Low-temperature-resistant construction high-voltage flexible cable

Abstract

The application relates to a low-temperature-resistant construction high-voltage flexible cable, which is characterized by comprising a plurality of heat preservation pipes, an insulated wire core composed of a plurality of insulated conductors, a filling body, an isolation sleeve, a steel wire armor layer, a winding and binding copper belt and an outer sheath; the cable is suitable for construction insulation and sheath cracking prevention under a low-temperature environment below -15 DEG C, can effectively make the cable laying construction no longer be restricted by the low-temperature environment of a construction region, has high construction efficiency and low cost, and has popularization and application value. In addition, in specific application, water vapor is introduced into the heat preservation pipe during laying construction, and the condensed water is left in the heat preservation pipe; when the cable is high-load heated, the condensed water left in the heat preservation pipe can absorb part of the heat, the heat load of the cable conductor is higher, the carrying capacity is larger, the aging degree of the insulation and sheath material in the cable due to high temperature is reduced, and the service life of the cable can be prolonged to a certain extent.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage flexible cable technology, and in particular to a low-temperature resistant high-voltage flexible cable for construction. Background Technology

[0002] Currently, during cable laying in cold regions, extreme low temperatures often cause the sheath and insulation rubber materials to become brittle and lose toughness. When the cable is dragged and bent during the laying process, stress concentration can damage the sheath and insulation layers, resulting in extremely high construction losses. Even if the cable is laid with difficulty, there are many small, hard-to-detect cracks and hidden damages on the insulation and sheath of the cable, which seriously affect the stability and efficiency of power supply.

[0003] Therefore, cable laying is avoided in extremely low temperature environments during construction. However, in extremely cold regions such as Northeast my country and Tibet, which are at high latitudes and high altitudes, the window of opportunity for laying power cables often cannot meet the needs of local economic development, which greatly restricts local economic development.

[0004] To solve these problems, the conventional solutions are as follows:

[0005] 1. Environmental monitoring: The ambient temperature must be continuously monitored before construction to avoid operations during periods of sustained low temperatures;

[0006] 2. Material pretreatment: Store the cable in a suitable temperature environment for a sufficient time to restore its performance at room temperature;

[0007] 3. Protective measures: Use equipment such as heated tents to create a suitable local temperature environment for the laying operation;

[0008] 4. Process adjustments: Reduce traction speed, increase bending radius, and use a special low-temperature lubricant;

[0009] However, all of the above solutions suffer from low construction efficiency and high cost. Summary of the Invention

[0010] This utility model addresses the problems mentioned in the background art by providing a low-temperature resistant high-voltage flexible cable that has minimal impact on cable sheath and insulation during low-temperature construction, high construction efficiency, and low cost.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A low-temperature resistant high-voltage flexible cable is characterized by comprising an insulated core consisting of several insulation pipes and several insulated conductors, a filler, an isolation sleeve, a steel wire armor layer, wrapped copper tape, and an outer sheath.

[0013] The insulation pipe is a hollow tube made of polytetrafluoroethylene material through extrusion and cooling. The insulation pipe includes a central insulation pipe and several outer insulation pipes. The central insulation pipe is set on the central axis between the insulated wires of the insulated core and is in contact with each insulated wire. The outer insulation pipes are set in the outer gap between two adjacent insulated wires and are in contact with the two adjacent insulated wires respectively.

[0014] The insulated wire includes a conductor, a conductor shield, an insulation layer, an insulation shield, a semi-conductive wrapping tape, and a loosely wound copper wire shield. The conductor shield, insulation layer, and insulation shield are extruded onto the conductor using a three-layer co-extrusion process. The semi-conductive wrapping tape covers the insulation shield and serves to even out the power distribution and isolate the loosely wound copper wire shield, preventing burrs on the copper wire from scratching the insulation layer. The loosely wound copper wire shield is formed by several annealed soft copper wires of the same diameter stranded at intervals at a certain pitch. It is used to create a gap between the insulation pipe and the insulated wire, providing space for the thermal expansion and contraction of the insulation pipe and preventing internal stress generated during thermal expansion and contraction from compressing and damaging the insulation layer of the insulated wire and the filler in contact with it.

[0015] The filler is a layer of chlorinated polyethylene rubber extruded onto the cable core assembly, which consists of insulated wire cores and heat-insulating tubes, and is used to fill and round the gaps on the surface of the cable core assembly, i.e., between each wire tube.

[0016] The filler body is covered with an isolation sleeve, which is made of chlorinated polyethylene rubber material and is extruded on the outer surface of the filler body to isolate the loosely wound copper wire shielding layer of the insulated wire core from the armored steel wire layer.

[0017] The steel wire armor layer is a low-carbon galvanized fine steel wire armor layer set between the isolation sleeve and the outer sheath, and is tightly bound by the copper strip wrapped with reverse gaps to prevent the steel wire armor layer from lifting.

