CN116682605A - Cross-linked polyethylene insulated medium-high voltage power cable - Google Patents

Abstract

The present invention relates to the technical field of power cables, and provides a cross-linked polyethylene insulated medium and high voltage power cable, which includes a wire core, a filling rope, a wrapping layer, a flame-retardant layer and an armor layer; the armor layer includes an inner layer and an armor layer. The first wrapping tape with the same twisting direction of the wire cores and the second wrapping tape at the outer layer opposite to the twisting direction of the wire cores, the first wrapping tape and the second wrapping tape The length of the cable is alternately wound to form alternating forward wraps and reverse wraps cyclically along the length of the cable; by changing the structure of the armor layer, it is possible to operate at increased transported AC current and/or reduced electrical conductor Improved cable performance in terms of cross-sectional area, cyclic inversion of the laying direction of the cable core and/or the winding direction of the armor wires along the length of the cable improves the mechanical properties of the cable and reduces hysteresis and eddy currents in the cable loss.

Description

XLPE insulated medium and high voltage power cables

technical field

The invention relates to the technical field of power cables, in particular to a cross-linked polyethylene insulated medium and high voltage power cable.

Background technique

Power cables are cables used to transmit and distribute electric energy. According to the voltage level, they can be divided into low-voltage, medium-voltage, high-voltage, and extra-high-voltage cables. In addition, they can also be divided into AC cables and DC cables according to the current system. Among them, in order to improve the mechanical strength of the cable for medium and high voltage power cables, one or more cable cores are usually surrounded by at least one armor layer in the form of metal wires, which is configured to strengthen the cable structure while maintaining suitable flexibility, However, due to the large loss of conventional armored cables, the armored cable has always had the defect that the load capacity of the same working temperature and the same environmental conditions is much smaller than that of the non-armored cable.

Studies have shown that the reduction of losses in armored cables enables an increase in the permissible rated current, thereby reducing the cross-section of the conductor and/or increasing the amount of current carried by the cable conductor, and enabling a reduction in the size of the cable and the manufacture of the cable The amount of material required and can increase the power carried by the cable.

Contents of the invention

The purpose of the present invention is to provide a cross-linked polyethylene insulated medium and high voltage power cable for the defects of the prior art, including:

Wire cores, a plurality of said wire cores are tangent to each other and twisted with each other;

The filling rope is filled in the stranding gap of the wire core, and is wound around the cladding together with the wire core to form a circular cross section;

a flame retardant layer coated on the outer wall of the wrapping layer;

The armor layer is wrapped around the outer wall of the flame-retardant layer;

The isolation layer is extruded on the outer wall of the armor layer;

an outer sheath, extruded on the outer wall of the isolation layer;

Wherein, the armor layer includes a first wrapping tape on the inner layer in the same twisting direction as the core and a second wrapping tape on the outer layer opposite to the twisting direction of the core, the first The wrapping tape and the second wrapping tape are alternately wound along the length direction of the cable to form forward wrapping parts and reverse wrapping parts that circulate alternately along the length of the cable;

The wrapping pitch of the second wrapping tape is greater than the stranding pitch of the wire core, and the wrapping pitch of the first wrapping tape is smaller than the wrapping pitch of the second wrapping tape.

Further, both the first wrapping tape and the second wrapping tape include a braid and at least two armored ropes, the armored ropes are arranged parallel to the length direction of the braid and are drawn by the The braided tape is braided and connected to form a wrapping tape.

Further, the armored rope includes a metal rope with a circular or polygonal cross section.

Further, the braided belt is cross-braided from a plurality of strands of aramid yarn to form an aramid yarn braided belt, and two adjacent armored ropes are connected through the aramid yarn braided belt.

Further, the braiding density of the aramid yarn braided belt is 90%-95%, and the included angle between the braided yarn and the axial direction of the cable in the aramid yarn braided belt is ≦30°.

Further, the wire core includes a conductor twisted into a circular cross-section, an insulating shielding layer extruded on the outer wall of the conductor, and a metal shielding layer wrapped on the outer wall of the insulating shielding layer.

Further, both the flame retardant layer and the isolation layer include a ceramic silicone rubber layer, the thickness of the flame retardant layer is 0.8mm-1.5mm, and the thickness of the isolation layer is 0.2mm-1.4mm.

Further, the outer sheath includes a low-smoke, halogen-free, flame-retardant polyolefin outer sheath with an oxygen index OI≥36%, and the extruded thickness of the low-smoke, halogen-free, flame-retardant polyolefin outer sheath is 1.8mm-5.0 mm.

