Silicone rubber insulation flame-retardant fireproof variable frequency cable with rated voltage of 3.6-10 kV

Abstract

The utility model discloses a silicone rubber insulation flame-retardant fireproof frequency conversion cable with a rated voltage of 3.6-10 kV. A conductor shielding layer is arranged on a conductor, an insulation layer is arranged outside the conductor shielding layer, an insulation shielding layer is arranged on the insulation layer, a metal shielding layer is arranged outside the insulation shielding layer, and a plurality of conductors are twisted into a cable core. An aramid fiber tensile element is arranged in the center of the cable core, the inner side and the outer side of the cable core are extruded and filled with magnesium hydroxide fireproof mud filling layers, a low-smoke halogen-free high-resistance belt is wrapped outside the cable core, a ceramic flame-retardant silicone rubber material extruded oxygen barrier layer is arranged on the outer side of the low-smoke halogen-free high-resistance belt, and the outer side of the low-smoke halogen-free high-resistance belt is wrapped with a flame-retardant silicone rubber material extruded oxygen barrier layer. A fire blocking layer is arranged on the outer side of the ceramic flame-retardant silicone rubber material extruded oxygen barrier layer, an armor layer is arranged on the outer side of the fire blocking layer, and a ceramic flame-retardant silicone rubber outer protective layer is extruded on the outer side of the armor layer. The cable provided by the utility model has the characteristics of high heat-resistant grade, good electrical performance, flame retardance, fire resistance, strong anti-interference performance and the like.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, and in particular to a 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant variable frequency cable. Background Technology

[0002] A frequency converter (VFD) is a device that uses frequency conversion technology and microelectronics to control the operation of an AC motor by changing the frequency of the power supply. The VFD is analogous to the accelerator pedal in a car; a larger accelerator pedal results in a higher speed, and a smaller pedal pedal results in a lower speed. In a VFD, a higher output frequency means a higher motor speed, and a lower output frequency means a lower motor speed. According to the physics principle P=UI, the power of a motor depends on its rated voltage and rated current. When the power is constant, a higher rated voltage results in a lower rated current, and vice versa. In motor manufacturing, higher voltage means higher insulation requirements, and higher current means thicker conductors. When the output voltage range is between 1kV and 35kV, it is called a medium-voltage VFD. Medium-voltage VFDs are widely used in various industrial applications, especially in large motor drive systems, such as fans, pumps, and compressors in industries like petrochemicals, municipal water supply, metallurgy, steel, power energy, mining, and building materials.

[0003] The main working principle of frequency converter cables is based on the interaction of electricity and magnetism. When the amplitude and frequency of the signal transmitted through the cable change continuously, electromagnetic waves and mutual inductance effects are generated, causing current to flow inside the cable. These currents create an electromagnetic field within the cable, generating an interaction force that allows the signal to be transmitted. Furthermore, frequency converter cables also have noise suppression capabilities. They employ techniques such as conductor shielding and insulation materials to suppress the influence of external interference signals and ensure transmission quality.

[0004] The fire-resistant design of high-voltage cables cannot be done by wrapping fire-resistant mica tape around the conductor like low-voltage cables, nor can it use copper core, copper sheath, and magnesium oxide insulation. The insulated core cannot have a fire-resistant layer; it must be placed on the outside of the cable core. Therefore, our company has designed and developed a 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable. Utility Model Content

[0005] The purpose of this utility model is to overcome the deficiencies of existing technologies and provide a 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant variable frequency cable.

[0006] This utility model is achieved through the following technical solution:

[0007] A 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant variable frequency cable includes a conductor, a conductor shielding layer on the conductor, an insulation layer outside the conductor shielding layer, an insulation shielding layer on the insulation layer, and a metal shielding layer outside the insulation shielding layer. Multiple conductors are stranded into a cable core. An aramid fiber tensile element is placed at the center of the cable core. The inner and outer sides of the cable core are filled with a magnesium hydroxide fireproof mud filling layer and wrapped with a low-smoke halogen-free high-resistance band. The magnesium hydroxide fireproof mud absorbs heat and lowers the temperature. At high temperatures, magnesium hydroxide decomposes and releases crystal water. This process can absorb a large amount of heat, thereby reducing the temperature of the environment around the cable and effectively delaying the spread of fire. The magnesium hydroxide fireproof mud can also dilute oxygen and combustible gases. The released water vapor can further dilute the concentration of oxygen and combustible gases in the air, further inhibiting the combustion reaction. It can also form a fire-resistant layer. At high temperatures, magnesium hydroxide will generate a magnesium oxide fire-resistant layer, effectively isolating the air in the combustion zone and further preventing combustion.

