JP2008180509A - Insulation deterioration diagnosis method of connection terminal, and cover for diagnosis used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation deterioration diagnosis method of a connection terminal capable of detecting discharge vibration surely with a few measuring points, and diagnosing insulation deterioration with high working efficiency by preventing a failure of a vibration sensor. <P>SOLUTION: A representative constitution of this insulation deterioration diagnosis method of the connection terminal arranged on a terminal connection part of a high tension cable 100 for power distribution has characteristics wherein a cover 200 for diagnosis comprising a metal plate is wound on the outer circumferential surface of the connection terminal so that a voltage detection zone 124 exposed on the outer circumferential surface is conductive with external semi-conducting layers 122, 123 connected to the earth, and vibration is measured by using an AE sensor 210 from above the cover 200 for diagnosis, to thereby detect discharge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for diagnosing insulation deterioration of a connection terminal disposed at a terminal connection portion of a high-voltage cable for power distribution.

  The terminal connection part of the high voltage cable for power distribution connected to a switch, a transformer, etc. is connected to an apparatus main body by the connection terminal which covered the terminal with the insulator. FIG. 3 is a diagram for explaining an example of the structure of a connection terminal.

  As shown in FIG. 3, a terminal 101 is attached to the end of the cable 100. A rubber insulating cylinder 120 is attached to the end of the cable 100 via a stress cone 110. An outer semiconductive layer 111 made of a semiconductor is formed on the outer peripheral surface of the stress cone 110. An internal semiconductive layer 112 electrically connected to the cable 100 is provided on the inner side of the stress cone 110 and is electrically connected to an internal semiconductive layer 121 provided on the inner peripheral surface of the insulating cylinder 120. The The semiconductor is a high-resistance material made conductive by mixing a conductor (carbon) into rubber.

  On the outer periphery of the insulating cylinder 120, a voltage detection band 124 is formed between the outer semiconductive layer 122 covering the outer peripheral surface on the device side (tip side) and the outer semiconductive layer 123 covering the outer peripheral surface on the cable 100 side. is doing. The outer semiconductive layers 122 and 123 and the voltage detection band 124 are all formed of a semiconductor. The external semiconductive layer 122 is pressed into contact with the device main body to which the cable 100 is connected, and further conducted through a semiconductive tape as necessary, and is connected to the ground through the casing of the device main body. The external semiconductive layer 123 is connected to the ground via the external semiconductive layer 111 of the stress cone 110.

  The detection band 124 is disposed at a position facing the inner semiconductive layer 121 inside the insulating cylinder 120. The inner semiconductive layer 121 and the voltage detection band 124 are insulated by rubber, which is the main material of the insulating cylinder 120. Rubber, which is the main material of the insulating cylinder 120, is exposed on the outer peripheral surface between the outer semiconductive layer 122 and the detection band 124 and between the detection band 124 and the outer semiconductive layer 123. Is formed.

  The power detection zone 124 is provided for diagnosing whether or not power is correctly supplied to the cable 100. When AC power is supplied to the cable 100, the internal semiconductive layer 121 is applied with an AC voltage via the terminal 101 and the internal semiconductive layer 112, thereby detecting voltage that is not connected to the external semiconductive layers 122 and 123. A voltage is induced in the band 124.

  FIG. 4 is a diagram illustrating a state in which the cable 100 is attached to the device main body 10. In a normal state, a semiconductive cover 127 having a length from the external semiconductive layer 122 to the external semiconductive layer 123 is fixedly attached. When checking the power supply state of the cable 100, the cover 127 is shifted and the induced state of the voltage detection band 124 is checked.

  In the connection terminal configured as described above, a distribution line accident has occurred in which the insulating rubber of the insulating cylinder 120 is deteriorated due to the humidity of the installation environment, leading to insulation breakdown (short circuit). An aggregate of moisture is formed inside the rubber, and an aqueous path is formed between the aggregates over time. When this is promoted, it is considered that a discharge occurs between the outer semiconductive layers 111, 122, 123, 127 and the inner semiconductive layers 112, 121, and finally dielectric breakdown (short circuit) is reached. Insulation deterioration tends to occur in a portion where the insulator is thin (a portion where the distance between the inner and outer semiconductors is short).