Further, the outer sheath has at least two channels opened along the length direction of the cable, the channels are pierced with a reinforcing core, and the inner diameter of the channels is larger than the outer diameter of the reinforcing core.

Further, the reinforcing core includes one fiber filament and six steel wires, which are twisted into a circular cross-sectional shape in a regular twisting manner of 1+6.

Compared with the prior art, the significant advantages of the cross-linked polyethylene insulated medium and high voltage power cable of the present invention are:

1. The cross-linked polyethylene insulated medium and high voltage power cable proposed by the present invention can improve the performance of the cable in terms of increased transported alternating current and/or reduced cross-sectional area of the electrical conductor by changing the structure of the armor layer, along the Cyclic reversal of the laying direction of the cable core and/or the winding direction of the armor wires along the length of the cable improves the mechanical properties of the cable (compared to constructions with overall co-laying), reduces hysteresis and Eddy current losses (compared to constructions with integral reverse lay-up);

2. The cross-linked polyethylene insulated medium and high voltage power cable of the present invention can limit the pitch between adjacent metal ropes by adding aramid wire braid, avoiding its deformation when the cable is bent and laid, and improving the armor. layer stability.

Description of drawings

The figures are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like reference numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings.

Fig. 1 is an axial view of a medium and high voltage power cable shown in an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of a medium and high voltage power cable shown in an embodiment of the present invention.

Fig. 3 is a schematic diagram comparing the winding direction of the armor layer and the stranding direction of the wire core shown in the embodiment of the present invention.

In the figure, the meaning of each reference mark is as follows:

1. Core; 11. Conductor; 12. Insulation shielding layer; 13. Metal shielding layer; 2. Filling rope; 3. Wrapping layer; 4. Flame retardant layer; 5. Armoring layer; 6. Isolation layer; 7. , outer sheath; 71, channel; 8, reinforcing core.

Detailed ways

In order to better understand the technical content of the present invention, specific embodiments are given together with the attached drawings for description as follows.

The cross-linked polyethylene insulated medium and high voltage power cable of the embodiment shown in Figures 1-3 includes a core 1, a filling rope 2, a wrapping layer 3, a flame retardant layer 4, an armor layer 5, an isolation layer 6 and an outer sheath Set of 7.

Among them, the wire core 1, a plurality of wire cores 1 are tangent to each other and twisted with each other. The wire core 1 includes a conductor 11 twisted into a circular cross-section, an insulating shielding layer 12 extruded on the outer wall of the conductor 11, and an insulation shielding layer 12 coated on an insulating layer. The metal shielding layer 13 on the outer wall of the shielding layer 12.

Furthermore, the conductor 11 is made of a plurality of pure oxygen-free copper ultra-fine copper wires, which are formed by twisting in a regular manner of 1+6+12. The oxygen-free copper ultra-fine copper wires have strong flexibility and good bending resistance, and are made of The conductor 11 has good flexibility and bending resistance.

The insulating shielding layer 12 includes a conductor shielding layer, an insulating layer and an insulating shielding layer which are sequentially coated from the inside to the outside in a three-layer co-extruded manner.

Among them, both the conductor shielding layer and the insulating shielding layer are made of semi-conductive shielding materials, which can eliminate the air gap on the surface of the conductive core and improve the ability to withstand partial discharge and branch discharge. , with the isolation of the inner semi-conductive shielding layer, the high temperature will not immediately impact the insulating layer, which reduces the temperature rise of the insulating layer to a certain extent and protects the main insulation, so it has a thermal barrier effect; the insulating layer is made of cross-linked polyethylene insulation XLPE insulating material has unique insulating properties, excellent mechanical properties and heat resistance.

Specifically, three layers of the insulating shielding layer 12 are co-extruded on the outer wall of the conductor 11 to form an insulating core.

As an optional example, the metal shielding layer 13 is made of a copper strip, and the copper strip is wrapped around the outer wall of the insulating core to form the metal shielding layer 13 . Among them, the number of wrapping layers of the copper strip is 1-2 layers, and the lapping rate of the wrapping is greater than 20%.

Further, the filling rope 2 is filled in the stranding gap of the core 1, and is wound around the cladding 3 together with the core 1 to form a cable core with a circular cross-sectional shape.

Among them, the filling rope 2 is made of glass fiber rope. The glass fiber rope has high strength, high modulus, low shrinkage, non-deformation, non-combustibility, and good heat insulation performance. It not only makes the cross-section of the cable more rounded, but also has good flame retardant performance.

