Crosslinked polyethylene insulation material impurity full-inspection equipment and system for high-voltage cable and application of crosslinked polyethylene insulation material impurity full-inspection equipment

Abstract

The invention relates to the technical field of material detection, in particular to a cross-linked polyethylene insulation material impurity full-detection device and system for a high-voltage cable and application, the detection device carries out detection based on single-row continuous flowing insulation material particles, and the detection device comprises a near infrared spectrum imaging unit, a visible light imaging unit and an image processor, and identifying black spot impurities and heterochromatic particles. The full-detection system provides a detection channel for installing full-detection equipment and comprises a current limiting pipe body and a camera obscura structure, and reflection spectrum and surface color information are collected in the camera obscura structure; the full-inspection system further comprises a buffer stock bin, a finished product stock bin, a pneumatic sorting module, a cyclone separator, a cooling fluidized bed and a metal separator. Impurity identification reliability is guaranteed through double optical detection, full-process online detection of insulation material impurities can be achieved, limitation of traditional sampling detection is broken through, full-detection coverage of insulation material particles is achieved, the impurity missing detection risk is eliminated, and the strict requirement of an ultrahigh-voltage cable for insulation material cleanliness is fundamentally met.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and in particular to a device, system, and application for full inspection of impurities in cross-linked polyethylene insulation material for high-voltage cables. Background Technology

[0002] In recent years, with the global economic development, the construction of offshore wind power infrastructure, and the increasing demand for electricity and cables due to submarine power transmission, traditional medium and low voltage cables can no longer meet the requirements of high load and long-distance power transmission. Cross-linked polyethylene (XLPE) is widely used as insulation material for high-voltage AC and DC cables due to its excellent electrical, mechanical, and weather-resistant properties. High-voltage AC and DC cables with XLPE insulation are characterized by simple structure and high current carrying capacity, and are widely used in high-voltage power cables.

[0003] Currently, cross-linked polyethylene (XLPE) insulation materials have achieved certain application results in China. However, with the increase in cable operating voltage levels and the growing demand for DC characteristics in submarine cables, the cleanliness requirements for XLPE insulation materials in AC and DC cables are becoming increasingly stringent. Impurities in XLPE insulation materials originate from various stages of production, including raw materials, extrusion granulation, and pipeline transportation. At present, impurity detection in domestic high-voltage polyethylene insulation materials is only at the sampling stage, failing to achieve full-scale impurity testing. This hinders the effective application of high-voltage XLPE insulation materials in ultra-high-voltage cables. Summary of the Invention

[0004] This invention provides a device, system, and application for full inspection of impurities in cross-linked polyethylene insulation material for high-voltage cables, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A comprehensive impurity testing device for cross-linked polyethylene insulation material used in high-voltage cables, based on the detection of a single, continuously flowing stream of insulation particles, including: The near-infrared spectral imaging unit includes a near-infrared light source in the 850nm-1550nm band and a corresponding near-infrared sensor. The near-infrared sensor collects the reflectance spectrum of the surface of the insulating material particles under the illumination of the near-infrared light source. The visible light imaging unit includes a visible light source in the 400nm-700nm band and an industrial high-speed camera. The industrial high-speed camera acquires the surface color information of the insulating material particles under the illumination of the visible light source. The image processor connects the near-infrared spectral imaging unit and the visible light imaging unit, identifies black spot impurities based on the wavelength offset of the reflected spectrum, and identifies discolored particles based on the color difference values ​​of the RGB three channels in the surface color information.

[0006] A comprehensive inspection system for impurities in cross-linked polyethylene insulation material for high-voltage cables, employing the aforementioned comprehensive inspection equipment for cross-linked polyethylene insulation material for high-voltage cables, and providing a detection channel for installing the inspection equipment, the detection channel comprising: The flow-limiting tube has an inlet diameter greater than or equal to three times the diameter of the insulating material particles, an outlet diameter of 1.2-1.5 times the diameter of the insulating material particles, and a linear transition from the inlet to the outlet with a transition length of 3-6 times the diameter of the insulating material particles. The dark box structure, with its inner wall coated with light-absorbing material, provides a detection space for insulating material particles flowing out from the outlet. The flow-limiting tube is fixedly connected to the dark box structure, and the reflection spectrum and surface color information are collected inside the dark box structure.

