JP2020120463A - Gas insulation switchgear and method for manufacturing the same - Google Patents

Abstract

To maintain high dielectric strength by surely suppressing floating of metallic foreign substances generated inside a gas insulation switchgear and adhering to an inner surface of a tank.SOLUTION: A gas insulation switchgear has a grounded tank and a high voltage conductor installed inside the tank and insulated therefrom. On an inner surface of the tank, a resin layer having a configuration in which a plurality of kinds of nonlinear resistance materials are mixed in resin is formed. A first nonlinear resistance material that is at least one kind of nonlinear resistance material out of a plurality of kinds of nonlinear resistance materials has higher operating electric field than a second nonlinear resistor material that is the other nonlinear resistor material of at least one kind out of the plurality of kinds of nonlinear resistor materials and a slope of a nonlinear characteristic curve significantly increases in a range of an electric field higher than the operating electric field.SELECTED DRAWING: Figure 2

Description

The present invention relates to a gas insulated switchgear and a method for manufacturing the same.

In the gas insulated switchgear, main circuit devices such as a power receiving disconnector, a circuit breaker, and a busbar disconnecting switch are housed in a hermetically sealed container in which an insulating gas such as sulfur hexafluoride (SF ₆ ) is sealed. The respective devices are connected by a main circuit conductor. The main circuit conductor is supported in the gas by an insulator installed in the container, and maintains insulation between the main circuit conductor and the closed container having the ground potential.

In the gas-insulated switchgear for power reception, electric power is drawn from the power system by a power cable or an overhead line, and power is supplied to the busbar via the power disconnector-circuit breaker-busbar disconnector. Further, in the case of a gas-insulated switchgear for power supply, power is received from a bus bar and power is supplied to a power cable or an overhead line connected to a load via the bus bar disconnector-circuit breaker-power supply disconnector. A gas-insulated switchgear that configures one bay with three phases as one line and a gas-insulated switchgear that configures an adjacent one bay are electrically connected by a bus bar.

In a gas insulated switchgear having an airtight container enclosing an insulating gas, and a main circuit conductor housed inside the airtight container, by forming a resin layer containing a non-linear resistance material on the inner surface of the airtight container. It has been studied to solve the problem that a high electric field is generated around a metal foreign substance generated inside a closed container and the metal foreign substance floats.

In Patent Document 1, a grounding tank filled with an insulating gas, a central conductor arranged inside the grounding tank, and a lower inner surface of the grounding tank are arranged. The insulating material contains a non-linear resistance material. And a non-linear resistance part, wherein the non-linear resistance part contains more non-linear resistance material on the center conductor side than on the ground tank side. It is described in this document that the above-described configuration produces an effect that it is possible to suppress the partial discharge around the metallic foreign matter mixed in the ground tank, and also to suppress the charge inflow from the ground tank to the metallic foreign matter. ..

International Publication No. 2015/136753

The high electric field around the metallic foreign matter generated inside the closed container of the gas insulated switchgear and the floating of the metallic foreign matter lead to the generation of corona discharge or streamer discharge inside the closed container, and the reduction of the dielectric strength.

In Patent Document 1, electric field-conductivity characteristics that differ depending on the type of nonlinear resistance material have not been sufficiently investigated.

A material having a low electric field exhibiting non-linearity has a gentle increase rate of conductivity, a small relaxation effect in a high electric field region, and a partial discharge easily occurs. Further, a material having a steep increase rate of conductivity has a relatively high electric field in which non-linearity appears, and has a small mitigation effect when the electric field is low, resulting in large variation in suppression of partial discharge.

An object of the present invention is to reliably suppress the floating of metallic foreign matters that are generated inside the gas insulated switchgear and adhere to the inner surface of the tank, and maintain a high dielectric strength.

The gas-insulated switchgear of the present invention has a grounded tank, and a high-voltage conductor installed inside the tank and insulated from the tank. A first non-linear resistance material, which is a non-linear resistance material of at least one kind among plural kinds of non-linear resistance materials, in which a resin layer having a structure in which resistance materials are mixed is formed, The second non-linear resistance material, which is another kind of non-linear resistance material, has a higher operating electric field and a larger slope of the non-linear characteristic curve in the electric field range higher than the operating electric field.

