JPH0444485B2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a wire drawing method.

<Conventional technology> As a conventional wire extension method, for example,
The one shown in Publication No. 19651 is known.

<Problem to be solved by the invention> This wire stretching method streamlines work by concentrating control devices for wire stretching equipment in one place, improves wire drawing quality through more precise control, and improves safety. There has been considerable progress in this respect. However, there are still many things that need to be done in terms of achieving a more ideal line quality. Specifically, (a) Each span is subject to the wire running environment, that is, the conditions of the steel wheels on the steel towers at both ends, such as the passage resistance of the wire itself and the protector due to the size of the included angle and horizontal angle, and the obstacles below. Since the condition of each object is different, the required drawing speed and drawing tension will naturally differ accordingly, but this conventional method transfers the necessary data to the drum field and engine field. Although it is taken from
Since specific data for each span was not collected, it was not possible to extend the wire with the minimum required tension for each span based on this data specific to each span, which ultimately led to considerable safety issues. This means that the wire has no choice but to be stretched with a wire tension that is higher than necessary considering the rate.

(b) For metal wheels with a large included angle, adjust the wire drawing speed and tension in advance when the protector approaches the metal wheel in order to soften the increase in wire tension and shock caused by the passage of the protector. Such measures are required. However, with this conventional line extension method, there was no way to automatically predict the approach of the protector's gold wheel, so observers were stationed at the necessary steel towers. However, if it is done manually in this way, the number of workers will increase, leading to increased costs, and visual inspection in harsh work environments such as mountainous areas cannot always be expected to provide accurate predictions. It is insufficient in that it is difficult to expect to always accurately capture the predicted timing that should differ depending on the linear velocity, and furthermore, it is not always possible to respond accurately due to the unavoidable time lag when communicating by telephone or radio. It is.

(c) The same thing can be said for (b) when monitoring the distance between the power line and obstacles below the line extension section.

(d) When passing a protector against a wire wheel with a large angle of embrace, if accurate prediction and appropriate response cannot be taken, an increase in wire tension and shock due to the passage of the protector will be unavoidable. This may put an unexpected burden on the equipment.

<Means for Solving the Problems> As a means for solving the above problems, this invention uses the height difference and span distance of each tower designed for each construction, the unit weight of electric wires, and the height and position of obstacles. ,
Data related to the design wire tension, wire speed, etc. are processed in advance based on predetermined specifications, and the control device into which the processing results are input is used to control the wire rolling cars, overhead wire winches, etc.
In addition to centrally and remotely controlling wire rolling equipment such as metal wheels, wire wheels and data acquisition machines are installed on required steel towers to measure the wire tension, and vibrations of the wire wheels as the wire passes through are measured. Data regarding the angle, the angle between the electric wire and the metal wheel, the hanging force generated on the metal wheel, etc. are transmitted to the control device via a data acquisition device that responds to calls from the control device, and from these various data. Based on a predetermined program that is pre-installed in the control device, it calculates the inlet-side tension, outlet-side tension, or both tensions occurring in the wire at the support section using the metal wheel, and automatically separates the wire from obstacles on the ground. The measurement result shall be transmitted to the control device via the data acquisition device, and a receiver will be installed on the metal wheel of the required steel tower, and this receiver will be able to measure the distance from the protector mounting part in the wire extension direction. A transmitter attached to the wire at a predetermined distance ahead of the wire detects that the wire passes the metal wheel as the wire advances, thereby predicting the approach of the protector's metal wheel, and uses this prediction data to transmit the data to the controller. The data shall be transmitted to the control device via the data acquisition device that responds to the call from the device, and at least two or more gold wheels shall be installed in series on the required steel tower in the direction of movement of the wire, and the protector's metal wheel shall be transmitted to the control device via the data acquisition device that responds to the call from the device. Based on prediction, the metal wheel on the front side in the direction of movement of the electric wire is positioned lower than the metal wheel on the forward side in the direction of movement, so that the protector can easily penetrate into the metal wheel, and the protector can easily penetrate the metal wheel on the front side in the direction of movement. After passing, the gist of the protector is to make it easier for the protector to escape from the metal wheel by positioning the metal wheel on the forward side in the direction of travel lower than the metal wheel on the near side in the direction of travel.

<Operation> In other words, the work is streamlined by central remote control of wire extending equipment by a control device into which various data are input in advance.