Further, the wrapping layer 3 is wrapped around the outer wall of the filling rope 2 with an elastic non-woven fabric material, which is mainly used to wrap the wire core 1 and the filling rope 2 together to form a cable core with a circular cross-section, and wrap and cover rate greater than 20%.

Further, the flame retardant layer 4 is coated on the outer wall of the wrapping layer 3; the flame retardant layer 4 is extruded on the outer wall of the wrapping layer 3 by using ceramic silicone rubber material through an extruder, and the thickness of the flame retardant layer 4 is 0.8mm -1.5mm.

Optionally, the anti-vibration ceramic silicone rubber is used as the ceramic silicone rubber material, which includes the following components in parts by mass: 20-100 parts of methyl vinyl silicone rubber, 20-800 parts of vinyl-terminated methyl vinyl silicone rubber 20-80 parts of fumed silica, 0.5-5 parts of platinum flame retardant, 2-8 parts of structural control agent, 5-10 parts of coupling agent, 10-500 parts of mineral silicate, 5 parts of magnesium hydroxide ～200 parts, 2～50 parts of zinc oxide, 2～50 parts of zinc borate. It can form a hard shell when burning, can overcome other mechanical strength damage such as abnormal vibration at the fire scene, protect the burned cable from damage, and maintain electrical signal transmission.

Further, the armor layer 5 is wrapped around the outer wall of the flame-retardant layer 4 .

In a preferred embodiment, as shown in FIG. 3 , the armor layer 5 includes a first wrapping tape on the inner layer in the same twisting direction as the core 1 and a second wrapping tape on the outer layer opposite to the twisting direction of the core 1. The wrapping tape, the first wrapping tape and the second wrapping tape are alternately wound along the length direction of the cable to form a forward wrapping portion 501 and a reverse wrapping portion 502 that circulate alternately along the length of the cable.

Specifically, the first wrapping belt and the second wrapping belt both include a plurality of metal ropes with a circular cross section, and the forward wrapping part 501 and the reverse wrapping part 502 are spirally wound by the wrapping machine through the wrapping machine along the length direction of the cable. In an optional embodiment, the outer diameter of the metal rope is 2mm-3mm.

In an optional embodiment, the metal rope can be a steel wire rope. Because the steel wire rope has good radial compression resistance, it is wrapped around the outer wall of the flame-retardant layer 4 to form a helical armor layer 5, and the diameter is achieved through the helical structure. Compression resistance in the radial direction, so that the cable has good radial compression resistance after being cabled, and provides armor protection for the cable after forming.

Based on the above-mentioned embodiments, the present invention divides the armor layer 5 into a forward wrapping part 501 and a reverse wrapping part 502. Compared with the twisting direction of the wire core 1 and the wrapping direction of the armor layer 5, and the wire core 1 The stranding direction is opposite to the winding direction of the armor layer 5 along the length of the cable, which can improve the performance of the cable in terms of increased transported alternating current and/or reduced cross-sectional area of the electrical conductors, along the length of the cable Cyclic reversal of the laying direction of the cable core and/or the winding direction of the armor wires improves the mechanical properties of the cable (compared to constructions with overall co-laying), reduces hysteresis and eddy current losses in the cable ( compared to a construction with monolithic reverse laying).

Since the twisting direction of the core 1 is opposite to the winding direction of the metal rope, the bending radius is greater than the bending radius of the twisting direction of the core 1 and the winding direction of the metal rope in the same direction, if the twisting direction of the core 1 is opposite to the winding direction of the metal rope , the pitch of the two is the same, which will cause the reverse wrapping portion 502 to be difficult to bend, which will affect the bending laying of the cable during use.

Further, the first wrapping tape is helically wound on the outer wall of the cable core by a wrapping machine, which is the same as the stranding direction of the core 1, and the wrapping pitch is greater than the twisting pitch of the core 1; the second wrapping tape is wound by winding The wrapping machine is spirally wound on the outer wall of the first wrapping tape, which is opposite to the wrapping direction of the first wrapping tape, and the wrapping pitch is greater than the wrapping pitch of the first wrapping tape.

In this way, by setting the wrapping pitch of the wrapping tape in the armor layer 5, after the cable is protected by the wrapping of the armor layer 5, the wrapping pitch of the reverse wrapping part is greater than the wrapping pitch of the same direction wrapping part , and the winding pitch of the reverse wrapping part is greater than the stranding pitch of the core 1, so that the cable is easier to bend after forming, and has the mechanical properties of radial compression resistance, which is convenient for the cable to be bent and laid.

