Rat-proof and ant-proof high-flame-retardant photovoltaic cable and preparation method thereof

Abstract

The invention discloses a rat-proof and termite-proof high-flame-retardant photovoltaic cable and a preparation method thereof. The rat-proof and termite-proof high-flame-retardant photovoltaic cable comprises a conductor, an insulating layer, a shielding layer, a liner layer, an armor layer and a sheath layer which are sequentially arranged from inside to outside, wherein the shielding layer is formed by weaving tinned copper wires, the liner layer is wrapped by a ceramic fire-resistant composite belt, the armor layer is wrapped by an aluminum belt, and the sheath layer is made of an irradiation low-smoke halogen-free flame-retardant polyolefin material added with a natural rat and ant repellent. According to the invention, the overall structural design is reasonable, through mutual cooperation of all layers of materials, the cable has good electrical conductivity and mechanical strength and also has good rat-and-ant-proof and high-flame-retardant performance, the performance of the photovoltaic cable is comprehensively improved, and the photovoltaic cable can stably and safely operate in a photovoltaic system.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic cables, and in particular relates to a rat- and ant-proof highly flame-retardant photovoltaic cable and a preparation method thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Photovoltaic cables are special cables specially used in solar photovoltaic power generation systems. Compared with ordinary power cables, control cables, etc., there are the following differences. First, the application environment is different. Photovoltaic cables need to withstand ultraviolet rays, high temperatures, and temperature differences between day and night for a long time, while ordinary power cables pay more attention to AC transmission and mechanical strength. Control cables are mainly used for signal transmission and have higher requirements for insulation and shielding, but there is no need to consider outdoor weather resistance; secondly, the performance requirements are different. Photovoltaic cables need to be resistant to ultraviolet rays, highly flame retardant, and rat and ant resistant, while ordinary cables have lower requirements for the above performance.

[0004] Existing photovoltaic cables are typically armored with steel tape or steel wire to increase their rigidity and prevent ants from gnawing on them. Some cables are also armored by adding irritating chemical repellents to the sheath. However, steel tape armor increases cable weight and reduces flexibility, making it difficult to install photovoltaic systems. Repellents are also volatile, and their effectiveness decreases after long-term outdoor exposure. Regarding flame retardancy, existing photovoltaic cables typically use ordinary XLPE (cross-linked polyethylene) or PVC as insulation and low-smoke halogen-free materials as sheaths. This results in a low fire rating, with the flame retardancy only meeting the requirements for single-cable combustion tests and failing to meet the requirements for bundled combustion. High-temperature performance is also insufficient. XLPE insulation typically has a temperature resistance of 90°C-105°C, while photovoltaic cables may operate at temperatures above 120°C for extended periods in high-temperature environments (such as desert power stations), accelerating aging and posing smoke toxicity issues. PVC cables release toxic gases such as hydrogen chloride (HCl) when burned, endangering personnel safety. Some low-smoke halogen-free materials have low flame retardancy, making it difficult to balance environmental protection and fire resistance. Summary of the Invention

[0005] The purpose of the present invention is to provide a rat-proof and ant-proof highly flame-retardant photovoltaic cable and a preparation method. By cooperating with each other in the various layers of materials, the cable has good electrical conductivity and mechanical strength, as well as excellent rat-proof and ant-proof and high flame-retardant properties, thereby comprehensively improving the performance of the photovoltaic cable and enabling it to operate stably and safely in the photovoltaic system.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In the first aspect, an embodiment of the present invention provides a rat-proof and ant-proof highly flame-retardant photovoltaic cable, comprising a conductor, an insulation layer, a shielding layer, a cushioning layer, an armor layer and a sheath layer arranged in sequence from the inside to the outside; wherein, the shielding layer is woven with tinned copper wire, the cushioning layer is wrapped with a ceramic fire-resistant composite tape, the armor layer is wrapped with an aluminum tape, and the sheath layer is made of an irradiated low-smoke halogen-free flame-retardant polyolefin material with an added natural rat-ant repellent.

[0008] As a further technical solution, the conductor is a tinned soft copper conductor, which is formed by twisting multiple fine wires and combining them with a tinning process.

