Low-temperature-resistant construction high-voltage flexible cable and laying construction method thereof

Abstract

The invention discloses a low-temperature-resistant construction high-voltage flexible cable and a laying construction method thereof. The low-temperature-resistant construction high-voltage flexible cable is characterized by comprising a plurality of thermal insulation pipes, an insulation wire core composed of a plurality of insulation wires, a filling body, an isolation sleeve, a steel wire armor layer, a winding copper strip and an outer sheath, the cable is suitable for construction insulation and sheath cracking in an environment with a low temperature of-15 DEG C or below, can effectively enable cable laying construction not to be restricted by a low-temperature environment of a construction region, is high in construction efficiency and low in cost, and has popularization and application values. In addition, in specific application, as water vapor introduced into the thermal insulation pipe is condensed into water and then is retained in the thermal insulation pipe during laying construction, when the cable generates heat with high load, the condensed water retained in the thermal insulation pipe can absorb a part of heat, so that the thermal load of the cable conductor is higher, the bearing power is higher, and the service life of the cable conductor is prolonged. The aging degree of insulation and sheath materials 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] The present invention relates to the technical field of high-voltage flexible cables, and in particular to a low-temperature resistant high-voltage flexible cable and a laying method thereof. Background Art

[0002] Currently, during cable laying in cold regions, the sheath and insulating rubber materials often become brittle and their toughness reduced due to extreme low temperatures. Dragging and bending the cables during installation can lead to stress concentration, damaging the sheath and insulation layers. This results in extremely high construction losses. Even when cable installation is successfully completed, numerous subtle cracks and hidden defects can easily develop on the insulation and sheath, severely impacting the stability and efficiency of power supply. Therefore, cable laying construction will be avoided in extremely low temperature environments during construction. However, in extremely cold areas such as my country's high latitudes and high altitudes, the window period suitable for laying power cable construction often cannot meet the needs of local economic construction, which to a large extent restricts local economic development.

[0003] To solve these problems, the general solutions are as follows: 1. Environmental monitoring: Continuously monitor the ambient temperature before construction to avoid working in a period of sustained low temperature; 2. Material pretreatment: Store the cable in a suitable temperature environment for a sufficient period of time to restore its normal temperature performance; 3. Protective measures: Use heating tents and other equipment to create a local temperature environment suitable for laying operations; 4. Process adjustment: reduce the pulling speed, increase the bending radius, and use a special low-temperature lubricant; However, the above solutions all have the problems of low construction efficiency and high cost. Summary of the Invention

[0004] In response to the problems mentioned in the background technology, the present invention provides a low-temperature resistant high-voltage soft cable and a laying construction method thereof, which has little impact on cable sheath and insulation during low-temperature construction, has high construction efficiency and low cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A low-temperature resistant construction high-voltage flexible cable, characterized by comprising a plurality of insulation tubes, an insulating core composed of a plurality of insulated conductors, a filler, an isolation sleeve, a steel wire armor layer, a wrapped copper tape and an outer sheath; The insulation tube is a hollow tube made of polytetrafluoroethylene material through extrusion and cooling through a die. The insulation tube includes a central insulation tube and a plurality of outer insulation tubes. The central insulation tube is arranged on the central axis between the insulated wires of the insulated core and contacts each insulated wire. The outer insulation tube is arranged in the outer gap between two adjacent insulated wires and contacts the two adjacent insulated wires respectively. The insulated wire includes a conductor, a conductor shield, an insulating layer, an insulating shield, a semi-conductive tape, and a sparsely wound copper wire shield. The conductor shield, insulating layer, and insulating shield are extruded onto the conductor through a three-layer co-extrusion process. The semi-conductive tape is coated on the insulating shield to uniformly distribute the power and isolate the sparsely wound copper wire shield, thereby preventing burrs on the copper wire from scratching the insulating layer. The sparsely wound copper wire shield is formed by twisting a number of annealed soft copper wires of the same diameter at intervals at a certain pitch, thereby forming a gap between the insulation tube and the insulated wire, providing a reserved space for the thermal expansion and contraction of the insulation tube, and preventing internal stress generated during thermal expansion and contraction of the insulation tube from squeezing and damaging the insulation layer of the insulated wire and the filler in contact therewith. The filler is a layer of chlorinated polyethylene rubber extruded on the cable core assembly consisting of an insulating wire core and a thermal insulation tube, and is used to fill the gaps between the wire tubes on the surface of the cable core assembly into a rounded shape. The outer surface of the filler body is covered with a layer of the isolation sleeve, which is made of chlorinated polyethylene rubber material and is extruded on the outer surface of the filler body to isolate the sparsely wound copper wire shielding layer of the insulated core and the armored steel wire layer; The steel wire armor layer is a low-carbon galvanized fine steel wire armor layer provided between the isolation sleeve and the outer sheath, and is fastened by the copper tape wound in reverse gap to prevent the steel wire armor layer from becoming flared. The outer sheath is a low-temperature resistant rubber elastic body sheath extruded on the steel wire armor layer.

