CN111681816A - High-current-carrying-capacity modified polypropylene insulated cable and modified polypropylene insulating material used by same - Google Patents

Abstract

The invention belongs to the field of cables, and particularly relates to a high-current-carrying-capacity modified polypropylene insulated cable and a modified polypropylene insulating material used by the same. The cable includes: the conductor, the modified insulating layer, the armor layer and the outer sheath are sequentially arranged from inside to outside; the outer sheath is a flame-retardant outer sheath; the modified insulating layer is a modified polypropylene insulating layer, and the modified polypropylene insulating layer is prepared from a modified polypropylene insulating material. The modified polypropylene insulating material is prepared from a polypropylene block copolymerization ethylene monomer; the content of the ethylene monomer is 2-3 wt% of the polypropylene. The invention replaces the cross-linked polyethylene with the modified polypropylene, thereby reducing the cost and improving the quality of the insulating layer; the current-carrying capacity and the actual bearable working temperature of the cable are obviously improved; the modified polypropylene can be recycled, and is more environment-friendly.

Description

High-current-carrying-capacity modified polypropylene insulated cable and modified polypropylene insulating material used by same

Technical Field

The invention belongs to the field of cables, and particularly relates to a high-current-carrying-capacity modified polypropylene insulated cable and a modified polypropylene insulating material used by the same.

Background

Most of medium-voltage cables at the present stage adopt crosslinked polyethylene as an insulating material, and the material takes the polyethylene as a base material and is crosslinked through a chemical reaction process to form the crosslinked polyethylene, so that toxic substances are generated in the crosslinking processing process of the insulating layer, and the difficulty is brought to later recovery and environmental protection; meanwhile, the crosslinked polyethylene cable still has the generation of insulation hidden troubles such as 'water tree branches' in operation, and brings certain influence to the urban power supply reliability with abundant underground water and high cable coverage rate. The cable industry is constantly looking for new materials and processes to replace crosslinked polyethylene.

For example, the patent of the invention of a crosslinked polyethylene insulated power cable disclosed by the chinese patent office in 12/26/2012 is granted with publication number CN202632858U, which includes a conductor, an insulating layer, a filling layer, a belting layer and an outer sheath, and the power transmission performance of the cable is improved by filling crosslinked polyethylene, but the current-carrying capacity of the cable still has a certain space for improving, and the technical scheme has limited overall flame retardant performance, low working temperature and difficulty in bearing high working temperature.

Disclosure of Invention

The invention provides a high-current-carrying-capacity modified polypropylene insulated cable and a modified polypropylene insulating material, and aims to solve the problems that a large amount of cross-linked polyethylene with high cost and limited performance is adopted in the existing cable, so that environmental pollution is caused, certain potential safety hazards exist in the actual use process, and the like.

The invention aims to:

1) the quality of the insulating layer is improved, and potential safety hazards in the actual operation process of the cable are reduced;

2) the current-carrying capacity of the cable is improved;

3) improving the service allowable temperature of the cable;

4) the structural stability of the cable is improved;

5) the heat conduction and radiation capacity of the cable is improved.

In order to achieve the purpose, the invention adopts the following technical scheme.

A high ampacity modified polypropylene insulated cable comprising:

the conductor, the modified insulating layer and the outer sheath are sequentially arranged from inside to outside;

the modified insulating layer is a modified polypropylene insulating layer, and the modified polypropylene insulating layer is prepared from a modified polypropylene insulating material.

As a preference, the first and second liquid crystal compositions are,

an inner shielding layer is arranged between the conductor and the modified insulating layer;

and an insulating shielding layer is arranged between the modified insulating layer and the inner sheath.

As a preference, the first and second liquid crystal compositions are,

a metal shielding layer is coated outside the insulating shielding layer;

the outer surface of the metal shielding layer is coated with a belting layer.

As a preference, the first and second liquid crystal compositions are,

further comprising: the inner sheath is coated on the outer surface of the belting layer, and the armor layer is coated outside the inner sheath;

the inner sheaths are all flame-retardant inner sheaths.

As a preference, the first and second liquid crystal compositions are,

the armor layer is a metal armor layer.

