KR20230030137A - Power Cable for Remote Radio Unit - Google Patents

Abstract

A power cable for remote wireless equipment comprises: an inner conductor composed of a conductor comprising a plurality of wires and an insulating layer that surrounds and insulates the conductor; a filler that surrounds the inner conductor and is decomposed by heating so as to be disposed in a core part along an axial direction of the inner conductor; a binder layer formed by surrounding the outside of the filler with a binder; and a jacket formed with an accommodation space capable of protecting and accommodating the binder layer from the outside. Therefore, the present invention is capable of having an effect of improving low combustion.

Description

Power cable for remote radio equipment {Power Cable for Remote Radio Unit}

The present invention relates to a power cable for remote wireless equipment, and more particularly, to a power cable for remote wireless equipment with improved flame retardancy.

A remote radio unit (RRU) type base station system separates a remote radio unit (RRU) from a conventional BTS (Base Transceiver Station) base station system, places it under a remote antenna, and remotely controls it. Power cable and optical cable to supply power and data from the baseband unit and power supply unit disposed at the lower part of the remote radio equipment (RRU) base station system to the remote radio equipment near the antenna can be used.

Such a power cable consists of a conductor made of a plurality of wires or a polyethylene insulator surrounding the conductor, a filler made of a resin string surrounding the conductor, a binder layer surrounding the filler, and a jacket forming the outer frame of the power cable.

However, in the event of a fire, this power cable is improved in low combustion and low toxicity by using flame retardant polymer materials to secure the flame retardancy of the cable. In the droplets/particles (1200s) test, there is a problem of not providing a high-level power cable for the standard, such as melting and falling particles.

Accordingly, an object of the present invention is to provide a power cable for remote wireless equipment that has improved combustibility and toxicity even when the cable is exposed to flame due to a fire, and further prevents the generation of spark particles that melt and fall due to a fire. .

In order to achieve the above object, a power cable for remote wireless equipment according to the present invention includes an inner conductor composed of a conductor including a plurality of wires and an insulating layer surrounding and insulating the conductor; a filler that surrounds the inner conductor wire and is decomposed by heating to be disposed in the core portion along the axial direction of the inner conductor wire; a binder layer formed by surrounding the outside of the filler with a binder; and a jacket having an accommodation space capable of accommodating and protecting the binder layer from the outside. Due to the filler made of a material that is decomposed by heating, even when the cable is exposed by fire, it is melted by heating and no melt flow is generated, improving combustibility and readability, and furthermore, melting and falling spark particles are not generated by fire. The low combustion, low toxicity and flame resistance of the power cable against fire can be improved.

Here, when the twist length of the plurality of strands is 12 to 25 times the combined outer diameter of the conductor, it is preferable to improve the shape retention stability of the inner conductor wire and improve the suitability of the material of the inner conductor wire.

In addition, when the limiting oxygen index of each of the insulating layer and the jacket is 28% or more, flame retardancy of the insulating layer and the jacket can be improved.

Here, when the sum of the cross-sectional areas of the insulating layer and the jacket in the axial direction and the vertical direction is 50 to 70% of the total cross-sectional area of the power cable, both the insulation characteristics and flame retardant characteristics of the power cable can be properly maintained. do.

In addition, when the insulating layer is made of cross-linked polyethylene (XLPE) whose chemical structure is modified through a cross-linking reaction using organic peroxides, insulating properties can be improved.

Here, the filler may be made of a non-polymeric material.

And the binder layer is made of at least two or more different types of flame retardant tapes, and after one of the at least two or more different types of flame retardant tapes surrounds the outside of the filler, at least another one surrounds the one, , If the number of turns surrounding the at least two or more different flame retardant tapes is 1.2 to 6, and the wrapping rate of the at least two or more different flame retardant tapes is 15 to 80%, the outer diameter of the power cable is not increased. It is preferable because it can improve flame retardant properties.

Here, the filler fills the accommodation space of the jacket so that the inner conductor is disposed in the core along the axial direction of the jacket so that the inner conductor can be located in the core so that noise for power can be improved It is desirable to have

In addition, when the filler is made of a material having a decomposition temperature of 200° C. or more, it is preferable to prevent the occurrence of falling particles that become sparks while the filler is melted by a fire in the event of a fire.

