JPH0613501Y2 - Partial discharge detector - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a partial discharge detection device for detecting a partial discharge generated inside an insulator or the like of a power cable in the form of a sound wave.

(Technical background of the invention and its problems) When a high voltage is applied to an insulator, if an electrical defect such as a void exists inside the insulator, an electric field concentrates on that portion and a partial discharge occurs. Occurs.

For example, if there is a defect in the high-voltage cable for power transmission or the insulator of its connection, a partial discharge occurs in the defective portion, the insulator, etc. deteriorates, and in the worst case, dielectric breakdown occurs. . In order to prevent this, a method of acoustically detecting a partial discharge that has occurred in the cable insulator in advance is known, and is usually called an acoustic emission method.

Generally, when a partial discharge occurs, a discharge sound is generated from the discharge location. This discharge sound propagates as a sound wave in the cable insulator. Therefore, conventionally, a sound wave detector is brought into contact with the outer circumference of the cable connection portion or the like to detect the location and extent of partial discharge. That is, FIG. 3 shows a conventional partial discharge detection device, which is provided with a horn 1 and a sound wave detector 2 such as PZT, which are arranged in a casing 3.

In use, the horn 1 is pressed against the peripheral surface of the cable connecting portion 5. Therefore, when a partial discharge occurs in the defect 7 inside the insulator 6, a sound wave is generated in this defect portion, and this sound wave propagates through the insulator 6 and is collected by the horn 1. It is possible to detect the place where the partial discharge occurs and the degree of the partial discharge.

By the way, a worker may move the partial discharge detection device during the exploration work. For this reason, the pressed end surface of the horn 1 slides on the peripheral surface of the cable connecting portion 5 to generate a weak sliding sound, and a noise signal due to the sliding sound is added to the detection signal of the sound wave detector 2. In some cases, it was not possible to accurately detect the location and extent of partial discharge due to overlapping.

(Object of the Invention) An object of the present invention is to provide a partial discharge detection device capable of accurately detecting a place and a degree of occurrence of partial discharge.

(Summary of the Invention) The present invention includes a sound collecting horn that collects a sound wave generated by a partial discharge by pressing the tip side against an object to be inspected where a partial discharge occurs, and a sound wave detector that detects the collected sound wave. In a partial discharge detection device having a sound collecting horn that collects sound waves generated by partial discharge by attaching a sliding sound generating member to a contact prevention plate arranged on the tip side of a noise collecting horn that collects external noise. When sliding on the object to be inspected, this sliding noise generating member generates a large sliding noise, and a noise signal with a large level is positively obtained by a sound wave detector for external noise detection. .

Embodiments of the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a partial discharge detection device according to the present invention, and 10 indicates a cylindrical casing. A handle 11 is attached to the upper wall of the casing 10, and an inner cylinder 12 is arranged inside the handle 11. Between the upper surface of the upper wall of the inner cylinder 12 and the lower surface of the upper wall of the casing 10, a plate-shaped sound insulating material 13 is provided.
Has been inserted. Flange portion 12a at the lower end of the inner cylinder 12
A bottom plate 14 is fixed to the bottom plate 14, and a sound absorbing material 15 is attached to the outer peripheral side of the lower surface of the bottom plate 14. Partition wall 1 inside the inner cylinder 12
It is divided into upper and lower parts by 6, and a preamplifier 17 is housed in the upper part.

