A kind of intelligent fireproof medium voltage cable and preparation method thereof

Abstract

The present invention discloses an intelligent fireproof medium-voltage cable and a preparation method thereof, comprising a trunk cable body, a temperature measuring layer and a sheath arranged in sequence from the inside to the outside; the trunk cable body comprises an insulating cable, a cooling metal tube, a filler and a flame-retardant buffer layer arranged in sequence from the inside to the outside, the insulating cable is formed by a conductor, a composite insulating layer, a semi-conductive buffer layer and a metal shielding layer tightly wrapped in sequence from the inside to the outside, and the cooling metal tube is arranged on the periphery of the metal shielding layer; the temperature measuring layer comprises an insulation layer, a temperature measuring optical fiber unit, a cooling metal tube and a buffer layer wrapped in sequence from the inside to the outside, the temperature measuring optical fiber unit comprises a temperature measuring optical fiber and a cooling metal tube, a plurality of temperature measuring optical fiber units are evenly wrapped between the insulation layer and the buffer layer, and the temperature measuring layer is located between the trunk cable body and the sheath; the sheath comprises a metal sheath and an outer sheath wrapped in sequence from the inside to the outside. The temperature measuring optical fiber unit independently arranged in the temperature measuring layer is convenient for installation and maintenance, and the evenly distributed temperature measuring optical fiber units have a low false alarm rate.

Description

Technical Field

[0001] The present invention relates to the technical field of fireproof medium-voltage cables, and in particular to an intelligent fireproof medium-voltage cable and a preparation method thereof. Background Art

[0002] According to statistics, more than 60% of all types of electrical fires in my country are caused by wires and cables. Among them, medium-voltage cables are widely laid in various occasions in cities and play an important role in power transportation. Therefore, temperature monitoring and fire protection performance of medium-voltage cables are important indicators of medium-voltage cables.

[0003] A Chinese utility model with announcement number CN209199657U discloses a temperature-measuring medium-voltage cross-linked power cable, comprising three medium-voltage cross-linked polyethylene insulated cores, a tape layer, an inner sheath layer and an outer sheath layer sequentially wrapped around the three medium-voltage cross-linked polyethylene insulated cores, a filler in the gap between the three medium-voltage cross-linked polyethylene insulated cores and the tape layer, and also comprising a temperature-measuring optical fiber unit, which is arranged in the gap formed between the three medium-voltage cross-linked polyethylene insulated cores, and has a temperature-sensing optical fiber, and the temperature-sensing optical fiber is sequentially wrapped with a stainless steel tube, a stainless steel braided mesh and a polyethylene sheath.

[0004] The applicant found that the above-mentioned temperature-measuring medium-voltage cross-linked power cable has only one temperature-measuring optical fiber unit arranged between three medium-voltage cross-linked polyethylene insulated wire cores. When the power is turned on, the temperature of the area between the three medium-voltage cross-linked polyethylene insulated wire cores is easy to rise, and the temperature-measuring optical fiber unit is easy to be damaged. Only one temperature-measuring optical fiber unit is easy to cause false alarms, affecting the normal use of the cable. On the other hand, the fire and heat resistance of the cable is poor. Summary of the invention

[0005] In order to overcome the above technical defects, the present invention provides an intelligent fireproof medium voltage cable and a preparation method thereof which has small temperature measurement error, a temperature measuring optical fiber unit that is not easily damaged, and is fireproof.

[0006] In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0007] The intelligent fireproof medium voltage cable of the present invention is characterized by comprising a main cable body, a temperature measuring layer and a sheath which are sequentially arranged from the inside to the outside;

[0008] The trunk cable body comprises an insulating cable, a cooling metal tube, a filler and a flame retardant buffer layer arranged in sequence from the inside to the outside, the insulating cable is formed by tightly wrapping a conductor, a composite insulating layer, a semi-conductive buffer layer and a metal shielding layer in sequence from the inside to the outside, and the cooling metal tube is arranged on the periphery of the metal shielding layer;

[0009] The temperature measuring layer includes a heat insulation layer, a temperature measuring optical fiber unit, a cooling metal tube and a buffer layer which are sequentially coated from the inside to the outside, the temperature measuring optical fiber unit includes a temperature measuring optical fiber and a cooling metal tube, a plurality of the temperature measuring optical fiber units are evenly wrapped between the heat insulation layer and the buffer layer, and the temperature measuring layer is located between the trunk cable body and the sheath;

[0010] The sheath comprises a metal sheath and an outer sheath which are sequentially covered from the inside to the outside.

