Novel preventive power cable and manufacturing method thereof

Abstract

The invention provides a novel preventive power cable and a manufacturing method thereof.The novel preventive power cable comprises a conductor, an insulating layer and a semiconductor electric layer are sequentially arranged on the outer side of the conductor from inside to outside, a drainage wire with conductivity is embedded in the semiconductor electric layer, and a leakage current collector is connected to the tail end of the drainage wire and used for collecting leakage current of the cable in real time; the cable leakage monitoring device can collect the electric leakage condition of the cable in real time, realize real-time diagnosis of the insulation state and life prediction, and judge whether the cable needs to be replaced immediately, so that line damage and greater damage can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a novel preventive power cable and a manufacturing method thereof. Background Art

[0002] Power cables, the core transmission medium for urban and industrial power supply, face leakage problems caused by aging insulation, which has become a major cause of electrical fires and power outages. Traditional cable structures typically employ a three-layer design: conductor, insulation, and shielding. For example, existing double-insulated, ant-proof cables offer some improvements in mechanical protection but lack a built-in mechanism for real-time insulation monitoring. Existing moisture-proof cables, while enhancing environmental adaptability through multiple water-blocking layers, still fail to address the technical bottleneck of online detection of insulation degradation.

[0003] Existing monitoring technologies have three major limitations:

[0004] 1. Offline detection hysteresis: Relying on periodic power outage tests (such as voltage withstand tests), it cannot capture sudden insulation defects;

[0005] 2. External sensor interference: For example, existing technologies use external current transformers, which are susceptible to electromagnetic interference and increase cable volume;

[0006] 3. Rough lifespan assessment: Statistical models based on historical data cannot correlate the quantitative relationship between dynamic changes in leakage current and remaining lifespan.

[0007] While some recent attempts have attempted to add monitoring units outside the shielding layer (such as Xinya Electronics' alternating silicone rubber layer structure), none have achieved in-situ collection of leakage current signals. Furthermore, the twisted metal wire layers used in new energy charging pile cables focus solely on mechanical protection, without exploiting their conductive properties for electrical parameter monitoring.

[0008] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0009] In order to solve technical problems such as the inability of existing technologies to detect cable leakage in real time, the present invention proposes a new type of preventive power cable and its manufacturing method, which can detect cable leakage in real time, realize real-time diagnosis and life prediction of insulation status, and determine whether the cable needs to be replaced immediately, which can effectively avoid line damage and greater harm.

[0010] In order to achieve the above object, the technical solution of the present invention is as follows:

[0011] On the one hand, the present invention provides a new preventive power cable, comprising: a conductor, wherein an insulating layer and a semiconductor layer are sequentially provided on the outside of the conductor from the inside to the outside, a drainage wire with conductive properties is embedded in the semiconductor layer, and the end of the drainage wire is connected to a leakage current collector for real-time collection of the leakage current of the cable.

[0012] The present invention provides a novel preventive power cable and its manufacturing method, which can detect cable leakage in real time, realize real-time diagnosis of insulation status and life prediction, and determine whether the cable needs to be replaced immediately, thus effectively avoiding line damage and greater harm.

[0013] As a preferred technical solution, the drainage wire includes: a copper wire drainage wire, a silver wire drainage wire or a gold wire drainage wire.

[0014] As a preferred technical solution, the diameter of the drain wire is 0.5-1.0 mm, and the volume resistivity of the semiconductor layer is ≤50Ω·cm.

[0015] As a preferred technical solution, the drain wire is directly dragged along the axial direction of the conductor and embedded into the semiconductor layer.

[0016] As a preferred technical solution, the conductor includes: a plurality of annealed oxygen-free flexible copper wires, which are tightly compressed and twisted, and the pitch-to-diameter ratio is 12 to 14 times.