[0009] As a further technical solution, the insulating layer is formed by extrusion of irradiated low-smoke halogen-free flame-retardant polyolefin material.

[0010] As a further technical solution, the lining layer is formed by wrapping three layers of ceramic refractory composite tapes in an overlapping manner.

[0011] As a further technical solution, the thickness of the lining layer is 0.15-0.3 mm.

[0012] As a further technical solution, the thickness of the aluminum strip is 0.2-0.3 mm.

[0013] As a further technical solution, the natural rat and ant repellent is piperine or limonene.

[0014] As a further technical solution, the braiding density of the shielding layer is greater than 80%.

[0015] In a second aspect, an embodiment of the present invention provides a method for preparing a rat- and ant-proof highly flame-retardant photovoltaic cable, comprising the following steps:

[0016] Tinned soft copper wires are twisted into conductors;

[0017] Extruding radiation cross-linked polyolefin material on the conductor to form an insulating layer;

[0018] Tinned copper wire is braided outside the insulation layer to form a shielding layer;

[0019] A ceramic refractory composite tape is wrapped around the outside of the shielding layer to form a lining layer;

[0020] The armor layer is extruded with irradiated low-smoke halogen-free flame-retardant polyolefin material added with natural rat and ant repellent to form a sheath layer.

[0021] As a further technical solution, the amount of natural rat and ant repellent added to the irradiated low-smoke halogen-free flame-retardant polyolefin of the sheath layer is 0.5%-1% of the total mass.

[0022] The beneficial effects of the above embodiments of the present invention are as follows:

[0023] (1) The present invention realizes the coordinated optimization of the anti-rat and ant performance and high flame retardant performance of the photovoltaic cable through the multi-layer composite structure design. In terms of anti-rat and ant, the physical protection (aluminum tape armor layer) and chemical repellent (natural piperine / limonene added to the sheath layer) are combined to greatly improve the protection efficiency against rat and ant bites; the metallic luster of the aluminum tape has a natural deterrent effect on rodents, reducing the probability of biting; in terms of flame retardancy, a ceramic fire-resistant composite tape is used to form a ceramic shell at high temperature to increase the fire resistance time. At the same time, after superimposing the aluminum tape armor, it passes the EN 50575Dca level certification. The whole material is halogen-free, the smoke density is ≤15% during combustion, and there is no release of toxic gases.

[0024] (2) The lining layer of the ceramic refractory composite tape of the present invention is mainly composed of silicate + bauxite, which expands at high temperature to form a porous ceramic layer, isolating flames and oxygen. The three-layer overlapping wrapping (overlap rate ≥ 15%) ensures seamlessness and avoids the delamination problem of traditional mica tape; the aluminum tape armor layer, with a thickness of 0.2-0.3mm, balances lightweight and protection. The melting point of aluminum is 660℃ and it is non-flammable and can reflect heat, forming a "physical + chemical" double flame retardant barrier with the ceramic layer: the ceramic layer is heat-insulating, and the aluminum tape blocks oxygen, thereby improving the fire resistance limit.

[0025] (3) The present invention adopts high-density tinned copper wire as the shielding layer, and its braiding density is greater than 80%, which reduces electromagnetic interference and the high-frequency harmonic noise of the inverter. In addition, the tinned copper wire is more corrosion-resistant than bare copper, which prolongs the service life. The anti-rat and ant additive added to the irradiated polyolefin sheath layer effectively prevents rats and ants from gnawing and damaging the cable, prolongs the service life of the cable, and improves the reliability of the cable in complex outdoor environments. At the same time, it cooperates with the aluminum tape armor to play a role in preventing rats and ants from gnawing. The sheath layer actively repels them, and the armor layer performs passive defense.

[0026] (4) The present invention adopts the fifth type of tinned soft copper conductor, and the twisting of multiple fine wires reduces the bending radius by 50%, which is suitable for photovoltaic array wiring; the tinned layer is resistant to oxidation, and the service life is extended to 25 years in the salt spray test. The irradiated cross-linked polyolefin insulation layer is used: after irradiation, the temperature resistance is improved, and the UV resistance is improved, and there is no risk of aging and cracking in high temperature environments such as desert power stations.