[0011] Preferably, at least five cooling metal tubes are evenly distributed on the periphery of the insulated cable.

[0012] Preferably, the trunk cable body comprises three insulating cables, and the three insulating cables are twisted into a cable.

[0013] Furthermore, three of the insulating cables are twisted around a cooling metal tube, and the remaining cooling metal tubes are evenly distributed on the periphery of the insulating cables.

[0014] Specifically, the temperature measuring optical fiber units are arranged in three of the cooling metal tubes located in the temperature measuring layer, and the angle between the three cooling metal tubes with the temperature measuring optical fiber units relative to the axis of the trunk cable body is 60°.

[0015] Preferably, the cooling metal tube is a corrugated copper tube.

[0016] Preferably, the composite insulating layer comprises an inner shielding layer, a cross-linked polyethylene insulating layer and an outer shielding layer which are arranged in sequence from the inside to the outside.

[0017] Preferably, the semi-conductive buffer layer is formed by winding a semi-conductive buffer water-blocking tape.

[0018] The present invention also provides a method for preparing an intelligent fireproof medium voltage cable, comprising the following steps:

[0019] (1) Preparing a conductor: drawing an oxygen-free copper rod to obtain a copper wire, and twisting a plurality of copper wires into a shape to obtain a twisted conductor structure;

[0020] (2) Composite insulation layer molding: extruding the inner shielding layer, the cross-linked polyethylene insulation layer and the outer shielding layer from the inside to the outside in sequence on the outer surface of the conductor in step (1), and completing cross-linking in a cross-linking pipe to form a composite insulation layer on the outer periphery of the conductor;

[0021] The inner shielding layer, the cross-linked polyethylene insulating layer and the outer shielding layer are extruded in one step by a three-layer co-extrusion method using a catenary cross-linking production line;

[0022] (3) preparing an insulated cable: wrapping a semi-conductive buffer water-blocking tape on the outer shielding layer of step (2) to form a semi-conductive buffer layer, and then wrapping a copper tape on the semi-conductive buffer layer by a copper tape shielding machine to form a metal shielding layer;

[0023] Among them, the overlap rate of the metal shielding layer is 10%-15%;

[0024] (4) Preparing the main cable body: twisting three insulated cables into a cable through a cabling machine, wrapping a flame retardant buffer tape around the cable to form a flame retardant buffer layer, filling a filler between the flame retardant buffer layer and the insulated cables, twisting the cooling metal tube and the insulated cables together into a cable, twisting the three insulated cables around a cooling metal tube, and wrapping a heat insulation layer around the flame retardant buffer layer;

[0025] The cooling metal tube is evenly wound around the outer circumference of the insulating cable, and the outer circumference of each insulating cable includes at least four cooling metal tubes; the thermal insulation layer is made of ceramic polyolefin material, extruded by an extruder, and coated on the flame retardant buffer layer;

[0026] (5) Preparation of temperature measuring optical fiber unit: The cooling metal tube uses a prefabricated corrugated copper tube to wrap the temperature measuring optical fiber unit inside, and the temperature measuring optical fiber unit is wrapped in the cooling metal tube;

[0027] (6) Winding the temperature measuring optical fiber unit: Winding a plurality of cooling metal tubes and the cooling metal tube wrapped with the temperature measuring optical fiber unit uniformly on the outer surface of the insulation layer through a cage twisting machine, and then wrapping the buffer layer around the outer circumference of the cooling metal tube;

[0028] (7) Wrapping the sheath: Wrapping the metal sheath and the outer sheath on the outer periphery of the buffer layer in sequence;

[0029] Among them, the outer sheath is made of low-smoke halogen-free polyolefin material.