In addition, by determining the inlet-side tension, outlet-side tension, or both tensions occurring in the wire at the part supported by the metal wheel, and using this data, it is possible to extend the wire with the minimum necessary wire tension for each span. This makes it possible to perform high-quality and highly safe wire-running work with less stress on the wires and wire-running equipment.

In addition, since the distance between the electric wire and obstacles on the ground is automatically measured and the measurement results are transmitted to the control device via the data acquisition device, it is possible to always accurately determine the distance between the wires and obstacles on the ground. Lines can be extended in safer conditions.

In addition, the approach of the protector to the metal wheel is automatically predicted by a combination of a transmitter attached to the wire and a receiver installed on the metal wheel, so it always accurately predicts the approach of the protector to the metal wheel. You can predict the optimal timing to perform an operation.

In addition, based on this prediction, two or more metal wheels connected in series are operated to facilitate the passage of the protector through the metal wheel, so the increase in wire tension and shock caused by the passage of the protector can be alleviated. Similarly to the above, high quality and highly safe wire extension work is now possible.

<Example> Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 11. In addition, in this specification,
"Electric wire" is a broad concept that includes wires used in wire extension work, messenger wires, traction wires, etc.

This wire drawing method is more suitable for carrying out so-called multiple wire drawing in which a plurality of wires are drawn at the same time, and is mainly composed of the matters listed below.

(A) Each steel tower Pi designed and planned for each construction project in advance
Height difference hi, span distance Si, unit weight of wire Wi,
Data regarding height Bi and position Ai of obstacles, designed wire drawing tension, wire drawing speed, etc. are processed by a computer based on predetermined specifications, and the results are input to the control device 1 via a floppy disk.

(B) The control device 1 uses a so-called personal computer, and corresponds to a main processing device 2 that plays a central role and a plurality of electric wires 3 ₁ and 3 ₂ that are extended at one time as a set. The sub-processing devices 6 _4-1 , 6 _4-2 , 6 _5-1 , 6 _5-2 are provided for each of the line rolling cars 4 ₁ , 4 ₂ and the overhead wire winches 5 ₁ , 5 ₂ . The main processing device 2 takes in various data that will appear in the following explanation, calculates and processes them, and at the same time, based on the results, the sub-processing device 6
The wire extension cars 4 ₁ , 4 ₂ , overhead wire winches 5 ₁ , 5 _{2 ,} and other various wire extension equipment are individually controlled via the wire extension controller 1 in accordance with a predetermined method described later. In the figure, 7i indicates the main processing unit 2 which collects various data obtained from various measuring means installed in the necessary steel tower Pi, drum station D, and engine station E.
This is a data acquisition machine for sending data to the main processing unit 2 in response to a call from the customer.

In addition, to connect each data importer 7i and the main processing unit 2, use a communication cable PC as shown in this example.
or wirelessly. As the communication cable PC, an optical fiber cable is preferable, but a general metal cable may also be used.

In addition, since the distance between each tower Pi is usually several hundred meters, securing power supply for each data acquisition machine 7i and other wire extension equipment installed on each tower Pi becomes an issue. One possible solution is to install solar cells on each tower Pi.

(C) Each sub-processing device 6i-i is provided with a corresponding color display 8i-i. On this color display 8i-i, various data processed by the above-mentioned main processing device 2 are appropriately displayed through processing by the sub-processing device 6i-i. An example of the display is shown in FIG.

(D) Each color display 8i-i schematically displays the entire line extension status, including the line extension progress, so that the overall status can be grasped at all times. The progress of the wire extension is displayed in different colors, such as green for the wire section 9 and red for the main line (electric wire) section 10.

(E) Predict the approach/passing of the protector Ci to the gold wheel 20i, the number of the protector Ci that is about to pass, the number of the corresponding steel tower Pi, and the corresponding steel tower.
The number of Pi and the approach distance are displayed on the color display 8i-i. A specific method of prediction will be described later.

(F) Based on this prediction, in order to make it easier for the protector Ci to pass through the metal wheel, for example, the wire drawing tension or the wire drawing speed is adjusted, or the metal wheel is operated as described later. In addition, the tension at the metal wheel portion described below
Preparations for measuring Tn and Tx will also be made. Note that the adjustment of the wire drawing tension and the wire drawing speed is performed while taking into account the tensions Tn and Tx occurring in the relevant steel tower Pi, the height difference hi of the steel tower Pi, etc.

(G) The length of the wire extension is displayed according to its progress, and the timing of the end compression process, that is, the timing of the temporary stop of the wire extension car ₄₁ and the overhead line winch 5i is managed.