Due to the influence of cable traction and bending during the cable laying process, the winding pitch of the metal rope may be deformed, causing the pitch between the partial metal ropes of the armor layer 5 to become larger. If the metal rope cannot be reset, the local metal rope If the ropes are tightly squeezed together, the local armor of the cable will be hard, which will affect the bending and laying of the cable, and the pitch of the local metal rope will become larger, which will cause the partial loss of armor protection of the cable.

In an optional embodiment, in order to limit the pitch between adjacent metal ropes. The first wrapping belt and the second wrapping belt both include a braid 52 and at least two armored ropes 51, the armored ropes 51 are arranged parallel to the length direction of the braid 52, and are braided and connected by the braid 52 to form a wrapping belt .

Optionally, the armored rope 51 includes a metal rope with a circular or polygonal cross-section; the braided belt 52 is cross-braided by multiple strands of aramid yarn to form an aramid yarn braided belt, and two adjacent armored ropes 51 are braided by aramid yarn with connection.

In a specific embodiment, when weaving, the multi-strand aramid yarns are cross-braided into an aramid yarn braid by a braiding machine. The steel wire rope extends along the length direction of the braided belt, and two adjacent steel wire ropes are braided and connected through the braided belt, and together with the braided belt, are woven by the braiding machine to form a composite braided belt.

Among them, the composite braided belt is arranged to be distributed sequentially along the width direction of the braided belt into an alternating structure of aramid braided braid-metal rope-aramid braided metal rope-aramid braided metal rope; The weaving density of the silk braided belt is 90% to 95%, and the included angle between the braided silk and the axial direction of the cable in the aramid silk braided belt is ≦30°.

Based on the above-mentioned embodiments, the distance between two adjacent metal ropes is limited by the aramid braided belt, and the high-density small-angle braid connects the two adjacent metal ropes, effectively limiting the pitch of the metal ropes , to prevent the pitch change of the metal rope when the cable is bent and laid, resulting in local compactness or local relaxation, improving the armoring stability of the armor layer 5, and the aramid yarn has good mechanical strength and tensile properties, and is light in weight. As a braided wire connected to the metal rope, to a certain extent, the tensile performance of the cable after forming is improved, and the safety of vertical laying of the cable after forming is enhanced.

Further, in order to prevent the metal rope of the armor layer 5 from repeatedly rubbing against the outer sheath to wear the outer sheath when the cable is bent and laid, as shown in Figure 2 and Figure 3, the outer wall of the armor layer 5 is extruded There is an isolation layer6.

Specifically, the isolation layer 6 is made of ceramic silicon rubber material with a thickness of 0.2mm-0.4mm; the ceramic silicon rubber layer forms a hard shell when burning, which can overcome other mechanical strength damages such as abnormal vibration at the fire scene, and protect the burned The cable is not damaged, and the transmission of electrical signals is maintained; ceramic silicone rubber material is used as the isolation layer 6, which can isolate the armor layer 5 and the outer sheath 7 on the one hand, so that the two will not be in direct contact and avoid wear and tear, on the other hand The flame retardant performance of the cable can be improved by using the ceramic silicone rubber material, and the communication time of the cable can be extended in case of a fire.

Further, the outer sheath 7 is extruded on the outer wall of the isolation layer 6 .

Specifically, the outer sheath 7 includes a low-smoke, halogen-free, flame-retardant polyolefin outer sheath with an oxygen index OI≥36%, and the extruded thickness of the low-smoke, halogen-free, flame-retardant polyolefin outer sheath is 1.8mm-5.0mm; Good wear resistance, tensile resistance and flame retardant properties, as the outer sheath, can play a good role in protecting the internal structure of the cable.

Further, in order to improve the tensile performance of the cable, as shown in Figure 2, there are at least two channels 71 opened along the length direction of the cable inside the outer sheath 7, and the reinforcing core 8 is pierced in the channel 71, and the channel 71 The inner diameter is larger than the outer diameter of the reinforcing core 8 .

As shown in Fig. 2 and Fig. 3, in this embodiment, there are 6 passages 71, and each passage 71 is provided with a reinforcement core 8. Since the inner diameter of the passage 71 is greater than the outer diameter of the reinforcement core 8, the When the cable is bent and laid, the reinforcing core 8 has an axial shifting space in the channel 71 to avoid bending of the reinforcing core 8 in the channel 71 and causing the outer sheath 7 to bulge.

