JPH08101247A - Partial discharge detection electrode - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an electrode for detecting partial discharge, which enables accurate measurement. A partial discharge detection electrode used in a partial discharge measuring method for detecting a partial discharge of an insulator to determine the insulation state of the insulator, the electrode being used for a partial discharge detection method and being close to a conductive member in which a high frequency pulse is induced by the partial discharge. Electrodes 6 for partial discharge detection for electrostatic coupling, which are arranged in such a manner that the metal foil 1 is bonded to one surface of the first sheet-like material 2 made of an elastic body, On the other surface, a second sheet-shaped material 3 made of an elastic body having an elastic modulus smaller than that of the first sheet-shaped material 2 is overlapped and partially fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode used in a partial discharge measuring method which is a method for determining the insulation state of an insulator such as a power cable or a transformer to which an AC high voltage is applied.

[0002]

2. Description of the Related Art When an ultra-high-voltage power cable or high-voltage equipment is actually used, if there are defects (voids, protrusions, foreign matter, etc.) in the insulator, partial discharge will occur due to voltage
Dielectric breakdown may occur after passing through an electrical tree. Therefore, in order to confirm the insulation performance, it is known that the insulator is pre-charged and the partial discharge is measured. The high frequency foil electrode method is one of the partial discharge measurement methods. When the partial discharge measurement of the power cable is performed by this method, for example, metal foils are directly attached to both sides of the insulation type intermediate connection portion of the power cable on the anticorrosion layer to form the electrodes. Then, when a partial discharge occurs in the cable insulator due to the application of voltage, a high frequency pulse is induced between the conductor and the ground side metal sheath, and this high frequency pulse is detected by the electrode. This electrode is connected to the detection impedance, and the output of the detection impedance is measured by the partial discharge measuring instrument. In the above-mentioned method, conventionally, a metal foil was directly attached on the anticorrosion layer at the connection portion and fixed with vinyl tape or the like to form an impedance with the ground side, which was used as a measurement electrode.

[0003]

However, the above-mentioned method for measuring the partial discharge of the power cable has the following problems. That is, 1) When the metal foil is directly attached on the insulator, an air layer remains between the insulator and the metal foil due to wrinkles of the metal foil during attachment. 2) Adhesion of the metal foil becomes non-uniform due to poor pressing of the metal foil. Due to the above reasons, the capacitance between the electrode and the conductive member such as the adjacent metal sheath in which a high frequency pulse is induced is changed. When the electrostatic capacitance between the electrode and the conductive member deviates from the measurement suitability value as described above, the detection sensitivity is lowered, and it is difficult to detect the partial discharge.

[0004]

The present invention provides an electrode for detecting partial discharge which solves the above problems, and detects the partial discharge of an insulator of an electrical article to which a high voltage is applied, An electrode for detecting partial discharge used in a partial discharge measuring method for determining the insulation state of an insulator, for detecting partial discharge for electrostatic coupling arranged close to a conductive member in which a high frequency pulse is induced by partial discharge In the electrode, a metal foil is adhered to one surface of the first sheet-like material made of an elastic material to form the first sheet.
On the other surface of the sheet-like article, a second sheet-like article made of an elastic material having a smaller elastic modulus than the first sheet-like article is overlapped and partially fixed. is there.

[0005]

As described above, when the metal foil is adhered to one surface of the first sheet-like material made of the elastic body, the metal foil bends,
It is possible to prevent the generation of wrinkles due to breakage, breakage, etc. When the metal foil is attached to the insulator, no air layer remains between the metal foil and the insulator. In addition, a second sheet-shaped material formed of an elastic body having a smaller elastic modulus than the first sheet-shaped material is overlapped and partially fixed to the first sheet-shaped material. Then, since the second sheet-like material is softer and easier to deform than the first sheet-like material, tension is applied to the second sheet-like material so that the second sheet-like material can be deformed in accordance with the surface shape of the insulator to which the metal foil is attached. By deforming the sheet-shaped material, the metal foil can be brought into close contact with the surface of the insulator with a uniform surface pressure via the first sheet-shaped material.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1A and 1B are a plan view and a cross-sectional view of an embodiment of a partial discharge detection electrode according to the present invention, respectively. The electrodes for detecting partial discharge are attached to both sides of the power cable insulating connection portion. In the figure, 1 is a copper foil electrode, 2 is a rubber sheet made of elastic ethylene propylene (EP) rubber, 3 is a rubber sheet made of natural rubber having a smaller elastic modulus than EP rubber, and 4 is a velcro tape (registered trademark). ) 5 is a connecting lead wire.