[0007] Furthermore, the sidewall of the current-limiting tube is integrated with a piezoelectric ceramic vibrator with a vibration frequency of 200-400Hz and an amplitude of 0.5-2mm.

[0008] Furthermore, the surface roughness Ra of the inner body of the current-limiting tube is ≤0.2μm, and the surface resistivity of the coating is 10. 6 -10 8 Ω antistatic coating.

[0009] Furthermore, two piezoelectric ceramic vibrating plates are attached to the outer wall of each of the current limiting tube bodies, and the two piezoelectric ceramic vibrating plates are arranged at an angle of 80°-100° in the circumferential direction of the current limiting tube body; The driving waveforms of the two piezoelectric ceramic vibrators have a phase difference of 80°-100°, and the driving waveforms of the two piezoelectric ceramic vibrators are the same asymmetric sawtooth wave, wherein the rise time of the asymmetric sawtooth wave is shorter than the fall time.

[0010] Furthermore, the rise time of the asymmetric sawtooth wave is ≤0.1ms, and the fall time is 8-12 times the rise time.

[0011] Furthermore, the full inspection system also includes a buffer hopper, a finished product hopper, and a pneumatic sorting module; The buffer hopper distributes the stored insulating material particles to several of the detection channels; The pneumatic sorting module removes the identified black spot impurities and discolored particles with compressed air pulses. The finished product silo receives the insulating material particles that have passed the testing channels.

[0012] Furthermore, the full inspection system also includes a cyclone separator and a cooled fluidized bed; The cooling fluidized bed cools the continuously fed insulating material particles, and the cyclone separator is connected to the cooling fluidized bed to remove dust from the inside of the cooling fluidized bed. The buffer silo stores and distributes insulating material particles from the cooled fluidized bed.

[0013] Furthermore, the full inspection system also includes a metal separator; The metal separator removes metal impurities from the insulating material particles from the cooled fluidized bed; The buffer silo stores and distributes insulating material particles from the metal separator.

[0014] A cable prepared from insulation particles detected by the cross-linked polyethylene insulation impurity inspection system for high-voltage cables as described above.

[0015] The technical solution of this invention can achieve the following technical effects: This invention targets continuously flowing insulating material particles in a single row. It ensures the reliability of impurity identification through dual optical detection, enabling online detection of impurities in the insulating material throughout the entire process. This breaks through the limitations of traditional sampling inspection, achieving full inspection coverage of cross-linked polyethylene insulating material particles, eliminating the risk of missed impurity detection, and fundamentally meeting the stringent requirements of ultra-high voltage cables for the cleanliness of insulating materials. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A framework diagram of a device for fully inspecting impurities in cross-linked polyethylene insulation material for high-voltage cables; Figure 2 This is a partial structural diagram of the detection channel; Figure 3 This is an exploded view of the flow-limiting tube and the dark box structure. Figure 4 A schematic diagram of a system for inspecting impurities in cross-linked polyethylene insulation material for high-voltage cables; Figure 5 A framework diagram of a system for comprehensive impurity testing of cross-linked polyethylene insulation material for high-voltage cables; Figure 6 An optimized framework diagram of a full inspection system for impurities in cross-linked polyethylene insulation material for high-voltage cables; Figure label: 01. Full inspection equipment; 1. Flow-limiting tube; 11. Inlet; 12. Outlet; 2. Dark box structure; 21. Threaded hole; 3. Buffer hopper; 4. Finished product hopper; 5. Pneumatic sorting module; 6. Cyclone separator; 7. Cooling fluidized bed; 8. Metal separator; 9. Packaging system. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] Example 1 like Figure 1 As shown, the cross-linked polyethylene insulation material impurity inspection equipment for high-voltage cables detects impurities based on a single-row continuous flow of insulation material particles, including: The near-infrared spectral imaging unit includes a near-infrared light source in the 850nm-1550nm band and a corresponding near-infrared sensor. Under the illumination of the near-infrared light source, the near-infrared sensor collects the reflection spectrum of the surface of the insulating material particles. In specific implementation, the near-infrared sensor may specifically include a grating beam splitting module and a 256-element InGaAs linear array detector. The visible light imaging unit includes a visible light source in the 400nm-700nm band and an industrial high-speed camera. Under the illumination of the visible light source, the industrial high-speed camera acquires the surface color information of the insulating material particles. The sensor of the industrial high-speed camera can be configured with an RGB three-channel filter array to obtain the color space information of the particle surface in the visible light band. The image processor connects the near-infrared spectral imaging unit and the visible light imaging unit, identifies black spot impurities based on the wavelength offset of the reflectance spectrum, and identifies discolored particles based on the color difference values ​​of the RGB three channels in the surface color information.