In an optional embodiment, the reinforcing core 8 includes one fiber filament and six steel wires, which are twisted into a circular cross-section in a regular twisting manner of 1+6.

In order to prevent the reinforcing core 8 from wearing the outer sheath 7, a layer of rubber sheath can also be extruded on the outer wall of the reinforcing core 8. On the one hand, it can prevent the twisted structure of the reinforcing core 8 from being loose, and on the other hand, it can prevent the wire from being stabbed or damaged. Abrasion of the outer sheath 7 causes abrasion or damage of the outer sheath 7, thereby enhancing the use safety and stability of the outer sheath 7.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art of the present invention may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims.

Claims (10)

1. A cross-linked polyethylene insulated medium and high voltage power cable, characterized in that it comprises: Wire cores (1), a plurality of said wire cores (1) are tangent to each other and twisted with each other; The filling rope (2) is filled in the stranded gap of the wire core (1), and is wound around the cladding (3) together with the wire core (1) to form a circular cross section; a flame retardant layer (4), coated on the outer wall of the wrapping layer (3); The armor layer (5) is wrapped around the outer wall of the flame retardant layer (4); The isolation layer (6) is extruded on the outer wall of the armor layer (5); An outer sheath (7), extruded on the outer wall of the isolation layer (6); Wherein, the armor layer (5) includes a first wrapping tape on the inner layer in the same twisting direction as the core (1) and a second wrapping tape on the outer layer opposite to the twisting direction of the core (1). Two wrapping tapes, the first wrapping tape and the second wrapping tape are alternately wound along the length direction of the cable to form forward wrapping parts (501) and reverse wrapping parts (501) and reverse wrapping parts ( 502); The wrapping pitch of the second wrapping tape is greater than the stranding pitch of the wire core (1), and the wrapping pitch of the first wrapping tape is smaller than the wrapping pitch of the second wrapping tape pitch. 2. The XLPE insulated medium and high voltage power cable according to claim 1, characterized in that, both the first wrapping tape and the second wrapping tape include a braid (52) and at least two armored A rope (51), the armored rope (51) is arranged parallel to the length direction of the braided belt (52), and is braided and connected by the braided belt (52) to form a wrapping belt. 3. The XLPE insulated medium and high voltage power cable according to claim 2, characterized in that the armored rope (51) comprises a metal rope with a circular or polygonal cross section. 4. The cross-linked polyethylene insulated medium and high voltage power cable according to claim 2, characterized in that, the braid (52) is cross-braided from multiple strands of aramid fiber into an aramid fiber braid, and two adjacent The armored rope (51) is connected through the braided aramid ribbon. 5. The cross-linked polyethylene insulated medium and high voltage power cable according to claim 4, characterized in that, the braiding density of the aramid braided belt is 90% to 95%, and the braided wire in the aramid braided belt The included angle with the cable axis is ≦30°. 6. The cross-linked polyethylene insulated medium and high voltage power cable according to claim 1, characterized in that, the core (1) includes a conductor (11) twisted into a circular cross-section, extruded around the conductor (11) an insulating shielding layer (12) on the outer wall and a metal shielding layer (13) covering the outer wall of the insulating shielding layer (12). 7. The cross-linked polyethylene insulated medium and high voltage power cable according to claim 1, characterized in that, both the flame retardant layer (4) and the isolation layer (6) include ceramic silicon rubber layers, and the flame retardant The thickness of the combustion layer (4) is 0.8mm-1.5mm, and the thickness of the isolation layer (6) is 0.2mm-0.4mm. 8. The cross-linked polyethylene insulated medium and high voltage power cable according to any one of claims 1-7, characterized in that the outer sheath (7) includes a low-smoke, halogen-free cable with an oxygen index OI≥36%. Flame-retardant polyolefin outer sheath, the extruded thickness of the low-smoke, halogen-free flame-retardant polyolefin outer sheath is 1.8mm-5.0mm. 9. The cross-linked polyethylene insulated medium and high voltage power cable according to claim 8, characterized in that, the inside of the outer sheath (7) has at least two passages (71) opened along the length direction of the cable, the A reinforcing core (8) is pierced in the channel (71), and the inner diameter of the channel (71) is larger than the outer diameter of the reinforcing core (8). 10. The cross-linked polyethylene insulated medium and high voltage power cable according to claim 9, characterized in that, the reinforcing core (8) comprises one fiber filament and six steel wires, which are stranded in a normal twisting manner of 1+6 circular cross-section.