[0008] An oxygen barrier layer made of ceramicized flame-retardant silicone rubber is extruded on the outer side of the low-smoke, halogen-free, high-resistance strip. This ceramicized flame-retardant silicone rubber extruded oxygen barrier layer forms a hard ceramic layer under high temperature or open flame conditions, effectively preventing flame spread and maintaining structural integrity. It burns slowly, without dripping, and does not produce toxic gases, improving safety and visibility at fire scenes. It begins to harden above 350℃ but can be used for extended periods in static environments above 350℃, exhibiting good heat resistance. The main residue produced during combustion is non-toxic silica, harmless to humans and the environment. It produces low-smoke, non-toxic smoke, meeting green manufacturing standards. It also possesses excellent electrical insulation, high volume resistivity, and high breakdown strength; it is resistant to ozone, heat oxygen, and ultraviolet aging, requiring no anti-aging agents or antioxidants; its special surface properties result in low moisture absorption and good mildew resistance.

[0009] A fire-resistant layer is provided on the outside of the oxygen barrier layer extruded from the ceramicized flame-retardant silicone rubber material. The fire-resistant layer adopts a multi-layer mica tape wrapped with a low-smoke halogen-free high-resistance tape. An armor layer is provided on the outside of the fire-resistant layer. The armor layer is woven from low-carbon galvanized steel wire and wrapped with a second low-smoke halogen-free high-resistance tape. A ceramicized flame-retardant silicone rubber outer protective layer is extruded on the outside of the second low-smoke halogen-free high-resistance tape.

[0010] The conductor is a multi-strand stranded flexible tin-plated copper conductor. The multi-strand stranded flexible tin-plated copper conductor has the following properties:

[0011] Conductivity: Tin-plated copper conductors retain the excellent conductivity of pure copper, which can meet the current transmission requirements of various electrical equipment.

[0012] Corrosion resistance: The tin plating layer can prevent copper wire from oxidizing in the air and forming verdigris, thereby maintaining the conductivity and mechanical properties of the conductor.

[0013] Flexibility and bending performance: The multi-strand stranded structure gives the conductor good flexibility and bending performance, enabling it to adapt to various complex environments and laying conditions.

[0014] Wear resistance: Tin-plated copper conductors have a smooth surface, and the tin plating layer can increase the wear resistance of the conductor and extend its service life.

[0015] The conductor shielding layer adopts a semi-conductive strip overlapping wrapping structure.

[0016] The insulating layer is made of high tear-resistant silicone rubber through vulcanization.

[0017] The aforementioned insulating shielding layer employs an overlapping semi-conductive tape wrapping structure. The semi-conductive tape absorbs and disperses charges in the electric field, resulting in a more uniform electric field distribution. This helps reduce partial discharge and breakdown, thereby improving the cable's insulation performance. The semi-conductive tape also ensures a uniform electric field on the insulation surface, preventing localized electric field concentration and thus improving the cable's voltage withstand capability. The semi-conductive tape reduces leakage current and insulation resistance, increasing the cable's insulation strength. It also reduces cable resistance and increases current-carrying capacity, allowing the cable to maintain good electrical performance even under high loads. The semi-conductive tape acts as a shield within the cable, suppressing external electric field interference from entering the cable insulation layer and preventing interference from external electromagnetic fields. Simultaneously, it prevents internal electromagnetic field interference from radiating to the outside, improving the cable's anti-interference capability. The application of semi-conductive tape reduces cable failure rates and maintenance costs. By improving electric field distribution and enhancing electrical performance, the semi-conductive tape helps extend cable lifespan and improve the stability and reliability of the cable system.

[0018] The metal shielding layer is made of tin-plated copper wire and is tied tightly with semi-conductive tape.

