JP2797658B2 - Compression work management method for transmission line anchoring clamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a case where an abnormal tension is applied to a steel core inside a termination clamp when a compression type retention clamp for a transmission line is crimped to an end of a wire by a reverse compression method. The present invention relates to a novel compression work management method for a transmission line retaining clamp that confirms and detects whether or not an accident has occurred and appropriately avoids the occurrence of an unexpected accident.

[Prior Art] As shown in FIG. 4, a transmission line has a steel core aluminum stranded wire (hereinafter referred to as ACSR) in which an aluminum stranded wire layer 11 serving as a conductive member is twisted around a steel core 12 serving as a tension member. 10) is used.

In order to hold this to the steel tower, it is usual to crimp a compression type holding clamp as shown in FIG. 4 to the end of the ACSR 10 and hold it.

That is, 1 is an aluminum clamp for crimping the aluminum stranded wire layer, 2 is a jumper terminal for connecting a jumper wire, and 3 is a steel core 12 in which the aluminum stranded wire layer 11 is stepped and exposed as shown in the figure. Reference numeral 4 denotes a steel clamp to be crimped, 4 denotes a stay metal fitting to be fixed to the tower-side metal fitting, 5 denotes a tapered portion, and 13 denotes a binding wire that binds the ends of the steel core 12 so as not to be loose.

At the time of this crimping, the end of the ACSR 10 was stripped off as shown in the figure, the aluminum clamp 1 was temporarily attached, and the steel core 12 was removed.
First, press the steel clamp 3 on the aluminum clamp 1
The come pullback coalesce and aluminum clamp 1 and steel clamps 3, it is sufficiently close to the gap G ₂ between the jumper terminal 2 and the anchor bracket 4 as shown in FIG. 6 after compression, the steel clamp 3 The tapered portion 5 and the tapered surface of the aluminum clamp 1 which fits the tapered portion 5 are brought into close contact with each other, so that rainwater does not enter from the end of the retaining clamp.

For this reason, conventionally, the normal compression method in which the steel clamp 3 and the aluminum clamp 1 are first brought into complete contact with each other, and the aluminum clamp 1 is sequentially compressed from the side of the retaining bracket 4 toward the tip of the ACSR 10 in this state has been used since ancient times. Has been adopted. However, in the case of the positive compression method, as the aluminum clamp 1 is sequentially compressed toward its tip, the internal aluminum stranded wire layer 11 is also compressed together to cause compression elongation, and especially the aluminum stranded wire layer is formed. In the case of a thick large-sized ACSR, its compression and elongation gathers at the tip of the aluminum clamp 1, causing birdcage-like laughter in the aluminum stranded wire layer 11. Moisture and dust are easily captured in this laughter, which may cause corrosion to progress, resulting in early disconnection.

For this reason, a reverse compression method has been developed in which, instead of forward compression, which compresses toward the distal end side, the reverse compression method is employed, in which the distal end side is reversely compressed toward the retaining bracket 4 side. In many cases, this decompression method has been adopted. According to this reverse compression method, aluminum clamp 1 and ACSR10
Is fixed first, and thereafter, the compression is sequentially performed toward the fastener 4 so that the laughter caused by the extension of the aluminum stranded wire layer is eliminated.

[Problems to be Solved by the Invention] In the reverse compression method, as described above, the tip of the aluminum clamp 1 is first compression-fixed to the electric wire, and then the aluminum clamp 1 is sequentially compressed toward the retaining fitting 4 side. This compression not only causes the aluminum clamp 1 to undergo compression elongation, but also causes the internal aluminum stranded wire layer 11 to undergo compression elongation. Therefore, when the decompression of the above may be set gap G ₁ between the end face and the end face of the anchor bracket 4 jumper terminal 2 of the aluminum clamp 1 as shown in FIG. 5, the decompressor Conversely aluminum clamp 1 sixth jumper terminal 2 and the anchor bracket 4 as shown in FIG is set so that the gap G ₂ capable of forming a snugly close contact when the aluminum clamp 1 has occurred compressed elongation by Compress.

