JPH0676641A - CV cable with double wire shield - Google Patents

Abstract

(57) [Abstract] [Purpose] From the viewpoint of performance, the spiral deformation due to the shield wire when the temperature rises is small, and the wire that can be manufactured with good workability by keeping the diameter of the shield wire below the current level (2.0 mmφ) in manufacturing. Provide shielded CV cable. [Structure] In a shielded CV cable, the wire shield layer has a double structure of an inner layer and an outer layer, and the winding direction of the inner layer wire is the same as the twisting direction of the conductor segments,
The winding direction of the outer layer wire shall be the opposite direction. Also,
Specifically, the wire diameter of the wire shield layer is 2.0 m.
mφ or less, the number of wires is 40 to 80 in the inner layer, and the number of wires in the outer layer is the same as the number of inner layers, or even if it is reduced, it should be 10% less than the number of inner layers and the winding pitch should be the same for both inner and outer layers. Is preferred.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a CV with a wire shield.
It is about cables.

[0002]

2. Description of the Related Art In a conventional CV cable with a wire shield, the wire shield is composed of 40 to 80 copper wires having a diameter of 1.2 to 2.0 mm and wound horizontally in a single pitch at a pitch 3 to 8 times the core diameter. S-Z roll is used.

FIG. 2 shows a sectional view of a conventional CV cable with a single horizontal winding wire shield.

Generally, the diameter and the number of used copper wires are determined by the ground fault and short-circuit current conditions, and the winding pitch is determined by mechanical conditions such that the cable does not buckle when subjected to bending deformation.

The conventional CV cable with a wire shield has a problem that when it thermally expands due to a temperature rise, spiral deformation occurs in the offset portion and lateral shake occurs in the vertical snake portion.

It has been confirmed that the above problem occurs in the direction in which the winding of the wire is loose in the case of the spiral wound wire shield, and in the direction in which the twist of the conductor segment is loose in the case of the SZ wound wire shield.

Further, the ground fault current and the short-circuit current of the line tend to be large, and the wire shield layer has, for example, 2.0 mm.
There are cases in which 80 φ copper wires are required,
In order to wind a large number of thick wires around the wire shield layer, it is necessary to install new equipment.

Furthermore, it is conceivable that the equipment for winding a thick wire around the core without bending will be considerably large. Further, the SZ winding of such a thick wire causes a large repulsion of the wire and is difficult to manufacture.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the prior art, and in terms of performance, the spiral deformation at the time of temperature rise is small. An object of the present invention is to provide a wire-shielded CV cable that can be manufactured with good workability by suppressing the current level (2.0 mmφ) or less.

[0010]

The above objects are achieved by the double wire shielded CV cable of the present invention.

That is, in a CV cable with a spiral wound wire shield, the wire shield layer has a double structure of an inner layer and an outer layer, and the winding direction of the inner layer wire is the same as the twisting direction of the conductor segments and the winding direction of the outer layer wire. Was achieved by providing a double wire shielded CV cable characterized in that

In the double wire shield CV cable of the present invention, the wire shield layer has a double structure of an inner layer and an outer layer, and the wire diameter of the wire shield layer is 2.0.
mmφ or less, the number of wires in the inner layer is 40 to 80, the number of wires in the outer layer is the same as the number of inner layers, or even if the number is smaller, the number is 10% less than the inner layer, and the winding pitch is the same in both inner and outer layers. It is preferably a heavy wire shielded CV cable.

The twisting of the wire-shielded CV cable occurs because the conductor is a divided conductor and the wire shield is spirally wound.

In the case of conductor Tensile force: _{F≈E cu} · (α-α _cu ) · ΔT · A / co
sβ torque: T = F · sinβ · d / 2 where, E _cu: Young's modulus of the conductor alpha: linear expansion coefficient of the cable alpha _cu: linear expansion coefficient of the conductor △ T: temperature change of the conductor A: a conductor cross-sectional area is there.

[0015] While in the case of wire shielding _{T> σ 0.2 · sinβ · d} / 2 · N · πD 2/4 , where, N: number of wires D: wire diameter sigma _0.2: Strength of wire copper (≒ 15 kg / mm ² ).

Therefore, 275kV CV cable 1x
In the case of 3000 mm ² (7-section conductor right twist, wire shield 2.0 φ × 80 left twist), the torque due to the conductor is 3.8% from the torque due to the wire shield, and the calculated torque is 7.0%. %, Ultra-high pressure, large size C where twisting torque is usually a problem
In the V cable, the torque due to the conductor is about 10% or less of the torque due to the wire shield.

