JPS61227326A - 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 the Invention] The present invention relates to a gas insulated switchgear, and particularly to a gas insulated switchgear with improved insulation performance.

[Technical background of the invention]

Gas insulated switchgear (hereinafter referred to as GIS) has come into use for the purpose of downsizing, reducing noise, and improving stain resistance of substation equipment and switchgear equipment. Gas insulated switchgear (hereinafter referred to as GIS) has been used to simplify maintenance and improve aesthetic appearance. There are some notable ones.

In recent years, with plans to introduce 500kV class substations in urban areas taking shape, further downsizing of GIS through rational design that makes full use of various analysis techniques and accumulated basic test data has begun to be considered. .

The major factors that determine the dimensions of each component of a GIS include insulation performance, current carrying performance, mechanical strength, etc., but insulation performance is the most dominant factor in determining the dimensions of equipment.

Conventionally, the insulation design of equipment has been based on the lightning impulse withstand voltage value (hereinafter referred to as L).
(referred to as IWL). In addition, L
IWL is specified for each rated voltage, and in Japan it is specified by the Institute of Electrical Engineers of Japan Electrical Standards Committee Standards (hereinafter referred to as JEC).

Therefore, when planning, please follow the L IWL specified by JEC.
The dimensions of each part of the device are determined so that when GIS is applied to the high voltage conductor of the GIS, the electric field value in each part of the GIS@device is below the allowable value EC. The allowable value EC is usually given by the following equation.

EC=Esa ・(1-3(n ・k−・・・・(
1) where Esa is the 50% breakdown electric field of SFsF2 gas edge gas) for the lightning impulse, and k is a constant. What is the 50% breakdown electric field? oEsn is the center value of the probability distribution of the breakdown electric field.
s As a function of gas pressure (absolute pressure) Es 11-63P+25 (kV/a)"" (2)
It is given in However, P is gas pressure.

Next, σ is the standard deviation when it is assumed that the probability distribution of the breakdown electric field follows a normal distribution, and the meaning of multiplying by (1-3σ) is the electric field where the probability of discharge is 0.14%, that is, the discharge occurs first. The purpose is to calculate a fear-free electric field. For reference, the relationship between Esa, standard deviation σ, etc. is shown in FIG. Further, k is a coefficient when considering surface roughness/area effects and design considerations. As an example, gas pressure is 4.5 IC! I/1i-abs, σ-10%.

If k-0.95, then E c -205k V/c11 (3). The insulation design of gas insulated switchgear is generally LI'WL.
On the other hand, it has been considered that the electric field stress Eu in each part should be made equal to or less than the value of EC. However, the above L IW
If equipment is designed based on the permissible electric field value EC for lightning impulses at L, the following problems will occur.

In other words, in a voltage class (for example, insulation class 500' in the 500kV class) where the impulse ratio (LIWL/normal ground operating voltage) (hereinafter referred to as ACwork) is small, the ACwork is 318kVrmsr for LIWL 15501V, and the impulse ratio is (1550/ 3
18) -4,87, and this value is about half of the impulse ratio of 9.19 (350/38.1) in the 66kV class), the electric field value of each part for LIWL is If it is designed to be less than EC, the impulse ratio will be small, so the operating electric field (hereinafter referred to as [:work) will conversely become high. In the GIS, metal foreign objects that were generated or remained on the inner surface of the grounded metal container during the equipment assembly stage are floated to the surface by the electric force generated by EWOrk. It is known that there is a reciprocating operation between the voltage conductor and the metal container.During this reciprocating movement of the metal foreign object,
Lightning strikes a high-voltage conductor, especially at the moment it approaches the high-voltage conductor.
System failure, breaker.

When a voltage such as a surge generated by opening and closing a new circuit device is applied, the electric field around this foreign object increases significantly due to the presence of the foreign object, and the discharge between the metal foreign object and the high voltage conductor is triggered, causing the high voltage conductor to This can lead to insulation breakdown between grounded metal containers, causing a ground fault and preventing smooth operation of the system.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to suppress the behavior of foreign matter remaining inside a metal container, and to improve the insulation performance of gas-insulated switchgear when various surge voltages are applied. The object of the present invention is to provide a gas-insulated switchgear with improved reliability.

[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, in which the normal ground voltage of the system is applied to the high-voltage conductor. The distance from the high voltage conductor is set so that the electric field value at the inner surface of the grounded metal container is 10 kV/cm or less. Further, when the electric field value is 10 kV/a1 or more,
The method is characterized in that an insulating layer is formed in a region where the electric field value on the inner surface of the grounded metal container is 10 kV/m or more.

