JPH05126708A - Electrical wire fatigue detection instrument - Google Patents

Abstract

PURPOSE:To obtain an electrical wire fatigue detection instrument which is used for detecting a degree of fatigue of the electrical wire while being erected on an electric pole, etc., by a non-destructive inspection. CONSTITUTION:This instrument consists of a holding member 3 which holds an exposed part of a conductor of an electrical wire so that it can be mounted and removed freely and an AE sensor part 4 which is sealed to or formed in one piece with the holding member 3. The holding member 3 consists of a pair of ceramic inner materials 9, 9 which contact the exposed part of the conductor of the electrical wire and a holder member 10 which holds the exposed part of the conductor of the electrical wire through the inner materials 9, 9 while holding the inner members 9, 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fatigue detecting tool used for nondestructive inspection of overhead transmission lines.

[0002]

2. Description of the Related Art Conventionally, after removing an electric wire from a utility pole, etc., the electric wire is disassembled and investigated, and the life of the electric wire is estimated from the degree of damage such as cracks inside the electric wire caused by fatigue. There was no non-destructive inspection that could detect and determine the degree of fatigue of electric wires when installed.

[0003]

Therefore, the present invention provides an electric wire fatigue detecting tool used when non-destructive inspection is performed to detect and judge the degree of electric wire fatigue while being installed on a utility pole or the like. The purpose is to

[0004]

SUMMARY OF THE INVENTION The present invention comprises a sandwiching member for detachably sandwiching a conductor exposed portion of an electric wire, and an AE sensor portion secured to or integrated with the sandwiching member. is there.

Further, the sandwiching member is a pair of ceramics inner members which come into contact with the conductor exposed portion of the electric wire, and a holder member which holds the inner member and sandwiches the conductor exposed portion of the electric wire through the inner member. It consists of and.

[0006]

According to the electric wire fatigue detecting tool of the first aspect of the present invention constructed as described above, the conductor-exposed portion is formed by using the clamping member as a screw-fastening fixture or a buckle-type fixture in a state where the electric wire is laid on a utility pole or the like. AE generated from electric wires that can be detachably attached to the
--Acoustic emission (abbreviated as AE below) ---- Waves can be detected by the AE sensor section through the sandwiching member.

Further, in the electric wire fatigue detecting tool according to a second aspect of the present invention, each inner member is fitted into the holder member to be brought into contact with the conductor exposed portion of the electric wire, and the buckling type fixing tool detachably attaches the holding member. It can be sandwiched between the electric wires, and the AE wave generated from the electric wires can be detected by the AE sensor unit via the inner member and the holder member.

Further, even when the electric wire laid on the utility pole or the like is in a live state, the inner member can insulate the AE sensor part and the exposed conductor part. In addition, the AE wave is passed through the inner member and the holder member,
When propagating to the AE sensor, the structure of the ceramic material used for the inner member is dense and hard, so that the AE wave is less attenuated and high detection accuracy can be obtained.

[0009]

The present invention will be described in detail below with reference to the drawings showing the embodiments.

1 and 2 show an electric wire fatigue detecting tool according to the present invention. The detecting tool is a sandwiching means for detachably sandwiching a conductor exposed portion 2 of an overhead transmission / distribution wire 1 such as a stranded aluminum wire. Wearing member 3
And an AE sensor section 4 fixed or integrated with the sandwiching member 3.

Specifically, the sandwiching member 3 has a pair of sandwiching bodies 7, 7 made of aluminum, ceramics or the like, and a bolt for detachably sandwiching the sandwiching bodies 7, 7 on the electric wire 1. It is equipped with screw-fastening fixtures 5 made of nuts.

Contact portions 6 and 6 are formed in the sandwiched bodies 7 and 7 in a circular arc shape with a predetermined curvature, and further through holes through which the bolts 5a and 5a of the screw fixing fixtures 5 and 5 are inserted. Has been formed.

Further, the AE sensor section 4 detects an AE wave which is generated when a damage such as a crack occurs inside the electric wire 1 due to a strain caused by vibration or the like, that is, an AE wave, that is, an elastic wave of acoustic emission. The AE sensor section 4 is fixed to the one sandwiching body 7 with an adhesive such as an epoxy resin.

Alternatively, although not shown, the AE sensor section 4 and the sandwiching body 7 are integrated (for example, the AE sensor section 4 is incorporated in the sandwiching body 7).

Then, the contact portions 6, 6 of the sandwiching member 3 are brought into contact with the conductor exposed portion 2 of the electric wire 1 supported by the insulator 20, and the sandwiched bodies 7, 7 are fixed by screws. , 5 to tighten the nuts 5b, 5b to bring the clamping member 3 into contact with the conductor exposed portion 2 and clamp it.