[0019] The advantages of this utility model are: the conductive core conductor of this utility model adopts a multi-strand stranded soft structure tin-plated copper conductor, a conductor shielding layer is provided on the conductor, the conductor shielding layer adopts a semi-conductive tape overlapping wrapping structure, an insulation layer is provided outside the conductor shielding layer, the insulation layer is made of high tear-resistant silicone rubber of different thicknesses extruded and vulcanized according to the cable voltage level, an insulating shielding layer is provided on the insulation layer, the insulating shielding layer adopts a semi-conductive tape overlapping wrapping structure, a metal shielding layer is provided outside the insulating shielding layer, the metal shielding layer is braided with tin-plated copper wire of equivalent total cross-section according to the fault current capacity of the cable, and tin-plated copper wire is used in the braided layer. The three conductive cores are twisted together and secured with semi-conductive tape. An aramid fiber tensile element is placed at the center of the core. A magnesium hydroxide fireproof mud filling layer is used to fill the gaps in the core, forming a solid circular shape of a certain thickness. A low-smoke halogen-free high-resistance tape is then wrapped around the core. An oxygen barrier layer, made of ceramicized flame-retardant silicone rubber, is then added. A fire-resistant layer, using a multi-layer mica tape and low-smoke halogen-free high-resistance tape wrapping structure, is then added. An armor layer, made of low-carbon galvanized steel wire braided and wrapped with low-smoke halogen-free high-resistance tape, is then added. The outer sheath is made of ceramicized flame-retardant silicone rubber. This cable features high heat resistance, good electrical performance, flame retardancy, fire resistance, and strong anti-interference capabilities. It enables the cable to transmit large amounts of electrical energy while providing excellent shielding and flame-retardant fire resistance. It can be widely used in various industries requiring 3.6-10kV frequency conversion power supply and for connecting frequency converters and controllers in speed control systems. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0021] like Figure 1As shown, a 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable includes a conductor 1, a conductor shielding layer 2 on the conductor 1, an insulation layer 3 outside the conductor shielding layer 2, an insulation shielding layer 4 on the insulation layer 3, and a metal shielding layer 5 outside the insulation shielding layer 4. Multiple conductors 1 are stranded into a cable core, an aramid fiber tensile element 6 is placed at the center of the cable core, and the inner and outer sides of the cable core are filled with magnesium hydroxide fireproof mud filling layer 7 by extrusion, and then wrapped with low smoke halogen-free material. High-resistance strip 8, with an oxygen barrier layer 9 extruded from ceramicized flame-retardant silicone rubber material on the outside of the low-smoke halogen-free high-resistance strip 8, and a fire barrier layer 10 on the outside of the ceramicized flame-retardant silicone rubber material extruded oxygen barrier layer 9. The fire barrier layer 10 adopts a multi-layer mica tape plus low-smoke halogen-free high-resistance strip wrapping structure. An armor layer 11 is provided on the outside of the fire barrier layer 10. The armor layer 11 is woven from low-carbon galvanized steel wire and wrapped around a second low-smoke halogen-free high-resistance strip 12 on the outside. A ceramicized flame-retardant silicone rubber outer protective layer 13 is extruded on the outside of the second low-smoke halogen-free high-resistance strip 12.

[0022] The conductor 1 is a multi-strand stranded soft structure tin-plated copper conductor.

[0023] The conductor shielding layer 2 adopts a semi-conductive strip overlapping wrapping structure.

[0024] The insulating layer 3 is made of high tear-resistant silicone rubber vulcanized.

[0025] The insulating shielding layer 4 adopts a semi-conductive tape overlapping wrapping structure.

[0026] The 3.6-10kV silicone rubber insulated flame-retardant and fire-resistant variable frequency cable provided by this utility model has the characteristics of high heat resistance, good electrical performance, flame retardancy, fire resistance and strong anti-interference performance. It can be widely used in various industrial occasions, especially in large motor drive systems, such as fans, pumps and compressors in industries such as petrochemical, municipal water supply, metallurgy and steel, power energy, mining and building materials.

[0027] The cable conductor 1 is a multi-strand stranded soft structure tinned copper conductor. In addition to having good conductivity, conductor 1 has better flexibility than stranded and solid conductors, which makes the cable have a smaller bending radius.

[0028] A conductor shielding layer 2 is provided on the conductor. The conductor shielding layer 2 adopts a semi-conductive strip overlapping wrapping structure. The conductor shielding can increase the roundness and stability of the conductor, avoid adverse phenomena such as multiple conductors and puncture of the insulation layer, homogenize the electric field, optimize the partial discharge of the cable, and enhance the stability and life of the cable.

[0029] An insulation layer 3 is provided outside the conductor shielding layer 2. The insulation layer 3 is made of high tear-resistant silicone rubber of different thicknesses extruded and vulcanized according to the cable voltage level. Silicone rubber is a thermosetting material with excellent high elasticity and electrical properties, which can enable the cable to operate at a temperature of 180°C and a short-circuit temperature of 350°C, which is a significant improvement compared to cross-linked polyethylene insulation.

[0030] An insulating shielding layer 4 is provided on the insulating layer 3. The insulating shielding layer 4 adopts a semi-conductive tape overlapping wrapping structure, which can effectively avoid the probability of metal wire puncturing the insulating layer and also play a buffering role.