However, at this time, not only the aluminum clamp 1 causes compression elongation, but also the internal aluminum stranded wire layer 11 also undergoes compression elongation in accordance with the compression elongation of the aluminum clamp 1, so in this reverse compression method, , As shown in FIG.
Aluminum As shown in Figure 6 the compression elongation of the aluminum stranded wire layer 11 may be set a predetermined distance [delta] ₁ in consideration, after completion of compression between the end of the steel clamp 3 and aluminum stranded wire layer 11 decompression is performed by setting so that a just appropriate intervals [delta] ₂ when compressed extend the twisted wire layer 11 has occurred.

This interval δ ₂ must be an interval allowed by design. For example, if the amount of compression of the die compression when compressing the aluminum clamp 1 is excessive, the aluminum stranded wire layer 11 may exceed the designed compression elongation. resulting elongation, this distance [delta] ₂ in some cases becomes smaller than the design value.

Simply there is no problem if only because the interval [delta] ₂ is smaller, the interval of [delta] ₂ is too small is to amyl twisted wire layer 11 is too resulting compressed elongation, such excessive compression The elongation also causes the inner steel core 12 to elongate, and there is a possibility that the elongation becomes excessive and an internal disconnection occurs.

If a break occurs in the steel core 12 that should become a tension member in this way, the holding force of the ACSR 10 due to the holding clamp is significantly reduced, and the ACSR 10 cannot withstand the overhead wire tension of the ACSR 10 and the ACSR 10 cannot be pulled from the holding clamp. There is a high possibility that it will lead to serious accidents such as falling off.

However, such an excessive compression and elongation of the aluminum stranded wire layer 11 and the accompanying internal disconnection of the steel core 12 cannot be confirmed from the outside at all, and the actual situation is that they rely solely on the skill and intuition of the workers. However, it is extremely dangerous if the anchoring operation is performed without noticing the abnormal compression.

For this reason, it has been proposed to check whether or not excessive stress has occurred by X-ray photography. However, according to the results of actual tests, it has been found that such an excessive stress cannot be confirmed. Was.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art, and when crimping a transmission line compression type clamp to a wire end by a reverse compression method, abnormal tension is applied to a steel core inside the clamp. It is an object of the present invention to provide a new method for managing the operation of compressing the retaining clamp, which can confirm and detect whether or not the occurrence of an accident and can appropriately avoid the occurrence of an unexpected accident.

[Means for Solving the Problems] The present invention provides a sensor capable of detecting a stress acting on a steel core when an overhead transmission line compression type clamping clamp is compressed by a reverse compression method from a distal end side of an aluminum clamp. The sensor monitors abnormal stress applied to the steel core by the sensor when the clamp is compressed, and a piezoelectric element is used as a typical example of such a sensor.

[Operation] If a clamp capable of detecting the stress acting on the steel core is provided when the retaining clamp is crimped to the end of the electric wire by the reverse compression method, and the stress applied to the steel core by the sensor is monitored when the clamp is compressed. In addition, it is possible to compress the retaining clamp while directly detecting the stress applied to the steel core. Then, when it is found that an abnormal stress has been applied to the steel core, the steel core is recompressed again, whereby it is possible to establish a highly reliable compression work without fear of disconnection of the steel core under overhead wire tension.

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

 FIG. 1 is an explanatory view showing an embodiment according to the present invention.

In the present invention, a sensor capable of detecting the stress applied to the steel core 12, that is, the tensile stress in this case, is attached to the backing clamp when the compression clamp 27 reversely compresses the retaining clamp.

As such a sensor, an ordinary appropriate sensor such as a magnetic displacement or a change in electric resistance can be used. In a most preferred embodiment, the piezoelectric element 20 is held by a magnet holder 21 as shown in FIG. It is good to attach to the metal fitting 4.

The piezoelectric element 20 is an element that can convert an acoustic signal into an electric signal by a so-called piezo effect.