In this way, the sandwiching member 3 can be easily and surely attached to the conductor exposed portion 2 of the electric wire 1, and the AE wave generated inside the electric wire 1 propagates through the conductor exposed portion 2 and reaches the surface. Can be detected by propagating from the surface of the conductor exposed portion 2 to the AE sensor portion 4 via the sandwiched bodies 7, 7.

Further, the nut 5 of the screw-fastening fixtures 5, 5
By loosening and removing b and 5b, the sandwiching member 3 can be easily removed from the conductor exposed portion 2 of the electric wire 1.

The curvatures of the contact portions 6, 6 of the sandwiched bodies 7, 7 are set so as to correspond to the diameters of the conductor exposed portions 2 of various electric wires 1, so that the conductor exposed portions are The contact rate with 2 is high, the measurement efficiency is good, and the AE wave can be detected with high accuracy.

Next, FIG. 3 shows another embodiment in which the screw-fastening type fasteners 5 and 5 of the previous example are replaced with buckle-type fastening means 8 and 8.

The hook 8 of this buckle type fixing tool 8, 8
a, 8a and stoppers 8b, 8b are the holding bodies 7, 7 respectively.
Are fixed to both side surfaces of the stopper with screws or the like, and the stoppers 8b,
By detaching 8b from the hooks 8a, 8a, the electric wire 1
The conductor exposed portion 2 (see FIG. 2) can be easily and reliably sandwiched between the detachable portions, and the AE wave generated from the electric wire 1 can be detected by the AE sensor portion 4 through the sandwiched bodies 7, 7. ..

Next, FIG. 4 shows another embodiment, in which the sandwiching member 3 holds a pair of ceramic inner members 9 and 9 and the inner members 9 and 9 while holding the inner members 9 and 9. A holder member 10 for removably sandwiching the exposed conductor portion 2 (see FIG. 2) of the electric wire 1 is shown.

The inner member 9, 9 has a conductor exposed portion 2 of the electric wire 1.
In order to increase the contact rate with the contact portions 6 and 6, the contact portions 6 and 6 are notched in a circular arc shape with a predetermined curvature (so as to have dimensions corresponding to the diameter dimensions of the conductor exposed portion 2 of various electric wires 1).

Further, the inner members 9 and 9 are formed in a shape that can be fitted into the fitting portions 11 and 11 that are recessed in the holder member 10.

The holder member 10 made of aluminum is
An upper member 10a, a lower member 10b, a hinge 12 that connects the upper and lower members 10a and 10b so that they can swing and open, and a buckle type fixture 8.
And consists of.

The upper portion of the upper member 10a is formed in an upwardly expanded shape, and a circular recess 13 into which the AE sensor portion 4 is fitted is formed on the upper surface thereof. Further, the upper and lower members 10a, 10
Fitting portions 11 and 11 are formed in b, respectively.

A hinge 12 is fixed to one side surface of the upper and lower members 10a and 10b with screws or the like, and the other side surface is
(Same as FIG. 3) The hook 8a and the stopper 8b of the buckle type fixing tool 8 are attached with screws or the like.

Then, the AE sensor unit 4 is mounted in the recess 13 of the holder member 10, the inner members 9, 9 are fitted in the fitting portions 11, 11 of the holder member 10, and the contact portions 6, 9 of the inner members 9, 9 are fitted. 6 on the exposed conductor 2 of the electric wire 1 (see FIG. 2), and the upper and lower members 10a, 10b.
To close and abut the stopper 8b of the buckle type fixture 8.
By engaging with the hook 8a, the inner members 9, 9 are brought into contact with and sandwiched between the conductor exposed portion 2.

In this way, the sandwiching member 3 can be easily and surely attached to the conductor exposed portion 2 of the electric wire 1, and the AE wave generated from the electric wire 1 can be applied to the inner members 9, 9 and the holder member 10.
It can be detected by the AE sensor unit 4 via.

Further, the stopper 8b of the buckle type fixture 8
By removing the hook from the hook 8a and opening the upper and lower members 10a and 10b, the sandwiching member 3 can be easily removed from the exposed conductor portion 2 of the electric wire 1.

However, since the inner members 9 and 9 are made of ceramics, preferably Al ₂ O _{3, it} is necessary to apply a voltage to the exposed conductor portion 2 of the electric wire 1 laid on a utility pole or the like. Even in the live state, the AE sensor portion 4 and the exposed conductor portion 2 can be insulated by the inner members 9 and 9, and the AE wave can be detected safely.

