JP2001305174A - Method for measuring direct-current leak current of high-voltage insulated equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC leak current measuring method for high-voltage insulated equipment which can accurately detect a variation component of a leak current, generated when an insulator of the high-voltage insulated equipment to be measured is electrified with a DC current, accurately with high precision. SOLUTION: A rectifying device 3 is connected to one end of a transformer 2 and a high DC voltage is applied from the rectifying device 3 to the high- voltage insulated equipment 10 through a protection resistor 4. A variation component of the leak current generated by the equipment 10 flows to a loop circuit formed of a measurer 7 and a coupling capacitor 6, so the variation component of the leak current can accurately be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring a DC leakage current of a high-voltage insulation device, and more particularly to a method of measuring a DC leakage current of a high-voltage insulation device capable of accurately measuring the fluctuation of the DC leakage current. About.

[0002]

2. Description of the Related Art Various measuring methods for diagnosing insulation performance and insulation deterioration of high-voltage dielectrics and high-voltage insulation equipment have been proposed.

FIG. 2 shows a measuring circuit used in a conventional method for measuring a DC leakage current of a high-voltage insulating device. The measuring circuit shown in FIG. 2 connects a transformer 2 to an AC power supply 1 having a commercial frequency and applies a rectifier 3 connected to one end of the transformer 2 in order to apply a high DC voltage to the high-voltage insulation device 10 to be measured. Is applied to the high-voltage insulation device 10 to be measured via the DC high-voltage output terminal 8 via the protection resistor 4. The low voltage side return path from the high voltage insulation device 10 to be measured forms a low voltage side return path returning to the other end of the transformer 2 via the leakage current measuring device 7. A smoothing capacitor 5 is connected between the DC high voltage output side from the rectifier 3 and the low voltage side return path. When the high-voltage insulation device 10 to be measured is short-circuited,
The transformer 2, the rectifier 3 and the like are protected from short-circuit current. In this measurement circuit, if the insulator of the high-voltage insulation device under test 10 is deteriorated, a DC leakage current flows. This DC leakage current is measured by the leakage current measuring device 7.

[0004]

However, according to the conventional DC leakage current measuring method for high-voltage insulation equipment, when the leakage current at the time of DC application fluctuates unstably, the protection connected to the DC generator is protected. Since the resistance suppresses the unstable fluctuation of the leakage current, the fluctuation of the leakage current cannot be detected.
There has been a problem that the accuracy of the measurement of the insulation performance of the insulator of the high-voltage insulation device or the accuracy of the insulation diagnosis is reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-voltage insulating device capable of accurately and accurately detecting a variation in leakage current generated when a DC voltage is applied to an insulator of a high-voltage insulating device to be measured. To provide a DC leakage current measuring method.

[0006]

According to the present invention, a DC high voltage is applied from a high voltage terminal of a DC voltage generator to a high voltage terminal of a high voltage insulation device via a protective resistor in order to achieve the above object. Measuring a DC leakage current with a DC leakage current measuring device disposed between a ground terminal of the high voltage insulation device and a low voltage side terminal of the DC voltage generator, and insulating the high voltage insulation device with the DC leakage current. In a DC leakage current measuring method for a high-voltage insulating device for performing body diagnosis, a coupling capacitor is arranged between an output side of the protection resistor and the low-voltage side terminal of the DC voltage generator, and the DC leakage current is supplied to the coupling capacitor. A DC leakage current measuring method for a high-voltage insulating device, wherein the DC leakage current measuring device measures the DC leakage current variation by flowing a current variation.

In order to achieve the above object, the present invention further comprises the step of applying the high DC voltage, wherein the step of applying the high DC voltage comprises the step of applying the high DC voltage between an input side of the protection resistor and a low voltage side terminal of the DC voltage generator. Arranging a smoothing capacitor for smoothing the DC high voltage, wherein the step of applying the DC high voltage includes the step of applying the DC high voltage to the high voltage terminal of a cross-linked polyethylene insulated high voltage cable as the high voltage insulating device. And a method for measuring a DC leakage current of a high-voltage insulation device.