[0027] (5) The overall structural design of the present invention is reasonable. Through the mutual cooperation of various layers of materials, the performance of the photovoltaic cable is comprehensively improved, so that it can operate stably and safely in the photovoltaic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a structural schematic diagram of the cross section of the rat and ant proof highly flame retardant photovoltaic cable of the present invention.

[0030] The diagram is for illustrative purposes only;

[0031] Among them, 1. Conductor; 2. Insulation layer; 3. Shielding layer; 4. Padding layer; 5. Armor layer; 6. Sheath layer. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0033] Example 1

[0034] In a typical embodiment of the present invention, Figure 1 As shown, a rat- and ant-proof highly flame-retardant photovoltaic cable is provided, comprising a conductor 1, an insulating layer 2, a shielding layer 3, a cushioning layer 4, an armoring layer 5 and a sheathing layer 6 arranged in sequence from the inside to the outside; wherein, the shielding layer 3 is woven with tinned copper wire, the cushioning layer 4 is wrapped with a ceramic fire-resistant composite tape, the armoring layer 5 is wrapped with an aluminum tape, and the sheathing layer 6 is made of an irradiated low-smoke halogen-free flame-retardant polyolefin material to which a natural rat- and ant-repellent agent is added.

[0035] This highly flame-retardant, rat- and ant-resistant photovoltaic cable overcomes the shortcomings of traditional photovoltaic cables in both rat- and ant-resistant and flame-retardant properties through the collaborative design of a tinned copper wire shield, a ceramic fire-resistant composite tape, an aluminum armor layer, and a sheath containing a natural repellent. Specifically, the synergistic flame retardancy of the ceramic fire-resistant composite tape and the aluminum armor layer ensures the photovoltaic cable's high flame retardancy, achieving a fire rating that meets the Dca fire rating requirements of EN50575. The synergistic effect of the aluminum tape and the natural repellent added to the sheath also ensures the photovoltaic cable's rat- and ant-resistant properties.

[0036] The conductors of existing photovoltaic cables generally use stranded hard copper conductors or non-tinned soft copper conductors. Bare copper conductors are easily oxidized (generating verdigris) in humid environments, resulting in increased contact resistance and increased heat risk. There is also the problem of large conductor bending radius, which makes it difficult to adapt to the complex wiring requirements of photovoltaic arrays. In addition, non-tinned copper conductors corrode quickly in salt spray or acid rain environments, and have a low average lifespan, which makes it difficult to meet the lifespan requirements of photovoltaic cables.

[0037] In this embodiment, the conductor 1 is a tinned soft copper conductor, which is a composite of multiple strands of fine wires twisted and tinned. Specifically, the tinned soft copper conductor is a fifth-class tinned soft copper conductor, which has good electrical conductivity and mechanical strength. After tinning, the oxidation resistance and corrosion resistance are enhanced, and the service life of the cable is extended. The multi-strand fine wire twisted structure (single wire diameter ≤ 0.21mm) makes the cable bending radius small, which is suitable for complex wiring of photovoltaic arrays. The tin plating layer improves the oxidation resistance of the conductor (especially in humid environments) and extends the service life of the photovoltaic cable.

[0038] Existing photovoltaic cables use ordinary cross-linked polyethylene or PVC as the insulation layer. Ordinary cross-linked polyethylene has a temperature resistance of only 90°C and is prone to aging and cracking in high-temperature environments (such as desert power stations). PVC releases toxic gases such as hydrogen chloride (HCl) when burned and is difficult to pass the EN50575 Dca-level test. Non-irradiated materials are prone to brittleness after long-term UV exposure, leading to insulation failure.

[0039] In this embodiment, the insulation layer 2 is extruded from irradiated low-smoke, halogen-free, flame-retardant polyolefin material. Irradiation cross-linking technology is used to cross-link the polyolefin's molecular structure, improving its mechanical and heat resistance properties. It also provides excellent electrical insulation, ensuring stable operation of the cable at high voltages and laying a solid foundation for subsequent rodent- and ant-proofing and flame-retardant design.

[0040] Existing photovoltaic cables are usually not provided with a shielding layer. Unshielded cables are susceptible to interference during the high-frequency switching of the inverter, resulting in distortion of communication signals.