[0020] This embodiment targets continuously flowing insulating material particles in a single row. It ensures the reliability of impurity identification through dual optical detection, enabling online detection of impurities in the insulating material throughout the entire process. This breaks through the limitations of traditional sampling inspection, achieving full inspection coverage of cross-linked polyethylene insulating material particles, eliminating the risk of missed impurity detection, and fundamentally meeting the stringent requirements of ultra-high voltage cables for the cleanliness of insulating materials.

[0021] Specifically, by working in conjunction with near-infrared spectroscopy and visible light imaging, near-infrared wavelength shift can capture micron-sized carbonized black spots. The principle is that when carbonized black spots exist on the particle surface, the strong absorption characteristics of carbon elements to light energy will block the material's reflection spectrum, causing the characteristic absorption peak position of the material to shift red or blue. By capturing this shift, subsurface carbonization defects invisible to the naked eye can be identified. RGB color difference values ​​identify discolored particles. The principle is that when dissimilar plastics are mixed into insulating material particles or oxidative degradation occurs, their surface color characteristics change, causing the RGB three-channel reflection intensity combination to deviate from the reference value. By calculating the color difference value, the degree of color deviation can be quantified, and obvious impurities caused by abnormal composition can be accurately separated.

[0022] In this embodiment, the threshold for judging wavelength offset and color difference value can be comprehensively considered based on actual accuracy requirements and empirical values. As an optimized implementation method, it can be identified as black spot impurities when wavelength offset > 50nm, and / or as heterochromatic particles when color difference value > 15.

[0023] Example 2 A comprehensive inspection system for impurities in cross-linked polyethylene insulation material for high-voltage cables is provided, employing the comprehensive inspection equipment for cross-linked polyethylene insulation material for high-voltage cables as described in Example 1. The system includes inspection channels for installing the inspection equipment; several inspection channels can be arranged side-by-side and activated as needed. Figure 2 and 3 As shown, the detection channels include: The flow-limiting tube 1 has an inlet diameter 11 that is greater than or equal to three times the diameter of the insulating material particles, and an outlet diameter 12 that is 1.2-1.5 times the diameter of the insulating material particles. The transition from inlet 11 to outlet 12 is linear, with a transition length of 3-6 times the diameter of the insulating material particles. In this embodiment, the diameter of inlet 11 restricts the free entry of the particle swarm, preventing blockage. The diameter of outlet 12 narrows, forcing particles to pass through in a single file. The linear transition between the two causes the particles to experience a continuous, gradual lateral force. The particle velocity increases at outlet 12, so at this position, subsequent particles will naturally create a gap with preceding particles due to inertia. This gap ensures comprehensive particle detection. The dark box structure 2 has its inner wall coated with light-absorbing material, providing a detection space for insulating material particles flowing out from the outlet 12; the flow-limiting tube 1 is fixedly connected to the dark box structure 2, and the reflection spectrum and surface color information are collected inside the dark box structure 2.

[0024] During implementation, several flow-limiting tubes 1 can be set up. This method can improve detection efficiency, but the distribution density needs to be controlled to ensure that each particle can obtain effective image acquisition and avoid missed detection. The specific distribution method and density can be designed according to the setting method of the near-infrared spectral imaging unit and the visible light imaging unit. In this embodiment, the light-absorbing material can be a nanoporous carbon coating to achieve ambient light isolation, thereby improving the detection sensitivity of near-infrared spectral characteristic peak shift and the signal-to-noise ratio of visible light imaging.

[0025] See details Figure 3 To ensure convenient installation of the flow-limiting tube 1 relative to the dark box structure 2, a threaded hole 21 can be opened on the dark box structure 2, and a threaded section can be set at the outlet 12 of the flow-limiting tube 1. The flow-limiting tube 1 can be quickly installed and replaced relative to the dark box structure 2 by connecting the threaded section with the threaded hole 21. The inner wall of the threaded section is cylindrical and the diameter is the same as the diameter of the outlet 12.

[0026] For the inlet 11 of the flow-limiting tube 1, it can be connected to the feeding part through a structure such as a tube or a box to ensure continuous and stable feeding.