[0017] As a preferred technical solution, an insulating polyester tape layer is provided outside the semiconductor layer. The insulating polyester tape layer comprises a polyester tape. The overlapping rate of the polyester tape wrapped around the outside of the semiconductor layer is 20% to 30%.

[0018] As a preferred technical solution, the annealing current of the annealed oxygen-free flexible copper wire is ≥600A, and nitrogen protection cooling is adopted.

[0019] As an optimal technical solution, it includes: a sheath, which is arranged on the outside of the insulating polyester tape layer.

[0020] As a preferred technical solution, the insulating layer includes a cross-linked polyethylene insulating layer, the semiconductor layer includes a semiconductive polyolefin layer, and the sheath includes a flame-retardant polyvinyl chloride sheath.

[0021] The present invention provides a method for manufacturing a novel preventive power cable, wherein the method comprises the following steps:

[0022] S1 uses multiple annealed oxygen-free flexible copper wires tightly twisted together, with a pitch-to-diameter ratio of 12 to 14 times to form a conductor;

[0023] S2 tightly extrude the cross-linked polyethylene material onto the conductor to form an insulating layer with no visible bubbles or impurities on the cross section;

[0024] S3: Extruding a semiconductor layer from a semi-conductive polyolefin material on the outer surface of the insulating layer, and during the extrusion process, directly dragging and embedding a drain wire along the axial direction of the conductor as a drain wire for collecting leakage current;

[0025] S4 is wrapped with polyester tape at an overlap rate of 20% to 30% to form an insulating polyester tape layer;

[0026] S5 is a flame retardant polyvinyl chloride sheath extruded on the outside of the insulating polyester tape layer to form a sheath with no visible bubbles and impurities on the cross section.

[0027] The present invention provides a novel preventive power cable and a manufacturing method thereof, which have the following beneficial effects:

[0028] 1) The present invention provides a novel preventive power cable and its manufacturing method, which can detect cable leakage in real time, perform real-time diagnosis of insulation status, and determine the service life of the cable and whether it needs to be replaced immediately, thereby effectively preventing line damage and further harm.

[0029] 2) The present invention provides a novel preventive power cable and its manufacturing method. A drain wire embedded in the semiconductor layer directly captures weak leakage currents at defects in the insulation layer, improving sensitivity compared to traditional external sensors. This structure, through the synergistic effect of the drain wire embedded in the semiconductor layer and the insulation layer, ensures stable transmission of microampere-level current to the acquisition terminal, eliminates electromagnetic interference, and improves the accuracy of cable leakage monitoring.

[0030] Based on 70-year lifespan data of high-performance cables, the correlation between leakage current growth rate and insulation failure indicators is analyzed. When the detection value exceeds the safety threshold or a pulse-like mutation occurs, a replacement warning is automatically triggered, facilitating timely cable replacement by staff.

[0031] This solution solves the hysteresis problem of traditional offline detection by embedding drainage wires in the semiconductor layer, and can detect signs of insulation layer degradation and leakage earlier than conventional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a novel preventive power cable provided by the present invention;

[0033] Among them, 1-conductor; 2-insulating layer; 3-semiconductor layer; 4-drain wire; 5-sheath. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the present invention provides a new preventive power cable, comprising: a conductor 1, wherein the outer side of the conductor 1 is provided with an insulating layer 2 and a semiconductor layer 3 from the inside to the outside, a drainage wire 4 with conductive properties is embedded in the semiconductor layer 3, and the end of the drainage wire 4 is connected to a leakage current collector (not shown) for real-time collection of the leakage current of the cable.

[0036] The present invention provides a novel preventive power cable and its manufacturing method, which can detect cable leakage in real time, realize real-time diagnosis of insulation status, determine the service life of the cable and whether the cable needs to be replaced immediately, thus effectively avoiding line damage and greater harm.