[0006] A further solution of the present invention is: the thickness of the conductor shield and the insulation shield is preferably 0.6mm-0.8mm, and the thickness of the EPDM rubber insulation is preferably 3.4mm; this thickness distribution can ensure the insulation effect while having a certain thermal conductivity, so that the heat in the insulation pipe passing high-temperature steam can penetrate into each layer of insulation and shielding rubber material, thereby better preventing the embrittlement of the insulating rubber material in a low-temperature environment.

[0007] A further solution of the present invention is: the diameter of the copper wire of the sparsely wound copper wire shielding layer is 0.75mm-1.13mm. The copper wire within this diameter range can ensure that the conductor will not be stretched or broken during the sparse winding process. The average gap between the sparsely wound copper wires is less than or equal to 4mm. In this way, the total area of ​​the sparsely wound metal shielding is larger than the metal braiding cross-sectional area, and can carry a larger fault short-circuit current.

[0008] A further solution of the present invention is that the thickness of the wall of the thermal insulation pipe is not less than 1.5 mm, and when connected to high-pressure and high-temperature steam, it can withstand a water vapor pressure of at least 1.3-1.8 MPa, and at the same time has a certain heat transfer performance.

[0009] The present invention also includes a method for laying the above-mentioned low-temperature resistant high-voltage soft cable, which is characterized in that during construction, one end of the insulation pipe is connected to the steam generator, high-temperature water vapor is introduced into it, and after the entire pipe body is ventilated and preheated, the other end is completely sealed first. After the steam pressure in the insulation pipe is filled, conventional laying construction can be carried out like ordinary cables.

[0010] The beneficial effects of the present invention are as follows: an insulation tube is arranged in the cable, and polytetrafluoroethylene is selected as the insulation tube material, which can withstand a temperature of 200°C, and will not deform after three vulcanizations, has a certain strength and will not collapse. At the same time, the steam heat in the insulation tube can be transferred to the surrounding copper wire, thereby heating and keeping the insulation core and sheath material warm. This situation has the same effect as putting the cable into a drying room for several hours before construction in a special low-temperature environment, and the effect of preventing the cable material from cracking at low temperature is much stronger than the latter. Because the cable after leaving the drying room quickly cools down in an extremely low temperature environment, excessive temperature changes lead to cracking. In comparison, the insulation tube filled with high-temperature water vapor inside has a relatively longer insulation duration from the inside to the outside, and when exposed to a low-temperature environment, the temperature will not change too much to cause the material to crack. It is suitable for cable construction in an environment below -15°C without cracking the insulation and sheath, and can effectively prevent the cable laying construction from being restricted by the low-temperature environment of the construction area. The construction efficiency is high, the cost is low, and it has promotion and application value.

[0011] In addition, in specific applications, due to the water vapor introduced into the insulation pipe during laying construction, it condenses into water and remains in the insulation pipe. When the cable is heated by high load, the condensed water retained in the insulation pipe can absorb heat, making the thermal load of the cable conductor higher and the carrying power greater. At the same time, it reduces the high-temperature aging rate of the cable insulation and sheath materials, which can extend the service life of the cable to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention. Example

[0014] like Figure 1 As shown, a low-temperature resistant construction high-voltage flexible cable includes several insulation tubes, an insulated core consisting of three insulated conductors, a filler 9, an isolation sleeve 10, a steel wire armor layer 11, a wrapped copper tape 12 and an outer sheath 13; The insulation tube is a hollow tube made of polytetrafluoroethylene material through extrusion and cooling by a die. The insulation tube includes a central insulation tube 8 and three outer insulation tubes 7. The central insulation tube 8 is arranged on the central axis between the insulated wires of the insulated core and contacts each insulated wire. The outer insulation tubes 7 are arranged in the outer gap between two adjacent insulated wires and contact the two adjacent insulated wires respectively. The insulated wire includes a conductor 1, a conductor shield 2, an insulating layer 3, an insulating shield 4, a semi-conductive tape 5 and a sparsely wound copper wire shield 6. The conductor shield 2, the insulating layer 3 and the insulating shield 4 are extruded on the conductor 1 through a three-layer co-extrusion process. The semi-conductive tape 5 is coated on the insulating shield 4 and is used to uniformly distribute the power and isolate the sparsely wound copper wire shield 6 to prevent burrs on the copper wire from scratching the insulating material. The sparsely wound copper wire shield 6 is formed by twisting a number of annealed soft copper wires of the same diameter at a certain pitch and arranged at intervals. It is used to form a gap between the insulation pipe and the insulated wire, providing reserved space for the thermal expansion and contraction of the insulation pipe, and preventing the internal stress generated by the thermal expansion and contraction of the insulation pipe from squeezing and damaging the insulating layer 3 of the insulated wire and the filler 9 in contact therewith; The filler 9 is a layer of chlorinated polyethylene rubber extruded on the cable core assembly consisting of the insulating wire core and the insulation tube, and is used to fill the gaps between the wire tubes on the surface of the cable core assembly into a round shape; The filler 9 is covered with a layer of the isolation sleeve 10. The isolation sleeve 10 is made of chlorinated polyethylene rubber material and is extruded on the outer surface of the filler 9 to isolate the sparsely wound copper wire shielding layer 6 of the insulated core and the armored steel wire layer 11. The steel wire armor layer 11 is a low-carbon galvanized fine steel wire armor layer provided between the isolation sleeve 10 and the outer sheath 13 and is fastened by the reverse gap-wound copper tape 12 to prevent the steel wire armor layer 11 from becoming flared. The outer sheath 13 is a low-temperature resistant rubber elastomer sheath extruded onto the steel wire armor layer 11 .