[0030] Preferably, the metal sheath in step (6) is a corrugated copper tube made by sequentially passing a copper tube through argon arc welding and a corrugator.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The intelligent fireproof medium voltage cable has a temperature measuring layer, which has a number of evenly distributed temperature measuring optical fiber units, which can measure the temperature in all directions of the cable, with a low false alarm rate, and the temperature measuring optical fiber unit is not easy to damage. The temperature measuring optical fiber unit is located on the periphery of the trunk cable body. When the temperature measuring optical fiber unit fails, it is easy to install, disassemble, repair and replace.

[0033] 2. The intelligent fireproof medium voltage cable includes a flame retardant buffer layer, a heat insulation layer and a cooling metal tube. The temperature measuring optical fiber unit is arranged inside the cooling metal tube, so that the fireproof performance of the overall structure of the intelligent fireproof medium voltage cable is remarkable. When the cable has high temperature, a warning of the high temperature part is issued in time. At the same time, the cooling metal tube cools the cable to prevent fire, effectively reducing the risk of fire.

[0034] 3. Through the preparation method of the present invention, by setting the temperature measuring optical fiber unit in the cooling metal tube, and then winding the cooling metal tube between the insulation layer and the buffer layer, the temperature measuring optical fiber unit is separated from the main cable body, which effectively solves the technical problem of installing the temperature measuring optical fiber unit in the cable. The setting of the temperature measuring layer independent of the main cable body greatly reduces the difficulty of installing the temperature measuring optical fiber unit, thereby reducing the difficulty of producing the intelligent fireproof medium voltage cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings, wherein:

[0036] Figure 1 is a cross-sectional schematic diagram of the intelligent fireproof medium voltage cable of the present invention;

[0037] In the figure:

[0038] 1- Trunk cable body;

[0039] 11-insulated cable, 111-conductor, 112-composite insulation layer, 113-semiconductive buffer layer, 114-metal shielding layer;

[0040] 12-Cooling metal pipe;

[0041] 13- filler;

[0042] 14-flame retardant buffer layer;

[0043] 2-temperature measuring layer, 21-insulating layer, 22-temperature measuring optical fiber unit, 23-buffer layer;

[0044] 3-sheath, 31-metal sheath, 32-outer sheath. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0046] like Figure 1 The figure shows the preferred structure of the intelligent fireproof medium voltage cable described in the present invention.

[0047] like Figure 1As shown, the intelligent fireproof medium voltage cable includes a main cable body 1, a temperature measuring layer 2 and a sheath 3 arranged in sequence from the inside to the outside. The main cable body 1 is used for conducting electricity, the temperature measuring layer 2 is used for monitoring the temperature of the cable, and the sheath 3 is used for protecting the cable from the complex external laying environment.

[0048] The main cable body 1 includes an insulating cable 11 , a cooling metal tube 12 , a filler 13 and a flame retardant buffer layer 14 which are arranged in sequence from the inside to the outside.

[0049] The insulated cable 11 is used to transmit power. The insulated cable 11 is formed by tightly wrapping a conductor 111, a composite insulating layer 112, a semi-conductive buffer layer 113 and a metal shielding layer 114 from the inside to the outside, and the cooling metal tube 12 is arranged on the periphery of the metal shielding layer 114. The conductor 111 is used for conducting electricity, the composite insulating layer 112 is used to prevent the conductor 111 from leaking electricity, the flame-retardant buffer layer 113 is used to buffer and weaken the electric field, and the metal shielding layer 114 is used to shield the electromagnetic field.

[0050] The conductor 111 is made of copper, and a plurality of oxygen-free copper rods formed by wire drawing are twisted together to form the conductor 111. The conductor 111 complies with the second conductor structure specified in GB / T3956-2008, which is a twisted conductor structure.

[0051] The composite insulating layer 112 is formed by tightly wrapping a shielding layer, a cross-linked polyethylene insulating layer and an outer shielding layer in sequence from the inside to the outside. The inner surface of the shielding layer is coated on the outer periphery of the conductor 111. The composite insulating layer 112 has good insulation effect and can significantly prevent leakage.