Conventionally, various connection terminal deterioration determination methods have been proposed. In Japanese Patent Laid-Open No. 7-104028 (Patent Document 1) “Distribution diagnosis method for high-voltage overhead cable branch connector for power distribution”, the deterioration state of the insulating portion is determined by examining the electrical conductivity of the semiconductive rubber adjacent to the insulating layer. A configuration for determination is described.
JP-A-7-104028

  By the way, when a discharge is generated inside the insulating rubber, vibration is accompanied. Therefore, it is possible to know whether or not the discharge is generated by measuring the vibration. As a vibration sensor for measuring vibration, an AE sensor (Acoustic Emission Sensor) using a piezoelectric element can be used. When the vibration is measured using the AE sensor, the cover 127 is shifted and the AE sensor 210 is applied to the outer peripheral surface of the insulating cylinder 120 as shown in FIG.

  However, as shown in FIG. 5B, since the rubber as an insulator has elasticity, it easily absorbs vibration, and when it is away from the discharge point, the vibration is rapidly attenuated. Therefore, the AE sensor is almost directly above the discharge point. If it is not applied, vibration cannot be detected. For this purpose, it is necessary to measure the measurement points finely, that is, to measure at many positions by shifting the AE sensor little by little, and there is a problem that work efficiency is poor.

  In addition, since the AE sensor has a piezoelectric element and an electric circuit at the end, the AE sensor breaks down when it touches the voltage detection band 124. On the other hand, the vicinity of the detection band 124 is also a portion where the insulator is thinned and is a portion where electric discharge is likely to occur (see FIG. 3). For this reason, it is necessary to measure a lot of the surroundings while using very careful so as not to touch the voltage detection band 124, and there is a problem that efficiency is poor.

  Accordingly, the present invention provides a method for diagnosing insulation deterioration of a connection terminal that can detect discharge vibration reliably at a small number of measurement points and can diagnose insulation deterioration with high work efficiency by preventing failure of the vibration sensor. The purpose is to provide.

  In order to solve the above problems, a representative configuration of a connection terminal insulation deterioration diagnosis method according to the present invention is a connection terminal insulation deterioration diagnosis method arranged at a terminal connection portion of a power distribution high-voltage cable. A diagnostic cover made of a metal plate is wound around the outer peripheral surface of the terminal so that the voltage detection band exposed on the outer peripheral surface is electrically connected to the external semiconductive layer connected to the ground. It is characterized by detecting discharge by measuring vibration using.

  According to the above configuration, since the diagnostic cover made of a metal plate transmits discharge vibration, vibration can be detected even if the position where the vibration sensor is applied is away from the discharge point. In addition, the conduction between the voltage detection band and the external semiconductive layer can prevent an induced voltage from being generated in the voltage detection band.

  It is preferable to use the vibration sensor in a state where the diagnostic cover is fastened to the outer peripheral surface of the connection terminal. By tightening the diagnostic cover, the discharge vibration generated inside can be more reliably transmitted to the diagnostic cover.

  In addition, a diagnostic cover according to the present invention includes a cylindrical portion made of a substantially cylindrical metal plate, a cutting portion for expanding the cylindrical portion, and a fastening portion for fastening the cutting portion. This is characterized in that it is longer than the width of the insulating band between the voltage detection band exposed on the outer peripheral surface of the connection terminal and the external semiconductive layer. By attaching the diagnostic cover so as to be in contact with both the voltage detection band and the external semiconductive layer, vibration transmission and generation of induced voltage can be prevented. The fastening portion is preferably a catch lock (patch lock) that can be fastened with one touch.

  Furthermore, it is preferable that the length of the cylindrical portion is longer than the combined length of the detection band on the outer peripheral surface of the connection terminal and the insulating bands on both sides thereof. By setting it as such a length, the outer periphery of a connection terminal can be covered so that an external semiconductive layer on both sides of an insulating band may be connected including an insulating band. As a result, the number of measurement points can be further reduced (integrated), and it is not necessary to shift the diagnostic cover, so that the work efficiency of deterioration diagnosis can be improved.

