JPH1138077A - Electric tree test method - Google Patents

Abstract

(57) [Summary] An electric tree test method capable of comparing and evaluating different types of insulating materials after simulating the influence of foreign matter in the insulating material is provided. In a test for evaluating the insulating property of an insulating material of a CV cable, a method is used in which an ultrafine metal wire is used as an electrode inside the insulating material. 20-200 in diameter as extra fine metal wire
It is desirable to use a μm metal wire. It is preferable to use a sheet-shaped conductive material so as to be in contact with the ultrafine metal wire, and to ensure conduction between the sheet-shaped conductive material and the voltage application side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical tree test method for optimally evaluating the insulation performance of an insulating material of a CV cable used as a power cable.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed for an electrical tree test method for evaluating the insulation performance of an insulating material. A method using a sheet-shaped conductive material having a tip angle of 30 ° as an electrode;
There is a method using a metal needle of 000 μm as an electrode.

[0003]

Among the above-mentioned prior arts, the first method, in which a sheet-like conductive material is used as an electrode, causes the insulating material and the sheet-like conductive electrode to be integrated at the time of pressing, resulting in a CV. There is a problem in that the influence of a foreign substance, which is a main cause of insulation breakdown in a cable, cannot be evaluated.

On the other hand, in the second method, in which a metal needle is used as an electrode, the electrode is made of a metal needle having a diameter of 1000 μm, which makes it difficult to integrate the tip of the metal needle with an insulating material, but the metal needle is too large. Therefore, there is a problem in that a foreign substance which is a main cause of dielectric breakdown in the CV cable cannot be simulated, and various insulating materials to be evaluated cannot be compared and evaluated.

Therefore, the problems to be solved by the present invention (objects)
An object of the present invention is to provide an electrical tree test method capable of comparing and evaluating different types of insulating materials after simulating the influence of a foreign substance in the insulating material.

[0006]

The electrical tree test method provided by the present invention comprises a method of using an ultrafine metal wire as an electrode inside an insulating material in a test for evaluating the insulating property of an insulating material of a CV cable.

[0007] The ultrafine metal wire has a diameter of 20 to 2 mm.
It is desirable to use a metal wire of 00 μm.

It is preferable to use a sheet-shaped conductive material so as to be in contact with the ultrafine metal wire, and to ensure conduction between the sheet-shaped conductive material and the voltage application side.

[0009]

FIG. 1 shows an embodiment of the present invention.
Specimens used in the electrical tree test method are abbreviated.
In FIG. 1, reference numeral 1 denotes an insulating material to be evaluated, 2 denotes a voltage-applying electrode provided in the insulating material 2, and 3 denotes a sheet-shaped conductive material provided in the insulating material 1 in contact with the electrode. .

Thus, an ultrafine metal wire having a diameter of 20 to 200 μm is used as the voltage application side electrode 2 provided in the insulating material 1, and the sheet-shaped conductive material 3 is formed in the insulating material 1 so as to be in contact with the ultrafine metal wire. The conductive material 3 is electrically connected to the voltage application side to apply a voltage to the ultrafine metal wire 2 in a state where there is no contact failure.

As shown in FIG. 1, two insulating materials to be evaluated are made to be the same type and the same shape, and one of them; an extra fine metal wire 2 as an electrode and a sheet-like material are placed on the lower insulating material. A test in which the ultrafine metal wire 2 was provided as a hollow inside the insulating material by placing the conductive material 3 on top of each other and placing the other; the upper insulating material on the sandwich and pressing the whole. What is necessary is just to produce a piece.

Conducting an electrical tree test;
FIG. 2 shows the results of the electrical tree test according to the above-described example for three types of crosslinked polyethylene, and FIG. 3 shows the results of the conventional electrical tree test. FIG. 4 shows the results of a destruction test of CV cables manufactured using the above three types of crosslinked polyethylene materials.

In this electrical tree test, the method of this embodiment was performed using ultrafine metal wires having diameters of 20 μm, 50 μm, and 100 μm as electrodes.

As a conventional example, two methods were used: a method using a sheet-like conductive material processed to a tip angle of 30 ° as an electrode and a method using a metal needle having a tip curvature radius of 10 μm and a diameter of 1000 μm as an electrode.

In the conventional method in which the sheet-shaped conductive material is used as the electrode, the voltage application condition is 50 Hz AC, 200 V / sec. Continuous step-up, and the conventional method in which the metal needle is used as the electrode and the method of the present embodiment are used. , The voltage application condition is 50Hz AC, 5kV / se
c. Step boosting. Other test conditions are the same,
The test temperature is room temperature, and the distance between the electrodes is 4 mm.