As a preference, the first and second liquid crystal compositions are,

the outer sheath is of a double-layer structure and is divided into an inner layer and an outer layer, and the inner layer and the outer layer are meshed through the arch grains.

As a preference, the first and second liquid crystal compositions are,

and an alkali lime layer is arranged between the outer layer and the inner layer of the outer sheath.

A modified polypropylene insulating material, which is prepared from polypropylene,

the modified polypropylene insulating material is prepared from a polypropylene block copolymerization ethylene monomer;

the content of the ethylene monomer is 2-3 wt% of the polypropylene.

As a preference, the first and second liquid crystal compositions are,

the modified polypropylene insulating material is also doped with Si-C-Al composite filler;

the doping amount of the Si-C-Al composite filler is 12-15 wt% of the modified polypropylene insulating material.

As a preference, the first and second liquid crystal compositions are,

the Si-C-Al composite filler is prepared by the following process:

mixing carbon source powder, aluminum powder and silicon powder into mixed powder, wherein the mass ratio of the carbon source powder to the aluminum powder to the elemental silicon powder is controlled to be 1: (1.9-2.1): (6.9-7.1), uniformly mixing the mixed materials to obtain mixed powder, pressing and forming to obtain an anode, placing a graphite electrode as a cathode, placing the anode and the cathode in an argon atmosphere protection environment, applying direct current between the cathode and the anode, wherein the direct current is 175-185A until the anode is worn and the reaction is blocked, cooling, and collecting the powder on the inner wall of a reaction container to obtain the Si-C-Al composite filler powder.

The invention has the beneficial effects that:

1) the modified polypropylene is used for replacing the crosslinked polyethylene, so that the cost is reduced, and the quality of the insulating layer is improved;

2) the current-carrying capacity and the actual bearable working temperature of the cable are obviously improved;

3) the modified polypropylene can be recycled, so that the environment is protected;

4) the whole cable has higher structural stability and stronger anti-distortion capability;

5) after the Si-C-Al doped cable has good heat conduction and heat dissipation performance.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is an enlarged view of portion A of FIG. 1;

FIG. 3 is a schematic view of the outer sheath;

in the figure: the cable comprises a conductor 1, an inner shielding layer 2, a modified insulating layer 3, an insulating shielding layer 4, a metal shielding layer 5, a belting layer 6, an inner sheath 7, an armor layer 8, an outer sheath 9, an outer layer 901, an inner layer 902 and an alkali lime layer 903.

Detailed Description

The invention is described in further detail below with reference to specific embodiments and the attached drawing figures. Those skilled in the art will be able to implement the invention based on these teachings. Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "circumferential", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., and "several" means one or more unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all those known to those skilled in the art.

Example 1

A high ampacity modified polypropylene insulated cable as shown in figure 1, comprising:

the cable comprises a conductor 1, an inner shielding layer 2, a modified insulating layer 3, an insulating shielding layer 4, a metal shielding layer 5, a belting layer 6, an inner sheath 7, an armor layer 8 and an outer sheath 9 which are arranged from inside to outside in sequence;

the conductor 1 is a common cable conductor 1 and can be stranded copper, single copper, copper plated after stranded, copper clad aluminum and the like;

the inner shielding layer 2 is tightly coated on the outer surface of the conductor 1 and is prepared by common shielding materials, preferably polypropylene shielding materials are adopted, the polypropylene shielding materials are thermoplastic polypropylene semiconductor 1 electric shielding materials, the arrangement of the inner shielding layer 2 is uniform for an electric field on the outer surface of the conductor 1, and the problem that the conductor 1 and an insulating part generate partial discharge due to the fact that the outer surface of the conductor 1 is not smooth and the defects of the conductor 1 are avoided;

modified insulating layer 3 inseparable cladding is at 2 surfaces on internal shield layer, closely laminates with internal shield layer 2, and it is prepared by modified polypropylene, modified polypropylene is prepared by polypropylene and ethylene monomer, and ethylene monomer quantity is 2 ~ 3 wt% of polypropylene, and this embodiment ethylene monomer quantity is 3 wt% of polypropylene, and the preparation flow is in proper order: mixing, block copolymerization, extrusion cooling, granulation and drying are carried out according to the proportion;

