted, and finally, the insulation damage and the failure are caused. Power cables for power distribution, transmission generally comprise an intermediate core, several insulating layers, semi-conducting layers, and outer protective layers, etc., wherein the operating state of the insulating layers is critical to the overall safety of the cable, while for measurements in which space charge can be measured to determine the state of charge build-up, assess the health of the cable. Therefore, establishing a corresponding space charge detection system suitable for the power cable is of great significance for ensuring safe operation of the cable. The electroacoustic pulse method is a cable space charge detection means which is widely used at present. At present, aluminum plates are generally used as electrodes and clamps and are fastened by screw clamps to ensure the close contact between the cables and the electrodes. The traditional electric pulse method detection device generally comprises 2-4 lead screws, a cable clamp, a lower electrode aluminum plate, a piezoelectric film, an organic glass sound wave absorption layer and a grounding metal shielding box, and the structure of the traditional electric pulse method detection device is shown in figure 1.

The prior art has the following defects and shortcomings: in the prior art, an aluminum plate is used as an electrode and a clamp, and a shielding box is arranged below the aluminum plate. The whole device is huge, the installation and the disassembly are complex, and the flow is complicated in the field actual operation. And the size of the aluminum electrode and the clamp is related to the thickness and the shape of the cable, so that the application range is narrow, and difficulty is brought to the installation and debugging of the system.

Disclosure of Invention

The present invention is directed to solve the above problems in the prior art, and an object of the present invention is to provide a device and a method for detecting space charge for an embedded cable, wherein the device has a small size, is easy to disassemble and assemble, and can measure power cables with different thicknesses and structures.

In order to achieve the purpose, the invention has the following technical scheme:

a space charge detection device for an embedded cable comprises a grounding metal shielding box, wherein a spring is arranged in an inner cavity of the grounding metal shielding box, a sound wave absorption layer is supported and arranged above the spring, a piezoelectric film is attached to the upper surface of the sound wave absorption layer, and a lower electrode is attached to the upper surface of the piezoelectric film; the lower electrode is contacted with the cable to be tested, and the cable to be tested is fixed through the fixing component.

In a preferred embodiment of the space charge detector of the present invention, the bottom electrode is made of a carbon black semiconductor material, and the thickness of the bottom electrode is 2mm to 3 mm.

As a preferable embodiment of the space charge detection apparatus of the present invention, the acoustic wave absorption layer is made of organic glass.

As a preferable scheme of the space charge detection apparatus of the present invention, the fixing component employs a binding band, an outer edge is extended from an upper surface of the grounding metal shielding box, and a through hole for the binding band to pass through is formed on the outer edge of the grounding metal shielding box.

As a preferable embodiment of the space charge detecting device of the present invention, the grounded metal shielding box is cylindrical, and the outer edge of the upper surface of the grounded metal shielding box is formed in a circular shape; the inner cavity of the grounding metal shielding box is of a cubic structure; the diameter of ground connection metal shielding box is 25mm, and is highly 20mm, and the diameter of its outer edge formation circle is 40mm, and the height of outer edge is 2 mm.

As a preferable mode of the space charge detecting device according to the present invention, the lower electrode is flush with the upper surface of the grounded metal shield case in the initial state.

The invention also provides an installation method of the space charge detection device for the embedded cable, which comprises the following steps:

stripping the surface layer of the cable to be tested to expose the insulating layer of the cable, and ensuring that the stripped surface layer has a long enough distance to prevent creeping discharge in the pressurizing process;

the exposed insulating layer of the cable to be tested is contacted with the lower electrode, and the cable to be tested is fixed through the fixing assembly.

As a preferable scheme of the installation method, silicone oil is dripped between the exposed insulating layer of the cable to be tested and the lower electrode to improve the contact effect.

As a preferable scheme of the installation method of the present invention, an aluminum foil is wound around the position where the cable to be measured is measured, so that a closed structure is formed by the aluminum foil and the grounded metal shielding box.

Compared with the prior art, the invention has the following beneficial effects: by using the electroacoustic pulse method, space charges in the insulating material are influenced by the pulse to generate vibration, and vibration sound waves are transmitted to the piezoelectric film through the lower electrode and converted into electric signals. The acoustic wave absorbing layer of the present invention serves to eliminate the effect of multiple reflections. The detection device has simple structure, can measure the power cables with different thicknesses and structures, is very convenient to use, and is easy to disassemble and assemble.

Furthermore, the lower electrode is made of carbon black semiconductor material, and the volume of the measuring device is greatly reduced by changing the material of the electrode and redesigning the structure of the device, so that the measuring device is more portable.