[0027] As a preferred embodiment, the sidewall of the current limiting tube 1 integrates a piezoelectric ceramic vibrator with a vibration frequency of 200-400Hz and an amplitude of 0.5-2mm.

[0028] By integrating a piezoelectric ceramic vibrator, the problem of particle adhesion in insulating materials can be solved with precise micro-amplitude, ensuring that particles flow independently. The transverse velocity component generated by the vibration creates gaps between particles within the flow-limiting tube 1, providing a stable single-particle imaging environment for subsequent optical detection and avoiding missed detections due to stacking. In addition, the transverse velocity component also allows particles to obtain a larger particle spacing after flowing out of the flow-limiting tube 1.

[0029] In this preferred embodiment, the vibration frequency is chosen to achieve an effective lateral particle separation velocity, preventing gap control failure, and also to avoid mechanical resonance, thus reducing fatigue damage to the tube structure. Regarding the amplitude, it is necessary to avoid excessive particle collision energy, which could cause surface micro-scratches.

[0030] In this embodiment, the piezoelectric ceramic vibrator integrated on the side wall of the current limiting tube 1 can be specifically achieved by attaching a piezoelectric ceramic sheet to the outer wall of the current limiting tube 1, bonding it with conductive silver glue, and covering it with a polyimide film after curing.

[0031] As a preferred embodiment of the above embodiment, the surface roughness Ra of the inner surface of the current-limiting tube 1 is ≤0.2μm, and the surface resistivity of the coating is 10. 6 -10 8An Ω-sized antistatic coating. In this preferred embodiment, the smooth surface eliminates microscopic mechanical anchor points, reducing the interaction force between the insulating particles and the tube wall. Combined with piezoelectric vibration energy, it can completely peel off contact particles, achieving zero mechanical embedding flow; electrostatic elimination allows vibration energy to be completely converted into particle kinetic energy, improving vibration transmission efficiency. The antistatic coating can specifically be a carbon nanotube composite coating.

[0032] To further ensure the accuracy of the final full inspection, as a preferred embodiment of the above embodiment, two piezoelectric ceramic vibrating plates are attached to the outer wall of each flow-limiting tube 1. The two piezoelectric ceramic vibrating plates are set at an angle of 80°-100° in the circumferential direction of the flow-limiting tube 1. The driving waveforms of the two piezoelectric ceramic vibrating plates have a phase difference of 80°-100°, and the driving waveforms of the two piezoelectric ceramic vibrating plates are the same asymmetric sawtooth wave, with the rise time of the asymmetric sawtooth wave being shorter than the fall time.

[0033] In this preferred embodiment, the rise time of the asymmetric sawtooth wave can be further optimized to ≤0.1ms, and the fall time is 8-12 times the rise time.

[0034] In this preferred embodiment, each piezoelectric ceramic vibrator is driven by an asymmetric sawtooth wave, and the driving waveforms of the two vibrators maintain a phase difference of 80°-100°, which can induce the spin motion of completely separated insulating particles. Specifically, for each independent piezoelectric ceramic vibrator, the rapid rise of the sawtooth wave can instantly bounce away the adhered insulating particles, solving the adhesion problem. The slow return under asymmetry can avoid strong rebound collisions and protect the surface of the insulating particles. Through the control strategy of coordinating the working timing of the two vibrators by the phase difference, taking a phase difference of 90° and using piezoelectric ceramic vibrator A and piezoelectric ceramic vibrator B respectively as an example, the start-up time of piezoelectric ceramic vibrator B is delayed by 1 / 4 cycle compared with piezoelectric ceramic vibrator A. In this embodiment, the specific setting of the two at a 90° angle is taken as an example, which can make the insulating particles generate axial spin motion, ensuring that the optical system captures the full surface morphology of the particles.

[0035] Example 3 Based on Embodiment 2 above, to obtain a more complete automated full inspection system, the full inspection system in this embodiment also includes a buffer hopper 3, a finished product hopper 4, and a pneumatic sorting module 5; such as Figure 4 and 5 As shown, The buffer silo 3 distributes the stored insulating material particles to several detection channels; The pneumatic sorting module 5 uses compressed air pulses to remove identified black spot impurities and discolored particles. Finished product silo 4 receives qualified insulating material particles from each testing channel.

