JP2811003B2 - Partial discharge detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a partial discharge detection device for detecting a partial discharge generated inside an insulator or the like of an electric cable.

(Technical Background of the Invention and its Problems) When a high voltage is applied to an insulator and an electric defect such as a void is present inside the insulator, an electric field is concentrated on the portion and a partial discharge occurs. For example, if such a partial discharge occurs in the insulator of a high-voltage cable for power transmission, the insulator deteriorates from that portion, and in the worst case, dielectric breakdown occurs.

In order to prevent this, there is known a method of acoustically detecting a partial discharge that has occurred in a cable insulator in advance. This is a method called an acoustic emission method among the nondestructive inspection methods.

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, if an acoustic detection element such as an ultrasonic sensor is brought into contact with the outer periphery of the cable insulator, it is possible to detect the location of the partial discharge and its degree.

However, when such acoustic detection is performed, countermeasures against external noise are particularly important.

For example, as shown in FIG. 4, a partial discharge sound detection sensor 2 is brought into contact with the outer peripheral surface of the cable connection portion 1 to detect a partial discharge sound generated in a defect 4 such as a void inside the insulator 3. Think about it.

The sensor 2 for detecting partial discharge noise has an acoustic sensor 2b housed inside a case 2a. This acoustic sensor 2b
Is configured in a horn shape to detect the minute discharge sound 4a.

However, the external noise 5 may be detected by the acoustic sensor 2b during the detection of the partial discharge sound 4a. In particular, there are many irregularities on the outer peripheral surface of the cable connection portion and the like. It is curved from the outside. Therefore, as shown in FIG. 5, a gap is easily generated between the sensor 2 and the partial discharge sound detection sensor 2. The noise 5 enters the acoustic sensor 2b shown in FIG. 4 from this gap. In this case, utilizing the fact that the property of the noise 5 that invades from the outside and the property of the discharge sound 4a are different,
It is also considered to electrically separate and process.

However, in practice, the manner in which the noise 5 penetrates varies depending on the handling of the sensor by the operator who measures the partial discharge, and this may not be completely separated and removed by uniform signal processing.

(Object of the Invention) The present invention has been made in view of the above points, and has effectively prevented the intrusion of noise when detecting a partial discharge sound in a highly uneven portion such as an outer surface of a cable connection portion. It is an object to provide a partial discharge detection device.

(Summary of the Invention) A partial discharge detection device according to the present invention includes a partial discharge sound detection sensor for detecting a partial discharge sound propagating inside an object facing the object, and a partial discharge sound detection sensor. And a signal processing circuit for processing a detection signal.The sensor for partial discharge sound detection has a sound insulation wall made of a cushion material surrounded by a soft soundproof rubber coating on a peripheral portion surrounding a detection surface facing the object. It is characterized by having been provided.

(Embodiment of the Invention) Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the partial discharge detection device of the present invention.

In the drawing, the partial discharge detection device includes an acoustic sensor 2b housed in a case 2a having an open bottom surface. The output of the acoustic sensor 2b is processed by a signal processing circuit 9 provided outside thereof.

On the other hand, a sound insulation wall 8 is provided on the lower end surface of the case 2a so that the partial discharge sound detection sensor surrounds the detection surface 2c facing the object.

The sound insulating wall 8 is composed of a cushion material 6 surrounded by a soft soundproof rubber coating 7 as shown in a partially enlarged view in the figure. The cushion material 6 is made of, for example, a sponge-like urethane foam. The soft soundproof rubber 7 is made of a synthetic rubber or the like that is thin enough not to lose flexibility.