[0052] The semiconductive buffer layer 113 is formed by winding a semiconductive buffer water-blocking tape around the outer circumference of the composite insulating layer 112. The semiconductive buffer water-blocking tape has a semiconductive property. While buffering and weakening the electric field strength, it also has a water-blocking property, which can prevent moisture from further diffusing along the longitudinal direction of the cable.

[0053] The metal shielding layer 114 is made of copper tape. The copper tape is wrapped around the outer surface of the semi-conductive buffer shielding layer to form the metal shielding layer 114. The copper tape can further shield the electromagnetic field to prevent the electromagnetic field from affecting external equipment during the power transmission of the cable.

[0054] Through the structure of the conductor 111, the composite insulating layer 112, the semi-conductive buffer layer 113 and the metal shielding layer 114 arranged in sequence from the inside to the outside, the insulated cable 11 can transmit power while preventing leakage and the influence of the external electromagnetic field on the user.

[0055] The cooling metal tube 12 is a corrugated copper tube, and a cooling medium is contained in the cooling metal tube 12. The cooling metal tube 12 is used to cool the cable to prevent the cable temperature from being too high. At least five cooling metal tubes 12 are evenly wound around the outer circumference of the insulated cable 11. When it is detected that the cable temperature is too high, the cooling metal tube 12 works, and the cooling medium flows in the cooling metal tube 12 to take away the heat, thereby cooling the cable.

[0056] The filler 13 is filled between the outer periphery of the insulated cable 11 and the flame retardant buffer layer 14. The filler 13 is a flame retardant filler, which can prevent the cable from catching fire due to high temperature. The use of the flame retardant filler can significantly improve the fire resistance of the intelligent fireproof medium voltage cable, thereby reducing the risk of fire due to overheating of the cable.

[0057] The insulating cable 11, which is composed of an insulating cable 11, a cooling metal tube 12, a filler 13 and a flame retardant buffer layer 14, is sequentially assembled from the inside to the outside. It has good fire resistance and high temperature resistance. The cooling metal tube 12 also plays a cooling role, which can effectively prevent overheating and burning during the use of the cable.

[0058] In this embodiment, preferably, the trunk cable body 1 includes three insulating cables 11. The three insulating cables 11 are twisted around a cooling metal tube 12 to form a cable, and the remaining cooling metal tubes 12 are evenly distributed on the periphery of the insulating cables 11. The periphery of each insulating cable 11 has at least four cooling metal tubes 12. By twisting the three insulating cables 11 around a cooling metal tube 12, a trunk cable body 1 structure with better conductive performance and cooling performance is formed.

[0059] The temperature measuring layer 2 includes a heat insulating layer 21, a temperature measuring optical fiber unit 22, a cooling metal tube 12 and a buffer layer 23. The heat insulating layer 21, the temperature measuring optical fiber unit 22, the cooling metal tube 12 and the buffer layer 23 are sequentially covered from the inside to the outside.

[0060] The heat insulation layer 21 is made of ceramic material. The heat insulation layer 21 can form honeycomb-shaped holes under heating conditions, which can effectively insulate and prevent the temperature of the external environment from being transferred to the trunk cable body 1, thereby improving the high temperature resistance of the intelligent fireproof medium voltage cable. In this embodiment, the heat insulation layer 21 is preferably made of ceramic polyolefin material.

[0061] As another embodiment, the heat insulation layer 21 is made of a ceramic silicone rubber material, which has significant heat insulation properties and can meet the use requirements of the intelligent fireproof medium voltage cable.

[0062] A plurality of cooling metal tubes 12 are uniformly arranged around the outer circumference of the heat insulation layer 21. The cooling metal tubes 12 are corrugated copper tubes.

[0063] The temperature measuring optical fiber unit 22 is arranged in the cooling metal tube 12. The cooling metal tube 12 can effectively protect the temperature measuring optical fiber unit 22 to prevent the temperature measuring optical fiber unit 22 from being damaged during the corrugation of the argon arc welding process. At the same time, the cooling metal tube 12 is a corrugated copper tube, which has strong thermal conductivity and can quickly transmit the temperature changes inside and outside the cable to the temperature measuring optical fiber unit 22. The temperature measuring optical fiber unit 22 can continuously monitor the temperature information of tens of kilometers of cables and detect the actual temperature in real time during the cable power transmission process.

