JPH01309303A - Tank-type lightning arrester and gas-insulated switchgear using it - Google Patents

Abstract

PURPOSE:To restrain surge voltage between the high voltage section of a gas insulated switchgear(GIS) and a sheath and between the grounding end of an arrester and a tank by installing an overvoltage restraint between the grounding end of the arrester and the tank. CONSTITUTION:A tank type arrester 2 connected to a gas bus 1 is gas- partitioned by a spacer 3. ZnO elements 5 and spacers 9 are laminated in a tank 4 connected to a grounding mesh 19 by a grounding line 21, and the ZnO elements 5 connected in series up to a grounding end 8 from a high voltage end 7 by crossovers 6. An electric-field relaxing shield 10 and a potential share equalizing ring 11 are mounted to the high voltage end 7. The grounding end 8 is connected to the grounding mesh 19 by a lead 15, terminals 16, 17 and a grounding line 18. The ZnO elements and an overvoltage restraining element 14 such as a capacitor are set up between a tank bottom 13 and the grounding line end 8. Even when the arrester is grounded by the grounding line 18 separate from the tank is grounded, the surge voltage of the tank 4 and the grounding end 8 can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tank-type lightning arrester (surge arrester) suitable for suppressing overvoltage in gas insulated switchgear (GIS) and a gas insulated switchgear to which this lightning arrester is applied.

[Conventional technology]

Conventionally, the grounding wire of the lightning arrester on the GIS side was
No. 443, Japanese Patent Application Laid-open No. 57-21085, etc., the lightning arrester tank is not connected to a separately grounded tank, but is insulated from the tank in accordance with Article 19 of the Electrical Equipment Technical Standards, etc., and installed at the substation. It was connected solely to the ground mesh. Also,
As seen in Japanese Patent Publication No. 59-50203, it is known that the grounding side of the lightning arrester element and the tank are directly connected, but it has not been put to practical use because it violates technical standards.

JP-A-58-165304 discloses a configuration similar to the present invention, but this is a voltage divider and is a completely different product and technology from the present invention.

Since it is a voltage divider, leads are naturally wired from the voltage-divided elements to measure the voltage. Naturally, an impedance is connected to the extraction lead.

Furthermore, Japanese Utility Model Application Publication No. 55-25325 also discloses a configuration similar to the present invention, but it is a completely different technology from the present invention. That is, a lead wire is wired from a part of the ground side of the lightning arrester element, and this wire is for monitoring the current of the lightning arrester. An impedance for current monitoring is connected from the leader wire to the ground.

[Problem to be solved by the invention]

The above-mentioned JP-A-54-66443, JP-A-57-2108
Publication No. 5 did not take into account the effect of the grounding wire of the lightning arrester on steep wave surges caused by lightning strikes, and there was a problem in that insulation coordination with the GIS that should be protected was not completely ensured. That is, there was a problem in that the potential drop of the grounding line was added to the limited voltage of the A lightning device.

There was also the problem that a high surge voltage was generated between the grounding end of the lightning arrester and the tank, resulting in dielectric breakdown between them.

On the other hand, the conventional technology disclosed in Japanese Patent Publication No. 59-50203
There is no problem in terms of insulation coordination with IS, but since the grounding end of the lightning arrester element is directly connected to the tank, there is a problem that it cannot comply with Article 19 of the Electrical Equipment Technical Standards, etc., and JEC-217
If a discharge current of 8/20 μs, as specified in the standards, flows, the potential of the tank will rise unnecessarily, causing a shock to the human body.

The purpose of the present invention is to reduce the potential drop of the grounding wire of a lightning arrester,
The object of the present invention is to provide a lightning arrester that solves the problems of GIS insulation coordination and the insulation of the grounding end of the lightning arrester, as well as the problem of not being able to comply with electrical equipment technical standards.

Another object of the present invention is to provide a GIS with high insulation reliability using this lightning arrester appropriately.

[Means to solve the problem]

The first object of the invention is achieved by connecting an overvoltage suppression device such as a zinc oxide element, a capacitor, etc. between the grounding end of the arrester element and the arrester tank.

Another object of the present invention is achieved by appropriately using a surge arrester employing the above means, making the sheath of the GIS continuous against surges, and grounding the tank of the surge arrester on the GIS side.