It can be seen that the spiral deformation of the offset portion and the lateral deflection phenomenon in the vertical snake portion of the CV cable with a wire shield at the time of thermal expansion are mainly caused by the horizontally wound wire shield and the conductor segment as a secondary cause.

Since the difference in the twisting torque between the inner and outer layers when the wire shield has two layers is proportional to the core diameter of the wire, the core diameters of the inner and outer layers are 120.0 mm and 1 respectively.
24.2 mm (wire diameter 1.6 mm, seat tape 0.
5 mm), the difference between the twisting torques of the inner and outer layers of the double wire shielded CV cable is calculated to be 3.5%.

Since the cable is a composite, the deformation and the lateral vibration phenomenon cannot always be theoretically elucidated, and it is impossible to predict the characteristics of all cables. In addition, a slight spiral deformation and lateral shake phenomenon can be tolerated practically without any problem.

Therefore, intentionally changing the wire diameter, the number of wires and the winding pitch of the wires in the inner and outer layers of the wire shield complicates the work and has no merit.

Therefore, when the wire shield has two layers, it is preferable that the inner layer and the outer layer are wound with the same number of wires and the same pitch at the same pitch.

If the number of wire shields is extremely small, the distance between the wires will become large, and irregularities will appear on the sheath. Reducing the number of wires will lead to an increase in the wire diameter, and as a result, the cable. It is not preferable because the outer diameter becomes large.

From the results of the above-mentioned examinations and the conventional results, the double wire shielded CV cable of the present invention has a wire diameter of 2.0 mmφ or less, and the number of wires is 4 in the inner layer.
It is possible to manufacture 0 to 80 pieces and the outer layer with the same number as the inner layer with good workability. Even if the number of wires in the inner and outer layers cannot be the same for some reason, it is preferable to keep the rate of reducing the number of outer layers within about 10%.

[0024]

【Example】

(Example 1) The short circuit current of the 500 kV underground power transmission line is 63
It is assumed to be kA x 0.2 seconds. When applying a wire-shielded CV cable to this line, in order to prevent the cable from having a thermal effect, use a copper conductor of 313 mm ²
Is required, and in the case of the conventional spiral wound wire shield cable, 76 wires are required by using 2φ copper wire for the wire.

As the wire-shielded CV cable for this purpose, the double wire-shielded CV cable of the present invention in which 78 copper wires each having a diameter of 1.6φ are horizontally wound in each of the inner layer and the outer layer shown in FIG. 1 is applied. I responded. Since the conductor segment is usually right-handed, the inner layer was right-handed and the outer layer was left-handed.

[0026]

EFFECTS OF THE INVENTION As a super high voltage, large size CV cable in which a twisting torque is a problem, a CV cable which has a small spiral deformation when the temperature rises and which can be manufactured with good workability has been required in terms of performance. The requirements can be met by applying the double wire shielded CV cable of the present invention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a CV cable with a wire shield according to the present invention.

FIG. 2 is a cross-sectional view of a conventional CV cable with a wire shield.

[Explanation of symbols]

 1 split conductor 2 insulator 3 copper wire (wire shield) 4 sheath 31 inner layer wire shield 32 outer layer wire shield

[Procedure amendment]

[Submission date] June 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

Further, the ground fault current and the short-circuit current of the line tend to be large, and the wire shield layer has, for example, 2.0 mm.
There are cases where 80 or more φ copper wires are required, but new equipment is required to wind such a large number of thick wires around the wire shield layer.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

Since the cable is a composite, its deformation and lateral deflection phenomenon cannot always be theoretically elucidated, and it cannot be predicted accurately for all cables. In addition, a slight spiral deformation and lateral shake phenomenon can be tolerated practically without any problem.

Claims (2)

[Claims] In a CV cable with a spiral wound wire shield, the wire shield layer has a double structure of an inner layer and an outer layer, and the winding direction of the inner layer wire is the same as the twisting direction of the conductor segments and the winding direction of the outer layer wire. CV cable with a double wire shield, characterized in that it is in the opposite direction. 2. In a CV cable with a spiral winding wire shield, the wire shield layer has a double structure of an inner layer and an outer layer, and the wire diameter of the wire shield layer is 2.0 mm.
φ or less, the number of wires is 40 to 80 in the inner layer, the outer layer is the same number as the inner layer up to 10% less than the inner layer, and the winding pitch is the same for both the inner and outer layers. 1. The double wire shielded CV cable described in 1.