[0064] In this embodiment, preferably, a temperature measuring optical fiber unit 22 is provided in three of the cooling metal tubes 12 located in the temperature measuring layer 2, and the angle between the three cooling metal tubes 12 relative to the axis of the trunk cable body 1 is 60°. The temperature measuring optical fiber unit 22 is provided in the cooling metal tube 12, which is easy to install and can prevent the temperature measuring optical fiber unit 22 from being damaged by external mechanical forces. The three temperature measuring optical fiber units 22 located at different angles can comprehensively monitor the internal and external temperatures of the cable, and send out temperature monitoring signals in a timely and multi-angle manner when the cable is at high temperature, thereby avoiding false alarms when local short-term high temperatures occur on the outside of the cable. The use of three temperature measuring optical fiber units 22 can prevent a single temperature measuring optical fiber unit 22 from malfunctioning and causing false alarms, thereby greatly improving the accuracy of temperature measurement.

[0065] The buffer layer 23 is formed by winding a semi-conductive buffer water-blocking tape around the outer periphery of the cooling metal tube 12. The semi-conductive buffer water-blocking tape has a semi-conductive property, and while weakening the battery strength, it also has a water-blocking property, which can prevent moisture from further diffusing along the longitudinal direction of the cable, and can buffer external mechanical pressure, cool the cooling metal tube 12 and the temperature measuring optical fiber unit 22.

[0066] The sheath 3 includes a metal sheath 31 and an outer sheath 32. The metal sheath 31 is wrapped around the outer periphery of the buffer layer 23, and the outer sheath 32 further wraps around the outer periphery of the metal sheath 31, thereby providing comprehensive protection. The metal sheath 31 is a copper sheath, which has strong thermal conductivity and can evenly transfer and disperse heat, effectively preventing the occurrence of heat concentration, and preventing flames from directly burning the internal structure, thereby enhancing the fire resistance of the cable.

[0067] As one implementation manner, the metal sheath 31 is a corrugated copper sheath, and the outer sheath 32 is made of a low-smoke halogen-free polyolefin material.

[0068] As another embodiment, the outer sheath 32 is made of flame-retardant PVC material.

[0069] The working principle of the intelligent fireproof medium voltage cable described in the present invention is:

[0070] The intelligent fireproof medium voltage cable has a temperature measuring layer 2, which has a plurality of evenly distributed temperature measuring optical fiber units 22, which can measure the temperature in all directions of the cable, have a low false alarm rate, and the temperature measuring optical fiber units 22 are not easily damaged. The temperature measuring optical fiber units 22 are located on the periphery of the trunk cable body 1, and when the temperature measuring optical fiber units 22 fail, they are easy to install, disassemble, repair and replace.

[0071] On the other hand, the intelligent fireproof medium voltage cable includes a flame retardant buffer layer 14, an insulation layer 21 and a cooling metal tube 12. The temperature measuring optical fiber unit 22 is arranged inside the cooling metal tube 12, so that the fireproof performance of the overall structure of the intelligent fireproof medium voltage cable is significant. When the cable has high temperature, a warning of the high temperature part is issued in time. At the same time, the cooling metal tube 12 cools the cable to prevent fire, effectively reducing the risk of fire.

[0072] For other structures of the intelligent fireproof medium voltage cable described in this embodiment, refer to the prior art.

[0073] Example 2

[0074] The present invention also provides a method for preparing an intelligent fireproof medium voltage cable, which is used to prepare the intelligent fireproof medium voltage cable described in the above-mentioned embodiment 1. Based on the preparation method provided by the present invention, the technical problem of installing the temperature measuring optical fiber unit 22 into the cable is solved, and the temperature measuring optical fiber unit 22 installed by the preparation method is easy to maintain and replace.