In the cable destruction test shown in FIG. 4, a CV cable having a conductor size of 100 mm ² and an insulation thickness of 6 mm is applied at an AC voltage of 20 kV / 10 min. Step-up and the test temperature is room temperature.

As shown in FIG. 3, in the conventional method using a sheet-shaped conductive material, the AC tree starting voltage of the material 3 is the highest, then the material 2 is high, and the AC tree starting voltage of the material 1 is the lowest. Was.

In the conventional method using a metal needle, almost no difference was found in the AC tree starting voltage among the three types of insulating materials.

On the other hand, as shown in FIG. 2, in the method of the present embodiment, in the case of a fine metal wire electrode having a diameter of 20 μm, there is a slight difference between the three kinds of insulating materials, and the fine metal wire electrode has a diameter of 50 μm.
In the case of μm, there was a difference in the AC tree starting voltage between the three types of insulating materials, and the material 1 had the highest AC tree starting voltage, the material 2 had the highest voltage, and the material 3 had the lowest AC tree starting voltage. . A similar tendency was observed when the metal wire electrode had a diameter of 100 μm. As shown in FIG. 4, the insulation performance of the CV cable manufactured using each of the three types of insulating materials showed the highest insulation performance using the material 1, and then showed the highest performance using the material 2. Material 3 had the lowest insulation performance.

The material evaluation method which has the same tendency as the result of the CV cable destruction test shown in FIG. 4 is shown in FIG.
And the method of the present invention using an ultrafine metal wire electrode of 100 μm. Therefore, in the electrical tree test method for evaluating the insulation performance of the insulating material used for the CV cable, the method according to the present invention using an electrode provided in the insulating material using an ultrafine metal wire having a diameter in the range of 20 to 200 μm. If this is the case, it is possible to evaluate the insulation performance of the insulation material used for the CV cable.

[0021]

According to the present invention as described above, there is provided an electrical tree test method capable of comparing and evaluating different types of insulating materials after simulating the influence of foreign matter in the insulating material. The task (purpose) of the period can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a test piece used in an electric tree test method according to an example of the electric tree test method of the present invention.

FIG. 2 is a graph showing the results of an AC electrical tree test by the electrical tree test method of the present invention.

FIG. 3 is a graph showing the results of an AC electrical tree test by a conventional electrical tree test method.

FIG. 4 is a graph showing the results of an AC breakdown test of CV cables using different types of insulating materials.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating material 2 Voltage application side electrode; Extra fine metal wire 3 Sheet conductive material

[Procedure amendment]

[Submission date] December 10, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

FIG. 1 shows an embodiment of the present invention.
Specimens used in the electrical tree test method are abbreviated.
In FIG. 1, reference numeral 1 denotes an insulating material to be evaluated, 2 denotes a voltage-applying electrode provided in the insulating material 1 , and 3 denotes a sheet-shaped conductive material provided in the insulating material 1 in contact with the electrode. .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

As shown in FIG. 1, two insulating materials to be evaluated are made to be the same type and the same shape, and one of them; an extra fine metal wire 2 as an electrode and a sheet-like material are placed on the lower insulating material. The conductive material 3 is placed on top of the other, on which the other; the upper insulating material is placed on a sandwich, and the whole is pressed, whereby the fine metal wire 2 is provided as an electrode in the insulating material. What is necessary is just to produce a test piece.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

In the conventional method in which the sheet-shaped conductive material is used as the electrode, the voltage application condition is 50 Hz AC, 200 V / sec. Continuous step-up, and the conventional method in which the metal needle is used as the electrode and the method of the present embodiment are used. The voltage application condition is AC 50Hz, 5kV / 5
The min step pressure was set. Other test conditions are the same,
The test temperature is room temperature, and the distance between the electrodes is 4 mm.

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

[Procedure amendment 5]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

Claims (3)

[Claims] 1. An electrical tree test method in which an ultrafine metal wire is used as an electrode inside an insulating material in a test for evaluating the insulating property of the insulating material of a CV cable. 2. A fine metal wire having a diameter of 20 to 200 μm.
The electrical tree test method according to claim 1, wherein a metal wire is used. 3. The electrical tree test method according to claim 1, wherein a sheet-shaped conductive material is used so as to be in contact with the ultrafine metal wire, and electrical continuity is ensured with the sheet-shaped conductive material on a voltage application side. .