(H) At the same time as constantly measuring the inlet side tension Tn and outlet side tension Tx (Fig. 3) actually occurring in the supporting part of the steel tower Pi, specifically, the metal wheel 20i,
The distance L between the electric wire 3 and an obstacle O in the span of the steel tower including the steel tower Pi is constantly measured, and the results are displayed on the color display 8i-i. At this time, the target obstacle O is the one with the smallest distance L in its span. Specific methods for measuring each tension Tn, Tx and distance L will be described later.

(I) The wire extension tension is individually controlled for each tower span through which the tip 17 of the electric wire 3 passes, using the data regarding the respective tensions Tn, Tx and the distance L obtained in this way. In addition, when controlling the wire drawing tension for each span individually using the tensions Tn and Tx, the tensions Tn and Tx obtained in the first wire drawing are
This also includes teaching that utilizes Tx data to set the conditions for the next cable extension.

(J) The actual wire drawing tension and wire drawing speed at drum station D and engine station E are shown on the color display 8i.
At the same time, these values and the preset planned values for these are displayed as tension deviations in percentage (%).
Based on this comparison, control is performed to always approach the planned value. This planned value is calculated for each span as the minimum necessary wire tension required for each span.

(K) The data input and displayed above will be recorded in a comparison table that compares the actual data with the planned values, and will be used as track extension history.

Method for predicting the approach of the protector to the gold wheel 20i Prediction of the approach and passage of the protector Ci to the metal wheel 20i is performed for the necessary steel tower Pi, that is, the steel tower Pi for which the gold wheel 20i there has a large angle of embrace.
This is achieved by a combination of rough prediction and accurate prediction (Figures 3 to 6).

Although we do not have an accurate grasp of the approach distance, we can roughly predict which protector Ci is the gold wheel 2 of which steel tower Pi.
The purpose is to make a prediction that can distinguish whether it is approaching 0i or not, and this is done by measuring the length of the wire 3 being paid out and grasping the progress (advance distance) of the protector Ci.

Accurate prediction is based on the magnetizing body 21 as a “sending body”
and magnetic limit switch 22 as a “receiver”
This is done in combination with That is, as shown in FIG. 4, the gold wheel 20i has
The frame 23 corresponds to the part through which the electric wire 3 passes.
A magnetic limit switch 22 is provided on the wire 3, and a magnetic generating body 21 is installed on the wire 3 at a position a certain distance ahead of the protector Ci mounting portion in the wire running direction (arrow A direction). The magnetic limit switch 22 detects when the magnetic body 21 passes the metal wheel 2i before passing the protector Ci, and the magnetic limit switch 22 detects that the magnetic body 21 passes through the metal wheel 2i. We are trying to predict the state and, in turn, the exact timing of passage. In addition, the magnetic limit switch 22 is
It is also possible to provide an arm body 24 as shown by imaginary lines in FIG. 2 on the metal wheel 20i.

As shown in FIGS. 5 and 6, the magnet 21 is made of a plastic magnet 25 embedded in a cover 26 made of plastic, specifically urethane, and is split into two. The electric wire 3 is fixed to the electric wire 3 using tape or wire using a groove 27 provided on the outer surface of the cover 26. In addition, 28 is a cover 26 for the magnet 25.
It is a lid to be embedded inside. The reason why the magnet 25 is embedded in the plastic cover 26 in this way is to prevent the electric wire 3 from being damaged.

The reason for using the combination of the magnetic generator 21 and the magnetic limit switch 22 as the combination of "emitter" and "receiver" is that various experiments have shown that this combination allows for the most accurate detection. However, it is of course possible to use other methods without departing from the spirit of the present invention.

How to measure each tension Each tension Tn, Tx is measured using a metal wheel for measuring wire tension, or a metal wheel equipped with a wire tension measurement function.
The metal wheel 20i for measuring the wire extension tension is measured via the metal wheel 20i as the wire passes.
Various data regarding the swing angle ψ of the electric wire, the angle Θ formed between the electric wire and the metal wheel 20i, the hanging force generated on the metal wheel 20i, etc. are measured, and the various data are sent to the corresponding data acquisition device 7i. Then, the main processing unit 2 calls the data importer 7i to transmit the data, and in response to this call, the various data transmitted are sent to the data importer 7i, and the height difference hi and diameter of each steel tower Pi, which have been inputted in advance as described above, are transmitted. Together with the data of the distance Si and the unit weight Wi of the wire, it is processed based on a predetermined program pre-installed in the main processing device 2, and the inlet side tension Tn or The outlet side tension Tx or both tensions are determined.