[0075] The preparation method of the intelligent fireproof medium voltage cable comprises the following steps:

[0076] (1) Preparing the conductor 111: An oxygen-free copper rod is drawn to obtain a copper wire, and a plurality of copper wires are twisted to form a twisted conductor 111 structure.

[0077] The twisted conductor 111 complies with the second conductor structure specified in GB / T3956-2008.

[0078] (2) Forming the composite insulating layer 112: The inner shielding layer, the cross-linked polyethylene insulating layer and the outer shielding layer are sequentially extruded from the inside to the outside on the outer surface of the conductor 111 in step (1), and cross-linking is completed in a cross-linking pipe to form a composite insulating layer 112 on the outer periphery of the conductor 111.

[0079] The inner shielding layer, the cross-linked polyethylene insulating layer and the outer shielding layer are extruded at one time in a three-layer co-extrusion manner using a catenary cross-linking production line.

[0080] At the same time, the connection structure between the inner shielding layer, the cross-linked polyethylene insulation layer and the outer shielding layer, which are extruded at one time, is tight, which reduces the gap between the insulation layer and the shielding layer and improves the insulation performance.

[0081] (3) Preparing an insulated cable 11: Wrapping a semi-conductive buffer water-blocking tape on the outer shielding layer of step (2) to form a semi-conductive buffer layer 113, and then wrapping a copper tape on the semi-conductive buffer layer 113 using a copper tape shielding machine to form a metal shielding layer 114.

[0082] In this embodiment, the overlap rate of the metal shielding layer 114 is preferably 10%-15%. By controlling the overlap rate of the metal shielding layer 114 to be 10%-15%, the shielding effect of the metal shielding can be ensured while saving copper tape.

[0083] (4) Preparing the main cable body 1: three insulated cables 11 are twisted into a cable by a cabling machine, and a flame retardant buffer tape is wrapped around the cable to form a flame retardant buffer layer 14. Filling material 13 is filled between the flame retardant buffer layer 14 and the insulated cables 11. At the same time, the cooling metal tube 12 is twisted into a cable together with the insulated cables 11. The three insulated cables 11 are twisted into a cable around a cooling metal tube 12, and a heat insulation layer 21 is wrapped around the outer periphery of the flame retardant buffer layer 14.

[0084] The cooling metal tubes 12 are uniformly wound around the outer circumference of the insulating cable 11 , and the outer circumference of each insulating cable 11 includes at least four cooling metal tubes 12 ; the heat insulation layer 21 is extruded by an extruder and coated on the flame retardant buffer layer 14 .

[0085] Specifically, the filler 13 is a flame retardant filler, and the cooling metal tube 12 is a prefabricated corrugated copper tube.

[0086] Specifically, the thermal insulation layer 21 is formed by adding ceramic material into an extruder and extruding it. The ceramic material will form a hard crust at a high temperature above 350°C and can form honeycomb-shaped pores under heating conditions. The honeycomb-shaped pores can make the thermal insulation effect of the thermal insulation layer more significant.

[0087] As one implementation manner, the heat insulation layer 21 is made of ceramic polyolefin material.

[0088] As another embodiment, the heat insulation layer 21 is made of ceramic silicone rubber material.

[0089] (5) Preparation of the temperature measuring optical fiber unit 22: The cooling metal tube 12 is a prefabricated corrugated copper tube, and the temperature measuring optical fiber unit 22 is wrapped in the cooling metal tube 12.

[0090] The temperature measuring optical fiber unit 22 wrapped by the cooling metal tube 12 can be suitable for various installations. The cooling metal tube 12 can protect the temperature measuring optical fiber unit 22 from damage during processes such as argon arc welding, which greatly reduces the difficulty of manufacturing the intelligent fireproof medium voltage cable.

[0091] (6) Winding the temperature measuring optical fiber unit 22: Winding a plurality of cooling metal tubes 12 and the cooling metal tubes 12 wrapped with the temperature measuring optical fiber unit 22 uniformly on the outer surface of the insulation layer 21 through a cage twisting machine, and then wrapping the buffer layer 23 around the outer circumference of the cooling metal tube 12.