[0041] In this embodiment, the shielding layer 3 is woven with tinned copper wire with a diameter of 0.2 mm. The weaving density of the shielding layer is greater than 80%, and it has excellent conductivity and shielding performance, which can effectively prevent electromagnetic interference. The woven tinned copper wire forms a continuous metal mesh structure, which can reflect or absorb external electromagnetic waves to prevent them from penetrating the interior of the cable. The electromagnetic field generated by the internal conductor is also constrained by the shielding layer to avoid outward radiation and interference with other equipment; at the same time, the tinned layer enhances the oxidation resistance of the copper wire, which is more corrosion-resistant than bare copper. It still maintains high shielding effectiveness after long-term outdoor use, thereby improving the stability and service life of the shielding layer.

[0042] Existing photovoltaic materials usually use mica tape or ordinary flame-retardant tape. Mica tape can only last 30 minutes at 800°C and is prone to delamination and falling off. In addition, the thickness of traditional mica tape is ≥0.4mm, which greatly increases the weight of the cable.

[0043] In this embodiment, the cushion layer 4 is formed by three layers of overlapping ceramic refractory composite tape; further, the thickness of the cushion layer is 0.15-0.3mm. The ceramic refractory composite tape has refractory materials with special properties. The main components are inorganic refractory materials such as silicate and bauxite. It can form a dense ceramic shell at high temperature, effectively preventing the spread of flames and the transfer of heat, providing good fire resistance for the cable, and is one of the key materials for achieving high flame retardant performance of the cable. The three-layer wrapping ensures that there are no gaps, and the ceramic expansion is uniform at high temperatures, which effectively improves the fire resistance time. At the same time, the overlapping wrapping process (overlap rate ≥ 15%) avoids cracking of the ceramic layer at high temperatures. The thickness of the cushion layer is limited to 0.15-0.3mm. This thickness range takes into account both lightweight (the outer diameter of the cable does not increase significantly) and fire resistance requirements. After superimposing with the aluminum tape, the total thickness is controlled within 0.5 to maintain the flexibility of the cable.

[0044] Existing photovoltaic cables are usually not equipped with an armor layer, and only use thickened sheaths to prevent rats and ants, which are easily bitten through; or they are armored with steel strips, which are usually thicker than 0.5mm, are heavy, easily rusted, and have poor flexibility.

[0045] In this embodiment, the aluminum tape has a thickness of 0.2-0.3 mm. The aluminum tape has high mechanical strength and excellent tensile and extrusion resistance, effectively protecting the cable's internal structure from mechanical damage. The aluminum tape itself has a certain degree of hardness, resisting the gnawing of rats and ants, providing solid physical protection for the cable. Its metallic texture also has a deterrent effect on some rats and ants, reducing the probability of gnawing. The aluminum tape also has certain flame retardant properties, further enhancing the flame retardant effect of the cable.

[0046] The sheath layer of existing photovoltaic cables usually uses ordinary PVC or non-irradiated polyolefin sheath, which is difficult to pass the bundled combustion test and has low flame retardant performance. In addition, PVC becomes brittle at low temperatures and softens at high temperatures, and has poor weather resistance.

[0047] In this embodiment, the sheath layer 6 is a low-smoke, halogen-free, flame-retardant polyolefin material that has been subjected to radiation cross-linking treatment. It has good resistance to environmental stress cracking, chemical resistance and mechanical properties, and can effectively resist erosion from the external environment. At the same time, by adding 0.5%-1% of natural repellents such as piperine and limonene to the sheath material, the smell of these repellents can repel rats and ants for a long time and prevent them from approaching the cable, so that the sheath layer has the function of preventing rats and ants from biting, thereby preventing rats and ants from damaging the cable.

[0048] During the actual production process, Category 5 tinned copper conductors are first twisted together. The cables are then processed sequentially through the following steps: extrusion of radiation-cross-linked polyolefin insulation, tinned copper wire braid shielding, wrapping with ceramic fire-resistant composite tape, wrapping with aluminum tape armor, and finally extrusion of a radiation-cross-linked polyolefin sheath. The resulting highly flame-retardant, rat- and ant-resistant photovoltaic cable meets the Dca fire rating requirements of EN50575. The cables also exhibit excellent rat- and ant-resistant properties and mechanical properties, making them suitable for a variety of outdoor photovoltaic system environments.

