JPS60238770A - Operating duty testing method of lightning arrester - Google Patents

Abstract

PURPOSE:To continuously measure immediately before and immediately after applying an impulse current, by connecting a series body of measuring and protecting resistors, and connecting said series body with a zinc oxide element in parallel, and connecting said circuit with a lighting arrester in series, applying a test voltage, and measuring a leakage current from the output voltage of the measuring resistor. CONSTITUTION:A volt-ampere characteristic of a series body of a leakage current measuring resistor 4 and a protecting resistor 9 is shown by a curve A, and that of a zinc oxide element 11 is shown by a curve B, therefore, a large current in case an impulse current from an impulse generator 3 is applied flows to the element 11, and only scores mA flow to the resistors 4, 9. Also, immediately after the impulse is applied, the element 11 shows high resistance, therefore, a leakage current passing through a lightning arrester 2 from an AC power source passes through the resistors 4, 9. Also, the breakdown of the resistor 4 is prevented by connecting a protecting diode 10 in parallel to the resistor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an operational duty testing method for applying a lightning impulse to a gapless type lightning arrester to test its operational duty.

[Conventional technology]

Conventionally, in the operational duty test method for determining whether the follow-on and breaking performance of a surge arrester is appropriate, an impulse is generated while a predetermined AC voltage is applied to the surge arrester 2 via the transformer 1, as shown in Fig. 3. By applying lightning impulses from the device 3, the adequacy of follow-on current and interrupting performance is determined. In this case, if a zinc oxide element is used as the surge arrester 2, no follow-on current will flow into the gapped surge arrester, but monitoring the leakage current flowing from the AC power supply immediately after the impulse is applied can be used to detect the current increase immediately after the impulse is applied. Electromagnetic images are useful for evaluating thermal stability characteristics.

Therefore, in the operational duty test method for lightning arresters using zinc oxide elements, a resistor 4 for measuring leakage current is connected between the transformer 1 and the lightning arrester 2 to measure the leakage current, as shown in Fig. 3. At the same time, a resistor 5 for impulse current measurement is connected between the lightning arrester 2 and the impulse generator 3 to measure the impulse current. The resistor 4 is set to several ohms because the leakage current is less than several lo〆mA, and the resistor 5 is set to several 1 milliohms.

However, in this method of measuring leakage current, a capacitive current flows through the resistor 4 in the direction shown by arrow A due to the capacitance 6 existing between the transformer 1 and the ground, and is combined with the leakage current component. Ru. Therefore, there was a problem in that only the leakage current component could not be accurately measured.

Therefore, a resistor 4 for leakage current measurement is connected in series to the lightning arrester 2 as shown in FIG. 4, and a switch 8'fc is connected in parallel to this resistor 4, and when an impulse is applied, a switch 8t? Attempts have also been made to close the resistor 4 to prevent it from burning out and measure the leakage current after applying the impulse. However, with this method, the measurement becomes discontinuous as the switch 8 is switched, and the leakage current is measured after applying the impulse. The drawback is that the leakage current immediately before and after cannot be measured continuously.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lightning arrester operational duty testing method that can continuously measure leakage current immediately before and after applying an impulse.

[Means and effects for solving the problem] The present invention connects a zinc oxide element in parallel to a series body of a resistor for leakage current measurement and a resistor for protecting the leakage current, and further connects this parallel body Connect the lightning arrester to be tested in series and apply the test voltage.
The alternating current leakage current is measured by the output voltage of a resistor for leakage current measurement.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

FIG. 1 is a test circuit diagram showing one embodiment of the present invention;
Lightning arrester to be tested, 3-wire impulse generator, 4
5 is a resistor for measuring impulse current, 9 is a protection resistor, 10 is a protection diode, 11 is a zinc oxide element, and 12 is a switch for applying AC voltage. .

In such a configuration, since the resistors 4 and rkg are linear resistors, their voltage/current ηC% characteristics are as shown by curve A in FIG. 2, and the voltage/current characteristics of the zinc oxide element 11 are as shown in the curve. The percentage is shown as B.

Therefore, a low current of @mA to several tens of mA flows through the resistors 4 and 9, a large current when an impulse is applied flows through the zinc oxide element 11, and the resistors 4 and 9 are connected to the curves A and B shown in FIG. No current higher than the intersection point C will flow. At this time, the terminal voltage of the zinc oxide element 11 reaches several KV, but the resistor 4
Since the terminal voltage is divided by the resistor 9, it becomes small, which often destroys the leakage current measuring device. Furthermore, since the zinc oxide element 11 exhibits a high resistance immediately after the impulse is applied, leakage from the AC power supply through the evacuator 2 [11] flows through the resistors 4 and 9. This makes it possible to continuously measure alternating current leakage current immediately before impulse application and immediately after turning on.

Further, at this time, the zinc oxide element has an extremely high resistance, and the leakage current measurement error is extremely small, about 1%.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a zinc oxide element is connected in parallel to a resistor for leakage current measurement, and a lightning arrester to be tested is connected in series to these parallel bodies to apply an impulse. Therefore, it is possible to continuously and accurately measure the alternating current leakage flow immediately before and after the impulse is applied. In addition, since a protective resistor is connected in series with the resistor for leakage current measurement, the leakage pressure between its terminals does not increase even when the impulse stiffness is 0, making it possible to safely measure leakage current. There is an effect.

[Brief explanation of drawings]

FIG. 1 is a test circuit diagram showing an embodiment of the present invention, FIG. 2 is a companion characteristic diagram illustrating the operation of the embodiment, and FIGS. 3 and 4 are conventional test circuit diagrams. 2... Lightning arrester, 3... Impulse generator, 4...
Resistor for measuring leakage current, 5... Resistor for measuring impulse current, 9... Resistor for protection, 10... Diode for protection, 11... Zinc oxide element, 12...・
switch. Figure 1, 7- Figure 2 (xi-Dou Figure 3)

Claims (1)

[Claims] In the operation duty test method for gapless lightning arresters using zinc oxide elements, a zinc oxide element is connected in parallel to a series body of a resistor for leakage current measurement and a resistor for its protection, and The operating responsibility of the lightning arrester is characterized in that the lightning arrester to be tested is connected in series to the body, a test voltage of 1-6 is applied, and the alternating current leakage current is measured by the output voltage of the resistor for measuring the leakage current. Test method.