[0031] A metal shielding layer 5 is provided outside the insulation shielding layer 4. The metal shielding layer 5 is braided with tinned copper wire of equivalent total cross-section according to the fault current capacity of the cable. If necessary, tinned copper wire is wrapped around the braided layer and tied with semi-conductive tape. This can better pass the fault current and the shielding effect at high and low frequencies, and can reduce electromagnetic interference between the wire cores and the outside world.

[0032] Three conductive cores are twisted into a cable, and an aramid fiber tensile element 6 is placed in the center of the cable core. The aramid has ultra-high strength and plays an effective role in tensile resistance and protection during the use of the cable.

[0033] The gaps in the cable core are filled with magnesium hydroxide fireproof mud, forming a solid circle of a certain thickness, and then wrapped with a low-smoke, halogen-free, high-resistance tape. Magnesium hydroxide is an inorganic mineral material that is not flammable. When the cable is exposed to fire, its inorganic mineral metal hydrate fills the gaps and gradually releases free water molecules and water of crystallization in the inner structure, evaporating and cooling the cable and slowing down the internal heat transfer rate. At the same time, the low-smoke, halogen-free, high-resistance tape ensures structural stability and improves flame retardancy.

[0034] An oxygen barrier layer is then set outside the low-smoke, halogen-free, high-resistance belt. The oxygen barrier layer is made of ceramicized flame-retardant silicone rubber material extruded. Under high temperature and flame erosion above 500℃, the ceramicized silicone rubber is sintered into a hard ceramic-like object. Moreover, the longer the erosion time and the higher the temperature, the more obvious the ceramicization effect. Some models of ceramicized silicone rubber can reach 1200-1500℃ without melting.

[0035] A fire-resistant layer is installed outside the oxygen barrier layer. The fire-resistant layer adopts a multi-layer mica tape + low smoke halogen-free high resistance tape wrapping structure. The synthetic mica tape has excellent high temperature resistance and flame resistance. In addition to its small expansion coefficient, the synthetic mica tape has a temperature resistance greater than 1000℃. When it is exposed to open flame, there is basically no volatilization of harmful smoke, which can effectively block the flame from damaging the inside of the cable.

[0036] An armored layer is installed outside the fireproof layer. The armored layer is made of low-carbon galvanized steel wire braided and wrapped with a low-smoke halogen-free high-resistance belt II. The steel wire can play a good tensile role, and the low-smoke halogen-free high-resistance belt II improves the flame retardant performance while preventing the wire ends from puncturing the sheath.

[0037] The outer sheath is extruded from ceramicized flame-retardant silicone rubber material. The sheath material rapidly forms a crust upon contact with fire, exhibiting excellent halogen-free, low-smoke flame-retardant properties. Through careful cable structure design and material selection, the cable possesses excellent flame-retardant, fire-resistant, and electrical properties, meeting its performance requirements.

Claims

1. A 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable, characterized in that: The cable includes a conductor, a conductor shielding layer, an insulation layer outside the conductor shielding layer, an insulation shielding layer on the insulation layer, and a metal shielding layer outside the insulation shielding layer. Multiple conductors are twisted into a cable core. An aramid fiber tensile element is placed at the center of the cable core. The inner and outer sides of the cable core are filled with magnesium hydroxide fireproof mud and wrapped with a low-smoke, halogen-free, high-resistance tape. An oxygen barrier layer made of ceramicized flame-retardant silicone rubber is extruded outside the low-smoke, halogen-free, high-resistance tape. A fire-resistant layer is placed outside the oxygen barrier layer made of ceramicized flame-retardant silicone rubber, using a multi-layer mica tape wrapped with low-smoke, halogen-free, high-resistance tape. An armor layer is placed outside the fire-resistant layer, made of low-carbon galvanized steel wire braided and wrapped with a second low-smoke, halogen-free, high-resistance tape. A ceramicized flame-retardant silicone rubber outer sheath is extruded outside the second low-smoke, halogen-free, high-resistance tape.

2. The rated voltage 3.6-10kV silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable according to claim 1, characterized in that: The conductor is a multi-strand stranded soft structure tin-plated copper conductor.

3. The 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable according to claim 1, characterized in that: The conductor shielding layer adopts a semi-conductive strip overlapping wrapping structure.

4. The 3.6-10kV rated voltage silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable according to claim 1, characterized in that: The insulating layer is made of high tear-resistant silicone rubber through vulcanization.

5. The rated voltage 3.6-10kV silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable according to claim 1, characterized in that: The insulating shielding layer adopts a semi-conductive tape overlapping wrapping structure.

6. The rated voltage 3.6-10kV silicone rubber insulated flame-retardant and fire-resistant frequency conversion cable according to claim 1, characterized in that: The metal shielding layer is made of tin-plated copper wire and is tied tightly with semi-conductive tape.

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