That is, focusing on the fact that the electric field strength at which the residual foreign matter in the grounded metal container moves due to the electric field is 10 kV/a1 or more, the electric field strength in the grounded metal container is 10 kV/cs+.
The purpose is to improve insulation performance by ensuring that the temperature does not exceed .

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. 1st
Figure (a) shows a coaxial cylindrical single-phase busbar in which a high voltage conductor 11 is arranged at the center of a grounded metal container 10 as shown in FIG.
When the outer diameter of the high voltage conductor is changed by φn, the electric field E1 on the surface of the high voltage conductor when LIWL is applied to the high voltage conductor and the inner surface of the metal container when the normal ground voltage is applied to the high voltage conductor. This is the result of calculating the electric field E2. This relationship applies to the conventional single-phase bus insulation design for each rated GIS from insulation stage No. 160 to No. 500 L/S.

As can be seen from the figure, El decreases as the high voltage conductor outer diameter φn increases, but reaches its minimum at φi/φn-e (where e is the base of the natural logarithm -2,71828-...) After that, it rises again. Furthermore, Et increases as the high voltage conductor outer diameter φn increases. Therefore, as shown in FIG. 3, the graph of <El intersects the allowable electric field value Ec on the surface of the high voltage conductor at two places, and E! For ≦EC, φ1≦φn≦φ
It turns out that it has to be 3. Regarding Et, it is assumed that metals that may be generated or remain in industrial GIS are present at the bottom of a grounded metal container, and as described below, this metal foreign material may rise, float, or touch the high voltage conductor and the metal container. The allowable electric field value Et on the inner surface of the metal container is determined from the electric field value crossing between
can be determined.

This graph of Et shows the allowable electric field value Et on the inner surface of the metal container and 1
They intersect at two places, and in order for E2≦Et to hold, φn≦φ2 must hold. In general GIS, φ1≦φ
Since 2≦φ3, the outer diameter of the high voltage conductor is required to satisfy φ1≦φn≦φ2 in order to prevent the insulation performance of the device from deteriorating.

This will be explained in more detail by giving a specific example.

Considering 500kV class equipment, LIWL 1550kV
ACwork55015-318kV as φn-5
Figure 2 (a) shows the results of calculations similar to those in Figure 1 for 00,600,700°8001m. :show. (Figure 2(b) is similar to Figure 1(b)
') is the same figure. ) The allowable electric field on the surface of the high voltage conductor is 205 kV/cm as mentioned in the technical background of the invention. Also, consider the allowable electric field inside the metal container as follows.
EPRI paper tnbestegatpon of
high-volt'age particle-1
nitiataed breakdown l n
According to SFa, if a metal foreign object exists in a GIS metal container, the electric field strength on the inner surface of the metal container will be 6 kVrms.
/cm, foreign matter will stand up, 12kVrms/1:
It can be interpreted that when it exceeds lI, it starts to float and run.

Moreover, this value is almost independent of gas pressure. Therefore, if the electric field on the inner surface of the metal container is suppressed to about 10 kVrmS/aR, the foreign objects inside the metal container will only stand up, but will not levitate or travel, and there will be almost no deterioration in insulation performance when a surge voltage is applied. Conceivable. Therefore,
Et is approximately 10 kVrms/cm. Considering the case where the inner diameter φ of the metal container is φ1-700m, El
The range of the outer diameter φn of the high voltage conductor in the metal container where <EC is 63 seconds and φo <525 mm.

On the other hand, when ACWOrk is applied, φ becomes Et<Et.
The range of n is φn<284am. Therefore, in terms of insulation performance, the range of high voltage conductor outer diameter φn that does not cause problems is 63 mm.
It can be seen that n<284 rin. Therefore, the above t! The outer diameter φn of the high voltage conductor may be determined by considering the temperature rise at the rated N current, the size of the supporting insulator, etc.

Also, considering the case where the inner diameter of the metal container is φs -500nV, the range of φn where Er < EC is 86j
Il<φn<304am. On the other hand, ACWOr
The range of φn where E2<Et when k is applied is φn<140
It's Maro. Therefore, the range of φn that does not cause problems in terms of insulation performance is 8
It can be seen that 6 shoes are φn<140 shoes.