ethylene-propylene rubber copolymer can be prepared by block copolymerization of 2-3% of ethylene monomer on a polypropylene main chain, and high-purity modified polypropylene insulating material is obtained by granulation, and has excellent electrical property, ageing resistance and mechanical and physical properties;

in addition, the prepared modified polypropylene belongs to a thermoplastic elastomer, has the advantages of both polyethylene and polypropylene, can resist low-temperature impact at minus 30 ℃, and has good insulating property, high and low temperature performance, high strength and low cost; not only the material is safe, but also the toxicity is low and the material can be recycled; the thermoplastic process can also make the insulation layer and the shielding layer contact more tightly, effectively avoid the generation of defects such as air gaps and the like, and bring higher temperature-resistant grade to the cable;

through calculation, the current-carrying capacity of the high-current-carrying-capacity modified polypropylene insulated cable insulated by the modified polypropylene can be further improved by about 6.93 percent;

the insulating shielding layer 4 is tightly coated on the outer surface of the modified insulating layer 3 and is prepared by common shielding materials, preferably, the polypropylene shielding material is a thermoplastic polypropylene semiconductor 1 electric shielding material, the insulating shielding layer 4 is mainly arranged by matching with the inner shielding layer 2, and the combination of the insulating shielding layer 4 and the inner shielding layer 2 is arranged, so that the problem that the optical cable is damaged due to partial discharge generated between the insulating layer and the metal shielding layer 5 can be avoided, and the partial discharge of the rest of the metal shielding layers 5 due to the defects of surface cracks and the like of the insulating shielding layer 4 can be effectively avoided;

the metal shielding layer 5 is formed by tightly wrapping a metal material with good conductivity such as a copper wire or a copper strip on the outer surface of the insulating shielding layer 4 in a wrapping mode and the like, and further tightly wrapping the metal shielding layer 5 by using a non-woven fabric wrapping tape to form a wrapping tape layer 6;

the metal shielding layer 5 mainly plays a role in shielding an electric field, and the wrapping tape can further stabilize the metal shielding layer 5 and protect the metal shielding layer 5 to a certain extent;

the inner sheath 7 and the outer sheath 9 are both made of flame retardant materials, the armor layer 8 is a metal armor layer 8, the inner sheath 7 is tightly coated on the outer surface of the belting layer 6, the metal armor layer 8 is tightly coated on the outer surface of the inner sheath 7, and the outer sheath 9 is tightly coated on the outer surface of the metal armor layer 8;

the inner sheath 7 and the outer sheath 9 are preferably made of flame-retardant soft polyvinyl chloride sheath material, or flame-retardant polyethylene sheath material, or thermoplastic low-smoke halogen-free flame-retardant polyolefin sheath material, and the like, wherein the flame-retardant soft polyvinyl chloride sheath material is the flame-retardant soft polyvinyl chloride sheath material at 90 ℃, and the thermoplastic low-smoke halogen-free flame-retardant polyolefin sheath material is the thermoplastic low-smoke halogen-free flame-retardant polyolefin sheath material at 90 ℃;

the metal armor layer 8 is formed by winding and coating a stainless steel band or a stainless steel wire;

as shown in fig. 3, the outer sheath 9 is of a double-layer structure and is divided into an outer layer 901 and an inner layer 902, the inner layer 902 and the outer layer 901 are both provided with axial ribs, the outer layer 901 and the inner layer 902 of the outer sheath 9 are engaged and fixed through the ribs, the ribs are designed to enable the inner layer 902 and the outer layer 901 of the outer sheath 9 to have certain anti-twisting capability, and on the basis, the inner layer 902 and the outer layer 901 can be combined more stably;

meanwhile, the arch grain has the characteristic of being directly extruded, prepared and formed, and the preparation is simple and convenient;

an extremely thin soda lime layer 903 is also paved and filled between the inner layer 902 and the outer layer 901 of the outer sheath 9;

the common flame-retardant outer sheath 9 can generate a large amount of hydrogen chloride gas under the action of high heat to realize the flame-retardant effect, but excessive hydrogen chloride generated during flame retardance can also cause corrosion and aging of the cable, so that the overall mechanical performance of the cable after flame retardance is rapidly reduced, the cable is easy to break and the like before maintenance and replacement, and the like;

the friction between the outer layer 901 and the inner layer 902 of the outer sheath 9 can be improved by laying the soda lime, and the structural stability of the outer layer 901 and the inner layer 902 can be further improved.