When the sensor 2 for detecting partial discharge noise is brought into contact with an object, the cushion material 6 is in close contact with the object, eliminates gaps, and plays a role of preventing sound from entering. However, with the cushion material alone, when the noise level is 60 horn or more, the effect of preventing sound from entering is reduced. In addition, a porous material such as a sponge is easily soiled and easily sucks water and the like. The soft soundproof rubber 7 completely surrounds the cushion material 6, prevents dirt and the like, and absorbs high-level noise. In general, synthetic rubber has a higher soundproofing effect than urethane foam. Here, in order to obtain an appropriate soundproofing effect only with synthetic rubber, it is necessary to increase the thickness of the synthetic rubber to some extent. However, as the thickness increases, the entire body becomes harder, and it is difficult to adhere along the unevenness of the object. Therefore, a very good soundproofing property is obtained by combining a soft soundproof rubber coating having a certain degree of flexibility and a cushion material filling the inside thereof.

In order to demonstrate the effect of the present invention, as shown in FIG.
The sensor 2 for detecting partial discharge according to the present invention was brought into close contact with the upper surface of the cable connection portion 1 via the sound insulation wall 8, and the output of the measuring instrument with respect to the noise level of the external noise was plotted.

 FIG. 3 is a graph showing the results.

In the figure, the output of the measuring instrument according to the conventional method shown in FIG. 5 is represented by a solid line. The output of the measuring instrument in the apparatus of the present invention is indicated by a broken line.

As described above, the apparatus of the present invention has a remarkable effect of preventing noise as compared with the conventional case, particularly when the noise level is in the range of 60 horn or more.

 The present invention is not limited to the above embodiments.

In the embodiment shown in FIG. 1, an example in which the sound insulating wall 8 is provided annularly at the lower end of the case 2a is shown. However, as the width T of the sound insulating wall 8 increases, the sound insulating effect increases, and The properties are also improved. For this reason, various modifications may be made, such as not only making the sound insulating wall 8 wide as it is, but also widening the outer wall of the device to provide the sound insulating wall. or,
The material of the soft sound-insulating rubber coating and the cushion material constituting the sound insulating wall 8 may be replaced with various known equivalent materials.

(Effect of the Invention) According to the partial discharge detection device of the present invention described above, since the sound insulation wall made of the cushion material surrounded by the soft soundproof rubber coating is provided around the acoustic sensor, the device is brought into contact with the object. During the operation of detecting the partial discharge noise, the gap between the device and the object is closed by the sound insulating wall, and the noise is cut off. In addition, the soft soundproof rubber coating more effectively blocks particularly high-level noise. As a result, a weak partial discharge sound can be detected with high sensitivity, and highly accurate partial discharge measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a partial discharge detecting device according to the present invention, FIG. 2 is a front view illustrating a use state of the device, FIG. 3 is a graph showing effects of the device of the present invention, FIG. Is an explanatory view of a conventional partial discharge sound measuring method, and FIG. 5 is a front view for explaining a use state of the conventional apparatus. 2 ... partial discharge sound detection sensor, 2a ... case, 2b ... acoustic sensor, 2c ... detection surface, 6 ... cushion material, 7 ... soft soundproof rubber coating, 8 ... sound insulation wall, 9 ... signal Processing circuit.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Norikazu Ozawa 2-1-1, Odaei, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. 2-1-1 1-1 Showa Electric Wire & Cable Co., Ltd. (72) Inventor Takahiro Yamashita 2-4-1 Nishi-Atsujigaoka, Chofu-shi, Tokyo Tokyo Electric Power Company R & D Headquarters Technology Research Institute (72) Inventor Toshiyuki Mochizuki Chofu, Tokyo 2-4-1, Ichinishi Azumigaoka Tokyo Technical Research Institute, Research and Development Headquarters, Tokyo Electric Power Company (56) References JP-A-63-8571 (JP, A) JP-A-63-204165 (JP, A) 42459 (JP, U) Fully open 1986-42460 (JP, U) Fully open 1986-42461 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 29/00-29 / 2 8

Claims (1)

(57) [Claims] 1. A partial discharge sound detection sensor for detecting a partial discharge sound propagating inside an object facing the object, a signal processing circuit for processing a detection signal of the partial discharge sound detection sensor. Wherein the partial discharge sound detecting sensor is provided with a sound insulating wall made of a cushion material surrounded by a soft soundproof rubber coating on a peripheral portion surrounding a detection surface facing the object. Detection device.