JPS60192303A - Lightning device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a lightning arrester used in a power system, such as an AC/DC converter station, to which a DC voltage including ripple is applied.

[Prior art]

Since the sintered body of metal oxide whose main component is zinc oxide has excellent non-linear resistance characteristics, it has conventionally been possible to create a lightning arrester without a series gap using a non-linear resistor element as a characteristic element, as shown in Figure 1. It was configured as shown.

FIG. 1 is a side sectional view showing a conventional lightning arrester.

In FIG. 1, the nonlinear resistor element n(1) is constructed by connecting in series a plurality of sintered elements of a metal oxide whose main component is zinc oxide. The metal hermetic container (2) houses the nonlinear resistor confectionery group (1) and encloses an insulating medium such as SF6 gas. The high voltage conductor (3) is connected to the non-linear resistor element group (1) and is insulated and supported in the metal hermetic container (2) by an insulating spacer (4).

FIG. 2 is a voltage-current characteristic diagram of the nonlinear resistor element shown in FIG. 1, in which the horizontal axis represents the current ■ and the vertical axis represents the voltage V. Second
As is clear from the figure, the lightning arrester shown in Figure 1 has excellent non-linear resistance characteristics of voltage-current characteristics, and the leakage current 11 at the normal ground voltage 1 is on the order of several μA to several mA, although it varies depending on the conditions. , -73, 10 KA, the limiting voltage when the lightning impulse current is energized is about 1.6 to 8 times the normal voltage. Therefore, by connecting the lightning arrester shown in FIG. 1 to a power system, it can be used as an abnormal voltage protection device for electrical equipment. In addition, since the non-linear resistor element group (υ) has no series gap, there is no discharge time delay unlike lightning arresters with gaps, making it an ideal protection device.

However, since there is no series gap, a group of nonlinear resistor elements whose characteristic element is the voltage stress of the normal ground voltage (
In addition to 1), this voltage stress may cause characteristics to change.

The deterioration characteristics of the zinc oxide element due to the application of AC voltage and DC voltage differ greatly, and the selection of the non-linear resistor element to be used is made depending on the application waveform.

Figure 8 is an accelerated charging life characteristic diagram of an AC non-linear element, with time T on the horizontal axis and current ■ on the vertical axis.The change in leakage current with respect to the initial value of the AC non-linear element is , DC charging is larger than AC charging.

Figure 4 is a diagram of the accelerated charging life characteristics of a DC nonlinear element, where the horizontal axis represents time T and the vertical axis represents current ■, where the characteristic line (c) is the DC charging characteristic line, and the characteristic line ( D) The change is larger for AC charging than for DC charging.

An AC/DC converter station that connects an AC power transmission system and a DC power transmission system basically uses a rectifier to convert AC voltage into DC voltage, so the voltage waveform inside the converter station has ripples as shown in Figure 6. This results in a very complex voltage waveform.

FIG. 6 shows a DC voltage waveform including ripples, with time T on the horizontal axis and voltage V on the vertical axis, showing a state in which the AC voltage Easlnwt is superimposed on the DC voltage Ed. The non-linear resistor elements of lightning arresters installed in areas where such voltage waveforms are applied are for alternating current.

Although it is desirable to have good life characteristics for both AC and DC applications, in reality, nonlinear resistance elements are used that are not suitable for either AC or DC applications.

For this reason, lightning arresters for DC voltages containing such ripples may be used at a relatively lower normal working voltage, or
It was necessary to add a series gap.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and is a non-linear resistor element # (1).
The purpose of this invention is to provide a lightning arrester that can be used in AC/DC converter stations where voltages including ripples are applied.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 is a side sectional view showing one embodiment of the lightning arrester according to the present invention. In the figure, the same parts as in FIG. 1 are given the same reference numerals. In FIG. 6, the first nonlinear resistor element group (
IA) is constructed by connecting a plurality of nonlinear resistor elements in series, each of which has zinc oxide as its main component and has excellent DC charging life characteristics. The second non-linear resistor element group (IB) is constructed by connecting in series a plurality of non-linear resistor elements that are mainly composed of zinc oxide and have excellent AC charging life characteristics.
The non-linear resistor elements (IA) are connected in series.

