JP4303147B2 - Solid insulation switchgear - Google Patents

Description

  The present invention relates to a solid-insulated switchgear in which an electric device such as a vacuum valve and a connection conductor constituting a power supply system is molded with an insulating material such as an epoxy resin.

  Conventionally, in electrical devices such as vacuum valves and connection conductors constituting the main circuit of the switchgear, in order to prevent these electrical devices from being affected by fouling and wetting, the dielectric strength is reduced. There is known a solid insulation type in which an insulating shell is formed by molding with an insulating material, and a grounding layer is provided on the exterior of the insulating shell (see, for example, Patent Document 1).

  In this molded electrical device, when the rated voltage of the switchgear becomes a high voltage of 6 kV or higher, the electric field strength increases, so that the insulation thickness becomes relatively thick, and furthermore, several kinds of fillers are mixed with epoxy resin. In addition, since excellent electrical characteristics and mechanical characteristics are obtained, the specific gravity becomes about 2 and becomes heavy.

  In order to solve this problem, an insulating layer having different dielectric constants formed in multiple layers so as to reduce the insulating thickness by controlling the electric field distribution in the insulating layer is known (see, for example, Patent Document 2). ). As shown in FIG. 5, the insulating layer 3 is divided into a high-voltage side insulating layer 4 and a ground-side insulating layer 5 between the high-voltage electrode 1 and the ground electrode 2, and is grounded more than the high-voltage side insulating layer 4. The dielectric constant of the side insulating layer 5 is reduced.

  As a result, the maximum electric field strength Ec of the high-voltage side insulating layer 4 is Ea, the maximum electric field strength of the ground-side insulating layer 5 is Eb, and the maximum electric field strength Ec when the insulating layer 3 having a single dielectric constant is provided. In comparison, the electric field strength can be suppressed. That is, the relationship between the maximum electric field intensity Ea when different dielectric constants are provided and the maximum electric field intensity Eb when a single dielectric constant is provided can be obtained.

And according to the ratio by which the maximum electric field strength was suppressed, each insulation thickness of the high voltage side insulating layer 4 and the ground side insulating layer 5 can be made thin.
JP 2001-286018 A (4th page, FIG. 4) Japanese Patent Laid-Open No. 11-262120 (5th page, FIG. 1)

The above-described conventional solid-insulated switchgear has the following problems.
Although the maximum electric field strength can be suppressed by the high-voltage-side insulating layer 4 and the ground-side insulating layer 5 having different dielectric constants, the maximum electric field strength differs, and the insulation thickness cannot be significantly reduced. That is, these maximum electric field strengths change depending on the dielectric constant and the insulation thickness, and the insulation thickness is determined by the higher maximum electric field strength.

  Therefore, it has been desired that the maximum electric field strengths of the high-voltage side insulating layer 4 and the ground-side insulating layer 5 are made the same, and the insulating thicknesses of the respective insulating layers 4 and 5 can be reduced. Thereby, the weight of the solid insulation switchgear comprised combining the molded electric equipment can be suppressed.

  The present invention has been made to solve the above problems, and an object of the present invention is to be able to reduce the weight of a solid insulating switchgear formed by combining electric devices molded with multilayer insulating layers having different dielectric constants.

  To achieve the above object, a solid insulated switchgear according to the present invention is a solid insulated switchgear that forms a power system by combining electrical devices molded with an insulating material to form a multilayer insulating layer, Around the device, the multi-layer insulating layer is formed by exposing the main circuit conductor end so that the dielectric constant decreases toward the outer peripheral direction, the electrode end of the electric device, and the multi-layer insulation It is characterized in that the electric field strength of each boundary surface portion of the layer is made equal.

  According to such a configuration, the insulating layer having the largest dielectric constant is provided on the electric device side, and a multi-layered insulating layer having a dielectric constant that decreases toward the outer circumferential direction is formed. Since the electric field strength of each boundary surface portion of the layers is the same, the insulation thickness of each insulating layer can be reduced, and accordingly, a power system is configured by combining these electric devices. Thus, the weight of the solid insulating switch gear can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, a solid insulation switchgear according to an embodiment of the present invention will be described with reference to FIGS. 1 is a side view showing a part of the configuration of a solid-insulated switchgear according to an embodiment of the present invention, FIG. 2 is a sectional view showing a blocking portion according to the embodiment of the present invention, and FIG. FIG. 4 is a characteristic diagram showing the relationship between electric field strength and dielectric thickness according to an embodiment of the present invention.

  As shown in FIG. 1, in the solid insulation switchgear, a power supply system is configured by a cable portion 10a on the back side, a central opening / closing portion 10b, and a busbar portion 10c on the front side.

  A cable head 11 is provided in the cable portion 10 a, and a power cable 13 penetrating the current transformer 12 is connected to the cable head 11.