As stated above, φ1. By selecting a combination of φn, it is possible to provide an excellent gas insulated switchgear with no worries in terms of insulation performance.

Next, various studies have revealed that when an insulating coating is provided on the inner surface of a metal container, the electric field for standing up, floating, and traveling electric fields for metallic foreign objects on the surface of the metal container becomes higher than when no coating is provided. Ta. This is because the insulating coating suppresses the mechanism of charge transfer between the metal container and the metal foreign object.

Therefore, by providing an insulating film, temporarily.

If Et increases by 20%, it will be allowable up to 1:work-12kV/cII. In other words, if φi=700m, φ is 328
This expands the range of conductor size selection. This can be an advantage in equipment design.

Furthermore, in the gas insulated switch 20 as shown in FIG. , the part facing the above shield (
In the part indicated by the symbol A in the figure), the electric field becomes high because the insulation distance is short. In a device having such a configuration, it is possible to improve the insulation performance of the device by providing an insulating coating only in the region A.

Furthermore, since the metal foreign matter exists on the bottom surface of the metal container, the insulating coating is applied only to the region 8 below the approximately horizontal plane passing through the central axis of the metal container 31, as shown in FIG. It is sufficient if it is provided. Further, it can be expected that the effect will be achieved even in the lower range C of 90@. Furthermore, by combining the parts to be used as necessary, it becomes possible to rationalize the system design of the switchgear. For example, equipment originally designed with a current rating of 11 may be changed to a current rating of 12 (12
When it becomes necessary to increase the capacity to >11> and the increased current rating I2 cannot be energized as it is, the following measures can be taken. In other words, the general approach is to use the metal container as is and increase the diameter of the high voltage conductor in consideration of economic efficiency. At this time, due to the increased conductor diameter, the electric field on the surface of the metal container
When k exceeds Et, an insulating coating is provided on the inner surface of the metal container, thereby suppressing the behavior of metal foreign matter and preventing a decrease in insulation performance.

As a method for forming the insulating wire coating, a method of applying an insulating paint or a method of pasting an insulating film can be considered. When applying a paint, it is desirable that the thickness of the insulating paint film be approximately 30 μm or more so as not to completely expose the metal base.

As described above, 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, and in which a high-voltage conductor is insulated and held in a grounded metal container. The electric field value at the inner surface is 10k
The distance to the high voltage conductor is set so that the voltage is V/ca+ or less, and the electric field value is 10 kV/c.
m or more, an insulating layer is formed in a region where the electric field value on the inner surface of the grounded metal container is 10 kV/cm or more.

In other words, focusing on the fact that the electric field strength at which the residual foreign matter inside the grounded metal container moves due to the electric field is 10 kV/cIR or more, the electric field strength inside the grounded metal container is 10 kV/cI.
This makes it possible to prevent foreign objects inside the grounded metal container from floating or moving, thereby significantly improving insulation performance.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a gas insulated switchgear with excellent insulation performance and reliability, which does not cause a decrease in insulation performance even if metal foreign matter is present inside the switchgear. .

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a diagram for explaining a specific example, and FIGS. 3 and 4 are diagrams for explaining another embodiment of the present invention. , FIG. 5 is a probability distribution diagram of the SFs gas breakdown electric field of lightning impulse. 10.26.31... Metal container, 11.25.32... High voltage conductor, 21... Fixed contact, 22... Shield, 23... Movable contact, 2
4...Insulating spacer. Applicant's agent Patent attorney Shikihiko Suzushi (b) (mm) Figure 3 Figure 4

Claims (5)

[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, the inner surface of the grounded metal container when the normal ground voltage of the system is applied to the high-voltage conductor. A gas insulated switchgear characterized in that a distance from the high voltage conductor is set so that an electric field value is 10 kV/cm or less. (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, the inner surface of the grounded metal container when the normal ground voltage of the system is applied to the high-voltage conductor. A gas insulated switchgear characterized in that an insulating layer is formed on the inner surface of the grounded metal container when an electric field value exceeds 10 kV/cm. (3) The insulating layer has an electric field value of 10 kV on the inner surface of the grounded metal container.
3. The gas insulated switchgear according to claim 2, wherein the gas insulated switchgear is formed in an area exceeding /cm. (4) The gas insulated switchgear according to claim 2, wherein the insulating layer has a thickness of 30 μm or more. (5) The gas insulated switchgear according to claim 2, wherein the insulating layer is formed in a region below a substantially horizontal plane passing through the central axis of the grounded metal container.