ADVANTAGE OF THE INVENTION According to this invention, the floating of the metal foreign material which generate|occur|produces inside a gas insulated switchgear and adheres to the inner surface of a tank can be suppressed reliably, and high dielectric strength can be maintained.

It is a fragmentary sectional view showing the whole gas insulated switchgear of the present invention. It is a schematic cross section which shows a part of tank of the gas insulated switchgear of this invention. It is sectional drawing which shows the example of arrangement|positioning of the resin layer 53 of FIG. It is a graph which shows the electric field-electric conductivity characteristic of zinc oxide which is a nonlinear resistance material. It is a graph which shows the electric field-conductivity characteristic of silicon carbide which is a nonlinear resistance material. It is a graph which shows an electric field-conductivity characteristic at the time of mixing two types of nonlinear resistance materials. It is a graph which shows an electric field-conductivity characteristic when the amount of addition of a nonlinear resistance material is made into a parameter. It is a graph which shows the result of the levitation test at the time of installing a metallic foreign substance in a tank. It is a flowchart which shows an example of the formation process of the resin layer of this invention.

TECHNICAL FIELD The present invention relates to a coating technology inside a tank of a gas-insulated switchgear, and more specifically, a circuit breaker and a disconnector installed in a gas-insulated hermetic container, and a power receiving unit for receiving power from a power system, and a circuit breaker and a disconnector. The present invention relates to coating of a non-linear resistance material inside a tank used in a gas insulated switchgear having a power supply unit that is installed in an insulating container and supplies power to a load side via a bus bar.

Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is a partial cross-sectional view showing the overall configuration of the gas insulated switchgear of the present invention.

In the figure, a gas-insulated switchgear 100 includes a ground tank 2 (hereinafter also simply referred to as “tank”) filled with an insulating gas (SF ₆ or the like) and a high-voltage conductor provided inside the ground tank 2. 1 and an insulating spacer 30 (hereinafter, also simply referred to as “spacer”) that supports and fixes the high-voltage conductor 1 inside the ground tank 2. In addition, the gas-insulated switchgear 100 includes a circuit breaker 20, a disconnector 21, a ground switch 22, a current transformer 23, a transformer 24, busbars 25, 26, and the like. Dry air is also used as the insulating gas filled in the tank.

The high-voltage conductor 1 is formed of a cylindrical metal (aluminum, copper, etc.). The grounding tank 2 is a cylindrical metal container. The high voltage conductor 1 is supported and fixed by an insulating spacer 30 inside the ground tank 2 and is insulated from the ground tank 2. Since the ground tank 2 is grounded, the potential is normally 0.

In this figure, a cone type (cone spacer) is shown as the insulating spacer 30, but other than this, there are various shapes such as a disk-shaped spacer and a columnar post spacer.

FIG. 2 is a schematic cross-sectional view showing a part of the tank of the gas insulated switchgear of the present invention.

As shown in the figure, a resin layer 53 is provided on the inner surface of the tank wall 51. The resin layer 53 is formed by coating a mixture of epoxy resin or the like with the nonlinear resistance materials 121 and 122 added and mixed. As the nonlinear resistance materials 121 and 122, zinc oxide (ZnO), silicon carbide (SiC), barium titanate (BaTiO ₃ ), diamond or the like is used.

That is, in the present invention, the nonlinear resistance materials 121 and 122 are in the form of particles and are composed of two or more kinds having different compositions.

Note that foreign matter 54 (metallic foreign matter) may adhere to the inner surface of the tank wall 51.

FIG. 3 is a cross-sectional view showing an example of the arrangement of the resin layer 53 of FIG.