[0036] In this embodiment, after the identification of black spot impurities and discolored particles is completed, the response time of the pneumatic sorting module 5 can be controlled to ≤5ms. While ensuring the accuracy of impurity removal, it adapts to the speed of industrial production lines and avoids production interruptions due to the detection process. In this embodiment, the pneumatic sorting module 5 can be equipped with corresponding pipelines for each independent detection channel. When multiple continuous flow bundles of insulating material particles are formed due to the installation of several flow-limiting tubes 1 on the dark box structure 2, several air jets that do not interfere with each other are set accordingly. Each air jet can be supplied with air through a pipeline connected to the detection channel. The angle of the air jet can be flexibly adjusted to correspond to different bundles of insulating material particles.

[0037] In this embodiment, the insulating material particles stored in the buffer silo 3 need to be maintained in a set state. Specifically, the content of various impurities needs to be controlled within a set range to avoid affecting subsequent processes. As an optimization method for the production line, the cross-linked polyethylene insulation material impurity full inspection system for high-voltage cables in Embodiment 3 has been further optimized and applied.

[0038] like Figure 6 As shown, the full inspection system can be further optimized by including a cyclone separator 6 and a cooling fluidized bed 7; the cooling fluidized bed 7 cools the continuously fed insulating material particles, the cyclone separator 6 is connected to the cooling fluidized bed 7 to remove dust inside the cooling fluidized bed 7; the buffer silo 3 stores and distributes the insulating material particles from the cooling fluidized bed 7.

[0039] For better testing results, the full inspection system also includes a metal separator 8; the metal separator 8 removes metal impurities from the insulating material particles from the cooled fluidized bed 7; and the buffer silo 3 stores and distributes the insulating material particles from the metal separator 8.

[0040] In this embodiment, the buffer silo 3 is connected to the continuously fed cooling fluidized bed 7, and the equipment system obtains a continuous production state. Compared with the buffer silo 3 only serving as an intermediate silo and not participating in continuous production, the efficiency improvement brought about by automation is obvious.

[0041] This embodiment provides a more intelligent production line system. Specifically, the cross-linked polyethylene insulation material after absorption can enter a cooling fluidized bed 7 equipped with a cyclone separator 6 via a rotary valve. The rotary valve can precisely control the amount of insulation material particles fed. The insulation particles are cooled in the cooling fluidized bed 7, for example, the particle temperature can be specifically controlled to 40-50°C. During the continuous fluidization and cooling process, the cyclone separator 6 removes powder or debris generated by friction between particles and pipes or between particles. After fluidization cooling and dust removal, the insulation particles are then detected and removed by a metal separator 8 to remove metal impurities. Through the above process, the online impurity detection system can achieve more accurate detection results.

[0042] The cyclone separator 6, the cooling fluidized bed 7, and the metal separator 8 used in this embodiment can be selected from existing equipment structures, which will not be elaborated here.

[0043] The insulating material particles flowing out of the finished product silo 4 can be transferred to the packaging system 9 for packaging. To further ensure the quality of the insulating material particles, the insulating material particles flowing out of the finished product silo 4 can be removed from the metal by the metal separator 8 before packaging, and can also be sampled again by the full inspection equipment 01.

[0044] In the specific implementation process, the image processor can be connected to the position tracking engine. Based on the fixed distance from the detection window to the nozzle, the real-time flow rate of the insulating material particles, and the inherent system delay, including the image processing delay and the air path response delay, the trigger delay time of the pneumatic sorting module 5 is calculated. The solenoid valve driver receives the delay signal and triggers the injection of compressed air. The rejected particles can be specifically deflected to the impurity collection chamber under the action of the airflow.

[0045] After the particles detach from the current-limiting tube 1, their motion state transforms into free fall motion dominated by the initial velocity. Preferably, the detection window is positioned at a distance of 50 mm or more from the outlet of the current-limiting tube 1 to ensure that the residual vibration amplitude decays to within the detection error range. As an alternative, the position tracking engine can calculate the delay time based on the uniform motion model of the particles. When the distance between the insulating material particles is sufficient and the distance from the detection window to the outlet 12 of the current-limiting tube 1 is within the set range, the uniform motion model can achieve simpler calculations.

[0046] Example 4 A cable is prepared from insulation particles detected by the cross-linked polyethylene insulation impurity inspection system for high-voltage cables as described in Example 2 or Example 3.