In FIG. 1, when the retaining clamp is compressed from the electric wire 10 side by the compression die 27, a tensile stress starts to be applied to the steel core 12, and the steel core 12 is stretched in accordance with the stress, whereby the steel core 12 is extended from the steel core. Acoustic emission (AE) occurs, and this AE is converted into an electric signal by a piezoelectric element. This electric signal is taken out by the lead wire 22,
The amplitude of the waveform in the constant frequency band of the AE can be measured by amplifying the signal with the preamplifier 23 and passing through the bandpass filter 24. If this is analyzed by the waveform analysis personal computer 25 and obtained as the AE count, the second The relationship between the compression work time and the AE count as shown in the figure can be printed out by the printer 26.

On the other hand, the relationship between the AE count and the tensile stress is obtained in advance by using a tensile tester at a factory separately as shown in FIG.

By comparing the graph of FIG. 3 with the measurement result of FIG. 2, the maximum stress value applied can be known. That is, in the case of the embodiment shown in FIG. ² , it can be understood that the maximum load applied to the steel core 12 by the compression of the retaining clamp is about 110 kg / cm ² .

Therefore, as a result of this measurement, if it is determined that excessive stress has been applied, it is possible to instruct re-starting the compression work of the retaining clamp, and to significantly improve the reliability after compressing the retaining clamp by reverse compression. Can be.

Also, by managing the load state in this way, it is possible to adjust the final compression allowance of the retaining clamp by adjusting the die compression.

For mounting the piezoelectric element 20, it is convenient to mount the magnet holder 21 on the retaining bracket 4; however, in order to increase the measurement accuracy by bringing it closer to the compression point of the steel core 12, it is necessary to cure the outer surface of the ACSR. It may be attached using a tool.

In the above, the case of applying the reverse compression, which is likely to cause a problem, has been described.However, the present invention is applied to the normal compression, and is used to manage whether or not abnormal elongation occurs in the steel core during compression. There is no problem.

[Effects of the Invention] As described above, according to the method for managing the work of compressing a retaining clamp according to the present invention, the presence or absence of abnormality in the compression and elongation of the inner steel core when the aluminum clamp is compressed using the reverse compression method is determined. It can be surely confirmed, and there is a great significance that the reliability of the reverse compression connection of the folded pattern and the arrest clamp, which is about to increase the size of the overhead transmission line in the future, is significantly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a relationship between a compression work time and an AE count in the embodiment,
FIG. 3 is a diagram showing the measurement results of tensile stress and AE count,
FIG. 4 is an explanatory view showing a state of attachment of the retaining clamp to the ACSR, FIG. 5 is an explanatory view showing a state before the aluminum clamp is compressed, and FIG. 6 is an explanatory view showing a completed state of the aluminum clamp compression. 1: Aluminum clamp, 2: Jumper terminal, 3: Steel clamp, 4: End fitting, 5: Taper, 10: ACSR, 11: Aluminum stranded wire layer, 12: Steel core, 20: Piezoelectric element, 21: Magnet holder , 22: Lead wire, 23: Preamplifier, 24: Band pass filter, 25: PC, 26: Printer, 27: Compression die.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuyoshi Unto 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki Hitachi Metals, Ltd. Metal Research Laboratory (56) References JP-A-51-125888 (JP, A) JP-A-63-129808 (JP, A) JP-A-1-276578 (JP, A) JP-A-3-107321 (JP, A) JP-A-60-42012 (JP, U) JP-A-60-60873 (JP, A) , U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02G 7/00-7/22 H02G 1/14 H02G 15/08

Claims (2)

(57) [Claims] When an overhead transmission line compression type clamping clamp is compressed by a reverse compression method from the distal end side of an aluminum clamp, a sensor capable of detecting a stress acting on a steel core is provided. A method for managing the work of compressing the clamps for transmission lines that compresses while monitoring abnormal stress applied to the heart. 2. The method according to claim 1, wherein the sensor is a piezoelectric element.