As shown in FIG. 1, the copper foil electrode 1 is bonded to the tape-shaped rubber sheet 2 over the entire surface. Further, the rubber sheet 2 is laminated on the rubber sheet 3, and is partially adhered to the rubber sheet 3 at the central adhesion portion 3a. Further, velcro tapes 4 are adhered to both ends of the rubber sheet 3 so as to face each other. The copper foil electrode 1 is separated into a V shape at the center, one of which is used as a calibration electrode and the other of which is used as a measurement electrode. The fact that the copper foil electrode 1 is separated in a V shape at the center is that when it is attached to the connection part of the power cable,
Avoid the convex part of the compound injection port at the connection part and avoid the copper foil electrode 1
This is to prevent the above from floating from the surface of the connecting portion. Further, the attaching portion 1a of the connecting lead wire 5 of the copper foil electrode 1 has no rubber sheet portion and is not adhered to the rubber sheet 2 and has a flexible structure. In this state, the copper foil electrode 1 receives an appropriate tension due to the elasticity of the rubber sheet 2 and uniformly adheres to the rubber sheet 2, and no wrinkles or the like are generated.

FIG. 2 is a side view showing a state in which the electrodes 6 for detecting partial discharge are mounted on both sides of the insulating cylinder portion 13 of the connection box 12 constituting the connection portion of the power cable 11, and FIG. FIG. In FIG. 3, 14 is a conductor,
Reference numeral 15 is an insulator and 16 is an anticorrosion layer. As shown in FIG. 2, the copper foil electrode 1 is connected to the connection box 12 of the partial discharge detection electrode 6.
To avoid the compound inlet 18 on the
It is wound on the anticorrosion layer 16 of the connection box 12 and fixed by the velcro tapes 4 and 4 adhered to both ends of the rubber sheet 3. At this time, the rubber sheet 3 has a smaller elastic modulus and is more likely to be deformed than the rubber sheet 2. Therefore, when tension is applied to the rubber sheet 3, a portion of the rubber sheet 3 which is not adhered to the rubber sheet 2 is easily deformed, The copper foil electrode 1 can be adhered to the anticorrosion layer 16 via the rubber sheet 2 with a uniform surface pressure.
Further, when the electrode 1 is attached to the insulating type junction box 12, if an insulating fluid such as silicone oil, silicone grease, or insulating oil is applied to the surface of the anticorrosion layer 16 at the attachment part of the junction box 12, it will be stable for a long time. A predetermined capacitance can be secured. In the present invention, the metal foil and the elastic body 2
The material and the shape of the kinds of sheet-like materials are not limited to those in the above embodiment. Further, the means for mounting and fixing the partial discharge detection electrode of the present invention is not limited to the magic tape, and a fastener such as a button or a hook may be used.

[0009]

As described above, according to the present invention, there is provided a partial discharge detection electrode used in a partial discharge measuring method for detecting partial discharge of an insulator to determine the insulation state of the insulator. The electrode for detecting partial discharge for electrostatic coupling, which is arranged in the vicinity of the conductive member in which the high frequency pulse is induced by the partial discharge, has a metal foil bonded to one surface of the first sheet-like material made of an elastic body. A second sheet-shaped article made of an elastic body having an elastic modulus smaller than that of the first sheet-shaped article is overlapped and partially fixed on the other surface of the first sheet-shaped article. Therefore, there is an excellent effect that the metal foil can be brought into close contact with the surface of the insulator with a uniform surface pressure without leaving an air layer, and the measurement can be performed accurately.

[Brief description of drawings]

1A and 1B are a plan view and a cross-sectional view, respectively, of an embodiment of a partial discharge detection electrode according to the present invention.

FIG. 2 is a side view showing a state in which the above embodiment is attached to a connection portion of a power cable.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

[Explanation of symbols]

 1 Copper foil electrode 1a Attachment part 2, 3 Rubber sheet 3a Adhesive part 4 Velcro tape 5 Lead wire 6 Partial discharge detection electrode 11 Power cable 12 Junction box 13 Insulation cylinder part 14 Conductor 15 Insulator 16 Anticorrosion layer 18 Compound injection port

Claims (1)

[Claims] 1. An electrode for detecting partial discharge used in a partial discharge measuring method for detecting a partial discharge of an insulator of an electric article to which a high voltage is applied to judge the insulation state of the insulator,
In a partial discharge detection electrode for electrostatic coupling, which is arranged in the vicinity of a conductive member in which a high frequency pulse is induced by partial discharge, a metal foil is bonded to one surface of a first sheet-like material made of an elastic body. A second sheet-shaped article made of an elastic body having an elastic modulus smaller than that of the first sheet-shaped article is overlapped and partially fixed on the other surface of the first sheet-shaped article. Partial discharge detection electrode.