[0037] The drain wire 4 embedded in the semiconductor layer 3 directly captures the weak leakage current at the defects of the insulating layer 2, which has improved sensitivity compared to traditional external sensors. This structure ensures the stable transmission of microampere-level current to the acquisition terminal through the synergistic effect of the drain wire 4 embedded in the semiconductor layer 3 and the insulating layer 2, eliminating electromagnetic interference and improving the accuracy of cable leakage monitoring.

[0038] Based on 70-year lifespan data of high-performance cables, the correlation between leakage current growth rate and insulation layer 2 failure index is analyzed. When the detection value exceeds the safety threshold or a pulse-like mutation occurs, a replacement warning is automatically triggered.

[0039] This solution solves the hysteresis problem of traditional offline detection by embedding the drain wire 4 in the semiconductor layer 3, and can detect signs of deterioration and leakage of the insulating layer 2 earlier than conventional methods.

[0040] Preferably, the drainage wire 4 includes: a copper wire drainage wire, a silver wire drainage wire or a gold wire drainage wire;

[0041] Copper wire drain wires are suitable for leakage current signal transmission in conventional environments due to their high cost-effectiveness and good conductivity (conductivity of approximately 58MS / m). Their tensile strength meets the mechanical stress requirements of cables.

[0042] Silver wire drain wires, due to their higher conductivity (conductivity of approximately 63MS / m), can capture weak leakage currents at the microampere level and are particularly suitable for high-precision insulation defect detection scenarios.

[0043] The gold wire drain wire maintains stable conductivity in extremely corrosive environments through its inert metal properties, avoiding signal attenuation caused by oxidation;

[0044] The three types of drainage wires are integrated with the semiconductor layer 3 to form an equipotential shielding layer, eliminating electromagnetic interference generated during cable operation and ensuring the purity of the collected signal.

[0045] Preferably, the diameter of the drain wire 4 is 0.5 to 1.0 mm, the volume resistivity of the semiconductor layer 3 is ≤ 50 Ω·cm, the diameter of the drain wire 4 is preferably 0.5 mm, 0.52 mm, 0.8 mm and 1.0 mm. Due to space limitations and for simplicity, the present invention no longer exhaustively lists the specific point values included in the range. The volume resistivity of the semiconductor layer 3 is preferably 50 Ω·cm, 40 Ω·cm, 30 Ω·cm, 20 Ω·cm and 10 Ω·cm. Due to space limitations and for simplicity, the present invention no longer exhaustively lists the specific point values included in the range. For the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range. The diameter of the drainage wire 4 is 0.5-1.0 mm. The diameter range of 0.5-1.0 mm balances conductivity and space occupancy, ensuring effective transmission of microampere leakage current (silver wire drainage wire can transmit as low as 10 μA signal at 1.0 mm) and avoiding deformation of the cable structure due to excessive wire diameter; the tensile strength of the copper wire drainage wire can reach 300 MPa at a diameter of 0.8 mm, matching the bending stress (GB 50217-2018 standard corresponding to the minimum bending radius parameter); by optimizing the diameter of the drain wire 4 to match the thickness of the semiconductor layer 3, a gradient conductive path is formed to suppress high-frequency electromagnetic interference (signal noise can be reduced to within ±0.5μA); the resistivity of ≤50Ω·cm enables the semiconductor layer 3 to form an effective equipotential surface, eliminating partial discharge on the surface of the insulation layer (meeting the GB 50168-2018 requirement of electric field distortion rate ≤5%); the low volume resistivity of the semiconductor layer ≤50Ω·cm can quickly guide leakage current from defects in the insulation layer to the drain wire 4 (40% higher collection efficiency than traditional 100Ω·cm materials);

[0046] The low resistance of the semiconductor layer (≤50Ω·cm) reduces Joule heat generated during operation, making the temperature distribution of the cable conductor more uniform (temperature difference control better than ±3°C), and slowing the aging rate of the insulation layer. When a 1.0mm diameter silver wire drain wire is combined with a 50Ω·cm semiconductor layer, the system can detect leakage of a smaller area (0.05mm level) of the insulation layer, and the early warning response time is shortened to 1 / 5 of that of the traditional solution. This parameter combination also meets the mandatory requirements of GB 50217-2018 for cable protection structure and electrical performance.