[0018] The outer sheath is a low-temperature resistant rubber elastomer sheath extruded onto a steel wire armor layer.

[0019] A further aspect of this invention is that the thickness of the conductor shield and the insulation shield is preferably 0.6mm-0.8mm, and the thickness of the ethylene propylene rubber insulation is preferably 3.4mm. This thickness distribution ensures the insulation effect while also having certain thermal conductivity, allowing the heat from the heat-insulating pipe through which high-temperature steam is introduced to penetrate into each layer of insulation and shielding rubber material, thus better preventing the insulation rubber material from becoming brittle in low-temperature environments.

[0020] A further aspect of this invention is that the diameter of the copper wire in the loosely wound copper wire shielding layer is 0.75mm-1.13mm. Copper wires within this diameter range can ensure that the conductor will not be thinned or broken during the loosening process. The average gap between the loosely wound copper wires is less than or equal to 4mm. In this way, the total area of ​​the loosely wound metal shielding is larger than the cross-sectional area of ​​the metal braid, and it can carry a larger fault short-circuit current.

[0021] A further aspect of this invention is that the wall thickness of the insulation pipe is not less than 1.5mm, and it can withstand a steam pressure of at least 1.3-1.8Mpa when connected to high-pressure, high-temperature steam, while also having certain heat transfer performance.

[0022] When laying the aforementioned low-temperature resistant high-voltage flexible cable, one end of the insulation pipe is connected to a steam generator, and high-temperature steam is introduced into it. After the entire pipe is ventilated and preheated, the other end is completely sealed. Once the insulation pipe is filled with steam pressure, it can be laid in the same way as a regular cable.

[0023] The beneficial effects of this utility model are as follows: By installing an insulation pipe within the cable and selecting polytetrafluoroethylene (PTFE) as the insulation material, which can withstand temperatures up to 200℃ and exhibits strength and does not collapse after three vulcanization processes, the heat from the steam inside the insulation pipe can be transferred to the surrounding copper wires, thereby heating and insulating the insulation core and sheath material. This method achieves a similar effect to placing the cable in a drying oven for several hours before construction in special low-temperature environments. However, it is far more effective in preventing low-temperature cracking of the cable material. This is because the cable cools rapidly in extremely low temperatures after leaving the drying oven, and excessive temperature changes can lead to cracking. In comparison, the insulation pipe filled with high-temperature steam provides longer-lasting insulation from the inside out, preventing excessive temperature changes that could cause material cracking when exposed to low-temperature environments. This method is suitable for cable construction in environments below -15℃ without causing cracking of the insulation and sheath. It effectively eliminates the constraints of low-temperature environments in cable laying, resulting in high construction efficiency, low cost, and significant application value.

[0024] In practical applications, the water vapor introduced into the insulation pipe during installation condenses into water and remains in the insulation pipe. When the cable is under high load and heats up, the condensate in the insulation pipe can absorb some of the heat, making the cable conductor's thermal load higher and its power carrying capacity greater. This reduces the degree of aging of the insulation and sheathing materials in the cable due to high temperature, and can extend the service life of the cable to a certain extent. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model. Detailed Implementation

[0026] 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. Example

[0027] like Figure 1 As shown, a low-temperature resistant high-voltage flexible cable includes several insulation pipes, an insulated core composed of three insulated conductors, a filler 9, an isolation sleeve 10, a steel wire armor layer 11, a copper wrapping tape 12, and an outer sheath 13.

[0028] The insulation pipe is a hollow tube made of polytetrafluoroethylene material through extrusion and cooling. The insulation pipe includes a central insulation pipe 8 and three outer insulation pipes 7. The central insulation pipe 8 is set on the central axis between the insulated wires of the insulated core and is in contact with each insulated wire. The outer insulation pipes 7 are set in the outer gap between two adjacent insulated wires and are in contact with the two adjacent insulated wires respectively.

[0029] The insulated wire includes a conductor 1, a conductor shield 2, an insulation layer 3, an insulation shield 4, a semi-conductive wrapping tape 5, and a loosely wound copper wire shielding layer 6. The conductor shield 2, insulation layer 3, and insulation shield 4 are extruded onto the conductor 1 using a three-layer co-extrusion process. The semi-conductive wrapping tape 5 covers the insulation shield 4 and serves to even out the electrical distribution and isolate the loosely wound copper wire shielding layer 6, preventing burrs on the copper wire from scratching the insulation material. The loosely wound copper wire shielding layer 6 is formed by several annealed soft copper wires of the same diameter stranded at intervals and twisted together at a certain pitch. It is used to form a gap between the insulation pipe and the insulated wire, providing space for the thermal expansion and contraction of the insulation pipe and preventing internal stress generated during thermal expansion and contraction from compressing and damaging the insulation layer 3 and the filler 9 in contact with it.

