JPH08130811A - Method for detecting discontinuity of conductor - Google Patents

Abstract

PURPOSE: To highly reliably detect discontinuity of the conductor of an electric wire covered with an insulating coating by exposing the conductor at both ends of the wire and fitting an accelerometer (vibrometer) to one end of the conductor and adapter to the other end of the conductor, and then, applying reproducible impacts to the conductor through the adapter and detecting discontinuity in the conductor from the waveform detected by the accelerometer. CONSTITUTION: An adapter 2 having a half-ring-like shape provided with an AE sensor 3 is attached to one exposed end of the conductor 12 of an electric wire 1 covered with an insulating coating 11 and another adapter 2 having the same shape is attached to the other exposed end of the conductor 13. Then the conductor 12 is vibrated by applying reproducible impulse waves to the adapter 2 on the right side in the Figure and the vibration of the conductor 12 is detected by means of the AE sensor 3. When the conductor is discontinued, the waveform of the vibration is distorted as indicated by A in the Figure. Therefore, the disconnection of the conductor 12 can be easily detected easily with high reliable accuracy over the full length of the wire 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting non-destructive disconnection of a conductor such as an electric wire used for an application to which repeated bending is applied or an overhead distribution line in which stress corrosion breakage is likely to occur.

[0002]

2. Description of the Related Art As one of the nondestructive detection methods for a conductor of an electric wire having an insulating coating on the conductor, there is a method using X-ray photography. However, in order to carry out this method, not only a qualification is required, but also a large device is required and only local imaging can be performed, so that the method is not easy to handle and is not a simple method.

As another method, a holder made of a material whose acoustic impedance is almost the same as that of the holder is attached to the covering portion of the overhead distribution line, and a vibrating jig is attached to the covering portion in the vicinity of the holder, and a vibrating jig is attached. There is proposed a method of detecting the deterioration of the overhead distribution line by detecting acoustic radiation from the overhead distribution line excited by the vertical movement of the antenna by an AE sensor provided in the holder (see Japanese Patent Laid-Open No. 6-133422). ).

However, such a method vibrates the aerial distribution line by operating a vibrating jig attached to the covering portion of the aerial distribution line, and the reproducibility of the degree of vibration is poor. . Further, both vibration and detection of acoustic radiation to the overhead distribution line are performed on the coating, and the reliability of the accuracy is poor.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a highly reliable conductor disconnection detection method, the first feature of which is an electric wire having an insulating coating on the conductor. Expose the conductors on both ends of, and attach an accelerometer (vibrometer) such as an AE sensor to one end of the conductor and an adapter to the other end,
In this method, a reproducible impact is applied to the conductor via the adapter, and at this time, the presence or absence of wire breakage of the conductor is detected from the vibration waveform detected by an accelerometer such as an AE sensor attached to the other end.

A second feature of the present invention is to expose a conductor at one end of an electric wire having an insulating coating on the conductor, attach an adapter and an accelerometer such as an AE sensor to the conductor, and connect the conductor to the conductor via the adapter. In this method, a reproducible impact is applied, and the presence or absence of disconnection of the conductor and the distance from the impact end are detected from the time difference between the impact applied wave and the reflected wave returning from the disconnection point.

A third feature of the present invention is that both ends of an electric wire having an insulating coating on a conductor are exposed, an adapter and an accelerometer such as an AE sensor are attached to the conductor, and the conductor is reproduced via the adapter. There is a method of detecting the presence / absence of wire breakage of a conductor by applying a shock having a certain property and using a damping coefficient calculated by using the peak value and the propagation time of the shock applied wave and the damping wave at the other end.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is an explanatory view of a concrete example of the disconnection detecting method of the present invention, and FIG. In the figure, 1 is an electric wire having an insulating coating 11 of vinyl chloride, polyethylene or the like on a conductor 12, and a half ring adapter in which an AE sensor 3 is provided at one end of the exposed conductor 12 at both ends of the electric wire 1. Attach 2,
On the other end of the exposed conductor 11, the same half ring adapter 2 is attached. And the adapter 2 on the right side of the figure
The conductor 12 is vibrated by applying a reproducible impact by a method described later. This vibration is detected by the AE sensor 3 attached on the left side of the figure, and the detected vibration waveform is transmitted to the recorder through the amplifier to obtain a vibration waveform diagram as shown in FIG.

In the electric wire to which the present invention is applied, there are cases where the conductor portion is exposed as shown in FIG. 1 (a) and cases where a connection terminal is attached to the conductor end portion like a moving cable. is there. When the connecting terminal is attached to the end of the conductor, the adapter 2'is attached to the outer circumference of the connecting terminal 4 attached to the end of the conductor 12 via the contact 5.

2 (a) to 2 (c) are schematic illustrations of means for applying a reproducible impact to an adapter attached to the end of a conductor. Fig.2 (a) shows how to vibrate the adapter 2'end with a hammer 6 that has a built-in AE sensor and shows the vibrating force.
FIG. 2B shows a method of vibrating the end of the adapter 2 ′ by the pendulum motion of the metal sphere 7 which performs pendulum motion, and FIG. Adapter 2 '
This is a method of applying vibration to the edge.