[Effect]

An overvoltage protection device such as a zinc oxide element, a capacitor, or a parallel connection of these connected between the grounding end of the arrester element and the tank is designed to prevent overvoltage surges caused by steep waves between the grounding end and the tank. When it occurs, it acts to suppress it.

For example, zinc oxide elements have excellent nonlinearity, so when an overvoltage surge reaches a predetermined value, a large current flows,
Acts to suppress overvoltage.

In the case of a capacitor, if an appropriate capacitance value of several thousand PF or more is selected, the impedance against steep wave surges will be reduced, which will have the effect of suppressing overvoltage surges. In addition, if a gap is connected in series with a zinc oxide element, capacitor, etc., the overvoltage protection device is always completely insulated, and if an overvoltage surge occurs, the gap will discharge to a predetermined value, so the overvoltage can be suppressed. Since such an overvoltage protection device allows only harmful short-term pulse currents to flow, it is possible to shorten the duration of potential rise in the tank.

〔Example〕

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

In order to suppress overvoltage of the GIS (not shown), a tank-type lightning arrester 2 of the present invention is installed via a gas bus 1, as shown in FIG.

The lightning arrester 2 is gas-separated from the gas bus 1 by a spacer 3 here. Zinc oxide elements 5 in a grounded pressure tank 4 are stacked in series from a high-pressure end 7 to a grounded end 8 via a crossover wire 6.

One column of zinc oxide elements 5 is insulated with a spacer 9. The high voltage end 7 is provided with an electric field relaxation shield 10 and a potential sharing equalization ring 11 of the zinc oxide element 5. Moreover, the zinc oxide element 5 is attached to the bottom part 1 of the tank 4 by the auxiliary plate 12.
3, while an overvoltage suppressor 14 according to the invention is inserted between the ground end 8 and the bottom 13. The ground end 8 is led to the outside of the tank 4 through the lead wire 15 and terminals 16 and 17, and is connected to the ground mesh 19 by a ground wire 18. Terminals 16,17 are insulated from tank 4.

The tank 4 is filled with high pressure SFa gas 20 having excellent insulation performance. Either the tank 4 is not grounded by the ground wire 18 and is connected to the ground mesh 19 by another dedicated ground wire 21, or the tank 4 and the GIS tank are electrically connected and the GIS ground wire is connected to the ground mesh 19. It may be substituted with.

The overvoltage suppression device 14 of the present invention can have a configuration as shown in FIG. (a) is when the zinc oxide element 30 is used, (b) is when the capacitor 31 is used, and (c) is when the zinc oxide element 32 and capacitor 33 are used in parallel.
d,) is a zinc oxide element or a capacitor 3
4 and the series gap 35 may be connected in series, or a simple gap may be used.

The present invention will be explained in detail with reference to FIG.

It is assumed that a lightning surge 41 enters the GIS 42 from the power transmission line 40 via the bushing 43 of the GIS 42.

GIS42 has gas busbar 44, lightning arrester 45, gas circuit breaker 4
It consists of 6 etc.

As mentioned above, the grounding of the GIS 42 is 1, for example, the sheath 47.
A grounding wire 48 is connected to the tank 49 of the lightning arrester 45, and a grounding wire 50 is connected to the tank 49 of the lightning arrester 45. The lightning arrester 45 is insulated from the tank 49 and is grounded by a grounding wire 51. When a lightning surge 41 enters, this voltage is transferred to the lightning arrester 45.
However, in conventional lightning arresters, the potential drop of the grounding wire 51 is added to the limiting voltage of the lightning arrester. When the impedance of the grounding wire 51 is made into an inductance, and the current flowing through the lightning arrester is given for i and time t, the potential drop V+
, is given by L di / d t, and the lightning surge 41
As VL becomes steeper, this potential drop VL becomes larger. Since the conventional lightning arrester did not have the overvoltage suppressor 52 of the present invention, the voltage between the high voltage part 53 of the lightning arrester 45 and the tank 49 was higher than the voltage between the terminal 53 of the zinc oxide element part 54 of the lightning arrester 45 and the ground terminal 55. Voltage will be applied.

FIG. 4 shows an example of the results of lightning surge analysis under the condition that the gas circuit breaker 46 is in an open state. GIS using conventional lightning arrester
In this case, the voltage between the high pressure part 56 of the gas circuit breaker 46 and the sheath 47 is 1672 KV as shown in FIG. 4(a). For example, the lightning impulse withstand voltage level (LIWL) is 155
If it is 0KV, it exceeds this.

