JPS5833682B2 - Lightning arrester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lightning arrester constructed by connecting a large number of metal oxide sintered bodies in series and parallel as non-linear resistance elements.

As is well known, if a sintered body mainly composed of zinc oxide, which has excellent non-linear resistance characteristics, is used as an element of a lightning arrester, it will be possible to use it in a leakage current range of approximately uA at a normal ground voltage, and the gap will be reduced. An unnecessary lightning arrester can be realized.

A conventional device of this type is shown in FIG.

In the figure, 1A to 1D and 2A to 2D are series connection columns 1
, 2 is a sintered element mainly composed of zinc oxide (resistance element having non-linear resistance characteristics, hereinafter referred to as zinc oxide element), 3A to 3D are forced voltage dividing elements, and 4 is an insulating spacer. , 5 is a conductor; 6 is a container; 7 is an intermediate conductive structure (hereinafter referred to as 8 is an insulating gas or liquid.

The zinc oxide elements 1A to ID, 2A to 2D are connected in series, held by a common intermediate fitting 7 on each series connection column 1, 2 arranged at the series connection point of each element, and forcedly separated. A predetermined potential is applied by the pressure elements 3A to 3D to the corresponding element connection point (division point) of each series connection column 1°2.
are at the same potential.

The lightning arrester having the above structure is connected to the equipment to be protected by the conductor 5, and its circuit is as shown in FIG.

In the figure, R1-a = R1-d is the resistance value of the zinc oxide elements 1A to 1D in the series connection column 1, and R2-a-R
2-d are zinc oxide elements 2A to 2D in series connection column 2
resistance values, C1-a-C1d and C2-a-C2-ct
is the capacitance of zinc oxide elements 1A to 1D and 2A to 2D,
Z1 to Z4 are the impedances of the forced voltage dividing elements 3A to 3D, and C4a to C4-d are the stray capacitances existing between the intermediate fitting 7 and the container 6.

FIG. 3 shows the current-voltage characteristics of the zinc oxide element when direct current or impulse voltage is applied.

In this type of element, it is extremely difficult to completely match the characteristics of each stage of a large number of combinations, and normally the characteristics of two series-connected columns 1 and 2 as shown in the figure are, for example, The resistance value R1 of the curve 11 is the resistance value R2 of the series connected column 2.
curve 12.

The voltage that is normally applied due to this difference in characteristics■.

The leakage current flowing through each of these is 11 + 12.

By the way, when zinc oxide elements 1A to ID and 2A to 2D are connected in series and parallel, since R1>R2, current i flows through one zinc oxide element -1D.

A part of is diverted to zinc oxide elements 2A to 2D, and 11 and i2
The difference is larger than when the zinc oxide elements 1A to ID and 2A to 2D are electrically independent.

This leakage current increases the temperature of the zinc oxide element, but
Zinc oxide elements 2A to 2D are better than zinc oxide elements 1A to 1D.
The temperature becomes higher.

Since the resistance value of the zinc oxide element decreases as the temperature increases, the limiting voltage characteristics are shown by the dotted lines in Figure 3, curves 111 and 1.
2/, and the leakage currents 11+12 increase to t/ and 12/, respectively.

At this time, since the temperature on the side of the zinc oxide elements 2A to 2D is high, i2'~+2>11'~11, and the leakage current is increasingly concentrated on the zinc oxide elements 2A to 2D.
2D deterioration accelerates.

That is, the deterioration of the zinc oxide element in a specific one of the plurality of series-connected columns progresses, and the life span becomes shorter than when each series-connected column is electrically independent.

This invention was made in order to eliminate the above-mentioned drawbacks, and the impedance of a capacitor, resistor, etc. The present invention aims to provide a lightning arrester that can apply an appropriate potential to the intermediate metal fittings by connecting the elements, and can also prevent deterioration of the non-linear resistance elements in a specific series-connected column.

The present invention will be explained below based on the illustrated embodiments.

FIG. 4 shows an embodiment of the present invention, including the configuration of series connection columns 1 and 2 formed by series connection of zinc oxide elements 1A to ID and 2A to 2D, forced voltage dividing elements 3A to 3D, intermediate fitting 7, etc. The arrangement is the same as that of the conventional one, but in this embodiment, the connection conductor 9 is arranged at the element support point of the intermediate metal fitting 7 so as to be insulated from the intermediate metal fitting 7 by an insulating ring 10, and the connection conductor of the series connection column 1 is 9 is connected to the corresponding intermediate fitting 7 by an impedance element 11 such as a capacitor, and the connecting conductor of the series connection column 2 is directly connected to the intermediate fitting 7.

Note that forced voltage dividing elements 3A to 3D are connected between each intermediate fitting 7, and a certain potential is applied as in the conventional case.The equivalent circuit of the lightning arrester with the above configuration is shown in FIG. Applied voltage V.

Even if there is some difference in limiting voltage characteristics between the series-connected pillars 1 and 2, the leakage current shunted from the other series-connected pillars becomes negligibly small.

Therefore, since there is no current increase due to shunting from other series-connected columns, the temperature rise of the zinc oxide element is suppressed and the degree of deterioration is weakened, and when the series-connected columns of zinc oxide elements are electrically independent of each other. The lifespan is approximately the same.

Note that the connection between the intermediate metal fitting 7 and the connection conductor 9 using the impedance element 11 may be performed on all the series connection columns.

As described above, according to the present invention, the connecting conductor is arranged at the dividing point of the non-linear resistance element insulated from the intermediate fitting to which a potential is applied by the forced voltage dividing element, and the connecting conductor is disposed between the intermediate fitting and the connecting conductor. Since the impedance element is connected to the non-linear resistance element, even if there is a slight difference in the limiting voltage characteristics of each series-connected column, current concentration on a specific series-connected column is prevented, and environmental deterioration of the non-linear resistance element is suppressed.

Furthermore, since the structure is such that the connecting conductor is disposed on the intermediate metal fitting via an insulating material, the external shape is not much different from the conventional one, and manufacturing is simple.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional lightning arrester using zinc oxide elements, Fig. 2 is an equivalent circuit diagram of the same device, Fig. 3 is a limiting voltage characteristic diagram of the zinc oxide element, and Fig. 4 is a diagram showing the current lightning arrester according to the present invention. A sectional view showing one embodiment of such a lightning arrester, and FIG. 5 is an equivalent circuit diagram of the same. 1.2...Series connection pillar, 1A~ID, 2A~2
D...Zinc oxide element, 3A to 3D...
Forced voltage dividing element, 7... Intermediate metal fitting, 9...
・Connection conductor, 10...Insulation non-stick, 11...
. . . Impedance element. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a lightning protection system in which multiple series-connected columns each having a plurality of non-linear resistance elements connected in series are connected in parallel, and the potential at the corresponding division point of each series-connected column is equalized by a forced voltage dividing element, the series-connected columns are A lightning arrester characterized in that an impedance element is connected between a dividing point and a predetermined potential point formed by a forced voltage dividing element.