JPS6211177A - Method for measuring partial discharge of cable - Google Patents

Abstract

PURPOSE:To prevent the invasion of external noise and to facilitate measurement, by a method wherein an auxiliary electrode having a movable electrode, which is freely extensible and contractible and contacted with and separated from a high voltage electrode by hydraulic pressure, is provided to a cable terminal box and used at the time of the calibration of sensitivity and at the time of the measurement of an electric constant. CONSTITUTION:A cable terminal box 8 is constituted so that an auxiliary electrode 10 having a movable electrode 12 performing extensible and contractible operation by hydraulic pressure is arranged at the position in the side opposite to a high voltage electrode 8a in opposed relation to said electrode 8a so as to be isolated from a metal case by an insulating plate 11. When discharged charge measuring sensitivity is calibrated and the electric onstant of a line is measured, the movable electrode 12 is extended from the auxiliary electrode 10 by hydraulic pressure to be contacted with the high voltage electrode 8a and the calibration pulse from a standard pulse generator 13 is applied to the auxiliary electrode 10 to allow said electrode 10 to function as a measuring lead. When high voltage is charged, the movable electrode 12 is contracted by hydraulic pressure operation to be housed in the auxiliary electrode 10 and arranged in a shield cover 9 and, therefore, the invasion of external noise is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for measuring partial discharge of a cable, and more particularly, to a method for measuring partial discharge of a cable whose entire length is coated with a metal body. It concerns the measurement method.

[Prior Art] Test equipment for measuring corona discharge of ultra-high voltage Cv cables, etc. is the most extensive testing equipment.

Next, FIG. 4 shows an example of the configuration of an i-testing device for measuring partial discharge of this ultra-high voltage cable. That is, a high-voltage electrode is connected to the input end of the power-supply side cable termination box 3 (in gas) via a lead cable 2 with a metal sheath that also serves as a coupling capacitor to a test transformer 1 whose terminal is submerged in oil. One end of the test cable 7 is connected to the high voltage electrode at the output end of the termination box 3, and the other end of the cable 7 is connected to the high voltage electrode of the cable termination box 8 in the gas. A detection element 4 is connected to the input end and the output end of the power supply side cable termination box 3, respectively, and a partial discharge detector 6 is connected between both ends via a balancer 5. Further, a standard pulse generator 13 for calibration is provided in the power supply side cable termination box 3.

In the test equipment configured in this way, partial discharge measurements and measurements of other electrical constants (conductor resistance, insulation resistance, capacitance, etc.) are performed, but in partial discharge measurements under high voltage application, It is advantageous to eliminate the charging exposed portion as much as possible in terms of preventing the intrusion of external noise and downsizing the device.

On the other hand, in order to calibrate the measurement sensitivity in partial discharge measurement, it is essential to inject a standard pulse for calibration into the high voltage side (when no voltage is applied) due to standards requirements, etc., making it ideal for measurement without any exposed charged parts. In this system, standard sensitivity calibration is impossible.

In addition, when measuring other electrical constants of the cable, it is necessary to take out the high-voltage side electrode, and this has conventionally been done by pulling out the terminal at the terminal end in gas, etc., before or after the partial discharge test. However, this has many inconveniences, as it requires a long work time and preparation time, especially for testing in the presence of the customer.

[Problems to be Solved by the Invention] The present invention aims to eliminate the drawbacks of the conventional measurement methods described above. An object of the present invention is to provide a method for measuring partial discharge in a cable, which can calibrate the sensitivity of partial discharge measurement and measure the electrical constants of a line.

[Means and effects for solving the problem] In the present invention, an auxiliary electrode is provided at the end of the cable, that is, in the cable end box, and has a movable electrode that is expandable and retractable by hydraulic pressure or the like and that moves toward and away from the high-voltage electrode. This is used to measure time and other electrical constants.