Further, the AE wave generated inside the electric wire 1 and propagating through the conductor exposed portion 2 and reaching the surface is transmitted from the surface of the conductor exposed portion 2 through the inner members 9 and 9 and the holder member 10.
When propagating to the sensor portion 4, the structure of the ceramic material used for the inner members 9 and 9 is dense and hard, so that the attenuation of the AE wave is small. Further, if the material used for the holder member 10 is the same as the conductor material of the electric wire 1, the sensitivity will be good,
High detection accuracy can be obtained.

By the way, the above-mentioned electric wire fatigue detecting tool is used when detecting and judging the degree of electric wire fatigue by a nondestructive inspection (described below).

In this nondestructive inspection, as shown in FIG. 2, the sandwiching member 3 is attached to the conductor exposed portion 2 while the conductor exposed portion 2 of the electric wire 1 is supported by the insulator 20 and laid on the electric pole or the like. As shown in, the AE wave generated from the electric wire 1 is detected by the AE sensor unit 4 via the sandwiching member 3 and converted into an electric signal,
The AE signal is taken out through the preamplifier 14 and the discriminator 15 and the value of the number of waves of the AE signal that exceeds a predetermined threshold value is displayed, and the degree of fatigue of the electric wire 1 is detected and judged from the value. To do.

The discriminator 15 is composed of a filter 16, a main amplifier 17, an envelope detection circuit 22 (used only when counting the event rate and the total number of events, which will be described later), and a discrimination circuit 18, and the discrimination circuit 18 counts the oscillation rate count, the event rate count, the total number of events or the total number of oscillations, and displays them on the display means 19 such as a dual counter.

As shown in FIG. 6, the oscillation rate counting is performed by comparing the wave of the AE signal with a threshold value of a predetermined voltage level (shown by a dotted line), and comparing the wave exceeding the threshold value within a unit time. It is the number counted. (In FIG. 6, the counted wave is shown.)

The total number of oscillations is a continuous count of oscillations, not unit time, that is, the wave of the AE signal is compared with a threshold value of a predetermined voltage level (shown by a dotted line), and It is the total number of waves that exceed the threshold.

Further, as for the event rate counting, as shown in FIG. 7, the envelope detection circuit 22 (see FIG. 5) performs envelope detection on the AE signal, and this envelope-detected wave is indicated by the dotted line.
This is a count of the number of waves exceeding the threshold value within a unit time by comparing with a threshold value of a predetermined voltage level. (In FIG. 7, the counted wave is shown.)

The total number of events is obtained by continuously counting events, not unit time. That is, the AE signal is subjected to envelope detection, and this envelope-detected wave has a predetermined voltage level (indicated by a dotted line). It is the sum of the number of waves that exceeds the threshold value as compared with the threshold value.

The number of oscillation rates, the number of event rates, the total number of events, or the total number of oscillations has a correlation with the degree of fatigue of the electric wire 1, and changes with the progress of fatigue. It is possible to obtain the relationship between the number of fatigues (degree of fatigue) of the electric wire 1 and the event rate count shown in FIG.

For example, in FIG. 8, if the event rate count counted by the discrimination circuit 18 at the threshold value 50 mv and displayed on the display means 19 is 10 counts, the breakage (life) of the electric wire 1 still remains. There is a margin, and if it is 100 counts, it can be understood that it is on the verge of breakage, and the degree of fatigue of the wire 1 (whether or not there is fatigue damage such as cracks inside the wire 1) can be determined.

Therefore, by using the graph showing the correlation of FIG. 8, the life limit value number (danger value) for judging the numerical value of the event rate count at which the electric wire 1 reaches the life is determined. It is possible to estimate the life of the electric wire 1 by presetting and comparing the life limit value with the event rate count counted by the discrimination circuit 18 and displayed on the display means 19.

Similarly, in the oscillation rate counting, the total number of events, or the total number of oscillations, a graph showing a correlation similar to that shown in FIG. Is set in advance, and the life limit of the electric wire 1 is estimated by comparing each life limit value with the number of oscillation rates counted by the discrimination circuit 18 and displayed on the display means 19, the total number of events or the total number of oscillations. You can

Specifically, in order to detect and determine the degree of fatigue of the electric wire 1 by nondestructive inspection using event rate counting or oscillation rate counting, the sandwiching member 3 having the AE sensor section 4 is inspected. It is sandwiched between the exposed conductors 2 of the target electric wire 1, and the strain of vibration or tension on the electric wire 1 is forcibly fixed by a vibration mechanism (not shown) (installed on a work vehicle at high places) (comparison of For a short time) to generate AE waves.