The voltage dividing capacitor (C) is connected to the first non-linear resistor element group (I
A) is connected in parallel. The voltage dividing resistor (R) is connected in parallel to the second non-linear resistor element 'm(1B).

Next, the operation will be explained. Since the lightning arrester of the present invention has voltage-current characteristics equivalent to those shown in FIG. 2, the effect of suppressing abnormal voltage is to support the entire voltage as shown in FIG. The applied voltage V is the DC voltage Ed and the AC voltage EaSlnw.
It is assumed that the sum of t is expressed by the following formula.

V = Ed 1 EaS! n wt・・・・・・・・・・
・(1)) 1st. Second non-linear resistor element # (IA)
, (IB) has a resistance r and a capacitance tc, but for the sake of simplicity, the resistance R of the voltage dividing resistor (R) is sufficiently smaller than the resistance r, and the capacitance C of the voltage dividing capacitor (C) is sufficiently larger than the capacitance C, then the first. The following voltages are applied to the second nonlinear resistor element group (IA) and (IB).

The first non-linear resistor element group (IA
) is applied to the second non-linear resistor element group (IB
), where α and β give a phase shift with respect to the AC applied voltage EaSinwt. The values of resistance R and capacitance C can be selected within a wide range, but for example, if the impedance ratio is selected to be 10 times, that is, R = 10 -, then equations (2 and L (8) will become It becomes as follows.

vA≠Ed1E 5in (wt1α) ・・・・・・・・・
・・・・・・ [4] 0 VB≠Easin (wt 1β) ・・・・・・・・・・・・
・・・・・・・・・・・・[5] That is, from the above formula, R=10
If X(-) is selected, the first nonlinear resistor element group (IA) with excellent DC current charging life
The alternating current voltage component applied to the seven voltages becomes extremely small, and the excellent direct current charging life of the first nonlinear resistor element group (IA) can be expected.

On the other hand, since most of the voltage VB applied to the second non-linear resistor element group (IB), which has an excellent AC charging life, is an AC component, the voltage VB applied to the second non-linear resistor element group (IB) has an excellent AC charging life. You can now expect an excellent AC charging life.

〔Effect of the invention〕

As described above, according to the present invention, in a lightning arrester for an AC/DC conversion station to which a DC voltage including ripples is applied, the first non-linear resistor element group which has an excellent DC section 11E life by using a voltage dividing resistor and a voltage dividing capacitor is provided. Almost only DC voltage is applied to
Since the voltage is divided so that only the AC voltage, which is a ripple component, is applied to the second non-linear resistor element group, which has an excellent AC charging life, it has the effect of greatly improving the charging life of the entire lightning arrester.

[Brief explanation of the drawing]

FIG. 8 is a side sectional view showing an embodiment of the lightning arrester according to the invention of the accelerated energization life characteristic diagram of an AC non-linear resistor. In the figure, (1) is a non-linear resistor element group, (IA) is a first non-linear resistor element group, (IB) is a second non-linear resistor element group, (2) is a metal sealed container, (3) is a high voltage conductor, and (4) is an insulating spacer. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa Figure 1 Figure 3 Figure 4 1 hour T- 1 hour T- Figure 5 1 hour T- Figure 6

Claims (1)

[Claims] (1) A first non-linear resistor element group consisting of a plurality of non-linear resistor elements which are mainly composed of zinc oxide and have excellent DC charging life and are connected in series; a second non-linear resistor element group configured by serially connecting a plurality of non-linear resistor elements with excellent longevity and connected in series to the first non-linear resistor element group; and the first non-linear resistor element group. A lightning arrester comprising: a voltage dividing capacitor connected in parallel to the body element group; and a voltage dividing resistor connected in parallel to the second nonlinear resistor element group.