The cable of the invention is tested and compared with a control group cable, the cable of the embodiment and the control group cable are respectively provided with 20 test groups, and the control group cable is only different from the cable of the embodiment in that the modified insulating layer 3 is replaced by a conventional insulating layer, namely, the modified polypropylene is replaced by crosslinked polyethylene, and the rest parts are the same:

and (3) testing the working temperature:

the cable can stably run at 105 ℃, and 2-week tests show that the cable can maintain good working stability in 105 ℃ environment, and the current-carrying capacity fluctuation is less than 0.5%;

the current carrying capacity of the control cable decreased by about 6.21% after running at 105 ℃ for 2 weeks;

and (3) carrying capacity measurement:

the current carrying capacity of the cable of the embodiment is 106.59-107.32% of that of the control group, the average value is 106.93% based on 100% of the current carrying capacity measured by the control group, and the current carrying capacity is improved by about 6.93%.

Example 2

The ethylene propylene rubber copolymer is further doped with a Si-C-Al composite filler, the addition amount of the Si-C-Al composite filler is 12-15 wt% of the ethylene propylene rubber copolymer, and the heat conduction and heat dissipation performance of the modified insulating layer can be further improved through the doping of the Si-C-Al composite filler, and the insulativity and the electric breakdown resistance of the modified insulating layer are improved to a certain extent;

the Si-C-Al composite filler is prepared by the following process:

mixing the coke powder, the aluminum powder and the elemental silicon powder into mixed powder, wherein the mass ratio of the coke powder to the aluminum powder to the elemental silicon powder is controlled to be 1: (1.9-2.1): (6.9-7.1), the mass ratio of the coke powder, the aluminum powder and the elemental silicon powder adopted in the embodiment is 1: 2: 7, uniformly mixing the mixed materials into mixed powder, pressing and forming to form a block material, placing the formed block material as an anode and a graphite electrode as a cathode in the protection of argon atmosphere, applying direct current between the cathode and the anode, wherein the direct current is 175-185A, 180A in the embodiment, until the anode is worn and blocked to react, cooling for 24 hours, and collecting powder on the inner wall of a reaction container to obtain Si-C-Al composite filler powder;

the Si-C-Al composite filler powder is doped by adopting the following process:

mixing 3 parts by weight of ethylene monomer and 100 parts by weight of polypropylene according to a ratio, adding 13.5 parts by weight of Si-C-Al composite filler in the mixing process, carrying out block copolymerization on ethylene and polypropylene by adopting a conventional process, then extruding and cooling to obtain an ethylene propylene rubber copolymer doped with the Si-C-Al composite filler, and then granulating and drying to obtain a modified polypropylene insulating material doped with the Si-C-Al composite filler;

the Si-C-Al composite filler is added in the mixing process, so that good and uniform doping can be realized, the doping of the Si-C-Al composite filler can be used as a polymerization center of subsequent block copolymerization, and the block copolymer can well coat the Si-C-Al composite filler due to the good affinity of silicon.

The same test as example 1 was conducted by replacing the modified polypropylene insulator of example 1 with a modified polypropylene insulator doped with a Si-C-Al composite filler, and comparing with the cables of example 1 and the control group.

