JP2000245039A - Design of armor rod for reducing distortion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the wire diameter and length of an armor rod effective for reducing distortion without excessive performance, by conducting design so that the cross-section coefficient of the armor rod may satisfy a particular expression against the cross-section coefficient of an electric wire and a target for reducing distortion. SOLUTION: This armor rod 1 consists of a plurality of stranded wires 2 formed in a spiral form, and the respective stranded wires 2 are mounted by being wound around the outer peripheral of an electric wire. The relationship of an armor rod cross-section coefficient Z2 and an electric wire cross-section coefficient Z1 satisfies the following expression: Z1/(Z1+Z2)<=a/100, and the armor rod cross-section coefficient Z2 is determined from the following expression: Z2=n×πd3/32 (mm2), where (n) is the number of the armor rods (number of pieces), (d) is the wire diameter of the armor rod (mm), and (a) is a target for distortion reduction, and the proportion of the target for distortion reduction to the case that no actions are taken is preferably set to 50-60%. It is thus possible to satisfy the effect of distortion reduction without excessive performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for designing an armor rod for reducing distortion.

[0002]

2. Description of the Related Art As a measure for preventing vibration fatigue of an electric wire in a gripping portion of an overhead power transmission line and a measure for preventing fusing, an armor rod is used in which a metal of the same system as the electric wire is wrapped around the power transmission line to reinforce the wire. .

[0003]

However, conventionally, there is no special design method for designing the diameter and length of the armor rod, and the wire diameter and length are roughly determined with a considerable margin. I was As a result, the obtained armor rod often has excessive performance, resulting in waste of the armor rod material.

Accordingly, an object of the present invention is to provide a method of designing an armor rod that can determine the diameter and length of an armor rod effective for reducing strain without causing excessive performance.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventor has conducted studies in consideration of the following points, and as a result, has arrived at the present invention.

[0006] The larger the diameter of the armor rod, the greater the effect of reducing distortion. However, if the diameter is excessively large, winding is difficult and uneconomical. Conversely, if it is too thin, the wire will be damaged first because the former is larger when comparing the wire-generated strain and the armor rod strain. This damage usually occurs in the area covered by the armor rod and cannot be found externally during inspection.

A longer length of the armor rod is advantageous because the wire generation distortion at the end of the armor rod is reduced, but an excessively long one is problematic in winding workability and is uneconomical.

That is, the design method of the present invention is based on the assumption that when the sectional modulus of the electric wire (sum of the sectional coefficients of the strands) is Z1, the sectional modulus of the armor rod is Z2, and the strain reduction target is a% without measures, Z2
Is designed to satisfy the following equation. Z1 / (Z1 + Z2) ≦ a / 100 Expression 1 where Z2 is determined by the following expression. ^{Z2 = n × πd 3/32} (mm 2) ... Equation 2 n: Amaroddo number (present) d: Amaroddo wire diameter (mm)

Here, the wire diameter of the armor rod is d (m
m), when the aluminum wire diameter of the electric wire is d1 (mm), it is desirable to determine the wire diameter of the armor rod so as to satisfy the following equation. d> d1 / 0.8 (mm) ... Equation 3

Usually, an electric wire has a design value of the wire breaking tension of 20%.
This is because it is considered that "Equation 3" needs to be satisfied in order to adopt the fatigue design coordination of the armor rod and the electric wire since the% tension is applied.

When the length of the armor rod is L (mm), it is preferable to determine the length of the armor rod so as to satisfy the following equation. More preferably, L is about 200d. L> 150 × d (mm)… Equation 4

Further, the distortion reduction target (a) is 50-
80% is practical, and more preferably 50-60%. It is usually sufficient if a distortion reduction effect of 50% can be obtained as compared with the case where no countermeasures are taken, and if it cannot be reduced to 80% or less, the distortion reduction effect is small.

Note that the upper limit of the armor rod diameter is given by "Equation 1".
And about 1.2 times the value that satisfies “Expression 2”.
As shown in the experimental results described later, when the diameter of the armor rod increases, the electric wire generation strain at the end of the armor rod increases,
This is the bending stiffness (E
This is because I, E: elastic modulus, I: second moment of area) are different. Therefore, in order not to have a large flexion inflection point at the end of the armor rod, the EI selected in "Equation 1" and "Equation 2" should be within the range with EI less than twice the EI selected. Is desired. The second moment of area is I = πd ⁴ (mm ⁴ ) for one armor rod. Equation 5 d: Armor rod diameter (mm) Therefore, to make EI twice or less, ⁴ 42 ≒ 1.19 This is because it is necessary to be less than twice.

The upper limit of the length of the armor rod is preferably up to about 2 m. When the present invention is applied to currently used overhead transmission lines (such as ACSR), the diameter of the armor rod is in the range of about 4 to 8 mm. The length of the armor rod is preferably set to a lower limit value satisfying “Equation 4” with respect to this wire diameter range, and is about 600 to 1200 mm. The armor rod length is usually divided in units of 100 mm, so if a fraction that does not exceed 100 mm comes out, it will be rounded up. Therefore, it may be at least about 10% longer than the lower limit of “Equation 4”. Furthermore, since the longer the armor rod length is advantageous except for the construction aspect and economy, in order to ensure the effect of reducing distortion,
It is considered that the length may be longer up to about 50% of the "length range of about 600 to 1200 mm". In particular, if it is 2 m or less, it is considered that there is no problem in construction, so the upper limit is 2 m.
Degree.