[0030] The filler 9 is a layer of chlorinated polyethylene rubber extruded onto the cable core assembly composed of insulated wire cores and heat-insulating tubes, used to fill and round the gaps on the surface of the cable core assembly, i.e., between each wire tube.

[0031] The filler 9 is covered with an isolation sleeve 10, which is made of chlorinated polyethylene rubber material and is extruded on the outer surface of the filler 9 to isolate the loosely wound copper wire shielding layer 6 of the insulated wire core from the armored steel wire layer 11.

[0032] The steel wire armor layer 11 is a low-carbon galvanized fine steel wire armor layer set between the isolation sleeve 10 and the outer sheath 13, and is tied tightly by the copper strip 12 wrapped with reverse gaps to prevent the steel wire armor layer 11 from lifting up.

[0033] The outer sheath 13 is a low-temperature resistant rubber elastomer sheath extruded onto the steel wire armor layer 11.

[0034] The conductor shield 2 and the insulating shield 4 are preferably 0.6mm-0.8mm thick, and the insulating layer 4 is preferably 3.4mm thick. This thickness distribution can ensure the insulation effect while also having a certain thermal conductivity, so that the heat in the heat-insulating pipe that is filled with high-temperature steam can penetrate into each layer of insulating and shielding rubber material, and better prevent the insulating rubber material from becoming brittle in low-temperature environments.

[0035] The copper wire diameter of the loosely wound copper wire shielding layer 6 is 0.75mm-1.13mm. Copper wires within this diameter range can ensure that the conductor will not be thinned or broken during the loosening process. The average gap of the loosely wound copper wires is less than or equal to 4mm. Thus, the total area of ​​the loosely wound metal shield is larger than the cross-sectional area of ​​the metal braid, and it can carry a larger fault short-circuit current.

Claims

1. A low-temperature resistant high-voltage flexible cable, characterized in that: It includes an insulating core consisting of several insulation pipes and several insulated wires, a filler, an isolation sleeve, a steel wire armor layer, wrapped copper tape, and an outer sheath; The insulation pipe is a hollow tube made of polytetrafluoroethylene material through extrusion and cooling. The insulation pipe includes a central insulation pipe and several outer insulation pipes. The central insulation pipe is set on the central axis between the insulated wires of the insulated core and is in contact with each insulated wire. The outer insulation pipes are set in the outer gap between two adjacent insulated wires and are in contact with the two adjacent insulated wires respectively. The insulated wire includes a conductor, a conductor shield, an insulation layer, an insulation shield, a semi-conductive wrapping tape, and a loosely wound copper wire shield. The conductor shield, insulation layer, and insulation shield are extruded onto the conductor using a three-layer co-extrusion process. The semi-conductive wrapping tape covers the insulation shield and serves to even out the power distribution and isolate the loosely wound copper wire shield, preventing burrs on the copper wire from scratching the insulation layer. The loosely wound copper wire shield is formed by several annealed soft copper wires of the same diameter stranded at intervals at a certain pitch. It is used to create a gap between the insulation pipe and the insulated wire, providing space for the thermal expansion and contraction of the insulation pipe and preventing internal stress generated during thermal expansion and contraction from compressing and damaging the insulation layer of the insulated wire and the filler in contact with it. The filler is a layer of chlorinated polyethylene rubber extruded onto the cable core assembly, which consists of insulated wire cores and heat-insulating tubes, and is used to fill and round the gaps on the surface of the cable core assembly, i.e., between each wire tube. The filler body is covered with an isolation sleeve, which is made of chlorinated polyethylene rubber material and is extruded on the outer surface of the filler body to isolate the loosely wound copper wire shielding layer of the insulated wire core from the armored steel wire layer. The steel wire armor layer is a low-carbon galvanized fine steel wire armor layer set between the isolation sleeve and the outer sheath, and is tightly bound by the copper strip wrapped with reverse gaps to prevent the steel wire armor layer from lifting. The outer sheath is a low-temperature resistant rubber elastomer sheath extruded onto a steel wire armor layer.

2. The low-temperature resistant high-voltage flexible cable as described in claim 1, characterized in that... The conductor shielding and insulation shielding thickness is preferably 0.6mm-0.8mm, and the ethylene propylene rubber insulation thickness is preferably 3.4mm.

3. A low-temperature resistant high-voltage flexible cable as described in claim 1 or 2, characterized in that... The diameter of the copper wires in the loosely wound copper wire shielding layer is 0.75mm-1.13mm, and the average gap between the copper wires is less than or equal to 4mm.

4. A low-temperature resistant high-voltage flexible cable as described in claim 1 or 2, characterized in that... The thickness of the insulation pipe wall is not less than 1.5mm.

5. A low-temperature resistant high-voltage flexible cable as described in claim 3, characterized in that... The thickness of the insulation pipe wall is not less than 1.5mm.

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