According to the present invention, even when the cable is exposed to flame due to a fire due to the filler made of a material that is decomposed by heating, it melts by heating and does not generate a melt flow, improving combustibility and toxicity. There is an effect that the low combustion, low toxicity and flame resistance of the power cable against fire can be improved by preventing the falling spark particles from being generated.

1 is an exemplary view of a remote wireless equipment type base station system to which a power cable according to the present invention can be applied.
2 is a cross-sectional view of a power cable for remote wireless equipment according to the present invention.
3 is an exemplary cross-sectional view of an insulating layer and a jacket.
4 is an exemplary view of a binder layer.

Hereinafter, a power cable 1 for a remote wireless device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary view of a remote wireless equipment type base station system to which a power cable according to the present invention can be applied.

The base station system of the remote wireless equipment method of the present invention is ground equipment, and in the conventional BTS-type base station system, except for the remote wireless equipment, etc. , Power Supply Unit) is provided, and the base station tower has an antenna 20, a plurality of remote wireless devices 40 connected to the antenna 20 and a coaxial feeder line 30, and a plurality of the remote wireless devices 40 A terminal box 70 connected to an optical unit and a power unit may be provided.

In addition, the baseband unit 11 on the ground, the power supply device 12, and the terminal box 70 may be connected through an optical cable 80 and a power cable 100, respectively.

Here, the terminal box 70 branches/connects the power applied through the power cable 100 to a plurality of power units 60 so that power can be supplied from the power supply device 12 to the remote wireless equipment 40, and , It performs a function of branching/connecting a plurality of optical fibers in the optical cable 80 to optical fibers in the plurality of optical units 50 so that data can be transmitted and received between the baseband unit 11 and the remote wireless equipment 40.

More specifically, in the base station system of the remote wireless equipment method of the present invention, the baseband unit 11 and the terminal box 70 are connected by an optical cable 80, and the optical cable 80 is connected to a plurality of optical fibers in the terminal box 70 After being branched into the unit 50, it can be connected to each remote wireless equipment 40. Similarly, after the power supply 12 and the terminal box 70 are connected with the power cable 100, the power cable 100 is connected to the terminal. After branching from the box 70 to a plurality of power units 200, it is connected to each remote wireless device 40 to provide power supply and communication functions to the plurality of remote wireless devices.

Here, each of the optical cable 80 and the power cable 100 may be configured as a unified optical fiber composite cable, and the optical unit 50 and the power unit 60 may also be configured in the form of a unified jumper cable. there is. Since the remote wireless equipment 40 can be installed directly below the base station antenna on the top of the base station tower, the length of the coaxial feeder line 30 for supplying the signal converted into an RF signal by the remote wireless equipment 40 to the antenna is Since it is minimized and RF signal attenuation generated during RF signal transmission through the coaxial feeder line 30 is not a problem, the amount of attenuation of the signal right before radiation is minimized, and the need for TMA, which used a lot of power consumption, is eliminated. This technical feature has become a feature of the base station system of the remote radio equipment method in terms of maintenance of the base station.

Here, the power cable 100 for remote wireless equipment is melted by heating and does not generate a melt flow even when the cable is exposed due to a fire due to a filler made of a material that is decomposed by heating, so that flammability and toxicity are improved. In addition, low combustion, low toxicity, and flame resistance of the power cable against fire can be improved by preventing the occurrence of falling spark particles melted by fire.

Figure 2 is a cross-sectional view of a power cable 100 for remote wireless equipment according to the present invention, Figure 4 is an exemplary cross-sectional view of the insulating layer 112 and the jacket 140, Figure 5 is an exemplary view of the binder layer 130 am.

The power cable 100 for remote wireless equipment includes an inner conductor 110, a filler 120, a binder layer 130, and a jacket 140.

The inner conductor 110 provides a movement path for moving power. The inner conductor 110 includes a conductor 111 and an insulating layer 112 .

The conductor 111 includes a plurality of wires. The conductor 111 may be configured by including a plurality of element wires united to have a set pitch. The conductor 111 may be configured as a composite conductor in which a plurality of element wires are combined to have a complex pitch after a plurality of element wires are aggregated to form a set element line having a set pitch. Here, the aggregation and composite directions may be the same direction or may be opposite directions. The conductor 111 is mainly made of copper (Cu).