[0015]

Embodiments of the present invention will be described below. A design example in which the electric wire generated strain of an ACSR (steel core aluminum stranded wire) 410 mm ² electric wire is reduced to 以下 or less is shown.

As shown in FIG. 1, the armor rod 1 comprises a plurality of spirally formed wires 2. Attachment to the electric wire is performed by winding each element wire 2 around the outer periphery of the electric wire. Here, the armor rod wire diameter indicates the diameter of one strand.

Armor rod (AR) wire diameter and its section modulus Z2
FIG. 2 shows the relationship with. In the wire section modulus Z1 that is indicated by broken line in this graph, Z2 is ^{Z2 = n × πd 3/32} (mm 2) ... Equation 2 n: Amaroddo number (present) d: Amaroddo wire diameter (mm) Required by

Accordingly, it can be seen that the armor rod diameter needs to exceed 5.2 mm to satisfy the following equation: Z1 / (Z1 + Z2) ≦ a / 100 (a = 50 in this case). Further, from the fatigue design coordination, since the aluminum element diameter of the electric wire is 4.5 mm, it is necessary that the diameter of the armor rod exceeds 5.6 mm according to Equation 3.

A strain measurement test was performed using armor rods having three types of wire diameters and two types of lengths, and the generated strain of the electric wires and the armor rods was measured. Fig. 3 shows the measurement method. Length 2m
A sample wire 3 (ACSR410mm ² ) is prepared, an armor rod 1 is attached to one end and held by a clamp 4, and the other end is a pulley 5
Weight 6 for applying a load and weight 7 for canceling the sample weight
Link with. Then, a load of 3 kg was applied to the sample wire 3 and the amount of strain at the time of clamping the sample wire 3 and at the end of the armor rod was measured.

The results are shown in FIGS. Figure 4 shows the length
FIG. 5 shows test results for an 800 mm armor rod, and FIG. 5 shows test results for an 1500 mm length armor rod.
The “armor rod part at the time of clamping” refers to the end of the armor rod on the clamp side, and the “wire part at the time of clamping”
Indicates an electric wire portion adjacent to the clamp, and "the end of the armor rod" indicates the end of the armor rod on the weight side (opposite the end on the clamp side). In addition, the “no action 1/2 line” indicates a value of の of the electric wire distortion amount when the armor rod is not provided.

As shown in FIGS. 4 and 5, the length is 1500 mm.
It has been confirmed that the armor rod having a wire diameter of 6.2 mm has a small amount of distortion particularly at the “wire portion at the time of clamping” and satisfies the distortion reduction effect.

Next, a similar test was performed on an armor rod having a wire diameter of 6.2 mm while changing the length. Figure 6 shows the results.
Shown in As is clear from this graph, the length is 1200 mm
From the above, it can be seen that the distortion reduction effect is satisfied.

Conventionally, ACSR (steel core aluminum strand) 41
The armor rod used for 0 mm ² electric wire has a wire diameter of 7.
Given that the length was 8 mm and the length was 2500 mm, the armor rod based on the design method of the present invention had a wire diameter of 6.2 mm and a length of 1200 mm.
It can be seen that the size has been significantly reduced.

[0024]

As described above, according to the present invention,
It is possible to design an armor rod capable of sufficiently obtaining a distortion reducing effect without excessive performance. Therefore, the material of the armor rod can be saved, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows an armor rod, (A) is an end view, and (B) is a side view of a strand.

FIG. 2 is a graph showing a relationship between an armor rod diameter and a sectional modulus Z2 thereof.

FIG. 3 is an explanatory diagram of a strain measurement test method.

FIG. 4 is a graph showing the results of a strain measurement test on an armor rod having a length of 800 mm.

FIG. 5 is a graph showing a strain measurement test result for an armor rod having a length of 1500 mm.

FIG. 6 is a graph showing the results of a strain measurement test performed on an armor rod having a wire diameter of 6.2 mm while changing the length.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Armor rod 2 Element wire 3 Sample wire 4 Clamp 5 Pulley 6 Weight for applying load 7 Weight for offsetting sample weight

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Go Fujishima 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries, Ltd. Osaka Works F-term (reference) 5G367 BA01 BB02 BB14

Claims (4)

[Claims] When the sectional modulus of an electric wire is Z1, the sectional modulus of an armor rod is Z2, and a strain reduction target is a% without measures, Z
2. A method for designing a strain reducing armor rod, wherein 2 is designed to satisfy the following equation. Z1 / (Z1 + Z2) ≦ a / 100 Expression 1 where Z2 is determined by the following expression. ^{Z2 = n × πd 3/32} (mm 2) ... Equation 2 n: Amaroddo number (present) d: Amaroddo wire diameter (mm) 2. The strain according to claim 1, wherein when the wire diameter of the armor rod is d (mm) and the wire diameter of the aluminum wire is d1 (mm), the wire diameter of the armor rod is determined so as to satisfy the following equation. How to design a reduction armor rod. d> d1 / 0.8 (mm) ... Equation 3 3. The method of claim 1, wherein the length of the armor rod is determined so as to satisfy the following equation, where the length of the armor rod is L (mm). L> 150 × d (mm)… Equation 4 4. The method for designing an armor rod for strain reduction according to claim 1, wherein a is 50 to 80%.