[0092] In this embodiment, preferably, the buffer layer 23 is formed by winding a semi-conductive buffer water-blocking tape around the outer surface of the temperature measuring optical fiber unit 22 and the cooling metal tube 12. The cooling metal tube 12 is evenly wrapped around the outer periphery of the buffer layer 23, so that the cooling metal tube 12 can support the semi-conductive buffer water-blocking tape to be wound around the outer periphery of the cooling metal tube 12, and the wrapped buffer layer 23 plays a role in limiting and fixing the cooling metal tube 12, so that the overall structure is firm.

[0093] (7) Sheath 3: The outer periphery of the buffer layer 23 is covered with a metal sheath 31 and an outer sheath 32 in sequence.

[0094] The metal sheath 31 is a copper sheath, which can disperse heat to prevent heat concentration and prevent flames from directly burning the internal structure, thereby enhancing the fire resistance of the cable.

[0095] The outer sheath 32 is extruded by a tube extrusion die. As one embodiment, the outer sheath 32 is made of low-smoke halogen-free polyolefin material. As another embodiment, the outer sheath 32 is made of flame-retardant PVC material.

[0096] In this embodiment, the metal sheath 31 in step (6) is preferably a corrugated copper tube made by sequentially passing a copper tube through argon arc welding and a corrugator.

[0097] Through the preparation method described in this embodiment, the temperature measuring optical fiber unit 22 is protected during the manufacturing process, so that the damage rate of the temperature measuring optical fiber unit 22 is greatly reduced. Moreover, the temperature measuring optical fiber unit 22 is wrapped in the cooling metal tube 12, and the hard cooling metal tube 12 is easy to install and wind, which greatly reduces the difficulty of installing the temperature measuring optical fiber unit 22 into the cable.

[0098] The working principle of the method for preparing the intelligent fireproof medium voltage cable of the present invention is:

[0099] Through the preparation method of the intelligent fireproof medium-voltage cable described in the present invention, by setting the temperature measuring optical fiber unit 22 in the cooling metal tube 12, and then winding the cooling metal tube 12 between the insulation layer 21 and the buffer layer 23, the temperature measuring optical fiber unit 22 is separated from the trunk cable body 1, and the technical difficulty of installing the temperature measuring optical fiber unit 22 in the cable is effectively solved. The setting of the temperature measuring layer 2 independent of the trunk cable body 1 greatly reduces the installation difficulty of the temperature measuring optical fiber unit 22. The temperature measuring optical fiber unit 22 is not easily damaged during the installation process, which reduces the production difficulty of the intelligent fireproof medium-voltage cable.

[0100] For other steps of the method for preparing the intelligent fireproof medium voltage cable described in this embodiment, refer to the prior art.

[0101] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An intelligent fireproof medium voltage cable, characterized in that: It comprises a main cable body (1), a temperature measuring layer (2) and a sheath (3) which are arranged in sequence from the inside to the outside; The trunk cable body (1) comprises an insulating cable (11), a cooling metal tube (12), a filler (13) and a flame retardant buffer layer (14) which are arranged in sequence from the inside to the outside; the insulating cable (11) is formed by a conductor (111), a composite insulating layer (112), a semi-conductive buffer layer (113) and a metal shielding layer (114) which are tightly wrapped in sequence from the inside to the outside; and the cooling metal tube (12) is arranged on the periphery of the metal shielding layer (114); The temperature measuring layer (2) comprises a heat insulating layer (21), a temperature measuring optical fiber unit (22), a cooling metal tube (12) and a buffer layer (23) which are sequentially coated from the inside to the outside; the temperature measuring optical fiber unit (22) is arranged in the cooling metal tube (12); a plurality of the temperature measuring optical fiber units (22) are evenly wrapped between the heat insulating layer (21) and the buffer layer (23); and the temperature measuring layer (2) is located between the main cable body (1) and the sheath (3); The sheath (3) comprises a metal sheath (31) and an outer sheath (32) which are sequentially covered from the inside to the outside; Wherein, the trunk cable body (1) comprises three insulating cables (11), and the three insulating cables (11) are twisted into a cable; At least five cooling metal tubes (12) are evenly distributed on the periphery of the insulating cable (11); three insulating cables (11) are twisted around one cooling metal tube (12), and the remaining cooling metal tubes (12) are evenly distributed on the periphery of the insulating cable (11); The temperature measuring optical fiber units (22) are arranged in three of the cooling metal tubes (12) located in the temperature measuring layer (2), and the angle between the three cooling metal tubes (12) having the temperature measuring optical fiber units (22) and the axis of the trunk cable body (1) is 60°; The composite insulating layer (112) comprises an inner shielding layer, a cross-linked polyethylene insulating layer and an outer shielding layer which are arranged in sequence from the inside to the outside; the inner shielding layer, the cross-linked polyethylene insulating layer and the outer shielding layer are extruded at one time by a three-layer co-extrusion method using a catenary cross-linking production line.