Furthermore, the fixing component adopts the binding belt, the cable to be tested and the grounding metal shielding box are fixed through the fixing component, and compared with the original fixture and screw rod fixing, the fixing component is simpler in installation and disassembly.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments are briefly described below, it should be understood that the following drawings only show some embodiments of the present invention, and it is obvious for those skilled in the art that other related drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a conventional electric pulse method space charge detection device;

FIG. 2 is a schematic structural diagram of a space charge detection device for an embedded cable according to the present invention;

FIG. 3 is a schematic diagram of the upper surface structure of the grounded metal shielding case according to the present invention;

in the drawings: 1-a cable to be tested; 2-binding band; 3-a lower electrode; 4-a piezoelectric film; 5-an acoustic wave absorbing layer; 6-a spring; 7-a grounded metal shield case; 8-through holes.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, those skilled in the art can also obtain other embodiments without creative efforts.

Referring to fig. 2, the space charge detecting apparatus for an embedded cable of the present invention includes a binding band 2, a lower electrode 3, a piezoelectric film 4, an acoustic wave absorbing layer 5, a spring 6, and a grounded metal shield case 7. Wherein, the upper surface of the grounding metal shielding box 7 is provided with four through holes 8 for the binding bands 8 to pass through, and the device of the invention is fixed on the cable 1 to be tested through the binding bands 8.

The invention does not adopt an aluminum plate as an electrode, the aluminum plate is hard and difficult to process, the required thickness is generally more than 20mm, and the volume is increased. The carbon black semiconductor is used as the lower electrode, the carbon black semiconductor is soft and easy to process, the cost is low, and the required thickness is about 2-3 mm. The grounding metal shielding box 7 of the present invention is a hollow metal shielding box, generally made of aluminum, and a spring 6 is arranged in the hollow metal shielding box for transmitting vibration signals. The sound wave absorption layer 5, the piezoelectric film 4 and the lower electrode 3 are sequentially and closely arranged on the upper part. The lower electrode 3 made of carbon black semiconductor, the piezoelectric film 4 and the sound wave absorption layer 5 made of organic glass are all flat plate structures.

Referring to fig. 3, the grounding metal shielding case 7 of the present invention is provided with a through hole 8 on the upper surface thereof for the strap 2 to pass through. The diameter of the through hole 8 is slightly larger than the width of the binding band 2, and the width of the binding band 2 used in the embodiment of the present invention is 4 mm. The cable 1 to be tested is in close contact with the lower electrode 3 by means of the mechanical force of the binding band 2. In the embodiment, the grounding metal shielding box 7 is cylindrical, and the outer edge of the upper surface of the grounding metal shielding box is circular; the inner cavity of the grounding metal shielding box 7 is of a cubic structure; the diameter of the grounding metal shielding box 7 is 25mm, the height thereof is 20mm, the diameter of the circle formed by the outer edge thereof is 40mm, and the height of the outer edge thereof is 2 mm. The location of the through-hole 8 should be between 25-40mm from the centre of the circle, i.e. outside the diameter of the grounded metal shield can 7.

The grounding metal shielding box 7 of the present invention can also be made into other shapes (such as rectangular cross section), and the lower height should be subject to accommodate the lower electrode 3, the piezoelectric film 4, the acoustic wave absorbing layer 5 and the spring 6.

The working principle of the invention is as follows: by using the electroacoustic pulse method, space charges in the insulating material are influenced by the pulse to generate vibration, and vibration sound waves are transmitted to the piezoelectric film 4 through the lower electrode 3, converted into electric signals, amplified by a subsequent amplifier and recorded. The acoustic wave absorbing layer 5 made of organic glass is used to eliminate the effect of multiple reflections.

The invention also provides an installation method of the space charge detection device for the embedded cable, which comprises the following steps:

firstly, the protective layer and the outer shielding layer of the tested cable 1 are stripped to expose the tested insulating layer, and the outer shielding layer is ensured to have enough distance with the cable section so as to prevent creeping discharge in the pressurizing process. And a little silicone oil is dripped between the insulation layer to be tested of the cable 1 to be tested and the lower electrode 3 to improve the contact effect. In order to ensure the grounding of the electrode and enhance the shielding effect, a layer of aluminum foil can be wound on the measured position of the measured cable 1 and is in contact with the grounding metal shielding box 7 to form a closed structure.

The device and the method for detecting the space charge of the embedded cable can be used in the field of measurement of the space charge of the direct current cable with any thickness. By changing the material of the electrode and redesigning the structure of the device, the volume of the detection device is greatly reduced, and the detection device is more portable. Through bandage 2 is fixed, compare original anchor clamps and screw rod fixed, all simpler in installation and dismantlement. The lower electrode 3 adopts a carbon black semiconductor, so that the material consumption is less, the cost is low, and the manufacturing cost is greatly reduced compared with the prior mode.

While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.