[0047] Preferably, the drain wire 4 is directly dragged along the axial direction of the conductor 1 and embedded in the semiconductor layer 3; the directly dragged embedded structure of the drain wire 4 enables the drain wire 4 and the semiconductor layer 3 to form a continuous conductive path, eliminating the annular air gap between the insulating layer 2 and the semiconductor layer 3, and avoiding local electric field distortion; the resistivity of the semiconductor layer ≤50Ω·cm matches the high conductivity of the drain wire 4, forming a current decreasing channel from the insulating layer 2 to the drain wire 4 (voltage gradient difference ≤0.5V / mm), thereby improving the transmission efficiency of microampere leakage current; after the drain wire 4 is embedded, it forms an equipotential composite shielding body with the semiconductor layer 3, which can reduce the electromagnetic interference generated during cable operation to ≤30dBμV (better than the GB / T 17626 electromagnetic compatibility standard limit); the semiconductor layer 3 acts as a low-pass filter medium, combined with the conductive path of the drain wire 4, effectively filtering out high-frequency noise signals above 10kHz, thereby ensuring the accuracy of leakage current collection.

[0048] Preferably, the conductor 1 comprises: a plurality of annealed oxygen-free flexible copper wires (not shown), the plurality of annealed oxygen-free flexible copper wires (not shown) are tightly twisted, and the pitch-to-diameter ratio is 12 to 14 times;

[0049] The annealing process enables the conductivity of a single annealed oxygen-free flexible copper wire (not shown) to reach 100% IACS standard. Combined with the oxygen-free treatment (oxygen content ≤ 5 ppm), the electron scattering effect of grain boundary impurities is effectively eliminated, and the DC resistivity of the annealed oxygen-free flexible copper wire (not shown) is reduced.

[0050] Compared to a single thick conductor, multiple annealed oxygen-free flexible copper wires (not shown) can reduce the skin depth during high-frequency transmission and significantly improve the AC resistance stability; the 12-14 times pitch-to-diameter ratio design balances the stiffness and flexibility of conductor 1; the tightly compressed twisted structure forms electromagnetic properties similar to those of a solid conductor, which can reduce the inductance value at a frequency of 1 MHz by 35%, reducing signal distortion caused by the proximity effect.

[0051] Preferably, an insulating polyester tape layer (not shown) is provided on the outside of the semiconductor layer 3, and the insulating polyester tape layer (not shown) includes: a polyester tape (not shown), and the overlap rate of the polyester tape (not shown) wrapped around the outside of the semiconductor layer 3 is 20% to 30%; the overlap rate of the polyester tape (not shown) wrapped around the outside of the semiconductor layer 3 is preferably 20%, 25% and 30%. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range. The overlap rate of 20% to 30% ensures that the polyester tape (not shown) forms an uninterrupted covering layer, blocking the semiconductor layer 3 from contacting the external conductor, thereby reducing leakage current; the polyester tape layer (dielectric constant 3.0 to 3.2) and the semiconductor layer 3 (dielectric constant 15 to 20) form a dielectric gradient, which reduces the maximum field strength on the conductor surface from 35 kV / cm to 20 kV / cm, reduces the probability of local discharge, and prevents conduction.

[0052] Preferably, the annealing current of the annealed oxygen-free flexible copper wire (not shown) is ≥600A, and nitrogen protection cooling is adopted; 600A high current annealing makes the temperature of the copper wire instantly reach above 600°C, accelerates lattice reorganization to eliminate work hardening, and the elongation of the copper wire is improved, achieving higher flexibility; nitrogen protection prevents the copper wire from reacting with oxygen at high temperature, and the oxygen content is stably controlled at ≤5ppm, and the amount of impurity oxides generated at the grain boundaries is reduced to ensure conductivity; the nitrogen layer isolates the oxidation reaction, and the surface roughness Ra value of the copper wire is controlled to be <0.8μm, providing better interface bonding for the subsequent insulation layer 2 coating.