A signal sensor unit 18 is housed below the inner cylinder 12. The signal sensor unit 18 includes a horn 19, and a lower portion of the horn 19 projects from the bottom plate 14. At the upper end of the horn 19, a PZT 21 which is a piezoelectric element as a sound wave detector is provided.
Is installed. The PZT 21 and the horn 19 are arranged in a cylindrical horn support 22, and the PZT 21 is fixed to the lower surface of the upper wall of the horn support 22. A bulging portion 22A having a large wall thickness is formed in the lower portion of the horn support 22, and an O-ring 23 is fitted in the annular recess 22a on the inner peripheral side of the bulging portion 22A. This O-ring 23 is a horn 19
The horn 19 is supported by airtightly contacting the lower part of the.
A coil spring 24 is arranged on the outer peripheral side of the horn support 22. The upper end of the coil spring 24 is fitted into the annular recess 16a provided on the lower surface of the partition wall 16, and the lower end thereof is another annular recess 2 provided on the upper surface of the bulging portion 22A of the horn support 22.
It is fitted in 2b. Therefore, the horn support 22 projects downward due to its own weight. And in this state,
The lower part of the horn 19 projects below the bottom plate 14, and there is a gap 2 between the upper wall of the horn support 22 and the lower surface of the partition wall 16.
5 results. A cylindrical guide member 26 is arranged on the outer peripheral side of the coil spring 24. The guide member 26 is provided to smoothly expand and contract the coil spring 24.

A micro switch 33 is fixed to the upper surface of the partition wall 16. The lever 33 a of the micro switch 33 is located in the through hole of the partition wall 16 and the push-up piece 34 is located below it.
Is located. The lower part of the push-up piece 34 is the horn support 22.
It is fitted into the upper wall of the. On the other hand, the live buzzer 35 is fixed to the upper wall of the casing 10. The piezoelectric buzzer 35 is pushed up by the lever 33a so that the micro switch 33
Stops the buzzer sound when is closed.

An external noise sensor unit 27 is housed below the inner cylinder 12 adjacent to the signal sensor unit 18. The external noise sensor unit 27 has a horn 28 and a PZT 30 attached to its upper end. The PZT 30 is fixed to the lower surface of the upper wall of the horn support 31, and the lower part of the horn 28 is airtightly supported by the bulging portion 31A of the horn support 31 via the ring 23. The upper wall of the horn support 31 is directly fixed to the lower surface of the partition wall 16 and has a bulge 31A.
Protrudes from the bottom plate 14. A contact prevention plate 32 for preventing the horn 28 from contacting the object to be inspected is fixed to the lower end surface of the bulging portion 31A. A Velcro fastener 37, which is generally called a magic tape, is attached to the lower surface of the contact prevention plate 32. The fastener 37 has a large number of hooks or loops on its lower surface and produces a large sliding sound when it comes into sliding contact with the object to be inspected. still,
Since the Velcro fastener 37 is clogged with dust adhering to the object to be inspected, it is preferable that it can be easily replaced.

Each lead wire 36 extending from the PZTs 21 and 30 penetrates the partition wall 16 and is connected to the operational amplifier 17.

The partial discharge detection device having the above-described configuration is pressed by the operator through the handle 11 against the object to be inspected such as the cable connection portion. That is, the lower end surface of the horn 19 and the Velcro fastener 37 are pressed against the object to be inspected. Therefore, when a partial discharge occurs due to a defect in the insulator of the object to be inspected, the sound wave generated thereby is collected by the horn 19, and the PZT 21
The detection signal is output from the PZT 21, and the detection signal is amplified by the preamplifier 17 and supplied to a signal processing circuit (not shown) for analysis. On the other hand, since the horn 28 of the external noise sensor unit 27 is held in a non-contact state via the contact prevention plate 32, it does not collect the above-mentioned sound waves, and therefore the PZT 30 does not output a detection signal.

When external noise such as automobile noise occurs in the surroundings, this noise enters both horns 19 and 28, so that a noise signal is output from PZTs 21 and 30. However, in this case, the noise signal of the PZT 30 prevents the detection signal including the noise signal of the PZT 21 from being supplied to the signal processing circuit by the blocking circuit (not shown). Then, since the blocking operation is released after the elapse of a certain time, only the detection signal detected by the PZT 21 is again supplied to the signal processing circuit and analyzed.

Next, if the worker accidentally moves the partial discharge detection device of the present invention during the exploration work, the horn 19 slides on the object to be inspected, and the weak sound wave generated by this sliding is transmitted to the PZT 21. And received as a sliding noise signal.
On the other hand, when the horn 19 slides, the Velcro fastener 37 also slides in the same manner, so that a large sliding noise is generated and this sliding noise is collected by the horn 28. Therefore, PZT
Since a noise signal having a level higher than 30 is output, the blocking circuit prevents the detection signal including the sliding noise signal of the PZT 21 from being supplied to the signal processing circuit in the same manner as described above. Then, after a certain period of time, the blocking operation is released,
Again, since only the detection signal detected by the PZT 21 is supplied to the signal processing circuit, the location and degree of partial discharge can be accurately detected by the analysis.