And (3) testing the working temperature:

the cable can stably run at 105 ℃, and 2-week tests show that the cable can maintain good working stability in 105 ℃ environment, and the current-carrying capacity fluctuation is less than 0.2%;

example 1 the cable had a ampacity variation of < 0.5% after 2 weeks of operation at 105 ℃;

the current carrying capacity of the control cable decreased by about 6.21% after running at 105 ℃ for 2 weeks;

and (3) carrying capacity measurement:

based on 100% of the current-carrying capacity measured by the control group, the current-carrying capacity of the cable in example 1 is 106.59-107.32% of the control group, the average value is 106.93%, and the current-carrying capacity of the cable in this embodiment is 108.43-109.16% of the control group, the average value is 108.82%, and the current-carrying capacity is about 8.82% of the current-carrying capacity, and the improvement is more remarkable compared with that in example 1;

measuring the temperature of the high-voltage power transmission cable:

the method comprises the steps of remotely monitoring the surface temperature of a service cable by adopting 120kV high-voltage power transmission, wherein the surface temperature of a comparison group cable can reach 68.7-68.9 ℃ through monitoring, the surface temperature of the cable in example 1 can reach 66.3-66.4 ℃, the surface temperature of the cable in this example is only 42.7-42.8 ℃, and the actual service temperature is reduced by 37.6-38.1 percent compared with that of the comparison group cable Medium loss, base temperature and other factors determine, and generally is a key factor limiting the actual transmission performance of the cable, compared with the existing crosslinked polyethylene insulated cable, the allowable maximum temperature increase in the actual service process of the embodiment 1 shows that the cable can carry out higher-voltage power transmission, and the embodiment 2 scheme enables the surface temperature of the cable in the actual service process to be significantly lower than the embodiment 1 scheme, so that the cable has a good heat conduction and dissipation effect, the cable performance can be further effectively improved, and the high-voltage power transmission capability can be further improved.

Claims (10)

1. A high ampacity modified polypropylene insulated cable, comprising:

the conductor, the modified insulating layer and the outer sheath are sequentially arranged from inside to outside;

the modified insulating layer is a modified polypropylene insulating layer, and the modified polypropylene insulating layer is prepared from a modified polypropylene insulating material.

2. The insulated cable of claim 1, wherein the modified polypropylene with high ampacity has a high ampacity,

an inner shielding layer is arranged between the conductor and the modified insulating layer;

and an insulating shielding layer is arranged between the modified insulating layer and the inner sheath.

3. The insulated cable of claim 2, wherein the modified polypropylene with high ampacity has a high ampacity,

a metal shielding layer is coated outside the insulating shielding layer;

the outer surface of the metal shielding layer is coated with a belting layer.

4. The insulated cable of claim 3, wherein the modified polypropylene with high ampacity has a high ampacity,

further comprising: the inner sheath is coated on the outer surface of the belting layer, and the armor layer is coated outside the inner sheath;

the inner sheaths are all flame-retardant inner sheaths.

5. The insulated cable of claim 4, wherein the modified polypropylene with high ampacity has a high ampacity,

the armor layer is a metal armor layer.

6. The insulated cable of claim 1, wherein the modified polypropylene with high ampacity has a high ampacity,

the outer sheath is of a double-layer structure and is divided into an inner layer and an outer layer, and the inner layer and the outer layer are meshed through the arch grains.

7. The insulated cable of claim 8, wherein the modified polypropylene with high ampacity has a high ampacity,

and an alkali lime layer is arranged between the outer layer and the inner layer of the outer sheath.

8. A modified polypropylene insulating material is characterized in that,

the modified polypropylene insulating material is prepared from a polypropylene block copolymerization ethylene monomer;

the content of the ethylene monomer is 2-3 wt% of the polypropylene.

9. The modified polypropylene insulation of claim 8,

the modified polypropylene insulating material is also doped with Si-C-Al composite filler;

the doping amount of the Si-C-Al composite filler is 12-15 wt% of the modified polypropylene insulating material.

10. The modified polypropylene insulation of claim 9, wherein,

the Si-C-Al composite filler is prepared by the following process:

mixing carbon source powder, aluminum powder and silicon powder into mixed powder, wherein the mass ratio of the carbon source powder to the aluminum powder to the elemental silicon powder is controlled to be 1: (1.9-2.1): (6.9-7.1), uniformly mixing the mixed materials to obtain mixed powder, pressing and forming to obtain an anode, placing a graphite electrode as a cathode, placing the anode and the cathode in an argon atmosphere protection environment, applying direct current between the cathode and the anode, wherein the direct current is 175-185A until the anode is worn and the reaction is blocked, cooling, and collecting the powder on the inner wall of a reaction container to obtain the Si-C-Al composite filler powder.

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