CN201773638U - Fireproof heat-resistant environmental protection power cable - Google Patents

Abstract

The utility model discloses a fireproof, heat-proof and environment-friendly power cable which comprises a core wire, an aluminum strip layer wrapped on the outer side of the core wire and an armored steel tape arranged on the outer side of the aluminum strip layer; a silicon carbide and mineral composite packing material is arranged in a gap between the core wire and the aluminum strip layer; a polyethylene inner sheath is arranged between the aluminum strip layer and the armored steel tape; and a polyethylene outer sheath is arranged on the outer side of the armored steel tape. The power cable has the advantages of good heat-dissipating capability, long service life, high flame retardance and fire resistance, power conservation, no toxin and environmental protection.

Description

Fireproof heat-resistant environmental protection power cable

technical field

The utility model relates to a power cable, in particular to a fireproof, heat-resistant and environment-friendly power cable.

Background technique

Existing flame retardant type A is filled with glass filaments. As we all know, the transmission capacity of the cable is determined by the temperature rise generated when the conductor transmits current, the temperature that the outer insulation material of the conductor can withstand for a long time, and the ability of the inner and outer insulation of the cable to dissipate heat to the surrounding medium. The traditional 8.7/10kV XLPE cables are three-core circular insulated cables, and the cores are filled with glass filaments with high thermal resistance. The external heat dissipation of the three-phase conductive core is extremely difficult, and most of the heat can only pass through the shield. The circumscribed edge of the copper strip and the outer sheath radiates to the surroundings, and the thermal resistance is extremely high due to the narrow effective area of radiating. Glass fiber filling brings a lot of trouble to the cable production workers and on-site construction personnel. When the workshop workers are filling the glass fiber into the cable, the glass fiber fiber is flying all over the workshop. It is painful and itchy on the skin and cannot be taken out, which will seriously affect the workers' occupation. Healthy and not environmentally friendly, the glass fiber filling only satisfies the flame retardant ability of the cable, and the disadvantages outweigh the advantages. Both the inner and outer protection are made of ordinary polyvinyl chloride, which contains chlorine, which is very poisonous. During the extrusion process of the factory, a large amount of harmful gases are floating, and these gases are relatively harmful to the human body.

Utility model content

Purpose of the utility model: Aiming at the problems and deficiencies of the above-mentioned existing longitudinal cable connectors, the purpose of the utility model is to provide a power connector with good heat dissipation performance, long service life, strong flame retardant and fire resistance, power saving, non-toxic and environmental protection. cable.

Technical solution: In order to solve the above technical problems, the technical solution adopted by the utility model is a fireproof heat-resistant environmental protection power cable, which includes a core wire, an aluminum strip layer wrapped around the outside of the core wire, and a steel strip layer on the outside of the aluminum strip layer. Armored, in which silicon carbide mineral composite filler is provided in the gap between the core wire and the aluminum tape layer, a polyethylene inner sheath is provided between the aluminum tape layer and the steel tape armor, and a polyethylene inner sheath is provided between the steel tape armor On the outside there is a polyethylene outer sheath.

The core wire includes a conductor, an insulating layer wrapped around the surface of the conductor, and a shielding layer of copper tape wrapped around the surface of the insulating layer.

The polyethylene inner sheath is wrapped or extruded on the surface of the aluminum tape layer.

The polyethylene outer sheath is wrapped on the surface of the steel tape armor.

The conductor is formed by twisting a plurality of copper wires.

The utility model adopts silicon carbide mineral composite filling to replace the existing glass fiber filling. After use, the heat of the conductor can be distributed to the surroundings relatively uniformly. The thermal resistance coefficient of the filling is low and the distribution area is large, so the filling material with low thermal resistance is used instead. Traditional high thermal resistance glass fiber type fill. In addition to reducing the wire loss and saving energy, the reduction of the temperature of the conductive core also prolongs the service life of the cable insulation and sheath, because the aging life of organic materials is closely related to its operating temperature.

Beneficial effects: 1. Filling with silicon carbide mineral effectively solves the temperature rise generated when the conductor transmits current, the temperature that the outer insulation material of the conductor can withstand for a long time, and the ability of the inner and outer insulation of the cable to dissipate heat to the surrounding medium. The heat generated by the conductor has a copper strip, filled with silicon carbide minerals, and wrapped around the aluminum strip to dissipate. This greatly improves the ampacity of the cable and the service life of the cable. 2. It replaces the traditional method of filling flame-retardant A-type power cables with glass filaments for a long time. Filling with silicon carbide minerals is not only environmentally friendly but also improves the flame and fire resistance of the cable. It also improves the carrying capacity of the cable more effectively and saves electricity for the country. 3. The inner and outer sheaths are made of environmentally friendly and non-toxic polyethylene materials. 4. Raw material consumption, due to the use of silicon carbide mineral filling with low thermal resistance, and the circular structure of the conductive wire core, the outer diameter of the cable is increased compared with the traditional structure, generally increased by 3-6mm, of course, the increase in the outer diameter will It brings about an increase in material cost and cable weight. Since the applied silicon carbide mineral filling is an environmentally friendly product, its advantages are obvious.

