JPH02251775A - Forced discharge method for direct-current withstand voltage test - Google Patents

Abstract

PURPOSE:To enable quick and safe forced discharge of a residual charge in a cable by detecting an electric field strength around a high-tension open charging element by an electric field detector and by moving a discharging element to approach the high-tension open charging element on the basis of said strength. CONSTITUTION:A mechanism with a discharging element 12, an electric field detector 13 and a motor 14 making these elements move to approach a high- tension open charging element 10, is provided. After completion of a direct- current voltage resistance test, the strength of an electric field around the charging element 10 due to a residual charge in a cable 1 is detected by the detector 13, and based on the detected strength, the motor 14 is controlled to move the discharging element 12 to approach the charging element 10. By controlling the rotation of the motor 14 so that the electric field strength be fixed, on the occasion, a fixed voltage can always be generated between the discharging element 12 and the charging element 10. Thereby a safe and quick discharging operation can be conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forcibly discharging residual charges in a cable after the cable has been subjected to a DC withstand voltage test.

[Conventional technology]

Generally, a DC withstanding voltage test device has a cable 1, a lead wire 2, a resistor 3, and a lead!, as shown in FIG. ! A DC high voltage generator 5 is connected via 4. In this device, in order to improve measurement accuracy and increase effective charging current, shield rings 6.7 and 8.9 are attached to the ends, and a pipe-shaped lead wire 2.4 is used. .

For this reason, shield ring 6.7.8.9 and lead wire 2
．． The air discharge from the high-voltage exposed charging portion 1o of 4 is extremely small. In the figure, 11 is an insulating lobe from which the resistor 3 is suspended from the ceiling.

On the other hand, after the DC withstanding voltage test of the cable is completed, it is necessary to quickly discharge the residual charge in the cable in order to move on to the next test operation. This discharge generates a high discharge voltage in long cables, so great care must be taken. Conventionally, humans used a discharge rod after the residual voltage in the cable had dropped to 200 kV or less due to natural discharge. A forced discharge was being performed. As shown in FIG. 3, the discharge rod 12 has an insulating part 12a and a discharge resistor part 12b, and the discharge resistor part 12b is grounded. The portion 12b is brought into contact with the cable 1 to forcefully discharge the residual charge within the cable 1.

[Problem to be solved by the invention]

However, as mentioned above, since the DC withstanding voltage test device is designed to significantly reduce air discharge from the high-voltage exposed charging section 10, it takes time for natural discharge after the DC withstanding voltage test is completed. There was a problem of extremely low efficiency. Also, when a person holds a discharge rod and exposes a high-voltage charging part to
Getting close to it was a very dangerous and unsafe task.

SUMMARY OF THE INVENTION An object of the present invention is to provide a forced discharge method capable of quickly and safely discharging residual charges in a cable after a DC withstanding voltage test of the cable is completed.

[Means to solve the problem]

The present invention has been made to achieve the above objects,
This is a method of forcibly discharging the residual charge in the cable after the completion of a DC withstanding voltage test in which a DC high voltage generator applies a DC high voltage to the conductor of the cable, and the electric field strength around the exposed high voltage live part is reduced. The electric field is detected by an electric field detector, and the discharge part is moved closer to the high-voltage exposed charging part based on the electric field strength.

The present invention will be explained below based on FIG. FIG. 1 is a schematic diagram of a DC withstanding voltage test device according to the present invention, where 1 is a cable, 2.4 is a lead wire, 3 is a resistor, 5 is a DC high voltage generator, 9 is a shield ring, and 10 is a high voltage Exposed live parts, 1
2 is a discharge section, 13 is an electric field detector, and 14 is a motor for moving the discharge section 12 close to the high-voltage exposed charging section 10. Cable with this test equipment! After the DC withstanding voltage test is completed, there is a residual charge in the cable 1. An electric field is generated around the high voltage exposed charging section 10 due to this residual charge. This electric field intensity is detected by an electric field detector 13 on the discharge section 12, and the motor 14 is controlled based on the electric field intensity to move the discharge section 12 close to the high-voltage exposed charging section 10. By controlling the rotation speed of the motor 14 so that the intensity is constant, a constant discharge voltage can always be generated between the discharge section 12 and the high-voltage exposed charging section 10, so that the discharge operation can be carried out safely and quickly. can be done.

〔Effect of the invention〕

As explained above, the discharging method of the present invention is a method in which the electric field strength around the high-voltage exposed charging part 10 is detected by an electric field detector, and the discharging part is moved closer to the high-voltage exposed charging part based on the electric field strength. Therefore, a safe and quick discharge operation can be performed without generating a high discharge voltage.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a DC withstanding voltage testing device according to the present invention, FIG. 2 is a schematic diagram of a conventional DC withstanding voltage testing device, and FIG. 3 is a schematic diagram of a discharge rod. 1 - cable, 2, 4 - lead wire, 3 - resistor,
5 ~ DC high voltage generator, 10 ~ High voltage exposed charging part,
12 - discharge section, 13 - electric field detector, 14 - motor. Figure 1

Claims (1)

[Claims] This is a method of forcibly discharging the residual charge in the cable after the completion of a DC withstanding voltage test in which a DC high voltage generator applies a DC high voltage to the conductor of the cable, and the electric field strength around the exposed high voltage live part is reduced. A forced discharge method for a DC withstand voltage test, characterized in that the electric field is detected by an electric field detector, and a discharge part is moved closer to the high-voltage exposed charging part based on the electric field strength.