[0053] Preferably, it comprises: a sheath 5, which is arranged outside the semiconductor layer 3 and provides protection for the cable core.

[0054] Preferably, the insulating layer 2 comprises a cross-linked polyethylene insulating layer, the semiconductor layer 3 comprises a semiconductive polyolefin layer, and the sheath 5 comprises a flame-retardant polyvinyl chloride sheath;

[0055] The cross-linked polyethylene insulation layer forms a three-dimensional network structure through a cross-linking process, and its surface resistivity is stable at ≥10^16Ω·m in a hot and humid environment, thereby preventing the formation of carbonization channels caused by surface discharge.

[0056] The dielectric constant difference between the semi-conductive polyolefin layer (dielectric constant 15-20) and the cross-linked polyethylene insulation layer (dielectric constant 2.3) forms a gradient transition, eliminating the influence of voltage distortion caused by interfacial charge accumulation on leakage detection, thereby improving the accuracy of leakage detection;

[0057] The flame retardant polyvinyl chloride sheath has an oxygen index of ≥32% (common PVC is about 26%) and a smoke density of <15% when burning (IEC 61034 standard), thus meeting the flame retardancy requirements of public places such as rail transit.

[0058] The present invention provides a method for manufacturing a novel preventive power cable, wherein the method comprises the following steps:

[0059] S1 uses multiple annealed oxygen-free flexible copper wires tightly twisted together with a pitch-diameter ratio of 12 to 14 times to form conductor 1, ensuring the roundness and flexibility of conductor 1;

[0060] S2 tightly extrude the cross-linked polyethylene material onto the conductor 1 to form an insulating layer 2 with no visible bubbles or impurities on the cross section. The insulating layer 2 has a rounded appearance, is fully cross-linked, and is easily peeled off from the conductor;

[0061] S3 extrude a semiconductor layer 3 from a semi-conductive polyolefin material on the outer surface of the insulating layer 2, and during the extrusion process, a drain wire 4 is directly dragged along the axial direction of the conductor 1 to be embedded as a drain wire 4 for leakage current collection. The drain wire 4 has good conductivity, and the surface should be smooth, round, and of substantially uniform color.

[0062] S4 is wrapped with polyester tape at an overlap rate of 20% to 30% to form an insulating polyester tape layer;

[0063] S5 is a flame retardant polyvinyl chloride sheath extruded on the outside of the insulating polyester tape layer to form a sheath with no visible bubbles and impurities on the cross section. The surface of the sheath is smooth, round and has basically uniform color.

[0064] The present invention provides a novel preventive power cable manufacturing method that can detect cable leakage in real time, realize real-time diagnosis of insulation status, determine the service life of the cable and whether the cable needs to be replaced immediately, thus effectively avoiding line damage and greater harm.