Description of drawings

Accompanying drawing is the structural representation of the utility model.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, further set forth the utility model, should be understood that these embodiments are only used for illustrating the utility model and are not intended to limit the scope of the utility model, after having read the utility model, those skilled in the art will understand this utility model The modifications of various equivalent forms of the utility model all fall within the scope defined by the appended claims of the present application.

As shown in the figure, a fire-resistant, heat-resistant and environmentally friendly power cable includes multiple core wires 1 and multiple silicon carbide mineral composite fillers 6, the core wire 1 is a conductor 7 twisted by multiple copper wires, wrapped around The insulating layer 8 on the surface of the conductor 7 and the copper tape shielding layer 9 wrapped on the surface of the insulating layer 8 are composed, the core wire 1 is bundled with the silicon carbide mineral composite filler 6, and the aluminum tape layer 2 is wrapped around it outside, and the aluminum tape layer 2 is wrapped on the aluminum The surface of the belt layer 2 is wrapped or extruded with a polyethylene inner sheath 3, and then the surface of the polyethylene inner sheath 3 is wrapped with a steel tape armor 4, and finally the steel tape armor 4 is wrapped with a polyethylene outer sheath 5 .

As a typical structure of a medium voltage cable: copper conductor, inner shield, insulation, outer shield, copper tape shield, interphase filling and outer sheath (PVC), where "filling" is the only change that affects the electrical and mechanical properties of the cable The smallest link - the function of filling in the cable is to maintain the shape of the cable and conduct heat to the outside, nothing more, so it is often ignored by people. In fact, the selection of cable filler will seriously affect the transmission capacity of the cable and the loss of the rated current in the conductor of the same cross-section. Shanghai Zhongyue Cable Technology Co., Ltd. and Shanghai Cable Factory Shifen Factory conducted the following comparative tests on 0.6/1kv～8.7/10kV and divided them into three groups of six cables, as shown in Table 1.

Table 1 Models and specifications of cable samples

No. 2 and No. 4 in the above six cable samples are traditional structures, and the conductors are copper fan-shaped. The corresponding No. 1 and No. 3 samples are consistent in conductor cross-section, both 4*70 and 3*120+ 70. The shape of the conductor of the new structure is circular and the interphase filling material is changed from the original glass fiber to a mineral material with low thermal resistance; No. 5 and No. 6 are the test groups of 8.7/10kV level. The conductor cross-section, shape, Insulation material and thickness, shielding and copper tape, and outer sheath material and thickness are all the same. The difference is that No. 5 is filled with minerals, and No. 6 is filled with traditional glass fiber. The test is carried out in two steps. The first part of the test is to connect the conductors of each phase of a pair of specimens with the same specification cross-section and different type fillings in series in series. And pass a constant current under the condition that the external ambient temperature is consistent (the test method is based on the IEC60287 standard to calculate the cross-sectional ampacity of the overhead laying cable), and the measured results are shown in Table 2. The second test method is: the external environment temperature is kept constant at 40°C, the conductor temperature of the six cables of the three groups of samples is controlled at 90°C, and the steady-state current value of the conductor is measured, see Table 3 for details.

Table 2

table 3

The above test report values are all provided by Shanghai Electric Cable Research Institute, and its test report number is 2004 Cable Research Test Zi No. 040342.

The following points can be drawn from the above test report:

1) After replacing the fiber-type filler with low thermal resistance mineral filler, its ability to conduct heat increases significantly, which can be obtained from the data in Table 2: the temperature of the old structure conductor (second comparison group) is high (105°C) However, the surface temperature of the sheath is low (77.3°C); the conductor temperature of the new structure is low (90°C), but the surface temperature of the sheath is high (78.8°C). Under the condition of the same cable conductor section, the carrying capacity of the comparison group increased by 8.7%, 10.2% and 22.8% respectively.

