JP2638259B2 - Transmission line tension measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transmission line tension for accurately measuring a variation in extension tension applied to an overhead transmission line when the transmission line is extended. It relates to a measuring device.

[Prior art] When an overhead power transmission line is installed between towers, a pulley (often called a wheel) is suspended from an arm of the tower to be overhead, and a messenger wire is first delivered over the pulley. The terminal of the electric wire sent from the drum place and the terminal of the messenger wire are connected, and the messenger wire is wound up in an engine place provided on the opposite side of the drum place, so that the electric wire is extended on the pulley. Finally, the wires are tightened so that the overhead wire tension is obtained and the wires are fixed to the tower.

During the extension of the power transmission line, the extension tension, which is a dynamic tension, is applied, and at the time of the tightening work, the static tension for setting the overhead wire tension is applied.

In the extension of ordinary transmission lines, it is common practice to install a tension meter at the exit of the extension line and monitor the approximate tension so that the extension tension is not excessively large or small. Was.

However, in recent years, there have been many cases in which an optical fiber composite overhead ground wire (hereinafter referred to as OPGW) other than a transmission line used as a live line is used as an overhead line.

Optical fiber combined with OPGW not only has low tensile strength because glass is used for the material, but also
It has the property of causing static load fatigue, and it is known that static stress rupture occurs in a very short time if stress is applied continuously even at a stress that does not lead to rupture.

For this reason, in the extension of the OPGW, it is necessary not only to carefully draw so that abnormal tension is not applied during the extension, but also to avoid the occurrence of stress concentration places in the optical fiber of the OPGW locally. It is necessary to measure the fluctuation of the dynamic tension in the longitudinal direction of the OPGW during the extension while constantly measuring the extension.

FIG. 3 is an explanatory view showing a conventional measuring device for measuring such a variation in the extension tension of the electric wire 20. As shown in FIG.

In the figure, 1 is a pulley, 2 is a pulley shaft, 3 is a pulley frame, 4
Is a mounting ring for suspending the entire pulley on a steel tower, 5 is a measuring bar, and 6 is a distance measuring element.

Now, assuming that the contact point where the electric wire 20 contacts the pulley 1 is A, the central angle θ formed by the line ▼ connecting the center O of the pulley 1 and the suspension center line ▲ ▼ of the pulley 1 is the tension applied to the electric wire 20. It changes according to the size of. This center angle θ is geometrically equal to the angle θ formed between the line Q which is in contact with the electric wire 20 and is orthogonal to the hanging center line ▲ ▼, and of course, this θ is It changes with the change in tension applied to the

Mounting measurement bar 5 as shown in Figure the top of the pulley frame 3, a distance measuring device capable of measuring the distance d ₀ between the wire 20 the center line of the measuring bar 5 ▲ from ▼ the end remote only l 6
Is attached so that the distance d ₀ can be measured continuously, the angle θ can be obtained by the following equation.

On the other hand, with respect to the load applied to the pulley 1, if a load cell is installed between the steel tower and the mounting ring 4, the load can be continuously known, and the load 20 is applied to the electric wire 20 from the angle θ and the load. The applied dynamic tension can be determined continuously.

[Problem to be Solved by the Invention] In the conventional tension measuring device described above, the length of the measuring bar 5 needs to be sufficiently long in order to increase the measurement accuracy of θ. As such the distance d ₀ is increased by increasing the length of the measuring bar 5, it is possible to reduce the influence based on an error as a whole.

For this reason, in a practically used measuring device, the length of l in FIG. 3 is set to a length of about 1.5 m. However, when the length l on one side is 1.5 m, the shape of the entire apparatus becomes large, and the work of attaching such a large shape to the tip of the tower arm is not very easy.
There is a drawback that handling is very poor.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art, and to provide a novel transmission line tension that is small and compact as a whole, easy to handle, and can sufficiently improve measurement accuracy. It is intended to provide a measuring device.

[Means for Solving the Problems] The present invention reduces the load applied to the transmission line from the load applied to the pulley suspended from the tower and the arc angle of the portion where the transmission line is in contact with the pulley. A device for measuring, wherein the pulley is provided with a switch that is turned on when a transmission line contacts and turned off when separated, and a rotation angle measuring unit that can accurately measure the rotation angle of the pulley is installed. A rotary encoder is used as such a rotation angle measuring means.