2. The intelligent fireproof medium voltage cable according to claim 1, characterized in that: The cooling metal tube (12) is a corrugated copper tube.

3. The intelligent fireproof medium voltage cable according to claim 1, characterized in that: The semi-conductive buffer layer (113) is formed by winding a semi-conductive buffer water-blocking tape.

4. A method for preparing the intelligent fireproof medium voltage cable according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) preparing a conductor (111): drawing an oxygen-free copper rod to obtain a copper wire, and twisting a plurality of copper wires to form a twisted conductor (111) structure; (2) forming the composite insulating layer (112): extruding the inner shielding layer, the cross-linked polyethylene insulating layer and the outer shielding layer sequentially from the inside to the outside on the outer surface of the conductor (111) in step (1), and completing cross-linking in a cross-linking pipe to form a composite insulating layer (112) on the outer periphery of the conductor (111); The inner shielding layer, the cross-linked polyethylene insulating layer and the outer shielding layer are extruded in one step by a three-layer co-extrusion method using a catenary cross-linking production line; (3) preparing an insulated cable (11): wrapping a semi-conductive buffer water-blocking tape on the outer shielding layer of step (2) to form a semi-conductive buffer layer (113), and then wrapping a copper tape on the semi-conductive buffer layer (113) by a copper tape shielding machine to form a metal shielding layer (114); Wherein, the overlap rate of the metal shielding layer (114) is 10%-15%; (4) preparing a trunk cable body (1): twisting three insulated cables (11) into a cable through a cabling machine, wrapping a flame retardant buffer tape around the cable to form a flame retardant buffer layer (14), filling a filler (13) between the flame retardant buffer layer (14) and the insulated cables (11), twisting a cooling metal tube (12) and the insulated cables (11) into a cable, twisting the three insulated cables (11) around a cooling metal tube (12), and wrapping a heat insulation layer (21) around the outer periphery of the flame retardant buffer layer (14); The cooling metal tube (12) is evenly wound around the outer circumference of the insulating cable (11), and the outer circumference of each insulating cable (11) includes at least four cooling metal tubes (12); the heat insulation layer (21) is made of ceramic polyolefin material, extruded by an extruder, and coated on the flame retardant buffer layer (14); (5) Preparation of the temperature measuring optical fiber unit (22): The cooling metal tube (12) is a prefabricated corrugated copper tube, and the temperature measuring optical fiber unit (22) is wrapped in the cooling metal tube (12); (6) Winding the temperature measuring optical fiber unit (22): winding a plurality of cooling metal tubes (12) and the cooling metal tube (12) wrapped with the temperature measuring optical fiber unit (22) uniformly on the outer surface of the insulation layer (21) through a cage twisting machine, and then wrapping the buffer layer (23) around the outer circumference of the cooling metal tube (12); (7) Wrapping the sheath (3): wrapping the metal sheath (31) and the outer sheath (32) on the outer periphery of the buffer layer (23) in sequence; The outer sheath (32) is made of low-smoke halogen-free polyolefin material.

5. The method for preparing the intelligent fireproof medium voltage cable according to claim 4, characterized in that: The metal sheath (31) in step (6) is a corrugated copper tube made by sequentially passing a copper tube through argon arc welding and a corrugating machine.

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