[Example] Hereinafter, an example of the measuring method of the present invention will be described with reference to the drawings. Figure 1 shows a cable termination box 8 used in the method of the present invention.
This cable termination box 8 is constructed by adding an auxiliary electrode 10 to be described below to the conventional termination box. That is, at a position opposite to the high-voltage electrode 8a, an auxiliary electrode 10 having a movable electrode 12 that expands and contracts by hydraulic pressure or the like is mounted on the insulating plate 1, facing the high-voltage electrode 8a.
1 and is separated from the metal case.

The auxiliary electrode 1o is used when calibrating the discharge charge measurement sensitivity and measuring the electrical constant of the line. That is, at the time of the above-mentioned calibration and measurement of electrical constants, as shown in FIG.
It is extended from 0 and brought into contact with the high voltage electrode 8a to be electrically connected to the high voltage electrode 8a, and at the same time, a calibration pulse from the standard pulse generator 13 is applied to the auxiliary electrode 10 to function as the n1 regular lead.

As described above, according to the 7111 method of the present invention, calibration and measurement of electrical constants can be performed without disassembling and removing the terminal.

When high voltage is applied, as shown in FIG. 1, the movable electrode 12 is contracted by hydraulic operation and is housed within the auxiliary electrode 10, thereby being disposed within the shield cover 9, thereby preventing intrusion of external noise.

Figure 3 shows the internal structure of the power-supplying side termination box 3, in which only the test cable 7 is connected to 111 when measuring electrical constants.
The structure is such that a part of the electrode can be removed and attached so that it can be separated as a fixed object. That is, an electrode 14 is provided at the tip of an insulating rod 15 that expands and contracts by the action of hydraulic pressure, etc., and which connects and disconnects from the high-voltage side electrode to disconnect and connect the line. An auxiliary electrode 17 having an electrode 16 is provided. The movable electrode 16 is configured to come into contact with and separate from only the electrode connected to the cable under test 7.

In the termination box 3 configured in this way, when the conductor resistance is AN constant, the insulating rod 15 is contracted to separate the electrode 14 from the high voltage electrode, while the movable electrode 16 is extended and the electrode 16 is connected to the test cable 7. contact the electrode that has been
Use this as a measurement lead on the other end.

In addition, when applying high voltage, the insulating rod 15 is extended and the electrode 1
4 is housed in contact with the half-split tulip contact 18 of the high-voltage electrode, while the movable electrode 16 is contracted and placed in a retracted state away from the high-voltage electrode.

[Effects of the Invention] As described above, according to the present invention, ■ A partial discharge measurement system can be configured without dismantling the terminal of a cable whose entire length is covered with a metal body, thereby preventing intrusion of external noise. This can be completely prevented and the device can be downsized.

■ By using a termination box equipped with an auxiliary electrode that has a movable electrode, it is possible to calibrate the amount of discharge charge by injecting a standard pulse into the high voltage side, and the electrical constants of the line can be easily measured without disassembling and removing the terminal. can.

It is possible to provide a cable partial discharge measuring method that achieves the above remarkable effect and achieves the object of the present invention.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams showing the structure and function of the cable termination box used in the measurement method of the present invention, and Figure 3 is a cable feed-through termination box used in the measurement method of the present invention. 4 is a schematic diagram showing an example of the configuration of a partial discharge measurement system for a cable whose entire length is covered with metal. 3.8...Cable termination part (termination box) 8a...
・・・・・・High voltage electrode 10.17・・・・・・Auxiliary electrode 12.16・・・・・・Movable electrode 1 Figure 2 Area % 3 Area 4 Figure

Claims (1)

[Claims] In a partial discharge measurement system for a cable in which the high-voltage charging part is shielded all around by a metal body, hydraulic pressure and gas pressure are applied to the cable end for sensitivity calibration of discharge charge measurement and measurement of electrical constants. A cable is provided with an auxiliary electrode having a movable electrode that is extendable and retractable and can be brought into contact with and separated from the high-voltage electrode, and is brought into conduction with the high-voltage electrode during sensitivity calibration and when measuring other electrical constants. Partial discharge measurement method.