[0008]

FIG. 1 shows a measuring circuit used in a DC leakage current measuring method for a high-voltage insulating device according to an embodiment of the present invention. This measurement circuit diagram includes a transformer 2 connected to an AC power supply 1 having a commercial frequency, and a rectifier 3 connected to one end of the transformer 2. The output side of the rectifier 3 is connected to the high voltage side of the high voltage insulation device 10 to be measured via the protection resistor 4 and the DC high voltage output terminal 8. The low-voltage side of the high-voltage insulation device 10 to be measured is connected to the other end of the transformer 2 via the low-voltage side return terminal 9 and the leakage current measuring device 7. Further, a smoothing capacitor 5 is connected between the output side of the rectifier 3 and the other end of the transformer 2, and a coupling capacitor 6 is connected between the output side of the protection resistor 4 and the other end of the transformer 2. I do. When a DC leakage current is generated in the high-voltage insulation device 10 to be measured with the application of the DC high voltage from the output terminal of the protection resistor 4, the DC leakage current can be detected by the leakage current measuring device 7. It is configured.

In the above configuration, the AC high voltage boosted by the transformer 2 is rectified by the rectifier 3 and smoothed by the smoothing capacitor 5 to be a DC high voltage. This DC high voltage is applied from the protective resistor 4 via the DC high voltage output terminal 8 to the high voltage insulation equipment 10 to be measured. At this time, if the insulator of the high-voltage insulation device 10 is deteriorated, a DC leakage current occurs. This DC leakage current is detected by the leakage current measuring device 7, and diagnosis of insulator deterioration is performed. In this diagnosis, even if a fluctuation is included in the DC leakage current, the DC current is bypassed to the coupling capacitor 6, so that the DC leakage current is not suppressed by the protection resistor 4 and can be accurately measured by the leakage current measuring device 7.

On the other hand, even if a short circuit occurs in the high-voltage insulation device 10, the protection resistor 4 suppresses the short-circuit current, so that the entire circuit is protected from the short-circuit current.

When the insulation of the crosslinked polyethylene high-voltage cable is diagnosed as the high-voltage insulation device 10, the DC high-voltage output terminal 8 is connected to the shield layer of the cable. In this measuring method, the water leak of the crosslinked polyethylene insulator can be diagnosed by measuring the DC leakage current by the measuring device 7.

[0012]

According to the method of measuring DC leakage current of a high-voltage electrical insulation device of the present invention, the variation of the leakage current suppressed by the protection resistor connected to the high voltage side of the DC high voltage generator of the measuring circuit is: Since the coupling capacitor installed between the output side of the protection resistor and the low voltage side of the DC high voltage generator is bypassed, there is an advantage that the fluctuation of the leakage current can be measured with high accuracy by a leakage current measuring device.

As a result, there is obtained an effect that the insulation performance of the insulator of the high-voltage insulation device or the insulation diagnosis can be accurately performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a measuring circuit showing a method of measuring a DC leakage current of a high-voltage insulating device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a measurement circuit showing a conventional method of measuring a DC leakage current of a high-voltage insulating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply (commercial frequency) 2 Transformer 3 Rectifier 4 Protection resistor 5 Smoothing capacitor 6 Coupling capacitor 7 Leakage current measuring device 8 DC high voltage output terminal 9 Low voltage side return terminal 10 High voltage insulation equipment to be measured

Claims (3)

[Claims] 1. A high-voltage terminal of a DC voltage generator is applied with a DC high voltage to a high-voltage terminal of a high-voltage insulation device via a protective resistor, and a ground terminal of the high-voltage insulation device is connected to a ground terminal of the DC voltage generator. In a DC leakage current measuring method for a high-voltage insulating device, a DC leakage current is measured by a DC leakage current measuring device disposed between low-voltage side terminals, and the insulator of the high-voltage insulating device is diagnosed by the DC leakage current. A coupling capacitor is arranged between the output side of the protection resistor and the low-voltage side terminal of the DC voltage generator, and the DC leakage current measurement device is configured to supply a variation of the DC leakage current to the coupling capacitor. A DC leakage current measuring method for high-voltage insulation equipment, characterized by measuring a variation of the DC leakage current. 2. The step of applying the high DC voltage includes the step of arranging a smoothing capacitor for smoothing the high DC voltage between an input side of the protection resistor and a low voltage side terminal of the DC voltage generator. The method for measuring a DC leakage current of a high-voltage insulating device according to claim 1, wherein: 3. The method of claim 2, wherein the step of applying a DC high voltage includes the step of applying the DC high voltage to the high voltage terminal of a cross-linked polyethylene insulated high voltage cable as the high voltage insulation device. Item 6. The method for measuring a DC leakage current of a high-voltage insulating device according to Item 1.