[0015] The thickness of the conductor shield 2 and the insulating shield 4 is preferably 0.6mm-0.8mm, and the thickness of the insulating layer 4 is preferably 3.4mm; this thickness distribution can ensure the insulation effect while having a certain thermal conductivity, so that the heat in the insulation pipe passed with high-temperature steam can penetrate into each layer of insulation and shielding rubber material, better preventing the embrittlement of the insulating rubber material in a low-temperature environment.

[0016] The diameter of the copper wire of the sparsely wound copper wire shielding layer 6 is 0.75mm-1.13mm. The copper wire within this diameter range can ensure that the conductor will not be stretched or broken during the sparse winding process. The average gap between the sparsely wound copper wires is less than or equal to 4mm. In this way, the total area of ​​the sparsely wound metal shielding is larger than the metal braiding cross-sectional area, and can carry a larger fault short-circuit current.

Claims

1. A low temperature resistant construction high voltage flexible cable, characterized by It includes several insulation pipes, several insulated wires consisting of insulated cores, filling bodies, isolation sleeves, steel wire armor layers, wrapped copper tapes and outer sheaths; The insulation tube is a hollow tube made of polytetrafluoroethylene material through extrusion and cooling through a die. The insulation tube includes a central insulation tube and a plurality of outer insulation tubes. The central insulation tube is arranged on the central axis between the insulated wires of the insulated core and contacts each insulated wire. The outer insulation tube is arranged in the outer gap between two adjacent insulated wires and contacts the two adjacent insulated wires respectively. The insulated wire includes a conductor, a conductor shield, an insulating layer, an insulating shield, a semi-conductive tape, and a sparsely wound copper wire shield. The conductor shield, insulating layer, and insulating shield are extruded onto the conductor through a three-layer co-extrusion process. The semi-conductive tape is wrapped over the insulating shield to uniformly distribute the power and isolate the sparsely wound copper wire shield. The sparsely wound copper wire shield is formed by twisting a number of annealed soft copper wires of the same diameter at a certain pitch and arranged at intervals to form a gap between the insulation tube and the insulated wire. The filler is a layer of chlorinated polyethylene rubber extruded on the cable core assembly consisting of an insulating wire core and a thermal insulation tube, and is used to fill the gaps between the wire tubes on the surface of the cable core assembly into a rounded shape. The outer surface of the filler body is covered with a layer of the isolation sleeve, which is made of chlorinated polyethylene rubber material and is extruded on the outer surface of the filler body to isolate the sparsely wound copper wire shielding layer of the insulated core and the armored steel wire layer; The steel wire armor layer is a low-carbon galvanized fine steel wire armor layer provided between the isolation sleeve and the outer sheath, and is fastened by the copper tape wound in reverse gap to prevent the steel wire armor layer from becoming flared. The outer sheath is a low-temperature resistant rubber elastic body sheath extruded on the steel wire armor layer.

2. A low temperature resistant construction high voltage flexible cable as claimed in claim 1, characterized in that The thickness of the conductor shield and insulation shield is preferably 0.6mm-0.8mm, and the thickness of the EPDM rubber insulation is preferably 3.4mm.

3. A low temperature resistant construction high voltage flexible cable as claimed in claim 1 or 2, characterized in that The diameter of the copper wires of the sparsely 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 construction high voltage flexible cable as claimed in claim 1 or 2, characterized in that The thickness of the wall of the thermal insulation pipe is not less than 1.5 mm.

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

6. A method for laying a low-temperature resistant high-voltage flexible cable according to any one of claims 1 to 5, characterized in that During construction, one end of the insulation pipe is connected to the steam generator, and high-temperature water vapor is passed into it. After the entire pipe body is ventilated and preheated, the other end is completely sealed first. After the steam pressure in the insulation pipe is filled, conventional laying construction can be carried out like ordinary cables.

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