[Operation] If a switch that turns on and off when the transmission line contacts and separates from the pulley is provided, it is possible to directly know the contact and separation of the wire to the pulley, and the pulley while the switch is ON. By knowing the rotation angle of the wire, the contact angle between the electric wire and the pulley can be easily known. In addition, since all of these devices are small and there is no possibility that the entire pulley will become large as in the conventional example even when attached to the measuring device, there is no hindrance in handling on a steel tower.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples.

FIG. 1 is an explanatory front view showing a state where switches 7, 7 and a switch signal detector 8 according to the present invention are mounted on a pulley 1. FIG.

Although detailed illustration is omitted, the switch 7 has an electric wire.
Turns on when 20 is in contact with the pulley and turns off when separated
And the switch signal detector 8 can detect ON-OFF of the contact.

If the rotation angle of the pulley 1 when the switch 7 is in the ON state can be detected, the center angle 2θ (see FIG. 3) of the arc of contact with the pulley 1 shown in FIG. 1 can be easily measured, and θ
Can be immediately known as the value of 1/2.

As such a rotation angle measuring means, various means such as one obtained from a change in electric resistance due to rotation and one obtained by dispersing minute contact points in the circumferential direction are conceivable, but the most preferable means is a rotary encoder. Good to use.

That is, FIG. 2 is an explanatory side view showing a state in which such a rotary encoder 9 is mounted on a side surface of the pulley frame 3 with a mounting base 11 and at the same time a calculation unit 10 such as a microcomputer is also mounted.

The wire 20 being extended moves on the pulley 1, and the wire
When the switch 20 is turned on when the switch 20 comes into contact with the pulley 1, the switching signal detector 8 detects the ON state of the switch 7 and sends a signal to notify the arithmetic unit 10 of the ON state.

The arithmetic unit 10 counts the number of pulses output by the rotary encoder 9 in response to the signal that the switch 7 is turned on. This counting is continued while the switch 7 is in the ON state. When the switch 7 rotates together with the pulley 1 and the electric wire 20 is separated from the pulley 1 on the opposite side and turned off, the counting is stopped. From the number of pulses, the rotation angle of the switch 7 and thus the central angle 2θ of the arc while the electric wire 20 is in contact with the pulley 1 can be known. If θ obtained in this way and the load applied to the pulley at that time are separately detected by a load cell or the like, and the result is calculated by a calculation device and the calculation result is displayed as necessary, the electric wire in the extended wire can be displayed. 20
The fluctuation of the tension applied to the device can be continuously monitored.

According to the apparatus according to the present invention, since the measurement accuracy is determined by the resolution of the rotary encoder 8, the measurement accuracy can be easily increased by increasing the resolution.

In the above embodiment, an example in which three switches 7 are provided is shown. However, in order to increase the measurement accuracy, it is preferable that the number of switches 7 is set to be an appropriate number and an average value thereof can be obtained. Good. However, if such fine precision is not required, a single switch 7 is acceptable.

Since the rotary encoder 9 is for transmitting a digital signal, it can be directly connected to a digitally operated calculation unit and a subsequent tension calculation device, thereby reducing the number of components for A / D conversion. It also has advantages.

[Effects of the Invention] As described above, according to the apparatus according to the present invention, the entire apparatus can be made extremely small and compact, and not only can the handling on a steel tower be significantly facilitated, but also its measurement accuracy can be improved. For example, by simply increasing the resolution of a rotary encoder, the reliability of the extension of the transmission line, especially the extension of the OPGW, is significantly significant.

[Brief description of the drawings]

1 is an explanatory front view of an embodiment according to the present invention, FIG. 2 is an explanatory side view thereof, and FIG. 3 is an explanatory view of a conventional example. 1: pulley, 2: pulley shaft, 3: pulley frame, 4: mounting ring, 7: switch, 8: switching signal detector, 9: rotary encoder, 10: arithmetic unit, 11: mounting base, 20: electric wire.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Hoshino 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki Hitachi Metals, Ltd. Metal Research Laboratory (56) References JP-A-56-55830 1-96519 (JP, A) JP-A-62-261029 (JP, A) JP-A-1-158901 (JP, U)

Claims (2)

(57) [Claims] 1. An apparatus for measuring a load applied to a pulley suspended from a steel tower and a tension applied to the transmission line from an arc angle of a portion where the transmission line is in contact with the pulley, wherein the tension is applied to the pulley. The pulley is equipped with a switch that turns on when the transmission line contacts and turns off when the transmission line separates, and is equipped with a rotation angle measuring means that can accurately measure the rotation angle of the pulley. apparatus. 2. The transmission line tension measuring device according to claim 1, wherein the rotation angle measuring means is a rotary encoder.