When measuring this tension, the protector Ci is
When passing through 0i, the wire tension fluctuates frequently within a short period of time. In other words, if you graph the fluctuations in wire tension over time with the wire tension on the vertical axis and time on the horizontal axis, under normal conditions, the wire tension will fluctuate in a sloping curve. Although,
When the wire passes through the protector wheel, it will fluctuate in a curve that changes drastically in a short period of time, such as a few seconds. Therefore, we have developed a system that can accurately capture these drastic fluctuations in the tension of the wire, as described above. Measures are taken in advance based on the predicted approach of the protector.

Specifically, when the approach of the protector Ci to the gold wheel 20i is predicted, the above-mentioned main processing unit 2 temporarily stops calling each data importer 7i, and thereby the remaining main processing unit 2 is By concentrating the interrogation ability on the data importer 7i of the steel tower Pi that has the metal wheel 20i that the protector Ci is approaching and passing, the amount of interrogation per hour is higher than usual, and the distance between the metal wheel and the wire angle is The idea is to be able to accurately capture drastic fluctuations.

The metal wheel 20i for measuring wire tension was previously proposed by the applicant in Japanese Patent Application No. 173063/1983 and Japanese Patent Application No. 173063/1983.
Either No. 293919 or the one proposed in Japanese Patent Application No. 102892/1988 can be used. Therefore, detailed explanation thereof will be omitted here.

Method for Measuring Distance There are four types of methods for measuring the distance L as follows.

(a) Calculation method using the tension Tn or Tx described above.

The details are explained in the aforementioned Japanese Patent Application No. 173063/1982 or Japanese Patent Application No. 102892/1982.

(b) Method using a video camera.

This involves setting a video camera (not shown) near obstacle O, and processing the images captured by this video camera in a predetermined manner to determine whether or not the distance is within the safe range. If it is out of range, for example, a warning signal is issued.

(c) Methods that use radio waves or sound waves.

This allows the transmitter to stay at a fixed position in the span of the tower, allows the transmitter to pass through the extended electric wire at the stay position, and then sends the signal from the transmitter to a receiver installed on the ground. The distance L is measured by determining the height of a specific point on the wire based on the best reception angle at the receiver.

Specifically, as shown in FIGS. 7 and 8, the radio wave (or sound wave) transmitter 30 is moored to the steel tower Pi with a rope (or wire) 31, and depending on the length of this wire 31, regulated steel towers
The electric wire 3 is allowed to pass through a part of the fixed mooring position from Pi, specifically at or near the lowest point X of the catenary curve formed by the electric wire 3 in extension. That is, this radio wave transmitter 30 stays at a certain span position from the lowest point X of the electric wire 3 to its vicinity, and moves up and down (arrow Y; FIG. 7) together with the electric wire 3 passing therethrough. It moves up and down according to the change in wire tension, and always embodies the up and down movement of the electric wire 3 due to changes in wire tension. The mooring position of the radio wave transmitter 30 is preferably at or near the lowest point X described above, but is not necessarily limited to this. Note that the residence position of the radio wave transmitter 30 is the aforementioned lowest point
If the horizontal distance between the lowest point X and the obstacle O is large, it may be made to stay directly above the obstacle O. However, the rope 31 is auto-reeled to the steel tower T, that is, the rope 31 is reeled out only when the pull-out load is above a certain value, and the rope 31 is reeled in when the pull-out load is below a certain value. By providing an auto reel and connecting the rope 31 to this auto reel, the rope 31 can always stay at the lowest point P. In addition, as a means for keeping the radio wave transmitter A at a fixed span position, in addition to mooring it to the steel tower T with a rope 31 as in this embodiment, for example, in this example, it can be moored to the steel tower T. The base end of the rope 31 is connected to a fixed position on the ground, that is, the part on the ground corresponding to the position where you want the radio wave transmitter A to stay, or you can transmit radio waves without using something like the rope 31. It is possible to use a device that allows the container 30 to naturally come to the lowest point X of the catenary curve due to its own weight.

