JPS6029905B2 - Grounded tank type lightning arrester - Google Patents

Description

[Detailed description of the invention] This invention can be used in a leakage current region of about A at a normal ground voltage using a non-linear resistance element such as a metal oxide competitive element whose main component is zinc oxide. This relates to a grounded tank type lightning arrester.

Conventionally, this type of device is connected to a protected device 4 by an insulating spacer 2 and a conductor 3, as shown in FIG.

A plurality of non-linear resistance elements 1 made of sintered metal oxide elements are connected in series and stacked together via an annular shield 5 to form a current protector 100 with a predetermined rated voltage, and a grounded tank made of metal. 6, and insulation between the ground tanks 6 is provided by an insulating medium 7. 8 is non-linear resistance element 1
and a compression spring for pressing down the shield 5.

The grounding side of the earth arrester 100 is connected to an insulating spacer 9 having a conductor 10, and the conductor 10 is connected to a grounding wire 12 via a shaft 11. Further, the grounding of the grounding tank 6 is connected to a grounding terminal 13 via a shaft 14 and then to a grounding line 12 . 30 is a rivet for fixing the shunt.

In such a configuration, if the stray capacitance existing between the shield 5 and the ground tank 6 is C2, and since the non-linear resistance element 1 has the function of a kind of ceramic capacitor under normal operating voltage, it is C. The equivalent circuit of FIG. 1 is expressed as shown in FIG.

Here (C, -1) is the shield (5-a), (5-b)
This is the equivalent capacitance of the nonlinear resistance element 1 that exists between . FIG. 3 shows the voltage-current characteristics of the nonlinear resistance element 1 when a direct current or impulse voltage is applied. Curve 15 is the normal state. If the nonlinear resistance element 1 has deteriorated for some reason, the voltage-current characteristic will be the curve 16 in Fig. 3.
to move to. Therefore, the current due to constant voltage changes from i, to i
Increased to 2. This phenomenon is a so-called acceleration phenomenon, and as the current increases, the thermal energy increases, and as a result, the nonlinear resistance element 1 is heated, and the current tends to increase further. Therefore, in order to detect deterioration of a non-linear resistance element, it is necessary to detect an increase in leakage current at an early stage and discover a tendency of deterioration. Conventionally, for this purpose, as shown in FIG. 4, a leakage current detection device 17 is inserted between the conductor 10 of the lightning arrester 100 and the grounding wire 12 to detect the presence or absence of an increase in leakage current to detect deterioration. I was looking for a way. However, with this method (C
, 1), even if the nonlinear resistance element corresponding to 1) deteriorates, there is a drawback that the increase in resistance current due to the deterioration is not sufficiently output to the leakage current detection device 17. This is due to the following reason. For ease of understanding, (C, -1) in Figure 4 is replaced by Z, (C, -2), (C, -3)...... (C,
1 n), (C2-2), (C2-3), ... (C2-(
Z is the equivalent impedance of n-1)), and Z3 is C2-1.
When replaced with , the equivalent circuit shown in FIG. 5 is obtained. For example, if we consider a lightning arrester with a rating of 420 KV, ``the number of nonlinear resistance elements 1 is several hundred, so Z is C,
Since the capacitance of a large number of non-linear resistors 1 except 1 becomes an impedance connected in series, its value is large, so a part of the resistance current flowing through 1 flows through Z to the ground.

As a result, the current 12 flowing through Z has a value smaller than the actual value, resulting in a defect that the accuracy of deterioration detection is reduced. The present invention has been made in view of the above points, and it is an object of the present invention to provide a grounded tank type lightning arrester capable of accurately detecting deterioration of a non-linear resistance element constituting a current arrester.

An embodiment of the present invention shown in FIG. 6 will be described below.

In FIG. 6, the difference from FIG. 1 is that the lightning arrester 100
Shafts 11 and 14 for grounding the grounding tank 6 made of metal are made of a flexible conductor, and the shunt 11 connects the lightning arrester 100 and the connecting parts of the shunt 14 and the grounding terminal 13 of the grounding tank 6 with bolts 23, respectively.
, 24, and parts A and B are connected to the ground tank 6 to the protected equipment 4 and the ground wire 25 through insulating collars 18, respectively, as shown in FIGS. 7 and 8. It is. In such a configuration, when deterioration of the non-linear element 1 is detected, the bolts 23 and 24 are removed and the earth protector 10 is removed.
0 and the shunt 11 and the connection between the ground terminal 13 and the shunt 14, and
Leakage current detection devices 17a and 17b are connected between the grounding member 13 and the shunt 14 by connecting wires 25 and 26, respectively.

As a result, the current 1 flowing through Z and Z in FIG.
2 and 13 are detected by leakage current detectors 17a and 17b, respectively, and all leakage currents of the entire lightning arrester 100 are detected. As described above, according to the present invention, when detecting leakage current, the grounding tank is electrically floating above the grounding potential, and since the leakage current detection device can be inserted between the lightning arrester and the grounding, and between the grounding tank and the grounding, the lightning arrester It has the advantage of being able to detect all leakage currents, enabling highly accurate deterioration detection and diagnosis.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional grounded tank type lightning arrester, Figure 2
The figure is a circuit diagram showing the equivalent circuit of Fig. 1, Fig. 3 is a characteristic curve diagram showing the limiting voltage characteristics of a non-linear element made of a zinc oxide lighting element, and Figs. 4 and 5 are also shown in Fig. 1. 6 is a sectional view showing an embodiment of the present invention, and FIGS. 7 and 8 show details of parts A and B of FIG. 6. FIG. In the figure, 6 is a grounded tank, 11 and 14 are shunts,
23 and 24 are bolts, 18 is an insulating collar, and 100 is a lightning arrester. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. A metal tank attached to a grounding member via an insulating material, a lightning arrester configured by stacking a plurality of non-linear resistance elements and fixed within the metal tank via an insulating material, and the non-linear a first grounding conductor that grounds the resistor; and a second grounding conductor that grounds the metal tank; the first grounding conductor, the nonlinear resistor, the second grounding conductor, and the metal tank; A grounded tank type lightning arrester characterized in that the two are detachably connected to each other, and a current measuring device can be inserted into each of the two connecting portions. 2. The grounded tank type lightning arrester according to claim 1, wherein the non-linear resistance element is a sintered element whose main component is a metal oxide. 3. The grounded tank type lightning arrester according to claim 2, wherein the metal oxide is zinc oxide.