JPS6051237B2 - Lightning arrester - Google Patents

Description

Detailed Description of the Invention (a) Description of the Technical Field The present invention relates to a lightning arrester that protects power equipment from impact overvoltages caused by lightning and line opening/closing. This article relates to a lightning arrester that uses a nonlinear resistor that is activated.

(b) Description of the Prior Art In recent years, many lightning arresters have been proposed that use nonlinear resistors that take advantage of the excellent nonlinearity of metal oxides.

This type of lightning arrester can be broadly divided into a so-called gapless surge arrester, which simply consists of a non-linear resistor, and a type in which a simple series gap is added to the non-linear resistor. However, the reliability of the former is still far from satisfactory, and gapless arresters are expected to be further improved in the future. For this reason, lightning arresters have been proposed that have a simple structure and have a series gap, which can cut the leakage current flowing at the normal ground voltage and improve reliability, as well as provide flat characteristics. Fig. 1 shows an equivalent wiring diagram of a conventional series gap arrester. High voltage electrode 1 connected to line L
A third electrode 3 is arranged between the high-voltage electrode 1 and the low-voltage electrode 2, and a parallel circuit of capacitance Cl and resistance R is inserted between the high-voltage electrode 1 and the third electrode 3. A parallel circuit including a capacitance Co and a resistor R2 is inserted between the capacitance Co and the resistor R2. A non-linear resistor 4 and an electrostatic capacitor ρ are connected in series with the aforementioned electrode and have one end grounded. parallel circuits are arranged. This circuit is housed within an insulating gas container. The outline of the operation in such a configuration is as follows. That is, a considerable amount of the surge voltage applied to the lightning arrester is shared by the gas gap G between the high-voltage electrode 1 and the low-voltage electrode 2, so that it can be operated easily. If the gap between the high voltage electrode 1 and the third electrode 3 is G1, and the gap between the third electrode 3 and the low voltage electrode 2 is G2, then by setting G1<G2, the gap G1 is first discharged in the impulse region. , due to the application of the instantaneous overvoltage, the gap G2 is also quickly discharged. Furthermore, by appropriately selecting Rl and R2, it is possible to reduce the voltage applied to the gap G1 considerably lower than that for an impulsive surge voltage with respect to a slow front surge voltage. As a result, the time characteristic (v
-t characteristic) can be obtained as a flat body. Further, when a commercial frequency voltage is constantly applied, leakage current flowing through Rl and R2 can be prevented from flowing into the nonlinear resistor 4 by appropriately selecting C3. However, if a DC voltage is constantly applied, a DC leakage current will flow through the nonlinear resistor 4. The non-linear resistor 4 is a dielectric material, and if an electric field in only one direction is constantly applied, polarization will occur, and the V-1 characteristic of the non-linear resistor will change.
As described above, the reliability of nonlinear resistors is still far from being sufficient, and direct current leakage current has become a very serious problem. (
C) Purpose of the Invention The present invention has been made in view of the above points, and it protects power equipment from lightning and switching surges, and also prevents leakage current from flowing through non-linear resistors when applied to a DC power transmission system. The purpose of the present invention is to provide a snow protector having such a structure.

(d) Structure of the invention An embodiment of the present invention will be described with reference to FIG.

In FIG. 2, the lightning arrester according to the present invention has a gas gap part ``A'' inserted and fixed into one open end of the metal body 1, and attached inside a metal plate 2 that closes the other open end of the metal body 1. It is roughly divided into ``゜B゛゛.'' The gas gap part ゜゜A'' is housed and fixed in the metal body 1 by a metal flange 11 fixed to the tip 3a of the hollow conical insulating spacer 3. This gas gap portion "4N' is constructed as follows. On the lower surface of the metal flange 11,
A plurality of insulating rods 5 are fixed on the same circumference,
Some of these insulating rods 5 are replaced by resistors 6. Further, a metal rod 7 is fixed on the central axis of the metal plate flange 11, and a high voltage electrode 8 is attached to the tip of the metal rod 7. A metal flange 9 is attached to the lower end of the resistor 6.
is attached to the metal flange 9, and a third electrode 12 is fixed to the metal flange 9. Further, on the lower surface of the metal flange 9,
Again, a plurality of insulating rods 13 are fixed on the same circumference, and some of these insulating rods 13 are replaced by resistors 25. A metal flange 14 is fixed to its lower end. Furthermore, a low voltage electrode 16 is fixed to the upper surface of the metal flange 14 via a metal rod 15 so as to face the high voltage electrode 8. In contrast to the gas gap section "A" constructed as described above, the non-linear resistor section "B" is constructed as follows.

a metal flange 17 fixed to the inner surface of the metal plate 2;
An insulating tube 18 is attached to the upper surface of the insulating tube 18, and a nonlinear resistor made of metal oxide is housed in the space formed by the insulating tube 18 and the metal flanges 14 and 17. The non-linear resistor 19 is a disk-shaped metal spacer 2
A large number of sheets are stacked as necessary via the metal flange 1, and a spring 21 provided at the upper end of the metal flange 1
It is fixed between 4 and 17. Note that the insulating cylinder 1
8 is provided with a ventilation hole 22. 12 and 1
6 is made of a material with excellent arc resistance, such as graphite.

Then, a metal container 1, a metal plate 2, and an insulating spacer 3
The interior of this device formed by the above is filled with SF6 gas, which has excellent insulation and arc-extinguishing performance. Further, a resistor 24 is juxtaposed to the insulating tube 18 and connected between the metal flanges 14 and 17. (e) Operation of the invention The outline of the operation according to the present invention is as described below.

FIG. 3 shows an equivalent wiring diagram of the lightning arrester according to the present invention. Here, the capacitances Cl and C2 are the capacitances between the third electrode 12, the high voltage electrode 8, and the low voltage electrode 16 described above. Also, the resistance R
1 is a resistor 6 inserted between metal flanges 4 and 9, resistor R2 is a resistor 25 inserted between metal flanges 9 and 14, and R3 is a resistor 25 inserted between metal flanges 14 and 17. This is the resistor 24. In such a configuration, the gas gap part ゜゜A'' will share a considerable amount of the surge voltage applied to the lightning arrester, and it can be operated easily.

Now, assuming that the gaps between electrodes 12 and 8 and between electrodes 12 and 16 are Gl and G2, respectively, by setting G1 minus G2, gap G1 will discharge first in the impulse region, and the instantaneous overvoltage will be applied to G2. This gap G2 also quickly discharges, and the protected equipment is protected from the surge voltage. On the other hand, by appropriately selecting the value of R, the gap G
1 can be significantly reduced compared to the impulsive surge voltage. That is, the time characteristic (vt characteristic) from discharge voltage to discharge of the lightning arrester according to the present invention is determined by the lengths of gaps Gl and G2, resistances Rl and R2, capacitance Cl,
By changing C2, it can be made flat. Furthermore, since the non-linear resistor 19 made of metal oxide is used, the three types of electrodes in the gas gap part are
Follow-up and breaking capabilities are not required, and the structure is simple and provides good protection performance. Moreover, the resistor R3 is the resistor Rl
, R2 are selected to be much smaller than the resistance value of the non-linear resistor 19 when the current flows in, and larger than the resistance value of the non-linear resistor 19 when an overvoltage is applied, so that the non-linear resistance is always maintained. No direct current leakage current flows through the body 19.

(f) Other embodiments FIG. 4 shows another embodiment of the invention.

The same parts as in FIG. 3 are given the same symbols. FIG. 4 shows a gas gap section "A" and a non-linear resistor section "B" housed in an insulator tube 29. In FIG. In addition, here 26 and 27 are insulator pipes 29
28 indicates a high voltage side terminal. Also, the resistor 24 in FIG. 2 is omitted. (g)
Overall Effects The present invention described above has the following effects.

1 When applied to a DC system, the DC leakage current does not flow through the non-linear resistor, so reliability is improved compared to gapless arresters.

Since a non-linear resistor with excellent 2-1 characteristics is used, a gas gap bridging ability is not required, resulting in a simple structure.

By appropriately selecting the three-part voltage impedance, a flat -t characteristic can be obtained.

4. If the non-linear resistor section is housed in an insulating cylinder, explosion-proof performance can be improved.

As described above, according to the present invention, it is possible to obtain a lightning arrester that has excellent protection performance, has a simple structure, and is inexpensive.

[Brief explanation of the drawing]

Fig. 1 is an equivalent wiring diagram of the conventional example, Fig. 2 is a vertical sectional view showing an embodiment of the present invention, Fig. 3 is an equivalent wiring diagram of Fig. 2, and Fig. 4 is an equivalent wiring diagram of the conventional example.
The figure is a longitudinal sectional view showing another embodiment of the present invention. 1...Metal body, 2...Metal plate, 3.
...Insulating spacer, 4...Metal flange, 5...Insulating rod, 6...Resistor, 7...
... Support rod, 8 ... High voltage electrode, 9 ... Metal flange, 10 ... Pole plate, 11 ... Support rod, 12 ... 3rd electrode, 13...Insulating rod, 14...Metal flange, 15...Support rod, 16...Low voltage electrode, 17...Metal flange , 18... Insulating tube, 19... Non-linear resistor, 20... Metal spacer, 21...
...Spring, 22...Vent hole, 23...
...Ground node, 24, 25...Resistor, 2
6, 27...Metal flange, 28...
High voltage side terminal, 29... Insulator tube, ゜゜A゛...
Gas gap part,゜"B゛...Non-linear resistor part.

Claims (1)

[Claims] 1 a container, an insulating gas sealed in the container, a non-linear resistor housed in the container in the axial direction of the container, and a counter connected to the resistor in the axial direction of the non-linear resistor. a surge arrester element consisting of a gap made up of electrodes; a pole plate housed in the container so as to surround the gap; and a third electrode located between the pole plate and the gap. A lightning arrester, characterized in that parallel circuits of capacitance and resistance are arranged between the gap and the third electrode, and a resistance is arranged in parallel with the non-linear resistor.