In this figure, the resin layer 53 is provided in the lower half region of the inner surface of the tank wall 51. A resin (epoxy resin or the like) containing no nonlinear resistance material is applied to the upper half region of the inner surface of the tank wall 51 to form a resin layer 131 (insulating resin layer). Since the foreign metal particles often fall downward due to gravity, it is often sufficient to provide the resin layer 53 in the lower half region. Further, by partially providing the resin layer 53 in this manner, the manufacturing cost can be suppressed.

Of course, the resin layer 53 may also be provided in the upper half region of the inner surface of the tank wall 51. In some cases, the resin layer 53 may be provided in the entire area of the lower half and a part of the area of the upper half. It is desirable that the resin layer 53 be provided in at least the entire lower half region.

Next, the function and effect of the resin layer 53 including the nonlinear resistance materials 121 and 122 will be described with reference to FIG.

When the foreign matter 54 (metal foreign matter) is generated inside the tank, the electric field is concentrated in the vicinity of the foreign matter 54 and becomes a high electric field. When the electric field to the nonlinear resistance materials 121 and 122 in this range rises, the electrical conductivity of the nonlinear resistance materials 121 and 122 increases, which is equivalent to electrically expanding the size of the tip of the foreign matter 54, and the foreign matter 54. Electric field concentration in the vicinity is reduced. This relaxation improves the dielectric strength when the foreign matter 54 is attached.

The thickness of the resin layer 53 is preferably 50 μm or more. In addition, the thickness of the resin layer 53 is preferably 1 mm or less, more preferably 200 μm or less from the viewpoints of the dimensions in the tank, material costs, and the like.

Examples will be described below.

FIG. 4 is a graph showing electric field-conductivity characteristics of zinc oxide, which is an example of a nonlinear resistance material. The horizontal axis represents the electric field and the vertical axis represents the conductivity. The concentration of zinc oxide in the resin layer is 10% by mass.

As shown in this figure, zinc oxide has a non-linear electric field-conductivity characteristic (non-linear characteristic). In the case of zinc oxide, the electric field where the steep rise of the electric field-conductivity curve starts (hereinafter referred to as “operating electric field”) is about 7 kV/mm. That is, in the case of zinc oxide, when the electric field becomes about 7 kV/mm, the slope of the nonlinear characteristic curve (hereinafter, also simply referred to as “curve”) becomes steep, the curve rises, and the conductivity sharply rises.

As an example of a more strict definition of the “operating electric field”, a value of the electric field at which the rate of change in the slope of the curve (second derivative) starts to increase above a predetermined value may be used. In this case, the operating electric field can be calculated by expressing the approximate expression of the curve by a Taylor polynomial of third or higher order and calculating the second derivative.

The operating electric field changes depending on not only the type of the nonlinear resistance material but also the concentration of the nonlinear resistance material in the resin. Therefore, when comparing operating electric fields for different types of non-linear resistance materials, in the present specification, non-linear characteristic curves measured at the same concentration on the mass basis and mixed with the same resin will be compared. .. Therefore, it can be expressed that the first nonlinear resistance material has a higher operating electric field than the second nonlinear resistance material, and that the slope of the nonlinear characteristic curve is large in the range of the electric field higher than the operating electric field.

FIG. 5 is a graph showing electric field-conductivity characteristics of silicon carbide, which is a nonlinear resistance material. The concentration of silicon carbide in the resin layer is 10% by mass.

As shown in the figure, in the case of silicon carbide, the operating electric field is low and the slope of the curve is relatively gentle. The rise of the curve (operating electric field) is about 4 kV/mm, and the slope of the curve becomes gentle at about 8 kV/mm or more.

FIG. 6 is a graph showing electric field-conductivity characteristics when two types of nonlinear resistance materials are mixed. The zinc oxide concentration in the resin layer is 10% by mass, and the silicon carbide concentration is 10% by mass.

In this figure, due to the action of silicon carbide having a low operating electric field, the slope of the curve starts to increase at about 4 kV/mm, and further increases at about 7 kV/mm or more.