Next, the AE wave generated from the electric wire 1 is detected by the AE sensor section 4 through the sandwiching member 3 and converted into an electric signal, and the preamplifier 14 amplifies the electric signal to a predetermined level. Further, the electric signal amplified by the preamplifier 14 is filtered to pass only a specific frequency component to remove noise, and only the AE (electrical) signal is taken out and the AE signal is sent to the main amplifier 17. To amplify.

Then, the event rate count value or the oscillation rate count value counted by the discrimination circuit 18 (appropriately through the envelope detection circuit 22) and displayed on the display means 19 and each count value are determined. The life of the electric wire 1 can be estimated by comparing with the number of life limit values.

When the inspection is completed, the sandwiching member 3 is removed from the electric wire 1, and another electric wire 1 to be inspected is inspected in the same manner as described above.

In order to detect and determine the degree of fatigue of the electric wire 1 by a nondestructive inspection using the total number of events (or the total number of oscillations), the sandwiching member 3 having the AE sensor unit 4 is used to expose the conductor 2. Attached to the preamplifier 14, discriminator
15 and the display means 19 are installed on a utility pole or the like on which the electric wire 1 is installed for a long period of time, and the AE wave generated from the distortion occurring in the natural state is always counted and displayed without forcibly adding the distortion to the electric wire 1. means
It is displayed on 19, and compared with the number of life limit values, the degree of fatigue of the wire 1 is detected and judged.

The present invention can be applied to various electric wires such as stranded wires made of various materials such as aluminum and copper.

Therefore, in the embodiment shown in FIGS. 1 to 4,
It has the following advantages.

For example, when the surface of the exposed conductor portion 2 of the electric wire 1 is coated with an adhesive such as an epoxy resin without using the sandwiching member 3 and the AE sensor portion 4 is directly fixed to that portion, It takes time for the resin to harden, the resin remains on the surface of the conductor exposed portion 2 after the inspection, and a defect occurs during the re-inspection. Further, the strength of the cured resin is large, and therefore the AE sensor unit is removed after the inspection. 4 may be damaged,
If the sandwiching member 3 is used, after the inspection, the resin of the adhesive does not remain on the surface of the conductor exposed portion 2 and the re-inspection can be performed in the same state as before the inspection.
Since the E sensor unit 4 is not adhered or separated, there is an advantage that the AE sensor unit 4 is not damaged and the inspection can be performed in a short time.

Although not shown in the drawings, it is also preferable to integrate the AE sensor section 4 into the sandwiching member 3 by integrating it.

[0052]

Since the present invention is constructed as described above, it has the following great effects.

In the detectors of claims 1 and 2, the sandwiching member 3 is sandwiched between the exposed conductor 2 of the electric wire 1 (especially in the case of a stranded wire) laid on a utility pole or the like in a simple and reliable manner in a detachable manner. The AE wave generated from the electric wire 1 can be worn by the sandwiching member 3
Can be detected with high accuracy by the AE sensor unit 4 via.

According to the detection tool of claim 2, even when the electric wire 1 is in a live state, the AE sensor portion 4 and the conductor exposed portion 2 can be insulated by the inner members 9 and 9, and the AE sensor portion 4 can be detected when detecting the AE wave. To the AE sensor section 4 when the AE wave is propagated from the surface of the exposed conductor 2 to the AE sensor section 4 through the inner members 9 and 9 and the holder member 10. Since there is little attenuation and the sensitivity is good, high detection accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a perspective view showing another embodiment.

FIG. 4 is a perspective view of another embodiment in a disassembled state.

FIG. 5 is a block diagram showing a nondestructive inspection method.

FIG. 6 is a diagram showing a half-wave rectified waveform of an AE signal.

FIG. 7 is a diagram showing a waveform of an AE event.

FIG. 8 is a graph showing the relationship between the event rate count and the number of fatigues.

[Explanation of symbols]

 1 Wire 2 Conductor Exposed Part 3 Clamping Member 4 AE Sensor Part 9 Inner Member 10 Holder Member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Fukumoto 3-4-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Cable Co., Ltd. Tokyo office

Claims (2)

[Claims] 1. A sandwiching member for detachably sandwiching a conductor exposed portion of an electric wire, and an AE fixed or integrated with the sandwiching member.
An electric wire fatigue detection tool comprising a sensor section. 2. A pair of ceramic inner members in which the sandwiching member contacts the conductor exposed portion of the electric wire, and a holder member for holding the inner member and sandwiching the conductor exposed portion of the electric wire via the inner member. The electric wire fatigue detection tool according to claim 1, comprising: