JPS61227323A - Gas insulated gear - 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 invention] The present invention relates to a gas insulated switchgear.

[Technical Background of the Invention and Problems Therewith] In recent years, gas insulated switchgears (GIS) have been widely used as switchgears for high voltage circuits used in substations. This gas-insulated switchgear houses busbars, circuit breakers, new line switches, and other accessory equipment in a grounded metal container. , an insulating gas such as SFg gas, which is odorless, harmless, and has a dielectric strength 2 to 3 times that of air, is sealed to maintain insulation, and is used as a switching device for a high-voltage circuit.

Such devices generally have a coaxial structure, and surges generated within the device propagate with almost no attenuation. It is a well-known fact that the operation of a disconnector or circuit breaker generates a steep surge in a gas-insulated switchgear. In particular, when the advanced current is cut off by a new circuit device, the rising portion of the wave crest is 2 to 3 nS, and the voltage change is about the same as the peak value of the constant operating voltage.
Then, the subsequent high-frequency vibration of several MHz may generate a surge voltage whose maximum peak value is the peak value of the constant operating voltage (2p, u, or more). There are examples of dielectric breakdown accidents in oil bushings caused by the steep head of this surge, and ground faults from the arc between the poles of a disconnector to a grounded metal container due to the high wave height of the surge. Examples have been reported. In addition, these surges are induced into the grounding system of gas-insulated equipment, causing various radio interference and destruction of low-voltage control circuits. Therefore, it is necessary to suppress the steep wave surge generated in gas-insulated equipment by some means.

By the way, a method shown in FIG. 7 has been considered as a method for suppressing high frequency surges that occur when operating a disconnector in a gas insulated switchgear.

That is, the figure is a cross-sectional view of a new circuit switch of gas-insulated switchgear. Insulating gas 3 is sealed. Inside the grounded metal container 1, a pair of fixed electrodes 4a and 4b are disposed closely facing each other with their axes aligned and supported by the insulating spacer 2, respectively. Each fixed electrode 4a, 4b is hollow, and contacts 5a, 5b are provided on the inner peripheral surface. A movable electrode 6 is provided in one of the fixed electrodes 4a, the outer peripheral surface of which is in contact with the contactor 5b, and which is slidable in the axial direction of the fixed electrode 4a.An arc contact 8 is also provided at the tip of the movable electrode 6. It is provided. Further, an operating mechanism 10 is provided outside the grounded metal container 1, and the operating force of this operating mechanism 10 is transmitted to the movable electrode 6 via the operating rod 9.
The movable electrode 6 can be moved forward and backward in the direction of the fixed electrode 4a, thereby allowing it to approach and separate from the fixed electrode 4a. 7 is a resistor provided at the tip of the fixed electrode 4a. Further, 11 is a high-voltage center conductor connected to each fixed electrode 4a, 4b, and 12 is a connection electrode.

In such a configuration, high frequency surges are handled by the resistor 7.
suppress by.

This is the same method as the so-called resistor closing of the circuit breaker, in which a resistor 7 is connected to the tip of the fixed electrode 4a of the new circuit switch, and if a re-ignition occurs between it and the movable electrode 6 of the circuit breaker. , this current will necessarily pass through the resistor 7. Therefore, the surge is quickly attenuated by this resistor 7, and the surge no longer occurs.

However, at this time, the inter-electrode voltage immediately before restriking is applied to the resistor 7, so in order to prevent dielectric breakdown along the surface of the resistor 7, its length must be at least the maximum inter-electrode length. The stroke of movement of the movable electrode becomes longer by that amount. For example, about twice as much is required as in the case where no resistance is used, and the new path device itself becomes longer.At the same time, the operating mechanism 10 also needs to be strong enough to handle a long stroke.

Therefore, the overall cost increases. Furthermore, the high voltage side fixed electrode has a complicated structure, which may cause a failure and reduce the reliability of the gas insulated switchgear.

In addition, consideration must be given to the heat generated by the flow of high current in the high-voltage side conductor, and at the same time, countermeasures against vibrations when operating the disconnector are also required. It is not a good idea to install a mechanism with a complicated structure in such a bad environment. Unlike circuit breakers, new line switches are usually installed in large numbers in a substation, so the cost and reliability of this part are very important to the cost and reliability of the entire substation.

Therefore, there is a need for the development of a gas-insulated switchgear that can effectively suppress circuit surges and has a highly reliable, compact, and inexpensive structure.

In addition, when a new line switch or breaker in a gas-insulated switchgear is operated, a sudden surge generated within the gas-insulated switchgear is induced to the grounding system outside the gas-insulated switchgear.
Transiently increases the potential of a grounded metal container. Such induced surges in the ground system pose a danger to personnel, destroy low-voltage control circuits, and become a source of noise for television, radio, and other communication waves, and must be suppressed to a low value by some means.

The insulating flange is one of the causes of the high frequency surge inside the gas insulated r11 device being guided to the grounding system outside the gas insulated switchgear. If a closed loop is formed in a grounding system that includes a grounded metal container, an alternating current will flow through the grounded metal container due to the alternating current magnetic flux interlinking within the closed loop.
A grounded metal container is heated. To prevent this, an insulating plate is sandwiched between the flanges for mechanically connecting each ground metal with bolts, and the left and right ground metal containers are electrically insulated to prevent a closed loop from forming. A method to prevent current from flowing may be adopted. For example, as shown in FIG. 8, grounded metal containers 1a, Ib
In between is the flange part 1f.

First, a spacer 2 for holding the high-voltage center conductor is placed and fixed with bolts.A metal flange 2a is provided on the outer periphery of the spacer 2, which connects both grounded metal containers 1a and Ib.
Since it becomes a conductive path, reduce the thickness of the metal 7 flange 2a,
A ring-shaped insulating plate 13 is interposed here. The grounding metal containers 1a and 1b are electrically separated by this insulating plate 13, and the mesh 14 of the underground mill and the grounding wires 15a and 15
b.

The closed loop with grounded metal containers 1a, 1b is broken.

When a steep wave surge occurs and propagates inside the gas-insulated switchgear with such a structure, the grounding wires 15a and 15b exhibit a large resistance value against the steep wave surge, and the grounding metal containers 1a and 1b exhibit a large resistance value. It becomes a disconnected state. When the steep wave surge passes through the flanges 1f and 1f', a voltage equivalent to the steep wave surge voltage is generated between both seven lunges, that is, at both ends of the insulating plate 13. Therefore, if the insulating plate 13 is held completely, the potential difference between the 7 langes 1f and if' will transiently be about the operating voltage,
A very large surge will be induced into the ground system.

However, in reality, dielectric breakdown occurs on the air side surface of the insulating plate 13 at a certain voltage, and the potential difference between the flanges 1 and 1f' is suppressed to a constant value. However, once an external discharge occurs, it is clear that this becomes a source of secondary surges. In order to suppress this phenomenon, the flange 1t
In some cases, a structure is adopted in which a nonlinear resistor 16 is connected to 1f' and 1f'.

However, the inventor's experiments revealed that the effect of such nonlinear resistance is small. The reason for this can be considered as follows. That is, the steep wave surge generated in the gas-insulated switchgear has a sudden voltage change at the wave crest and includes extremely high frequency components. For example, in a 550kV system, a voltage change of about the peak value in a time of 20ns or less,
That is, it changes by about 450 kV. In response to such steep waves, the inductance of the nonlinear resistance lead wires 16a and 16b exhibits a large resistance value, and a large voltage is generated in these parts, making it possible to suppress the dielectric breakdown of the 7 langes 1f and 16b. It becomes difficult.

Therefore, it is desired to develop a gas insulated switchgear that is completely pollution-free and highly reliable by reducing the induction of steep wave surges generated in the gas insulated switchgear to the ground system.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide a highly reliable, compact and inexpensive structure that can effectively suppress the generated surge. An object of the present invention is to provide a gas insulated switchgear.

[Summary of the Invention] That is, in order to achieve the above object, the present invention provides a gas insulated switchgear in which a high voltage conductor is insulated and held in a grounded metal container together with an insulating gas. A resistor for forming an induced current flow path is provided surrounding the resistor, and this resistor is grounded.

Further, a resistor is interposed between the flange portion of the insulating spacer and the flange portion of the grounded metal container to form a conductive path between these flange portions.

This resistor is used to attenuate the surge.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front cross-sectional view showing one embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals and their explanation will be omitted.

As shown in the figure, this device eliminates the conventional surge absorbing resistor 7 provided on the fixed electrode 4a, shortens the distance between the fixed electrodes 4a and 4b, and controls the operation system of the movable electrode 6. In addition, the electrode structure is simplified due to the absence of the resistor 7. Instead, a cylindrical resistor 101 is prepared, and this is used as the fixed electrode 4a.

It is installed in the grounded metal container 1 in such a manner that it is arranged between insulating spacers 2 so as to surround the installation area of 4b.

At this time, the center axis inside the grounded metal container 1 and the resistor 10
It is preferable that the central axes of 1 coincide with each other in terms of insulation design. In addition, the grounded metal container 1 has a center part larger than the inner diameter of the flanges if and 1f', and the grounded metal container 1 and the resistor 1
01, a gap 3a is provided between the two. Both ends of the cylindrical resistor 101 are electrically connected to the grounded metal container 1 . Here, the resistance value of the cylindrical resistor 101 in the central axis direction is R [Ω] per 1 m, and when the inner diameter of the cylindrical resistor 101 is d'' and the inner diameter of the grounded metal container 1 is d, R is an appropriate value that satisfies the following formula: 0.12 tn (:r)<R<120 tn(6)
-” (1) However, the unit is [Ω].

There is no need to connect a resistor to the movable electrode 6, and a conventionally used electrode is used.

Generally, the grounded metal container 1 is made of aluminum or the like.

This device has a cylindrical resistor 10 provided inside this.
1 to attenuate and absorb induced surges. High conductivity grounded metal container such as aluminum 1
Although it tends to seem pointless to install the resistor 101 inside the sensor, it turns out that this is actually not the case. High frequency current tends to flow where the inductance is minimum.

For example, when a high-frequency current flows through a conductor in a coaxial structure, the current tends to flow outside the inner conductor and inside the outer conductor. Therefore, if the cylindrical resistor 101 is installed inside the grounded metal container 1, the high frequency M flow will be transmitted through the resistor 101.
Trying to flow to 1. This is because the inductance will be smaller if it flows through this area. That is, when a current flows through the cylindrical resistor 101, the inductance becomes smaller by the amount of the magnetic field generated in the air 1!13a than when the current flows through the grounded metal container 1. Generally, the self-inductance per unit length of a coaxial structure, which is the diameter dl of the inner conductor and the inner diameter d2 of the outer conductor, is L=-! at total 9...Song (2) 2π d.

However, μ is the magnetic permeability and JlnO is the natural logarithm.

It can be expressed as Applying the equation (2) to FIG. 1, when the current flows through the cylindrical resistor 101, the self-inductance per meter in the central axis direction is L=An(, ;') ・・
(3) where d is the inner diameter of the grounded metal container, and dr is the inner diameter of the cylindrical resistor.

becomes smaller. By the way, a large resistance value is preferable in order to attenuate high frequencies, but if the resistance value of the resistor 101 is made too large, the current will no longer flow through the resistance paper 101 but will flow through the grounded metal container 1. Therefore, it can be seen that there is an optimum resistance value that most effectively attenuates the high frequency current. For a high frequency whose frequency is f, (the impedance of the inductance shown in equation 3 is 2
πfL=fμtn(d!;) [Ω) ·−(4), and a resistance value of this level absorbs high frequencies most efficiently.

The reason for this becomes clear when considering the equivalent circuit shown in FIG. In other words, when a constant current with a frequency f flows through a parallel circuit of a resistor 2o1 (resistance value R) and an inductance 202 (inductance [1!L), the impedance exhibited by the inductance 202 is j2πJL (j is an imaginary unit), and this parallel If the voltage applied to the circuit is V, the energy E consumed by the resistor 201 is given by the following equation.

R at which E is maximum is 2πl, or inductance 20
When the impedance is equal to 2.

Therefore, the resistance per unit length in the central axis direction of the cylindrical resistor 201 is 1i! ! Let R be equal to the value shown in equation (4).

Here, the frequency of the high-frequency surge generated within the gas-insulated switchgear varies depending on the size and configuration of the gas-insulated switchgear, and is considered to range from 100 kHz to 100 MHz. The upper limit of frequency 100MHz is 2,000MHz at the wave crest of the surge.
This is a frequency component indicated by a rising edge of 5 nS. By substituting this frequency into equation (A) and substituting the magnetic permeability in vacuum as the value of μ, the following equation is obtained as the value of R.

・・・・・・(6) The value of R in the range given by formula (0) depends on the individual gas-insulated switchgear, and also what frequency components are to be suppressed. For example, it can cause dielectric breakdown in oil bushings, or it is the main cause of induced surges in the ground system.For steep waves at the front of surge waves, it is most effective to choose a value that is .

Now, if dr-400mm and d-500mm, R-
270, which is more than 2000 times higher than the resistance value of 11Ω, which takes into account the skin effect of the grounded metal container itself.
It is possible to attenuate high frequencies quite effectively even at around m. The fundamental frequency of new circuit surge in general gas-insulated switchgear is 2 MHz to 5 MHz. For example f
If it is 2MH2, then it becomes. And dr-400m
, d -5001w+ becomes R-0.5Ω, 1
Although the resistance value per m is small, if such a structure is adopted for a large number of disconnectors, considerable attenuation can be expected since there are a large number of new disconnectors. Further, the larger the value of d, the greater the effect.

As described above, in the present invention, since the cylindrical resistor is installed in a grounded metal container surrounding the high voltage center conductor, it is not directly affected by the heat generated by the high voltage center conductor. Furthermore, since the structure can be simplified and the distance between the fixed electrodes 4a and 4b can be shortened, the mechanical strength of the operating system for the movable electrode can be reduced, and it can therefore be manufactured at low cost. In addition, the resistor 101
Its outer diameter is approximately the inner diameter of the 7th rank part of the grounded metal container 1.

Since it is installed on a member on the ground potential side, there is less risk of it coming off due to loosening of the connecting bolt and causing dielectric breakdown. Furthermore, the influence of vibration during operation of the disconnector is small, and high condylar properties can be maintained.

The above was a structure in which a cylindrical low resistance 101 was provided,
Similar effects can be expected even if a resistor layer 101a is formed on the inner wall of the grounded metal container 1, as shown in FIG. At this time, if we approximate that the high-frequency current flows almost uniformly in the resistor layer 101a, then when the thickness of the resistor layer 101a is t, dr tone d-t -...■
The following formula holds true, and by substituting this into formula (61), we obtain.

Although the resistance value per 1 m is smaller than that of the 0 type, this method allows the diameter of the grounded metal container 1 to be made small.
It will be much more effective if used in more parts of gas-insulated switchgear.

Further, in the embodiment shown in FIG. 1, a cylindrical resistor 101 is used, but the cylindrical resistor 101 may be a mesh or a porous body, or it may be a plurality of rod-shaped resistors. Even if it is configured by arranging it in a cylindrical shape, the same effect can be obtained. Such a structure is effective in suppressing surges, capturing metal foreign objects, and cooling.

Moreover, although the embodiment has been described here for a unit bus, the effect is exactly the same when applied to a three-layer collective bus.

Figure 4 shows a cylindrical structure 1 made of magnetic material such as iron.
02 is installed in a grounded metal container 11, and a resistor 101 having a cylindrical structure is installed inside it. The cylindrical structure 102 made of a magnetic material is electrically insulated from the grounded metal container 1 and the resistor 101. Also, the resistor 101
Both ends thereof are electrically connected to a grounded metal container 1. It is preferable that the central axis of the grounded metal container 1, the central axis of the cylindrical structure 102, and the central axis of the resistor 101 coincide with each other in terms of insulation design.

Here, the central axis 11 of the resistor 101! The resistance value R[
Ω] is selected so as to satisfy the following formula. That is, when the non-permeability of the magnetic cylindrical structure 102 is μ, the outer diameter is DOS, and the inner diameter is DOS.

With such a configuration, the high frequency current generated within the gas insulated switchgear will tend to flow where the inductance is minimized.For example, when a high frequency current flows through a conductor of a coaxial structure, the current will flow through the outside of the inner conductor and the outer conductor. trying to flow inside. Therefore, if the cylindrical resistor 101 is installed inside the grounded metal container 1, the high frequency current will flow through this resistor 101.
trying to flow. This is because the inductance will be smaller if it flows here. That is, when a current flows through the resistor 101, the inductance is smaller by the magnetic field generated within the cylindrical structure 102 made of magnetic material than when the current flows through the grounded metal container 1. The self-inductance per meter in the central axis direction of the magnetic cylindrical structure 102 is: where μ0 is the magnetic permeability in vacuum, μ is the relative magnetic permeability of the magnetic cylindrical structure 102, and d is the magnetic cylindrical structure The outer diameter of the structure 102, dl is the inner diameter of the magnetic cylindrical structure 102, and 1n() is the natural logarithm.

It can be expressed as Therefore, the high frequency current flows through the resistor 1
01, the inductance becomes smaller by L given by equation (12).

As mentioned above, a large resistance value is preferable in order to attenuate high frequencies, but if the resistance value of the resistor 101 is made too large, the current will not flow through the resistor 101 but into the grounded metal container 1.

Therefore, it can be seen that there is an optimum resistance value of the resistor 101 that most effectively attenuates high frequencies. In order to find this optimum value, consider the equivalent circuit shown in FIG. A resistor 201 represents the resistance value (RΩ) of the resistor 101, and an inductance 202 represents the inductance of the magnetic cylindrical structure 102 given by equation (12). When a current ■ with a frequency f flows through this parallel circuit, the resistance 2
The energy E consumed in 01 is expressed by the above equation 0, where ■ is the terminal voltage of the resistor 201.

is given by From this, the value of R at which E becomes maximum is when R becomes equal to the impedance of the magnetic cylindrical structure 102.

The frequency of high-frequency surges generated in gas-insulated switchgear is 100kHz, depending on the size and configuration of the gas-insulated switchgear.
to 100MH2. Frequency upper limit 100
MHz is a frequency component indicated by 2.5 ns of the wave front portion of the surge. By substituting this frequency into equation (13) and substituting 4πxio-y as the value of μ0, the following equation is obtained as the value of R.

The value of R in the range given by equation (14) depends on the individual gas-insulated switchgear, and depends on what frequency components are desired to be suppressed. For example, in a typical 500 kV gas insulated switchgear, the frequency of new circuit surge is 2 MHz to 4 MH2. (13
) By substituting J-2MHz into the equation, the following relational expression can be obtained. When iron is used as the magnetic material, the value of μ is about 5000. d o as thickness 1α
=50cm, and by substituting di-48m into equation (15), we get R240(Ω) (16). Since the characteristic impedance of a gas-insulated switchgear is about 700, R given by equation (16) is more than three times the characteristic impedance. Therefore, due to the resistance per meter,
High frequency surges can be attenuated to 1/3 or less.

A resistor of 240Ω acts more effectively on high frequencies of 2MH2 or more. That is, frequency components of 2 MHz or higher are attenuated faster by the 240Ω resistor than frequency components of 2 MH2. Therefore, the steep portion of the surge wave crest, which causes dielectric breakdown of the oil bushing or is the main cause of induced surge to the grounding system, attenuates most quickly.

In this way, due to the large relative magnetic permeability of the magnetic material, it is possible to set R to a large value, and it is possible to efficiently attenuate high frequency surges with a short resistor.

For a commercial frequency of 50H2, the impedance of equation (13) is 1/40000 compared to the case of 2MHz, and 1/40000 of the current flowing through the grounded metal container 1.
This means that the current does not flow into the resistor 101, so there is no need to worry about heat generation.

If permalloy with a μ of 100,000 or pure iron with a μ of 200,000 is used instead of iron as the magnetic material, the same effect can be obtained with an even smaller magnetic cylindrical structure.

As shown in FIG. 4, when a cylindrical structure 103 made of a magnetic material such as permalloy powder has a relative magnetic permeability μ and at the same time has a resistance value due to the addition of carbon powder or the like, the fourth Effects similar to those shown in the figure can be expected. At this time, the structure 103 is electrically connected to the grounded metal container 1 at both ends thereof. Further, in this case, there is no problem even if the entire outer peripheral surface of the structure 103 is in contact with the grounded metal container 1. Assuming that the structure 103 has a resistance of R per meter in the central axis direction, and approximating that the high-frequency current flows almost uniformly within the structure 103, the condition for R corresponding to equation (14) is as follows: ...Obtain α.

In the configuration shown in FIG. 4, it is assumed that a conductive magnetic material such as iron is used as the structure 102, but if a high-resistance magnetic material such as ferrite is used, the grounding metal container 1 and the resistor 1 can be used.
There is no need to maintain electrical insulation from 01.

Furthermore, in the explanations so far, no particular mention was made of the shapes of the resistor 101 or the magnetic cylindrical structure 102 or 103. However, the effect is the same even if holes are placed in appropriate locations in these structures, and these holes are effective for trapping metal foreign objects that can cause earth damage and for cooling high-voltage conductors. .

Moreover, although the embodiment has been described for a single-phase bus, the effect is exactly the same when applied to a three-phase collective bus.

Particularly in the case of a three-phase integrated bus, the sum of the currents flowing inside the magnetic material cylinder is zero, which is advantageous since there is no need to consider heat generation of the magnetic material.

Next, suppression of dielectric breakdown due to surge in the insulated flange portion between the grounded metal containers 1 in the gas insulated switchgear will be explained. The feature here is that a resistance plate or a nonlinear resistance plate is used instead of the insulator sandwiched between the seven insulating rungs.

The configuration of the present invention will be explained with reference to FIG. 6 showing one embodiment thereof. The spacer 2 is a grounded metal container 1a.

At the same time, it is held between 7 langes 1t and 1f' of 1b,
A resistance plate 104 is installed between the 7 langes 1t and 1f'. This resistance plate 104 has flanges 1f' on both sides.
The resistance plate 104 is in electrical contact with the metal flange 2a of the spacer 2, and has a resistance value of 601Ω or more in the thickness direction, and a resistance value of 1.0Ω per 1M of thickness.
It should be 5Ω or less.

In such a configuration, the resistance plate 104 has seven flange 1f'
and 28 are connected at the shortest distance, so there is no inductance. Therefore, no matter what kind of high-frequency surge propagates, this surge always flows inside the resistance plate 104. Therefore, the surge is attenuated by the resistive plate 104, making it possible to suppress the occurrence of secondary surges.

Next, the values of the alternating current and steep wave surge current flowing through this resistance plate 104 will be considered. For alternating current voltages, the inductance of the grounding wires 15a, 15b exhibits only a small resistance value. For example, if the length of these rising lines is 1 m, each line will have approximately 1 μH, and two lines will have a length of 2 μH. For an alternating current of 50H2, the impedance of this inductance is 2π JL-0,6[-Ω]. Therefore, if the resistance value of the resistance plate 104 is set to 60-Ω or more, the current flowing through the ground metal container 11 is 1% or less of the current flowing through the ground mesh 14 or the ground riser wires 15a and 15b, which is a value that does not cause any problem. For example, if a fault current of 60 kA flows, the grounded metal container 1 has a fault current of 600 A or less! Only the sink flows, resistance plate 1
The terminal voltage of 04 is 36V or less, and there is no safety problem.

For steep surges, the grounding lines 15a and 15b exhibit very large impedance, and most of the current flows through the resistor plate 104. Generally, the maximum surge voltage generated inside gas-insulated equipment is considered to be about twice the peak value. Therefore, in a 275kV system, a surge of about 300kV can occur. The characteristic impedance of gas insulated equipment is 7
Since it is 00~80Ω, surge 1! The flow becomes. When this current flows through the resistance plate 104, if the resistance value per 1jw length of the resistance plate 104 is set to 1.5Ω or less, the voltage per 1slI becomes 6.48kV or less.

From an experiment using a protrusion, the voltage intensity per meter was 6.5.
Since it is known that dielectric breakdown occurs when the voltage exceeds kV, it is impossible for dielectric breakdown to occur at both ends of this resistance plate 104. Therefore, all the surge current flows inside the resistor plate 104 and is attenuated there, and at the same time, there is no fear of the formation of a secondary surge source due to external dielectric breakdown.

As mentioned above, almost no alternating current flows through the grounded metal container of gas-insulated equipment, and all steep wave surges propagating inside gas-insulated equipment flow through the resistor plate and are efficiently attenuated. No external discharge occurs due to the terminal voltage of , and there is no source of secondary surges. Therefore, it is possible to provide a highly reliable gas insulated switchgear that is not dangerous to the human body, does not cause pollution such as radio wave interference, and does not cause destruction of the low voltage suppression circuit.

Furthermore, since the resistance plate 104 is housed inside the flanges 2a and 1f', it naturally looks good from the outside. If the resistance plate 104 is made of an elastic material such as conductive rubber, there will be no gap between the flanges 2a and 1f' and a completely sealed structure can be achieved, so there is no need to worry about rain getting in. The problem of rust and the problem of electrical contact of the resistance plate 104 can also be solved at the same time.

Further, in the above invention, the same effect can be obtained even if a nonlinear resistor is used instead of the resistor plate 104. At this time, the best performance can be obtained by using a high-performance nonlinear resistor such as a zinc oxide element, but there is no problem with a nonlinear resistor such as silicon oxide.

In this case, the characteristic voltage of the nonlinear resistor (terminal voltage when a current of 1 A flows) is 7.2 V or more, and the thickness is 1 jw +
It is desirable to use a nonlinear resistor that has a characteristic voltage of 6.5 kV or less. At the currently used maximum rated current of 12 kA, a voltage of 7.2 V is generated at the impedance of the grounding line of 0.6 IQ.
If the characteristic voltage of the nonlinear resistor is kept above this value, the alternating current can be completely cut off. Also, 6 per 1 jll thickness
．． If the characteristic voltage is set to 5 mV or less, external dielectric breakdown will not occur for the reason mentioned above.

Here, the embodiment has been explained using a single-phase bus, but
The effect is exactly the same in a three-phase collective bus.

[Effects of the Invention] As explained above, according to the present invention, it is possible to effectively prevent alternating current from flowing into a grounded metal container, and to prevent steep wave surges generated in gas-insulated equipment from being induced into the grounding system. It is possible to provide a gas-insulated switchgear that is safe, has no ineffective damage, and has high reliability.

[Brief explanation of drawings]

FIG. 1 is a front cross-sectional view showing one embodiment of the present invention, FIG. 2 is an equivalent circuit diagram for explaining the present invention in detail, and FIGS. Front sectional views showing other embodiments of the invention, FIGS. 7 and 8 are diagrams for explaining conventional examples. 1...Grounded metal container, 1f, if'...flange,
2... Spacer, 2a... Metal 7 flange of spacer, 3... Insulating gas, 4a, 4b... Fixed electrode, 5a
, 5b... Contact, 6... Movable electrode, 7... Resistor, 8... Arc contact, 9... Operating rod, 10...
...Operating mechanism, 11...High voltage center conductor, 12...
Connection electrode, 1Q'l, 101a...Resistor, 102.
...Cylindrical structure made of magnetic material, 103...Magnetic material structure having a resistance value, 104-...Resistance plate. Applicant's agent Patent attorney Shikihiko Suzutsutsu Figure 2

Claims (2)

[Claims] (1) In a gas-insulated switchgear in which a high-voltage conductor is insulated and held in a grounded metal container together with an insulating gas, a resistor for forming an induced current flow path is provided surrounding the high-voltage conductor in the grounded metal container. A gas insulated switchgear characterized in that this resistor is also grounded. (2) In a gas-insulated switchgear in which a high-voltage conductor is insulated and held in a grounded metal container together with an insulating gas, an insulating spacer is placed between the flanges of the grounded metal container and holds the high-voltage conductor within the grounded metal container. A gas insulated switchgear characterized in that a resistor is provided in the flange-held portion of the grounded metal container to form an electric path between the flanges of the grounded metal container.