The twist length (pitch) of the plurality of wires may be 12 to 25 times the combined outer diameter of the conductor 111 . If the twisting length (pitch) of the plurality of wires is short, the length of the entire twisted inner conductor 110 is increased, which may increase material consumption and increase resistance. If the twisting length (pitch) of the plurality of wires is long, the structure is not stable, and thus it is difficult to maintain the shape of the entire inner conductor 110, and flexibility and elasticity may be deteriorated.

The insulating layer 112 may be formed surrounding the conductor 111 . The insulating layer 112 may be made of a material such as XLPE (Cross Linked-Polyethylene). The limiting oxygen index of the insulating layer 112 may be 28% or more, so that the flame retardancy of the insulating layer 112 is improved. Preferably, the limiting oxygen index of the insulating layer 112 may be 32% or more.

The insulating layer 112 may be formed of cross-linked polyethylene (XLPE) whose chemical structure is modified through a cross-linking reaction using organic peroxides, and insulating properties may be improved.

The filler 120 may be made of a material that surrounds the inner conductor 110 and is decomposed by heating so as to be disposed in the inner core portion of the binder layer along the axial direction of the inner conductor 110 . The filler 120 may fill the accommodation space of the jacket 140 so that the inner conductor 110 is disposed in the core portion along the axial direction of the jacket 140 . The filler 120 may be made of a material having a decomposition temperature of 200° C. or higher. Preferably, it is made of a non-polymeric material such as insulating paper having a decomposition temperature of 240 to 290 ° C. It can melt and prevent sparks from falling even in the event of a fire.

The binder layer 130 is formed by surrounding the outside of the filler 120 with a binder. The binder layer 130 is made of at least two or more different types of flame retardant tapes, and after one of the two or more different types of flame retardant tapes surrounds the outside of the filler 120, at least one of the other types may be formed surrounding either one. there is.

The binder layer may be composed of a metal tape containing a metal component or a flame retardant tape containing a synthetic resin and a flame retardant component such as mica or glass fiber, and may also be composed of a flame retardant polymer resin or non-woven fabric, preferably Mica tape, glass tape, etc. may be applied.

The binder layer 130 may include 1.2 to 6 overlapping turns of at least two different flame retardant tapes, and a wrap rate of 15 to 80%. In the case of the binder layer 130 composed of at least two different types of flame retardant tapes, the sum of the number of turns of the first flame retardant tape and the second flame retardant tape may be 1.2 to 6, and an average wrap rate may be 15 to 80%. .

The range of the number of turns (lap rate) of the flame retardant tape means an optimal range considering the balance of flame retardant performance and the outer diameter of the cable. That is, if the number of turns is small, the flame retardant property is not good, and if the number of turns is large, the outer diameter of the cable increases.

The jacket 140 protects the binder layer 130 from the outside and forms an accommodation space capable of accommodating it. The jacket 140 may be made of a low smoke zero halogen (LSZH) flame retardant material. The jacket 140 may use a non-halogen flame retardant polyolefin resin that does not emit halogenated hydrogen gas during combustion.

Here, the sum of the cross-sectional areas of the insulating layer 112 and the jacket 140 in the axial direction and the vertical direction may be 50 to 70% of the total cross-sectional area of the power cable 100 . Among all cable components, components that are vulnerable to fire and have the greatest influence on smoke and acidity are the insulating layer 112 and the jacket 140. If the cross-sectional area ratio of the insulating layer 112 and the jacket 140, which are the components, is high, the flame retardant property is not good, and if the cross-sectional area ratio is low, the insulation properties that the power cable should have are not satisfied.

In addition, the insulating layer 112 and the jacket 140 may be made of a material having a smoke density of 150 [Dm] or less to provide excellent flame retardancy.

3 is an exemplary cross-sectional view of the insulating layer 112 and the jacket 140 .

3 (a) is the total cross-sectional area A1 of the power cable 100 including the insulating layer 112 and the jacket 140.

3 (b) is a cross-sectional area (A2+A3) including only the insulating layer 112 and the jacket 140.

In FIG. 3 , it is shown that the sum of the cross-sectional areas of the insulating layer 112 and the jacket 140 in the axial direction and the vertical direction constitutes 50 to 70% of the total cross-sectional area of the power cable 100 .

4 is an exemplary view of the binder layer 130, which is formed of a first flame retardant tape 131 and a second flame retardant tape 132.

