JPH0886830A - Dielectric breakdown testing method - Google Patents

Abstract

PURPOSE: To accurately measure dielectric breakdown voltage value of an insulating material and accurately observe a broken hole thereof by maintaining a test tank filled with a metal heated and melted and a liquid other than water with a specific gravity smaller than that of the metal and a melting point below that of the metal at a specified temperature and immersing the insulating material to be measured in the test tank. CONSTITUTION: A test tank 9 is filled with a metal 11 heated and melted and an antioxidant liquid 12 other than water with a specific gravity smaller than that of the metal and a melting point below that of the metal. The test tank 9 is maintained at a temperature above the melting point of the metal 11 and below the boiling point of the liquid 12. When an insulating material 13 is immersed into the test tank 9, the insulating material 13 is brought into contact with the liquid 12 while the liquid, not being water, adheres to the surface of the insulating material in stead of being infiltrated into the insulating material 13. Thereafter, as the insulating material is immersed into the melted metal 11, the liquid 12 adhering thereto is separated from the insulating material 13 because of difference in specific gravity and the insulating material comes into close contact with the melted metal 11. Thus, even when insulation equipment has a complicated shape, the melted metal comes into close contact with the surface of the equipment and the surface tension is so large that there is no metal adhering to the surface of the insulating material even when the insulating material is taken out of the test tank 9.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dielectric breakdown test method.

[0002]

2. Description of the Related Art Conventionally, a ground layer is provided to measure the dielectric breakdown voltage of an insulating device having a complicated shape. As for the insulation device having a relatively simple shape, as shown in FIG. 3, by winding a conductive tape such as tin foil 1 around the insulation device 2 or by sticking the tin foil 1 through a medium such as petrolatum 3 as shown in FIG. A ground layer is provided and a dielectric breakdown test is conducted.

On the other hand, for insulation devices having complicated shapes,
A dielectric breakdown test is performed by applying the conductive paint 4 as shown in FIG. 5 or immersing the insulating device 2 in the bath 6 filled with tap water 5 as shown in FIG.

[0004]

By the way, Japanese Unexamined Patent Publication No.
When a dielectric breakdown test of an insulating material such as an insulating support member to which mica powder described in 276707 is electrostatically adhered is performed, mica powder has a strong affinity with water, and therefore an insulating device having a normally complicated shape is used. When a dielectric breakdown test in water as shown in FIG. 6 is performed, the mica powder absorbs water and the breakdown voltage value cannot be accurately measured.

Further, when an insulating layer similar to the above insulating support member is provided on a conductor having a complicated shape such as the insulating device 2 of FIG. 6 and, for example, tin foil is wound around to form a ground layer, a gap between the insulating layer and the tin foil is formed. In some cases, a gap may be created, and the breakdown voltage value cannot be measured accurately. To improve adhesion,
Even if the tin foil is pasted with petroleum jelly as a medium, a gap may occur in a complicated shape.

Further, when a conductive paint is applied, the breakdown voltage can be measured, but it is not suitable for observing the broken portion. An object of the present invention is to provide a dielectric breakdown test method capable of accurately measuring a dielectric breakdown voltage value and observing a breakdown hole in any insulator.

[0007]

In order to achieve the above-mentioned object, the present invention fills a metal melted by heating and a liquid other than water having a specific gravity smaller than that of the metal and a boiling point not higher than the melting point of the metal. It is a gist to perform a dielectric breakdown test by maintaining the test tank above the melting point of the metal above the boiling point of the liquid and immersing the measurement object (insulator) in the test tank.

[0008]

In such a structure, since the metal is heated and melted and used, even in the case of an insulating device having a complicated shape, it does not float or break like a tin foil and adheres to the surface of the device and has a large surface tension. Even if the insulator is taken out of the bath, no metal adheres to the surface of the insulator. Also, since no water is used, there is no absorption of water in the insulator. Therefore, it is possible to obtain an effective ground layer and observe the fracture holes.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining a dielectric breakdown test method showing an embodiment of the present invention. In the figure, the insulation breakdown test device is an AC high voltage generator 7 (maximum output voltage 1
00 (kV), capacity 10 (kVA), Tokyo Transformer Co., Ltd.
Manufactured) and test tank section 8 (inner product 100 × 100 × 100 (m
m)), and the test tank 9 is equipped with a mantle heater 10 for melting the metal 11. Metal 11 (melting point 70 ° C, Hirano Seizaemon Shoten, 0.80 liter) and antioxidant liquid 12 (silicone oil Toshiba Silicone TS)
F-433, 0.01 l). Both liquids are maintained at 100 ° C.