The radio wave receiver 32 is provided on the ground in a direction intersecting the line extension direction at a horizontal distance S from the radio wave transmitter 30. This radio wave receiver 32 is equipped with an antenna 33 that is constantly rotating in a vertical plane parallel to a line connecting the radio wave transmitter 30 and the radio wave receiver 32. The receiving angle Θ can be searched (tracked). The antenna 33 as described above is used as a tracking mechanism for the radio wave receiver 32 because
This is because the required distance measurement accuracy is in meter (m) units, so the tracking accuracy does not need to be that high, so the cost is kept low, but other tracking mechanisms are not required. Of course, it is possible to adopt

In this way, when the best reception angle Θ at the radio wave receiver 32 is determined, from this Θ, H=StanΘ, the vertical distance from the radio wave receiver 32 to the radio wave transmitter 30, that is, from the lowest point X of the electric wire 3 to the The distance H between the electric wire 3 and the obstacle O can be determined by correcting this H by the height Bi of the obstacle O, which is known in advance.

(d) Method using a reflection distance measuring device This example uses a reflection distance measuring device 4 that uses sound waves.
0 is used, but of course, a reflection type distance measuring device using electromagnetic waves may also be used.

Specifically, the reflection type distance measuring device 40 is made to stay at a certain distance position in the same way as the radio wave transmitter 30 in the method using radio waves or sound waves described above,
The electric wire 3 is allowed to pass through a part of it, and the vertical movement of the electric wire 3 due to changes in wire tension is always reflected. And this reflective distance measuring device 40
The sound waves emitted from the ground are reflected by the ground or the obstacle O, and the distance H between the electric wire 3 and the ground is calculated from the round trip time. From this H, the distance between the electric wire C and the obstacle O is calculated.
LO can be found indirectly, or the distance L between the electric wire C and the obstacle O can be found directly.

Operation of gold wheels (Figures 10 and 11) This is an operation to make it easier for the protector to pass. For example, two (or more than two) gold wheels are placed on a steel tower Pi with a large angle of embrace. 20i-1, 20i
-2 are connected in the traveling direction of the electric wire (this means that the two gold wheels do not necessarily have to be separate, they may be integrated), and the aforementioned protector Ci's gold wheel approach prediction can be used. Based on this, in advance, the metal wheel 20i-1 on the near side in the direction of movement of the electric wire 3 is replaced with the metal wheel 20i-1 on the forward side in the direction of movement.
By positioning it lower than i-2, protector Ci can easily enter the metal wheel 20i-1,
Metal wheel 20i-1 with protector Ci on the front side in the direction of travel
After passing the gold wheel 20 on the opposite side in the direction of travel.
By locating i-2 lower than the metal wheel 20i-1 on the near side in the direction of movement, the protector Ci is made easier to escape from the metal wheel 20i-2. This technique utilizes the technique previously proposed by the applicant in Japanese Patent Application No. 62-215220, so a detailed explanation will be omitted.

<Effects of the Invention> This invention, as explained above, has the following effects.

(a) Since the wire extension equipment is centrally and remotely controlled by a control device into which various data are input in advance, work can be streamlined.

(b) The inlet-side tension, outlet-side tension, or both tensions occurring in the wire at the support part using the metal wheel are determined, and this tension data is used to extend the wire, so the required minimum Wire can be stretched with a maximum wire tension, which makes it possible to perform high-quality and highly safe wire-stretching work with less stress on the wires and wire-stretching equipment.

(c) Since the distance between the electric wire and obstacles on the ground is automatically measured and the measurement results are transmitted to the control device via the data acquisition device, the accurate distance status can be grasped at all times. , the line can be extended in safer conditions.

(d) Since the approach of the protector to the metal wheel is automatically predicted by the combination of the transmitter attached to the wire and the receiver installed on the metal wheel, it is always accurate and the various changes that occur as the protector passes. It is possible to predict the optimal timing for performing operations.

(e) Based on the prediction of the approach of the protector's metal wheel, two or more connected metal wheels are operated to facilitate the passage of the protector's metal wheel, thereby reducing the increase in wire tension and shock caused by the passage of the protector. As the wire tension can be softened, it is possible to perform high-quality and highly safe wire-stretching work in the same manner as described above.