Specifications for each component of the power cable 100 for remote wireless equipment are shown in Table 1 below.

Count structure ingredient note Composite Outer Diameter (mm) thickness
(mm) individual cross-sectional area
(mm ² ) Individual cross-sectional area ratio
(%) material Flame retardant properties conductor 2 2.6~6.7 - 9.6~34.2 7.2~15.3 COPPER Isolation 2 3.7~8.4 0.5~0.8 13.7~33.3 9.5~15.4 XLPE LOI ≥ 28 [%] SMOKE DENSITY ≤ 50 [Dm] filler N 7.4 to 16.8 - 26.5 to 92.4 19.9~40.0 Decomposition temperature≥200 [ºC] binder 1 - - 0.1~0.2 - - binder 2 - - 0.1~0.2 - - jacket One 11.4~22.9 1.4~2.3 56.6 to 117.2 33.8 to 63.8 LSZH LOI ≥ 28 [%] SMOKE DENSITY ≤ 50 [Dm]

The power cable 100 is classified as flame retardant by EN 13501-6 among New EU cable Fire Safety Regulations (CPR).

(1) Euroclassification

(2) Test items

(3) Additional test grading

(4) Number of test samples

* How to indicate cable rating

The flame retardancy of the power cable 100 is inspected according to the above criteria. In the case of general cables, especially in the case of (3) additional test grade classification (Table 5), particles (sparks) that melt and fall due to heat are generated, so the higher grade in the flame retardancy test cannot be obtained The melting and falling particles (sparks) caused by such heat are often caused by materials in which fillers can be melted by heating or ignited by heating, so power cables are made of materials that are decomposed by heating. It is preferable to be made of.

Due to the above power cable 100 for remote wireless equipment, even when the cable is exposed due to a fire due to the filler made of a material that is decomposed by heating, no melt flow is generated while melting by heating, so that combustibility and toxicity are reduced. Furthermore, low combustion, low toxicity, and flame resistance of the power cable against fire can be improved by preventing spark particles that melt and fall by fire from occurring.

100: power cable for remote wireless equipment
110: inner conductor 111: conductor
112: insulating layer
120: filler
130: binder layer 131: first flame retardant tape
132: second flame retardant tape
140: jacket

Claims (10)

In the power cable for remote wireless equipment,
An inner conductor made of a conductor including a plurality of wires and an insulating layer enclosing and insulating the conductor;
a filler that surrounds the inner conductor so as to be disposed in the core portion along the axial direction of the inner conductor and is decomposed by heating so that no melt flow occurs;
a binder layer formed by surrounding the outside of the filler with a binder; and
A power cable for remote wireless equipment comprising a jacket having an accommodation space capable of accommodating and protecting the binder layer from the outside.
According to claim 1,
The twisted length of the plurality of wires is 12 to 25 times the combined outer diameter of the conductor.
According to claim 1,
The limiting oxygen index of each of the insulating layer and the jacket is a power cable for remote wireless equipment made of 28% or more.
According to claim 1,
The power cable for remote wireless equipment wherein the sum of the cross-sectional areas of the insulating layer and the jacket in the axial direction and the vertical direction is 50 to 70% of the total cross-sectional area of the power cable.
According to claim 1,
The insulating layer is
A power cable for remote wireless equipment made of cross-linked polyethylene (XLPE) whose chemical structure is modified through a cross-linking reaction using organic peroxides.
According to claim 1,
The filler is a power cable for remote wireless equipment made of a non-polymeric material.
According to claim 1,
The binder layer,
A power cable for remote wireless equipment made of at least two or more different types of flame retardant tapes, wherein one of the at least two or more different types of flame retardant tapes surrounds the outside of the filler, and then at least another one surrounds the one.
According to claim 7,
The sum of the number of turns surrounding the at least two different types of flame retardant tapes is 1.2 to 6 times, and the average value of the wrapping rate of the at least two different types of flame retardant tapes is 15 to 80%. .
According to claim 1,
The filler,
A power cable for remote wireless equipment formed to fill the accommodating space of the jacket so that the inner conductor is disposed in the core portion along the axial direction of the jacket.
According to claim 9,
The filler,
A power cable for remote wireless equipment made of a material with a decomposition temperature of 200℃ or higher.

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