As a result, the electric field around the foreign matter is relaxed from the state where the applied voltage is low. Further, a sufficient electric field relaxation effect can be obtained at high voltage. Since the operating electric field is lowered, the variation in electric field relaxation is reduced, and the floating of foreign matter at a low voltage can be prevented. Further, since the slope of the non-linear characteristic curve becomes large, the electric field relaxation effect at a high voltage becomes large, partial discharge can be prevented, and the floating electric field of foreign matter can be increased.

The resin (coating material) containing the non-linear resistance material is applied to the inner surface of the tank wall 51 by spray coating or brush coating.

In summary, from FIGS. 4 and 5, the first non-linear resistance material, zinc oxide, has a higher operating electric field than the second non-linear resistance material, silicon carbide, and is non-linear in the electric field range higher than the operating electric field. It can be said that the slope of the characteristic curve is large. The curve of FIG. 6 has a shape in which the curves of FIGS. 4 and 5 are superposed. Therefore, an appropriate conductivity and operating electric field can be obtained.

The operating electric field of the resin layer of this example is preferably 3 kV/mm or more. This is because if the operating electric field is too low, the insulating function of the resin layer will be insufficient. The operating electric field of the resin layer of this example is preferably 5 kV/mm or less. The operating electric field of the resin layer corresponds to the desired range of the operating electric field of the second nonlinear resistance material.

FIG. 7 is a graph showing electric field-conductivity characteristics when the addition amount of the nonlinear resistance material is used as a parameter.

In this figure, zinc oxide and silicon carbide are added so that the concentrations in the resin layer are equal, and the respective concentrations are 5% by mass, 10% by mass, and 15% by mass. That is, when the concentration of zinc oxide is 5% by mass and the concentration of silicon carbide is 5% by mass (each 5% by mass), the concentration of zinc oxide is 10% by mass and the concentration of silicon carbide is 10% by mass ( 10% by mass), the concentration of zinc oxide is 15% by mass, and the concentration of silicon carbide is 15% by mass (15% by mass each).

As shown in this figure, the electric field-conductivity characteristic of the coating material changes depending on the addition amount of the nonlinear resistance material. Specifically, the start of the rising of the curve (operating electric field) is about 7 kV/mm for each 5 mass %, about 5 kV/mm for each 10 mass %, and about 4 kV/mm for each 15 mass %.

Therefore, when the amount of the non-linear resistance material added is small and the foreign matter is present on the inner surface of the tank wall, the electric conductivity may not be sufficiently increased when the electric field is concentrated, and the electric field may not be relaxed.

In order to solve the above problems, the total addition amount of a plurality of types of non-linear resistance materials is in the range of 5% by mass to 50% by mass, the electric field relaxation effect, the electric field-conductivity characteristic, and the viscosity of the coating material in the coating operation. Is preferred. The addition amount of the nonlinear resistance material is more preferably in the range of 5% by mass to 20% by mass, and particularly preferably in the range of 5% by mass to 15% by mass.

Further, the mixing ratio of the non-linear resistance material having a low operating electric field (eg, silicon carbide) and the non-linear resistance material having a high operating electric field (eg, zinc oxide) is between 1:4 and 4:1. It is preferable because it has characteristics and an electric field relaxation effect occurs around the foreign matter. This mixing ratio is more preferably 1:3 to 3:1, and particularly preferably 1:2 to 2:1.

FIG. 8 is a graph showing the results of the levitation test when the metallic foreign matter is installed in the tank. The vertical axis represents the relative value of the breakdown voltage. Here, the breakdown voltage means a voltage at which the metallic foreign matter floats up under a predetermined condition. This voltage is also called a metal foreign matter levitating voltage.

In this figure, when the inner surface of the tank wall is a metal surface (without coating), the value of the floating electric field of the foreign matter is 1.0. When coated with an insulating film made of only resin (resin coating), the floating electric field has an average value of about 1.3 and a variation of about 20%.

When a coating material containing zinc oxide alone is applied (non-linear resistance material coating (single body)), the average value is as high as about 1.5, but the variation is about 20%, which is equivalent to the resin coating.