  The opening / closing portion 10 b is provided with a blocking portion 14, and one main circuit end of the blocking portion 14 is connected to the main circuit end of the cable head 11 by a U-shaped connection conductor 15. The shut-off portion 14 is provided with a vacuum valve 16 having a pair of contact points that can be contacted and separated. The vacuum valve 16 has an end portion of the main circuit conductor exposed, and an insulating material such as epoxy resin is molded around the vacuum valve 16 to form a first insulating layer 17 and a first insulating layer 17. A second insulating layer 18 is provided around the substrate. Further, a ground layer 19 is provided around the second insulating layer 18.

  An operating mechanism 21 that opens and closes a pair of contacts in the vacuum valve 16 is provided at the other main circuit end of the blocking portion 14 via an insulating operating rod 20 in the axial direction. Further, the external electrode of the vacuum valve 16 is in sliding contact with the connecting conductor 22 in a direction orthogonal to the axial direction.

  The bus bar portion 10 c is provided with a disconnecting portion 23, one main circuit end is in sliding contact with the connecting conductor 22, and the other main circuit end is connected to the bus bar 24. The disconnecting portion 23 is provided with a vacuum valve 25 similar to the blocking portion 14, and an operation mechanism 27 that opens and closes a pair of contacts in the vacuum valve 25 via an insulating operation rod 26 in the axial direction of the vacuum valve 25. Is provided.

  In addition, the main circuit ends of the molded electrical equipment such as the blocking portion 14, the disconnecting portion 23, the connecting conductor 15, and the bus bar 24 are all interface connecting portions formed in a tapered shape, and are not shown in the drawing. The main circuit ends are connected to each other through an insulator.

  Of these molded electric devices, the details will be described with reference to FIG. As shown in FIG. 2, the blocking portion 14 exposes the main circuit conductor end portions at both ends of the vacuum valve 16, and firstly provides the first insulating layer 17 by molding an insulating material such as an epoxy resin, After the surface of the first insulating layer 17 is subjected to, for example, sandblasting to improve adhesion, the second insulating layer 18 is provided by molding an insulating material such as an epoxy resin. A grounding layer 19 is provided on the exterior of the second insulating layer 18 by spraying a conductive paint such as a carbon paint.

  Here, the dielectric constants of the first insulating layer 17 and the second insulating layer 18 are smaller in the second insulating layer 18 than in the first insulating layer 17. As shown in FIG. 3, the electric field strength characteristic at the end of the vacuum valve 16 is E1, the electric field strength characteristic at the interface between the first insulating layer 17 and the second insulating layer 18 is E2, and the first This is because when the dielectric constant of the insulating layer 17 is ε1 and the dielectric constant of the second insulating layer 18 is ε2, the electric field strength characteristics E1 and E2 intersect each other when the dielectric constant ratio is ε1 / ε2 = 3. .

  That is, when the dielectric constant ε1 of the first insulating layer 17 is tripled relative to the dielectric constant ε2 of the second insulating layer 18, these electric field strengths become the same value, and each has the lowest value. Here, if the insulating thickness of the first insulating layer 17 is t1, and the insulating thickness of the second insulating layer 18 is t2, the ratio is t1 / t2 = 0.5. The ratio of the insulating thickness was in the same tendency in which the electric field strength characteristics E1 and E2 intersect each other in the range of t1 / t2 = 0.25 to 0.8.

  In addition, adjustment of a dielectric constant can be performed by changing the filling amount of the silica powder with which an epoxy resin is filled, for example.

  Next, the insulating thickness of the first insulating layer 17 and the second insulating layer 18 is larger in the insulating thickness t2 of the second insulating layer 18 than the insulating thickness t1 of the first insulating layer 17. is doing. As shown in FIG. 4, when the electric field strength characteristic at the end of the vacuum valve 16 is E3, and the electric field strength characteristic at the interface between the first insulating layer 17 and the second insulating layer 18 is E4, This is because the electric field strength characteristics E3 and E4 are both V-shaped curves, and the electric field strength characteristics E3 and E4 are the lowest when the ratio of the insulation thickness is t1 / t2 = 0.5 to 0.6.

  That is, the electric field strength can be suppressed most by doubling the insulating thickness t2 of the second insulating layer 18 with respect to the insulating thickness t1 of the first insulating layer 17. Here, the ratio of the dielectric constant ε1 of the first insulating layer 17 to the dielectric constant ε2 of the second insulating layer 18 is when ε1 / ε2 = 3. The ratio of dielectric constants in the range of ε1 / ε2 = 1.5 to 4.5 had the same tendency for the electric field strength characteristics E3 and E4 to be V-shaped curves.

  On the other hand, as shown in FIG. 2, the maximum electric field strength is located at the A portion of the vacuum valve 16, that is, at the electrode end in the blocking portion 14. This is because the inside of the vacuum valve 16 is vacuum-sealed and becomes a sharp edge by welding or the like. The breakdown voltage characteristic having such a sharp edge does not cause dielectric breakdown immediately even when reaching the criticality at which the first insulating layer 17 breaks due to the electric field strength at a local site. In order for dielectric breakdown to occur, the electric field strength further increases, the first insulating layer 17 becomes a high electric field and is polarized, and the electric field strength in that state must reach a critical level.

  The electric field strength that leads to this dielectric breakdown is 1.1 times the electric field strength before polarization occurs in the blocking portion 14 having a sharp edge. That is, as shown in FIG. 3, the electric field strength Ex increased by 1.1 times contributes to the actual dielectric breakdown with respect to the lowest electric field strength Ew at which the electric field strength characteristics E1 and E2 cross each other and have the same value. It will be a thing. This makes it practical to use the electric field strength Ex that contributes to actual dielectric breakdown. When the ratio of the dielectric constant below this electric field strength Ex is obtained, the ratio is ε1 / ε2 = 1.5-4. The range is 5. When the dielectric constant ratio is ε1 / ε2 = 1.5 or less, or ε1 / ε2 = 4.5 or more, the electric field strength Ex is exceeded, which causes dielectric breakdown.

  Similarly to the above, as shown in FIG. 4, in the electric field strength characteristics E3 and E4, the electric field strength Ez increased 1.1 times with respect to the lowest electric field strength Ey of the V-shaped curve. It contributes to dielectric breakdown. This makes it practical to use the electric field strength Ez that contributes to actual dielectric breakdown. When the ratio of the insulation thickness below this electric field strength Ez is determined, the ratio is t1 / t2 = 0.25-0. .8 range. When the ratio of the insulation thickness is t1 / t2 = 0.25 or less, or t1 / t2 = 0.8 or more, the electric field strength Ez is exceeded, which causes dielectric breakdown.

  Note that when the first insulating layer 17 causes breakdown due to the electric field strength Ex or the electric field strength Ez, the second insulating layer 18 also causes dielectric breakdown, and finally the first insulating layer 17 and the first insulating layer 17 The two insulating layers 18 cause dielectric breakdown in all paths.

  According to the solid-insulated switchgear of the above embodiment, the first insulating layer 17 having a large dielectric constant is provided on the vacuum valve 16 side, and the dielectric constant is higher than the first insulating layer 17 around the first insulating layer 17. The second insulating layer 18 having a small thickness is provided, and the exterior of the second insulating layer 18 is a ground layer 19, and the electric field strength at the electrode end portion of the vacuum valve 16 and the boundary surface portion between the first insulating layer 17 and the second insulating layer 18 is provided. Therefore, the insulating thicknesses of the insulating layers 17 and 18 can be reduced. Moreover, the weight of the solid insulation switchgear which combines this electric equipment can be reduced.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of invention, it can implement in various deformation | transformation. In the above embodiment, two insulating layers having different dielectric constants have been described. However, the dielectric constant of the insulating layer on the electric equipment side is maximized, and the dielectric constant of the insulating layer on the ground side is set to be three or more. The electric field strength at the electrode end portion of the electric device and the boundary surface portion of each insulating layer may be substantially the same.

  Moreover, although the molded electric device was demonstrated by the interruption | blocking part 14, it can be used also for the disconnection part 23, the connection conductor 15, etc. FIG.

  Furthermore, although the ground layer 19 is provided on the outer periphery of the second insulating layer 18, the ground layer 18 is not provided if each phase is independently fixed via an air gap that can withstand a predetermined rated voltage. May be. In this case, since the air gap is also an insulating medium, the electrode end portion of the electric device, the boundary surface portion between the first and second insulating layers 17 and 18, and the boundary surface portion between the second insulating layer 18 and the insulating medium, That is, the electric field intensity along the second insulating layer 18 may be made similar.

The side view which shows the structure of the solid insulation switchgear which concerns on the Example of this invention in partial cross section. Sectional drawing which shows the interruption | blocking part which concerns on the Example of this invention. The characteristic view which shows the relationship between the electric field strength which concerns on the Example of this invention, and a dielectric constant. The characteristic view which shows the relationship between the electric field strength which concerns on the Example of this invention, and insulation thickness. Explanatory drawing explaining the electric field strength of the multilayer insulating layer which consists of a different dielectric constant.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High voltage electrode 2 Ground electrode 3 Insulating layer 4 High voltage side insulating layer 5 Ground side insulating layer 10a Cable part 10b Opening and closing part 10c Busbar part 11 Cable head 12 Current transformer 13 Power cable 14 Breaking part 15 Connection conductors 16 and 25 Vacuum valve 17 First insulating layer 18 Second insulating layer 19 Grounding layer 20, 26 Insulating operating rods 21, 27 Operating mechanism 22 Connecting conductor 23 Disconnecting portion 24 Busbar

Claims (1)

A solid insulated switchgear that constitutes a power supply system by combining electrical devices molded with an insulating material to form a multilayer insulating layer,
Around the electrical equipment, the multilayer insulating layer is formed by exposing the end portion of the main circuit conductor so that the dielectric constant decreases toward the outer peripheral direction,
A solid insulating switchgear characterized in that the electric field strength of each of the electrode end portion of the electric device and the boundary surface portion of the multilayer insulating layer is equal.

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