By the way, when the partial discharge detection device of the present invention is moved on the cable connection part and the velcro fastener 37 is slid, the blocking circuit does not operate only once after sliding 31 times, and the sliding noise signal is superimposed on the detection signal. It had been. On the other hand, in the case of the partial discharge detection device having only the contact prevention plate, the sliding noise is small after sliding 9 times, so the blocking circuit does not operate three times and the sliding noise signal becomes the detection signal. It was superimposed.

In the above embodiment, instead of the Velcro fastener 37, for example, as shown in FIG. 2, a plate member 38 fixed to the contact prevention plate and a large number of rod-shaped members having rigidity and flexibility provided on the lower surface of the plate member 38. A sliding sound generating member including the body 39 may be used. In this sliding sound generating member, when the rod-shaped body 39 generates sliding noise in sliding contact with the object to be inspected, and at the same time when the bent rod-shaped body 39 returns to its original state, the rod-shaped bodies 39 come into contact with each other and generate noise (e.g. Sound is generated.

As the sliding noise generating member, any member that has a large frictional force with respect to the object to be inspected and has abrasion resistance,
Further, the sliding contact portion may be formed in a protrusion shape or a fiber shape.

Therefore, when Kapton tape, metal mesh member, cellophane tape, etc. are used as the sliding noise generating member, the frictional force is small and the sliding noise is small. The sliding noise signal is superimposed.

(Effect of the Invention) According to the present invention, the sliding noise generating member is attached to the contact prevention plate disposed on the tip side of the horn that collects external noise, and the sliding noise generating member is used when the device is moved. Since a large sliding noise is generated, a noise signal with a large level is positively obtained by a sound wave detector for external noise detection, and the detection signal on which the sliding noise signal is superimposed is analyzed. Can be prevented. Therefore, it is possible to provide a partial discharge detection device capable of accurately detecting the location and extent of partial discharge.

[Brief description of drawings]

FIG. 1 is a sectional view of a partial discharge detection device according to the present invention, and FIG.
FIG. 3 is a view showing another embodiment of the sliding noise generating member according to the present invention, and FIG. 3 is a sectional view showing a conventional partial discharge detecting device together with a cable connecting portion. 16 ... Partition plate, 19, 28 ... Horn, 21, 30 ... PZT, 24 ... Coil spring, 32 ... Contact prevention plate, 37 ... Velcro fastener, 38 ... Plate material, 39 ... Rod-shaped body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Jiro Kawai, 2-1-1, Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture, Showa Electric Wire & Cable Co., Ltd. 1-1-1 Showa Cable Denki Co., Ltd. (72) Inventor Yasumitsu Ebinuma 2-1-1 1-1 Koda Eikawa Kawasaki-ku, Kawasaki-ku, Kanagawa Kanagawa Pref. 72-in-1 Showa Cable Denki Co., Ltd. Kawasaki Kanagawa 2-1-1 Oda Sakae, Kawasaki-ku, Showa Electric Wire & Cable Co., Ltd. (72) Creator Toshihiko Amemiya 2-1-1, Odae Sakae, Kawasaki-ku, Kawasaki, Kanagawa (56) References Special Kai 63-8571 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A portion having a sound collecting horn whose tip is pressed against an object to be inspected in which partial discharge occurs and which collects sound waves generated by the partial discharge, and a sound wave detector which detects the collected sound waves. In a discharge detection device, a noise collection horn that collects external noise, a sound wave detector that detects the collected external noise, and a noise collection horn that is arranged at the tip end side of the noise collection horn. A contact prevention plate for preventing contact with the inspection body, and a sliding sound generating member for generating a large sliding sound when slidingly contacting the inspection body is attached to the contact prevention plate. Partial discharge detection device.