[0065] like Figure 1 As shown, the present invention provides a new preventive power cable, comprising: a conductor 1, wherein the outer side of the conductor 1 is provided with an insulating layer 2, a semiconductor layer 3, an insulating polyester tape layer (not shown) and a sheath 5 in sequence from the inside to the outside, and a drain wire 4 with conductive properties is embedded in the semiconductor layer 3 along the axial direction of the conductor 1, and the end of the drain wire 4 is connected to a leakage current collector (not shown) for real-time collection of leakage current of the cable, and the drain wire 4 comprises: a copper wire drain wire, a silver wire drain wire or a gold wire drain wire; the diameter of the drain wire 4 is 0.5 to 1.0 mm, and the volume resistivity of the semiconductor layer 3 is ≤50Ω·cm; a plurality of annealed oxygen-free flexible copper wires are tightly twisted with a pitch-to-diameter ratio of 12 to 14 times to form the conductor 1; in the semiconductor layer 3 is provided with an insulating polyester tape layer (not shown), which includes: a polyester tape (not shown), and the polyester tape (not shown) is wrapped around the outside of the semiconductor layer with an overlap rate of 20% to 30%; the annealing current of the annealed oxygen-free flexible copper wire (not shown) is ≥600A, and nitrogen protection cooling is adopted; the sheath 5 is provided on the outside of the insulating polyester tape layer; the insulating layer 2 is a cross-linked polyethylene insulation layer, the semiconductor layer 3 is a semi-conductive polyolefin layer, and the sheath 5 is a flame-retardant polyvinyl chloride sheath; this can collect the cable leakage situation in real time, realize real-time diagnosis of the insulation status, determine the service life of the cable and whether the cable needs to be replaced immediately, which can effectively avoid line damage and greater harm.

[0066] It will be appreciated that the present invention is described through some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are subject to various changes or equivalent substitutions. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope protected by the present invention.

Claims

1. A new preventive power cable, characterized in that: include: The conductor has an insulating layer and a semiconductor layer on the outside of the conductor, and a conductive drain wire is embedded in the semiconductor layer. The end of the drain wire is connected to a leakage current collector for real-time collection of the leakage current of the cable.

2. The novel preventive power cable according to claim 1 is characterized in that: The drainage wire includes: a copper wire drainage wire, a silver wire drainage wire or a gold wire drainage wire.

3. The novel preventive power cable according to claim 1 is characterized in that: The diameter of the drain wire is 0.5-1.0 mm, and the volume resistivity of the semiconductor layer is ≤50Ω·cm.

4. The novel preventive power cable according to claim 1 is characterized in that: The drain wire is directly dragged along the axial direction of the conductor and embedded in the semiconductor layer.

5. The novel preventive power cable according to claim 1 is characterized in that: The conductor comprises: a plurality of annealed oxygen-free flexible copper wires, which are tightly compressed and twisted, and have a pitch-to-diameter ratio of 12 to 14 times.

6. The novel preventive power cable according to claim 1 is characterized in that: An insulating polyester tape layer is provided outside the semiconductor layer. The insulating polyester tape layer comprises a polyester tape. The overlapping rate of the polyester tape wrapped around the outside of the semiconductor layer is 20% to 30%.

7. The novel preventive power cable according to claim 5, characterized in that: The annealing current of the annealed oxygen-free flexible copper wire is ≥600A, and nitrogen protection cooling is adopted.

8. The novel preventive power cable according to claim 6, characterized in that: include: A sheath is arranged on the outside of the insulating polyester tape layer.

9. The novel preventive power cable according to claim 8, characterized in that: The insulating layer comprises a cross-linked polyethylene insulating layer, the semiconductor layer comprises a semiconductive polyolefin layer, and the sheath comprises a flame-retardant polyvinyl chloride sheath.

10. A novel method for manufacturing a preventive power cable, characterized in that: Manufacturing the novel preventive power cable according to any one of claims 1 to 9 comprises the following steps: S1 uses multiple annealed oxygen-free flexible copper wires tightly twisted together, with a pitch-to-diameter ratio of 12 to 14 times to form a conductor; S2 tightly extrude the cross-linked polyethylene material onto the conductor to form an insulating layer with no visible bubbles or impurities on the cross section; S3: Extruding a semiconductor layer through a semi-conductive polyolefin material on the outer surface of the insulating layer, and during the extrusion process, directly dragging and embedding a drain wire along the axial direction of the conductor as a drain wire for leakage current collection; S4 is wrapped with polyester tape at an overlap rate of 20% to 30% to form an insulating polyester tape layer; S5 is a flame retardant polyvinyl chloride sheath extruded on the outside of the insulating polyester tape layer to form a sheath with no visible bubbles and impurities on the cross section.

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