  According to the present invention, it is possible to reliably detect discharge vibration at a small number of measurement points using a vibration sensor, and even when the vibration sensor includes an electric element or an electric circuit like an AE sensor. Since the failure can be prevented, it is possible to diagnose the insulation deterioration of the connection terminal arranged at the terminal connection portion of the high-voltage cable for power distribution with high work efficiency.

  Embodiments of a connection terminal insulation deterioration diagnosis method and a diagnostic cover according to the present invention will be described. FIG. 1 is a diagram for explaining the structure of a diagnostic cover, and FIG. 2 is a diagram for explaining an insulation deterioration diagnosis method. . Note that dimensions, materials, and other specific numerical values shown in the following embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified.

  A diagnostic cover 200 shown in FIG. 1 includes a cylindrical portion 201 made of a substantially cylindrical metal plate, a cutting portion 202, and a fastening portion 203 for fastening the cutting portion 202.

  The cylinder part 201 has a C-shaped cross section, and the cutting part 202 is parallel to the axis of the cylinder part (on the bus bar). The cylindrical part 201 can be developed by the presence of the cutting part 202, and the cable 100 can be wound around the outer periphery of the insulating cylinder 120 without removing it from the device main body 10. The fastening portion 203 can have various configurations, but a hook-type so-called catch lock (also referred to as a patch lock) is used.

  In the present embodiment, the vibration sensor uses the AE sensor 210. The AE sensor 210 includes a piezoelectric element at the tip, and can convert vibration into a change in voltage for measurement.

  As shown in FIG. 2A, when performing the insulation deterioration diagnosis, first, the cover 127 is shifted, the cylinder portion 201 is wound around the outer periphery of the insulating cylinder 120, and is fastened by the fastening portion 203. Then, the discharge is detected by applying vibration to the AE sensor 210. The measurement is desirably performed on the entire insulating cylinder 120, and the measurement is performed while shifting the diagnostic cover 200 in the axial direction. However, from experience, discharge (insulation degradation) occurs most often at the boundary between the external semiconductive layer 123 and the insulating band 125, and then there are many boundaries between the external semiconductive layer 122 and the insulating band 125 (see FIG. 3), measuring these two positions is sufficient in most cases.

  Further, as shown in FIG. 2B, since the diagnostic cover 200 made of a metal plate transmits the discharge vibration, the vibration can be detected even if the position where the AE sensor 210 is applied is away from the discharge point. In the experiment, it was possible to detect the vibration waveform even at a distance of 90 ° or more from the discharge point, so it was possible to reduce (integrate) the number of measurement points that were 10 or more on one circumference to two. It was. As a result, the measurement accuracy was improved and the efficiency was improved by shortening the measurement time.

  In particular, by using a catch lock, it can be fastened / unfastened with a single touch, and even when a non-free insulating glove is worn, the user can work comfortably. Further, when the connection terminal is attached to the insulating cylinder 120, it can be fastened to the outer peripheral surface thereof (tightened), so that vibration generated inside the insulating cylinder 120 can be transmitted more efficiently. .

  In addition, the axial length h of the cylindrical portion 201 is longer than the width w1 (see FIG. 3) of the insulating band 125 in the present embodiment. Accordingly, the diagnostic cover 200 can be attached so as to be in contact with both the voltage detection band 124 and the external semiconductive layer 122 (or the external semiconductive layer 123). Thus, by electrically connecting the voltage detection band 124 and the external semiconductive layer 122, it is possible to prevent an induced voltage from being generated in the voltage detection band 124. For this reason, even when the AE sensor 210 is applied to the voltage detection band 124 when measuring the vicinity of the voltage detection band 124, no failure is caused.

  Further, the length h of the cylindrical portion 201 may be formed longer than the total length of the width w2 of the voltage detection band 124 and the width w1 of the insulating bands 125 on both sides thereof. With such a length, the outer periphery of the connection terminal can be covered so as to connect the external semiconductive layers 122 and 123 on both sides of the insulating band 125 including the insulating band 125. As a result, vibration can be transmitted from a wider range, the number of measurement points can be reduced, and the number of times the diagnostic cover 200 can be shifted can be reduced, so that the work efficiency of deterioration diagnosis can be improved.