2) It can be seen from the percentage of carrying capacity increase that the effect of the medium voltage level 8.7/10kV is significantly better than that of the 0.6/1kV voltage level, and the reason is obvious: the traditional 8.7/10kV XLPE cables are three-core circular Insulation, the core is filled with high thermal resistance glass fiber or polypropylene tearing rope, the external heat dissipation of the three-phase conductive core is extremely difficult, and most of the heat can only pass through the outer edge of the shielded copper tape and the outer sheath Distribute to the surrounding, because the effective area of radiation is narrow, so the thermal resistance value is extremely large; after replacing it with mineral materials with low thermal resistance, the heat of its conductive core can be distributed to the surroundings relatively evenly, and the thermal resistance coefficient of the filling is low, and the heat dissipation The area is large, and it is understandable that the superposition of the advantages of the two makes the current carrying capacity of the core increase to 122.8%. 0.6/1kV level low-voltage cables, whether it is four cores with equal cross-section or 3+1 cores, the conductor shape is basically surrounded by fan-shaped cores into a circle, and the filling amount between the core insulation is originally very small, so the filling material with low thermal resistance is used instead of the traditional one. The increase of the heat dissipation effect of the high thermal resistance fiber-type filling is not as obvious as that of the medium-voltage cable. Although there is still an 8-10% increase in value, a considerable part of it depends on the conductive insulating core from fan-shaped to After being rounded, the heat dissipation surface of the conductor changes from the sum of the fan-shaped arc surfaces to the sum of the circumference of the multi-core, due to the increase of the heat exchange interface (filling of low thermal resistance mineral materials between phases).

3) After the medium voltage 8.7/10kV system is replaced with low thermal resistance mineral filling, its current carrying capacity value is still maintained at the original rated current value of 264 (A), its conductive core temperature is only 66 ° C, and the surface temperature of the outer sheath It is only 56°C, which is much lower than the 90°C and 62°C of the traditional structure with the same specification. According to the relationship between the resistivity of the copper conductor and the temperature, it can be deduced that the line loss at 66°C is only 93% of the line loss at 90°C . This conclusion is positive for the current situation when power plants are being built and urban overhead lines are yet to be put into the ground.

4) In addition to the reduction of the temperature of the conductive wire core to reduce the line loss and save energy, it also prolongs the service life of the cable insulation and sheath, because the aging life of organic materials is closely related to its operating temperature.

5) Due to the use of mineral filling with low thermal resistance, and the circular structure of the conductive wire core, the outer diameter of the cable is increased compared with the traditional structure, generally 3-6mm. Of course, the increase in the outer diameter will bring material costs With the increase of the weight of the cable, because the mineral material used in the structure is an environmentally friendly product, the material cost will only increase by 1-1.5% compared with the ordinary flame-retardant cable of the same specification, and the weight will increase by 3-8%. As for the cable hardness and bending radius, there is no significant difference for cables for fixed laying, especially cables for medium-voltage systems, and they can be regarded as equivalent.

Based on the advantages and disadvantages above, the following conclusions are drawn: it is feasible to use minerals with low thermal resistance in the structure of medium-voltage cables instead of fiber-type materials as fillers in the manufacturing process. In terms of technical performance parameters (increased transmission capacity and reduced line damage, prolonging the service life) is excellent (the flame retardant ability of the new structure can reach Class A and above, and the flame retardant ability of the cable filled with minerals {popular electricity} has been published in the second issue of 2002 "Resistance The types and selection of fuel cables have been introduced), which is reasonable in terms of economic cost and competitive in terms of sales price. Therefore, the concept of replacing the traditional glass fiber or polypropylene rip rope with low thermal resistance and high flame retardant mineral material is an effective and safe new way to greatly improve the comprehensive transmission capacity of medium voltage cables.

Claims (5)

1. fireproofing and heat resistant environmental-friendly power cable, comprise heart yearn (1), wrapped aluminium strip layer (2), be provided with steel-tape armouring (4) in aluminium strip layer (2) outside in heart yearn (1) outside, it is characterized in that: the gap between heart yearn (1) and aluminium strip layer (2) is provided with carborundum mineral composite filler (6), between aluminium strip layer (2) and steel-tape armouring (4), be provided with polyethylene inner sheath (3), be provided with polyethylene oversheath (5) in steel-tape armouring (4) outside.

2. according to the described fireproofing and heat resistant environmental-friendly power cable of claim 1, it is characterized in that: described heart yearn (1) comprises conductor (7), wrapped insulating barrier (8) and wrapped copper strips screen (9) on insulating barrier (8) surface on conductor (7) surface.

3. according to the described fireproofing and heat resistant environmental-friendly power cable of claim 1, it is characterized in that: described polyethylene inner sheath (3) is wrapped or be extruded in aluminium strip layer (2) surface.

4. according to the described fireproofing and heat resistant environmental-friendly power cable of claim 1, it is characterized in that: described polyethylene oversheath (5) is wrapped on steel-tape armouring (4) surface.

5. according to the described fireproofing and heat resistant environmental-friendly power cable of claim 2, it is characterized in that: described conductor (7) is by many stranded the forming of copper cash.

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