On the other hand, when the coating material containing two types of non-linear resistance materials (zinc oxide and silicon carbide) according to the present embodiment is applied (non-linear resistance material coating (mixing)), the average value of the levitation electric field is 1 6 or more, and the variation is as small as about 5%. This means that the smaller the variation is, the higher the average value is, and the floating of the metallic foreign matter does not occur at a low voltage. As a result, even if the metallic foreign matter is present inside the tank, the floating of the metallic foreign matter can be restricted and a high dielectric strength can be maintained.

When two types of non-linear resistance materials are divided into one type and a coating material is applied and applied to the inner surface of the tank, and two resin layers are stacked, the non-linear resistance that contacts metal foreign matter Since it is strongly influenced by the characteristics of the material, the effect of this embodiment cannot be obtained.

FIG. 9 is a flow chart showing an example of a step of forming the resin layer of the present invention.

As shown in the figure, first, a surface treatment agent and a non-linear resistance material are mixed (S101). This mixture is added to the resin (S102). This is stirred (S103). As a result, the non-linear resistance material is prevented from agglomerating, and the non-linear resistance material is uniformly dispersed in the coating material. A silane coupling agent is an example of the surface treatment agent. Further, in step S102 or S103, a resin curing agent is also mixed.

The coating material after stirring is applied to the inner surface of the tank wall by a spray gun (S104). The applied coating material is cured under predetermined conditions (S105).

By using the surface treatment agent in step S101, the non-linear resistance material is uniformly dispersed in the resin after the stirring in step S103. Therefore, in the range where the coating material is applied, the electric field relaxation effect around the metallic foreign matter is effective. As a result, the effect of improving the floating electric field of the metallic foreign matter is stabilized. The addition amount of the surface treatment agent is preferably in the range of 0.1% by mass to 5% by mass.

The above-mentioned coating material may be applied to the inner surface of the tank as an undercoat of an insulating resin alone containing no non-linear resistance material, and then to the application surface. In this case, it is desirable to undercoat the insulating resin alone, then cure it once, and then apply the coating material to the application surface. As a result, the insulating resin layer formed by undercoating prevents the charge from being charged from the tank to the foreign matter, and the resin layer containing the non-linear resistance material can alleviate electric field concentration and suppress partial discharge.

The thickness of the insulating resin layer is preferably 30 μm or more. The thickness of the resin layer (coating layer) containing the nonlinear resistance material is preferably 50 μm or more. The thickness of each of these layers is preferably 1 mm or less, more preferably 200 μm or less, from the viewpoints of the dimensions in the tank, material costs, and the like. This upper limit is the same for the coating layer alone.

1: high-voltage conductor, 2: ground tank, 20: circuit breaker, 21: disconnector, 22: ground switch, 23: current transformer, 24: transformer, 25, 26: busbar, 30: insulating spacer, 51 : Tank wall, 53: resin layer, 54: foreign matter, 100: gas insulated switchgear, 121, 122: non-linear resistance material, 131: resin layer.

Claims (26)