[Brief explanation of drawings]

Figure 1 is a schematic side view showing an overview of wire extension work using the wire extension method according to the present invention, Figure 2 is a schematic diagram of a color display screen, and Figure 3 is a simplified diagram. Fig. 4 is an enlarged schematic side view of the metal wheel portion, Fig. 5 is a schematic side view equivalent to Fig. 1;
6 is a schematic sectional view taken along the arrow line in FIG. 5, FIG. 7 is a schematic side view corresponding to FIG. 3, and FIG. 7 is a schematic side view seen from the direction of the arrow, FIG. 9 is a schematic side view corresponding to FIG. 3, and FIGS. 10 and 11 are schematic side views showing the operating state of the successive metal wheels. It is. 1... Control device, 3... Electric wire, 4... Line extension car,
5... Catenary winch, 7i... Data acquisition machine,
20i... Gold wheel, 21... Magnetizing body (transmitter), 2
2... Magnetic limit switch (receiver), O...
Obstacle, L... Separation, Tn... Inlet side tension, Tx...
...Exit side tension, Pi...steel tower.

Claims (1)

[Claims] 1. Data regarding height differences and span distances of each steel tower designed for each construction project, and unit weight of electric wires are processed in advance based on predetermined specifications and input into the control device. In addition to installing a metal wheel to measure the tension of the wire on the required steel tower, we also installed a data acquisition machine corresponding to this metal wheel, and measured the swing angle of the metal wheel as the wire passed, and the relationship between the wire and the metal wheel. Data regarding the angle formed by the metal wheel, the suspension force generated on the metal wheel, etc. is transmitted to the control device via a data acquisition device that responds to calls from the control device, and from these various data, data is transmitted to the control device in advance. 1. A wire drawing method characterized in that the inlet-side tension, the outlet-side tension, or both tensions occurring in the wire at the support portion by the metal wheel are determined based on a predetermined program. 2. By processing the obtained inlet side tension or outlet side tension based on a predetermined program that is pre-installed in the control device, the distance between the electric wire and obstacles in the span of the steel tower, including the relevant steel tower, is determined. The wire drawing method according to claim 1, characterized in that: 3. A receiver is installed on the metal wheel of the required steel tower, and in this receiver, a transmitter attached to the wire at a predetermined distance ahead of the protector attachment part in the direction of line extension, transmits the metal wheel as the wire advances. By detecting the passing of the gold wheel, the approach of the protector's gold wheel is predicted, and this predicted data is transmitted to the control device via a data acquisition device that responds to a call from the control device, and this transmitted predicted data is 1. A method for extending a line, characterized in that, based on the above, various operations required for the protector to pass through a gold wheel are performed via a control device. 4. At least two or more metal wheels are installed in series on the required steel tower in the direction of movement of the electric wire, and based on the prediction of the proximity of the metal wheel of the protector described in claim 3, the metal wheel on the near side in the direction of movement of the electric wire is moved in advance. By positioning it lower than the metal wheel on the destination side, the protector can easily enter the metal wheel, and after the protector passes the metal wheel on the near side in the direction of travel, it moves on the metal wheel on the forward side in the direction of travel. A wire extension method characterized by making it easier for the protector to escape from the metal wheel by locating it lower than the metal wheel on the near side in the direction. 5 Based on predetermined specifications, data regarding the height difference and span distance of each steel tower designed for each construction work, unit weight of electric wire, height and position of obstacles, design wire tension, wire speed, etc. The control device into which the processing results are input centrally and remotely controls wire rolling equipment such as wire rolling cars, overhead line winches, and metal wheels. A data acquisition machine is installed, and the control device receives data about the swing angle of the metal wheel as the wire passes, the angle between the wire and the metal wheel, the hanging force generated on the metal wheel, etc. as measured by the metal wheel. The data is transmitted to the control device via a data acquisition device corresponding to The tension, exit side tension, or both tensions shall be determined, and the distance between the electric wire and obstacles on the ground shall be automatically measured, and the measurement results shall be transmitted to the control device via the data acquisition machine, and the required steel tower shall be determined. A receiver is provided on the metal wheel, and this receiver allows the transmitter, which is attached to the wire at a predetermined distance ahead of the protector attachment part in the wire extension direction, to pass through the metal wheel as the wire advances. By detecting this, the approach of the protector's gold wheel is predicted, and this prediction data is transmitted to the control device via the data acquisition machine that responds to a call from the control device, and to the required steel tower. At least two or more metal wheels are arranged in series in the traveling direction of the electric wire, and the metal wheel on the near side in the traveling direction of the electric wire is positioned lower than the metal wheel on the forward side in the traveling direction based on the prediction of the approaching metal wheel by the protector. This makes it easy for the protector to enter the metal wheel, and after the protector passes the metal wheel on the near side in the direction of travel, the metal wheel on the forward side in the direction of travel is positioned lower than the metal wheel on the near side in the direction of travel. A wire extension method characterized by making it easier for the protector to escape than the metal wheel.