[0047] The technical effects achieved in this embodiment are the same as those in the above embodiments, and will not be repeated here.

[0048] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A device for detecting all impurities in a crosslinked polyethylene insulating material for high voltage cables, characterized in that, The application discloses a full-inspection system for insulation material particles based on single-column continuous flow, and relates to the technical field of full-inspection systems. The full-inspection system comprises a near-infrared spectrum imaging unit, a visible light imaging unit and an image processor. The near-infrared spectrum imaging unit comprises an 850nm-1550nm waveband near-infrared light source and a corresponding near-infrared sensor. The visible light imaging unit comprises a 400nm-700nm waveband visible light source and an industrial high-speed camera.

2. A system for detecting all impurities in crosslinked polyethylene insulation material for high voltage cables, using the crosslinked polyethylene insulation material impurity detection apparatus for high voltage cables according to claim 1, characterized in that, The image processor is connected to the near-infrared spectrum imaging unit and the visible light imaging unit. The image processor identifies black point impurities based on wavelength shift of the reflection spectrum and identifies color-irregular particles based on color difference values of RGB three channels in the surface color information. The full-inspection system further comprises a detection channel for installing the full-inspection device. The detection channel comprises a flow-limiting pipe body, a dark box structure and a flow-limiting pipe body.

3. The crosslinked polyethylene insulation compound impurity detection system for high voltage cables according to claim 2, characterized in that, The flow-limiting pipe body has an inlet diameter greater than or equal to three times the diameter of the insulation material particles and an outlet diameter of 1.2-1.5 times the diameter of the insulation material particles.

4. The crosslinked polyethylene insulation for high voltage cables impurities detection system according to claim 2, characterized in that, The flow restriction tube inner surface roughness Ra≤0.2μm, and the coated surface resistance is 10 6 -10 8 Ω of the antistatic coating.

5. The crosslinked polyethylene insulation for high voltage cables impurities detection system according to claim 3, characterized in that, The dark box structure has an inner wall coated with light-absorbing material to provide a detection space for the insulation material particles flowing out of the outlet. The reflection spectrum and the surface color information are collected in the dark box structure.

6. The system for detecting impurities in crosslinked polyethylene insulation for high voltage cables according to claim 5, characterized in that, The flow-limiting pipe body is fixedly connected to the dark box structure.

7. The system for detecting all impurities in the crosslinked polyethylene insulation material for high voltage cables according to claim 2, characterized by, The flow-limiting pipe body is provided with a piezoelectric ceramic vibrator integrated on the side wall. The vibration frequency of the piezoelectric ceramic vibrator is 200-400Hz and the amplitude is 0.5-2mm. Each flow-limiting pipe body is provided with two piezoelectric ceramic vibration pieces attached to the outer wall. The two piezoelectric ceramic vibration pieces are arranged at an angle of 80°-100° in the circumferential direction of the flow-limiting pipe body.

8. The system for detecting impurities in crosslinked polyethylene insulation for high voltage cables according to claim 7, characterized in that, The driving waveforms of the two piezoelectric ceramic vibration pieces have a phase difference of 80°-100°. The driving waveforms of the two piezoelectric ceramic vibration pieces are asymmetric sawtooth waves. The rising time of the asymmetric sawtooth wave is less than 0.1ms and the falling time is 8-12 times the rising time.

9. The system for detecting impurities in crosslinked polyethylene insulation for high voltage cables according to claim 8, characterized in that, The full-inspection system further comprises a buffer bin, a finished product bin and a pneumatic sorting module. The buffer bin distributes the stored insulation material particles to the detection channels. The pneumatic sorting module removes the identified black point impurities and color-irregular particles by compressed air pulses. The finished product bin receives the qualified insulation material particles from the detection channels. The full-inspection system further comprises a cyclone separator and a cooling fluidized bed. The cooling fluidized bed cools the continuously supplied insulation material particles. The cyclone separator is connected to the cooling fluidized bed to remove dust in the cooling fluidized bed. The buffer bin stores and distributes the insulation material particles from the cooling fluidized bed. The full-inspection system further comprises a metal separator. The metal separator removes metal impurities from the insulation material particles from the cooling fluidized bed. The buffer bin stores and distributes the insulation material particles from the metal separator.

10. A cable prepared from the insulation particles detected by the system for detecting impurities in crosslinked polyethylene insulation for high voltage cables according to any one of claims 2-9.

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