Here, the insulator 13 having the shape and structure as shown in FIG. 2 is immersed in the test tank 9. First, the insulator comes into contact with the antioxidant liquid 12, but since it is not water, it does not penetrate into the inside of the insulator 13 and adheres to the surface thereof. afterwards,
When the molten metal 11 is immersed, the adhered liquid is dissociated from the insulator 13 due to the difference in specific gravity, and the insulator 13 adheres to the molten metal 11.

When a dielectric breakdown test was conducted in this state, a breakdown hole was found at the position shown in FIG. 2, and it was found that an effective ground layer was formed on the surface even with an insulator having a complicated shape.

After the test, the insulator 13 was taken out of the test tank 9, and no metal adhered. As described above, according to the present embodiment, even in the case of an insulating device having a complicated shape, it does not float or break like a tin foil and adheres to the device surface, and since the surface tension is large, the insulator is taken out from the bath. However, no metal adheres to the surface of the insulator. Further, since water is not used as a liquid for preventing oxidation, there is no absorption of water in the insulator, so that an effective ground layer can be obtained and the fracture holes can be observed.

Further, since the product is not damaged by moisture absorption, water absorption, etc., it is possible to inspect all the products instead of the sampling inspection, so that the quality of the products can be improved. Next, in the second embodiment of the present invention, an alloy having a melting point of 47 ° C. (Hirano Seizaemon Shoten Co., Ltd.) was used as the molten metal, ethanol was used as the antioxidant liquid, and both were maintained at 60 ° C. Similar results were obtained. Also,
When the sample was observed after 1 hour, it was not necessary to wash it after the test, because the adhesion of ethanol was not observed due to volatilization.

That is, although mercury has been used in the past, it was necessary to wash the insulator after the test because mercury has a safety problem. However, if a safe and volatile liquid, such as ethanol, is used as the antioxidant liquid as in the second embodiment, in addition to the effects of the first embodiment, safety can be ensured and insulation after the test is performed. No need to wash things.

The antioxidant is not limited to ethanol, but acetone, chloroform, hexane, heptane, carbon tetrachloride, propanol, tertiary amyl alcohol, methyl propyl ketone, diethyl ketone,
As long as it is safe and has volatility such as methyl formate and ethyl butyrate, the same effect as in the second embodiment can be obtained.

[0016]

As described above, according to the present invention, a metal melted by heating and a test tank filled with a liquid having a specific gravity smaller than that of the metal and having a boiling point not lower than the melting point of the metal and other than water are used, Since the dielectric breakdown test is performed by maintaining the temperature above the melting point of the metal and below the boiling point of the liquid and immersing the measurement object in this test tank, it is possible to obtain an accurate breakdown voltage for any measurement object. It is possible to measure values and observe fracture holes.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a test apparatus for explaining an example of a dielectric breakdown test method of the present invention.

FIG. 2 is an insulator 1 tested by the test apparatus of FIG.
3 is a schematic diagram of 3. FIG.

FIG. 3 is a diagram for explaining a dielectric breakdown test method by winding a typical tin foil tape.

FIG. 4 is a view for explaining a dielectric breakdown test method using a typical petrolatum.

FIG. 5 is a diagram for explaining a dielectric breakdown test method using a typical conductive paint.

FIG. 6 is a diagram for explaining a dielectric breakdown test method using a typical bath filled with water.

[Explanation of symbols]

7 ... AC high voltage generator, 9 ... Test tank, 10 ... Mantle heater, 13 ... Insulator

Claims (2)

[Claims] 1. A test tank filled with a metal melted by heating and having a specific gravity smaller than that of the metal and having a boiling point not lower than the melting point of the metal and a liquid other than water, and a boiling point of the liquid not lower than the melting point of the metal. A dielectric breakdown test method, which is performed by immersing a measurement object in this test tank while maintaining the temperature below. 2. The liquid is acetone, chloroform,
The dielectric breakdown test according to claim 1, which is at least one of ethanol, hexane, heptane, carbon tetrachloride, propanol, tertiary amyl alcohol, methyl propyl ketone, diethyl ketone, methyl formate and ethyl butyrate. Method.