[0049] The above cable structure does not use any combustible organic materials in the cable itself, so the cable will not spontaneously combust and can avoid causing self-sourced fires. In exogenous fires, the cable will not spontaneously combust and will not support combustion, which can reduce the fire and smoke and reduce personal injuries.

[0050] Example 2

[0051] In a typical embodiment of the present invention, there is provided a method for preparing a rat- and ant-proof highly flame-retardant photovoltaic cable according to any one of claims 1 to 8, characterized in that it comprises the following steps:

[0052] Tinned soft copper wires are twisted into conductors;

[0053] Extruding radiation cross-linked polyolefin material on the conductor to form an insulating layer;

[0054] Tinned copper wire is braided outside the insulation layer to form a shielding layer;

[0055] A ceramic refractory composite tape is wrapped around the outside of the shielding layer to form a lining layer;

[0056] The armor layer is extruded with irradiated low-smoke halogen-free flame-retardant polyolefin material added with natural rat and ant repellent to form a sheath layer.

[0057] Furthermore, the amount of the natural rat and ant repellent added to the irradiated low-smoke halogen-free flame-retardant polyolefin of the sheath layer is 0.5%-1% of the total mass.

[0058] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A highly flame-retardant photovoltaic cable that is resistant to rats and ants, characterized in that: It includes a conductor, an insulating layer, a shielding layer, a lining layer, an armor layer and a sheath layer arranged in sequence from the inside to the outside; wherein, the shielding layer is woven with tinned copper wire, the lining layer is wrapped with a ceramic fire-resistant composite tape, the armor layer is wrapped with an aluminum tape, and the sheath layer is made of an irradiated low-smoke halogen-free flame-retardant polyolefin material added with a natural rat and ant repellent.

2. The rat- and ant-proof highly flame-retardant photovoltaic cable according to claim 1, characterized in that: The conductor is a tinned soft copper conductor, which is formed by twisting multiple fine wires and performing a tinning process.

3. The rat-proof and ant-proof highly flame-retardant photovoltaic cable according to claim 1, characterized in that: The insulating layer is formed by extrusion of irradiated low-smoke halogen-free flame-retardant polyolefin material.

4. The rat-proof and ant-proof highly flame-retardant photovoltaic cable according to claim 1, characterized in that: The lining layer is formed by wrapping three layers of ceramic refractory composite tapes in an overlapping manner.

5. The rat- and ant-proof highly flame-retardant photovoltaic cable according to claim 4, characterized in that: The thickness of the lining layer is 0.15-0.3 mm.

6. The rat-proof and ant-proof highly flame-retardant photovoltaic cable according to claim 1, characterized in that: The thickness of the aluminum strip is 0.2-0.3 mm.

7. The rat- and ant-proof highly flame-retardant photovoltaic cable according to claim 1, characterized in that: The natural rat and ant repellent is piperine or limonene.

8. The rat-proof and ant-proof highly flame-retardant photovoltaic cable according to claim 1, characterized in that: The braiding density of the shielding layer is greater than 80%.

9. A method for preparing a rat- and ant-proof highly flame-retardant photovoltaic cable according to any one of claims 1 to 8, characterized in that: The following steps are involved: Tinned soft copper wires are twisted into conductors; Extruding radiation cross-linked polyolefin material on the conductor to form an insulating layer; Tinned copper wire is braided outside the insulation layer to form a shielding layer; A ceramic refractory composite tape is wrapped around the outside of the shielding layer to form a lining layer; The armor layer is extruded with irradiated low-smoke halogen-free flame-retardant polyolefin material added with natural rat and ant repellent to form a sheath layer.

10. The method for preparing the rat-proof and ant-proof highly flame-retardant photovoltaic cable according to claim 9, characterized in that: The amount of the natural rat and ant repellent added to the irradiated low-smoke halogen-free flame-retardant polyolefin of the sheath layer is 0.5%-1% of the total mass.

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