The vibration waveforms detected by the method of the present invention are as shown in FIGS. 3A and 3B. FIG. 3A shows a good product and FIG. 3B shows a broken product. The vibration waveform of the good product in Fig. 3 (a) is a damping wave of a sine wave,
As for the vibration waveform of the disconnected product, the waveform is distorted as shown by A in FIG.

FIG. 4 is an explanatory view of an embodiment based on the second feature of the present invention. As shown in the drawing, the conductor 12 at one end of the electric wire 1 having the insulating coating 11 on the conductor 12 is exposed, and the adapter 2 and the accelerometer 3 such as an AE sensor are attached to the exposed conductor. Then, a reproducible impact is applied to the conductor 12 via the adapter 2, and the presence or absence of disconnection is detected from the time difference between the impact applied wave and the reflected wave returning from the disconnection point, and the impact end of the conductor disconnection point is detected. To detect the distance from.

FIG. 5 is an explanatory diagram of an embodiment based on the third feature of the present invention. As shown in the drawing, the conductors 12 at both ends of the electric wire 1 having the insulating coating 11 on the conductor 12 are exposed, and the adapter 2 and the accelerometer 3 such as an AE sensor are attached to the exposed conductor 12. Then, a reproducible shock wave is applied to the conductor 12 via one of the adapters 2 as shown in the figure, and as shown in FIG. 6, the peak value A of the shock applied wave and the peak value A ′ of the damping wave at the other end. And the propagation time (difference in detection time between the shock applied wave and the output wave) T are measured, and the attenuation coefficient α is calculated using the following equation. Attenuation coefficient α = − (lnA ′ / A) T As a result, if α ≧ χ (χ is a value peculiar to the wire), it is understood that the wire is broken.

The above detection method was applied to an actual electric wire. Applicable wire: High voltage EP rubber insulation lead wire Voltage 6600V Size 1 × 60mm ² Single length 5m Number of conductor wires 380 Conductor structure 19/20 / 0.45mm Insulation thickness 5mm The results are shown in Table 1. In the electric wire samples 3 and 4 having the attenuation coefficient α> 400, 100 or more breaks occurred.

[0015]

[Table 1]

[0016]

As described above, according to the conductor disconnection detecting method of the present invention, a reproducible impact is applied to the conductor through the adapter attached to the end of the conductor, and this is attached to the conductor. Since it is detected by an accelerometer such as a sensor, the reliability of its accuracy is improved. Further, compared with the conventional X-ray photography, a large device is not required, and the detection work can be easily performed over the entire length of the electric wire.

[Brief description of drawings]

FIG. 1A is an explanatory view of a specific example based on the first feature of the conductor disconnection detection method of the present invention, and FIG. 1B is an explanatory view of another example of an adapter attached to a conductor end portion. Is.

FIGS. 2A to 2C are schematic explanatory views of means for applying a reproducible impact to an adapter attached to a conductor end portion.

3A and 3B are vibration waveform diagrams detected by the method based on the first feature of the present invention. FIG. 3A shows a good product and FIG. 3B shows a broken product.

FIG. 4 is an explanatory diagram of a specific example of the disconnection detection method based on the second feature of the present invention.

FIG. 5 is an explanatory diagram of a specific example of the disconnection detection method based on the third feature of the present invention.

FIG. 6 is an explanatory diagram of a shock application wave and a damping wave detected by the method according to the third feature of the present invention.

[Explanation of symbols]

 1 Insulated wire 11 Insulation coating 12 Conductor 2.2 'Adapter 3 AE sensor 4 Contact terminal 5 Contact piece

Claims (3)

[Claims] 1. A conductor at both ends of an electric wire having an insulating coating on the conductor is exposed, an accelerometer such as an AE sensor is attached to one end of the conductor, and an adapter is attached to the other end, and the conductor is reproducible through the adapter. A shock was applied, and at this time, A was attached to the other end.
A conductor disconnection detection method comprising detecting the presence or absence of conductor disconnection from a vibration waveform detected by an accelerometer such as an E sensor. 2. A conductor at one end of an electric wire having an insulating coating on a conductor is exposed, an adapter and an accelerometer such as an AE sensor are attached to the conductor, and a reproducible impact is applied to the conductor through the adapter, A conductor disconnection detection method, comprising detecting the distance from the impact end of the conductor disconnection point from the time difference between the shock application wave and the reflected wave returning from the disconnection point. 3. A conductor having insulating coatings on both ends is exposed, an adapter and an accelerometer such as an AE sensor are attached to the conductor, a reproducible impact is applied to the conductor through the adapter, and the impact is applied. A conductor disconnection detection method comprising detecting the presence or absence of a conductor disconnection based on an attenuation coefficient calculated by using a crest value and a propagation time of an applied wave and an attenuation wave at the other end.