A grounded tank,
A high-voltage conductor installed inside the tank and insulated from the tank,
On the inner surface of the tank, a resin layer having a configuration in which a plurality of types of nonlinear resistance materials are mixed with resin is formed,
The first non-linear resistance material, which is at least one non-linear resistance material among the plurality of non-linear resistance materials, is the second non-linear resistance material, which is at least one other non-linear resistance material among the plurality of non-linear resistance materials. A gas-insulated switchgear having an operating electric field higher than that of the resistance material, and having a larger slope of the nonlinear characteristic curve in the electric field range higher than the operating electric field. The gas-insulated switchgear according to claim 1, wherein the total amount of addition of the plurality of types of nonlinear resistance materials is in the range of 5% by mass to 50% by mass. The gas insulated switchgear according to claim 2, wherein a mixing ratio of the first nonlinear resistance material and the second nonlinear resistance material is in a range of 1:4 to 4:1. The gas-insulated switchgear according to claim 1, wherein the resin layer contains a surface treatment agent. The gas-insulated switchgear according to claim 4, wherein the amount of the surface treatment agent added is in the range of 0.1% by mass to 5% by mass. The gas insulated switchgear according to claim 1, wherein the resin layer has a thickness of 50 μm or more and 1 mm or less. The gas-insulated switchgear according to claim 1, wherein an insulating resin layer containing no nonlinear resistance material is provided between the inner surface of the tank and the resin layer. The gas-insulated switchgear according to claim 7, wherein the insulating resin layer has a thickness of 30 μm or more and 1 mm or less. The gas insulated switchgear according to claim 8, wherein the resin layer has a thickness of 50 μm or more and 1 mm or less. The gas insulated switchgear according to claim 1, wherein the non-linear resistance material is two or more kinds selected from the group consisting of zinc oxide, silicon carbide, barium titanate and diamond. The first nonlinear resistance material is zinc oxide,
The gas insulated switchgear according to claim 1, wherein the second non-linear resistance material is silicon carbide. The gas insulated switchgear according to claim 1, wherein the operating electric field of the second nonlinear resistance material is 3 kV/mm or more and 5 kV/mm or less. The gas insulated switchgear according to claim 1, wherein the resin layer is formed in at least a lower half region of the inner surface of the tank. A grounded tank,
A high-voltage conductor installed inside the tank and insulated from the tank,
On the inner surface of the tank, a resin layer having a configuration in which a plurality of types of nonlinear resistance materials are mixed with resin is formed,
The first non-linear resistance material, which is at least one non-linear resistance material among the plurality of non-linear resistance materials, is the second non-linear resistance material, which is at least one other non-linear resistance material among the plurality of non-linear resistance materials. A method for manufacturing a gas-insulated switchgear, which has a higher operating electric field than a resistance material and has a large slope of a non-linear characteristic curve in a range of an electric field higher than the operating electric field
A step of preparing a coating material by mixing the resin and the plurality of types of non-linear resistance materials,
Applying the coating material to the inner surface of the tank,
And a step of curing the coating material to form the resin layer. The method for manufacturing a gas insulated switchgear according to claim 14, wherein the total amount of addition of the plurality of types of nonlinear resistance materials is in the range of 5% by mass to 50% by mass. The method for manufacturing a gas insulated switchgear according to claim 15, wherein a mixing ratio of the first nonlinear resistance material and the second nonlinear resistance material is in a range of 1:4 to 4:1. 15. The method for manufacturing a gas insulation switchgear according to claim 14, wherein a surface treatment agent is mixed with the plurality of types of non-linear resistance materials and then further mixed with the resin to prepare the coating material. The method for manufacturing a gas insulated switchgear according to claim 17, wherein the amount of the surface treatment agent added is in the range of 0.1% by mass to 5% by mass. The method for manufacturing a gas insulated switchgear according to claim 14, wherein the resin layer has a thickness of 50 μm or more and 1 mm or less. 15. The gas insulation according to claim 14, wherein an insulating resin simple substance not containing the non-linear resistance material is applied to the inner surface of the tank to form an insulating resin layer, and then the coating material is applied to the surface of the insulating resin layer. Switchgear manufacturing method. The method of manufacturing a gas insulated switchgear according to claim 20, wherein the insulating resin layer has a thickness of 30 μm or more and 1 mm or less. 22. The method for manufacturing a gas insulated switchgear according to claim 21, wherein the resin layer has a thickness of 50 μm or more and 1 mm or less. 15. The method for manufacturing a gas insulated switchgear according to claim 14, wherein the non-linear resistance material is two or more kinds selected from the group consisting of zinc oxide, silicon carbide, barium titanate and diamond. The first nonlinear resistance material is zinc oxide,
The method for manufacturing a gas insulated switchgear according to claim 14, wherein the second nonlinear resistance material is silicon carbide. The method for manufacturing a gas insulated switchgear according to claim 14, wherein the operating electric field of the second non-linear resistance material is 3 kV/mm or more and 5 kV/mm or less. The method for manufacturing a gas insulated switchgear according to claim 14, wherein the resin layer is formed on at least a lower half region of the inner surface of the tank.

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