Therefore, when the overvoltage suppressing device 52 of the present invention is inserted between the grounding end 53 of the lightning arrester and the tank 49, the voltage corresponding to FIG. 4(a) becomes as shown in FIG. 4(b), 529 K.
The LIWL of 1550KV was achieved by reducing V2. Here, the overvoltage suppressor 52 uses the zinc oxide element (a) shown in FIG. 2. The reason why the voltage was able to be reduced in this way is that the overvoltage suppressor 52 was able to effectively reduce the influence of the potential drop VL of the grounding line 51.

In addition, as shown in FIGS. 4(c) and 4(d), the voltage between the grounding end 53 of the evacuator and the tank 49 ranges from 353 KV to 8 KV.
It was possible to reduce it to V. The reason for this reduction is also due to the insertion of the same overvoltage suppressor 52 as described above.

According to this embodiment, it is possible to suppress the surge voltage between the high-voltage part of the GIS and the grounded sheath, which has increased due to the potential drop in the lightning arrester grounding wire. Surge voltage can also be suppressed, and the grounding method for lightning arresters stipulated in the electrical equipment technical standards can also be satisfied.

FIG. 5 shows another modification. The ground end 8 of the lightning arrester and the bottom 13 of the tank 4 were insulated by an insulating plate 70, and an overvoltage suppressor 71 of the present invention was provided between the lead wire 15 and the bottom 13 of the tank 4 beside the insulating plate 70.

In this modification, a good effect can be obtained by simply adding the overvoltage suppressing device 71 to the lightning arrester having the same structure as the conventional one.

Further, FIG. 6 is another modification, and the difference from FIG. 5 is that an overvoltage suppressing device 72 of the present invention is provided between the air outer grounding terminal 17 and the tank 4. This modification has the advantage that the overvoltage suppression device 72 can be easily inspected outside the air.

FIG. 7 shows an example of the configuration of a GIS using the lightning arrester 80 of the present invention. In some GIS, the sheath 81 of the GIS is insulated and partitioned by a spacer 82. When using the lightning arrester of the present invention in such a GIS, a capacitor or a zinc oxide element is provided between the terminals of the insulating section to make it equivalent to a continuous sheath against surges, and the grounding of the tank of the lightning arrester 80 is
It is not installed at the lightning arrester position, but at the grounding wire 83 on the GIS side.

By configuring the GIS as described above, it is possible to provide a GIS with high insulation reliability because the surge arrester can suppress surge voltage more effectively than before. 84 is the ground wire.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the influence of the potential drop of the lightning arrester grounding wire, and it is possible to suppress the surge voltage between the high voltage part of the GIS and the opening of the sheath, and the surge voltage between the grounding end of the lightning arrester and the tank. ′

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the overvoltage suppressing device of the present invention, FIG. 3 is a detailed explanatory diagram of the present invention, and FIG. 4 is a diagram showing the effects of the present invention. Figures 5 to 7 showing the results of lightning surge analysis are cross-sectional views of other embodiments of the present invention. 4...Tank, 5...Zinc oxide element, 8...Grounding end, 14...Overvoltage suppressor, 18.21...Grounding wire, NuZ diagram (a) Cb)
(cn (cl) field!;
Figure 6

Claims (7)

[Claims] 1. A tank-type lightning arrester provided in a gas-insulated switchgear, characterized in that an overvoltage suppression device made of a zinc oxide element or the like is provided between a grounding end of the lightning arrester that is insulated from the tank and the tank. 2. Claim 1 provides that, as the overvoltage suppressing device, the zinc oxide element, the capacitor, a combination of these elements, a configuration in which these elements and a gap are connected in series, and the simple gap are used. Characteristic tank type earth arrester. 3. The tank type lightning arrester according to claim 1, wherein the overvoltage suppressing device is provided directly below the grounding end of the stacked zinc oxide elements that are elements of the lightning arrester. 4. The tank type lightning arrester according to claim 1, wherein the overvoltage suppressing device is provided between a grounding lead wire inside the tank and the tank. 5. The tank type lightning arrester according to claim 1, wherein the overvoltage suppressing device is provided between the tank and a grounding conductor in the air outside the tank. 6. A gas-insulated switchgear characterized by using a tank-type lightning arrester having the features set forth in claim 1, 2, 3, 4, or 5. 7. The gas insulated switchgear according to claim 6, wherein the grounding of the tank is integrated with a sheath of a GIS.