  Further, in the above configuration, the cylindrical portion 201 is unfolded by being bent, but a hinge portion (not shown) may be provided on the substantially opposite side of the cutting portion 202 so as to be opened and closed. In this case, the rigidity of the cylinder part 201 can be increased, and the cylinder part 201 can be appropriately tightened even when the length of the cylinder part 201 is increased.

  As described above, in the insulation deterioration diagnosis method in which the discharge vibration in the insulating cylinder 120 is measured by the vibration sensor, it is possible to detect even a position away from the discharge point by using the diagnostic cover 200. It is possible to reliably detect the discharge vibration with a small number of measurement points. In the above-described embodiment, the vibration sensor has been described using the AE sensor as an example. However, the present invention is not limited to this, and the present invention is not limited to this, as long as the sensor measures vibration transmitted to the outer peripheral surface of the connection terminal. Can benefit from. As the vibration sensor, in addition to the AE sensor (piezoelectric element), for example, a capacitance type, an eddy current type, a laser Doppler type, an electromagnetic type, or the like can be used.

  Further, according to the present invention, even when the vibration sensor includes an electric element or an electric circuit, a failure due to the induced voltage can be prevented. For this reason, attention required for work is reduced, and workability can be improved.

  Furthermore, the improvement in detection performance and workability as described above eliminates the portion depending on the individual skill, so that it can be a test method that can be carried out without requiring skill.

  In the above-described embodiment, the connection terminal is described as being made of rubber. However, in the present invention, the connection terminal is not necessarily made of rubber, and any connection terminal may be used. This is because if the insulating coating generates a discharge due to deterioration, it can be detected by vibration, and the benefits can be obtained by applying the present invention.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a method for diagnosing insulation deterioration of a connection terminal arranged at a terminal connection portion of a high-voltage cable for power distribution.

It is a figure explaining the structure of the cover for diagnosis. It is a figure explaining an insulation degradation diagnostic method. It is a figure explaining the example of the structure of a connection terminal. It is a figure which shows the state in which the cable was attached to the apparatus main body. It is a figure explaining the conventional insulation degradation diagnostic method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Device main body, 100 ... Cable, 101 ... Terminal, 110 ... Stress cone, 111 ... External semiconductive layer, 112 ... Internal semiconductive layer, 120 ... Insulating cylinder, 121 ... Internal semiconductive layer, 122 ... External semiconductive layer , 123 ... outer semiconductive layer, 124 ... voltage detection band, 125 ... insulating band, 127 ... cover, 200 ... diagnostic cover, 201 ... cylinder part, 202 ... cutting part, 203 ... fastening part, 210 ... vibration sensor

Claims (4)

A method for diagnosing insulation deterioration of a connection terminal arranged at a terminal connection portion of a high-voltage cable for power distribution,
A diagnostic cover made of a metal plate is wound around the outer peripheral surface of the connection terminal so as to conduct the voltage detection band exposed on the outer peripheral surface and the external semiconductive layer connected to the ground,
A method for diagnosing insulation deterioration of a connection terminal, comprising: detecting discharge by measuring vibration from above the diagnostic cover using a vibration sensor.   2. The connection terminal insulation deterioration diagnosis method according to claim 1, wherein the vibration sensor is used in a state where the diagnostic cover is fastened to an outer peripheral surface of the connection terminal. A diagnostic cover used for insulation deterioration diagnosis of a connection terminal arranged at a terminal connection portion of a high-voltage cable for power distribution,
A cylindrical portion made of a substantially cylindrical metal plate;
A cutting portion for expanding the cylindrical portion;
A fastening portion for fastening the cutting portion,
The length of the said cylinder part in the axial direction is longer than the width | variety of the insulation zone between the electric detection zone exposed to the outer peripheral surface of the said connection terminal, and an external semiconductive layer, The diagnostic cover characterized by the above-mentioned.   4. The diagnostic cover according to claim 3, wherein the length of the cylindrical portion is longer than the combined length of the detection band on the outer peripheral surface of the connection terminal and the insulation bands on both sides thereof.

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