JP2014165970A - Insulation structure of electrical equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation structure of electrical equipment capable of improving an insulation performance by reducing a conductor part area having an electric field strength equal to or more than 90% and equal to or less than 100% of a maximum electric field strength, and extending a creepage destruction path on the barrier, when the barrier is inserted between a conductor part of an opening/closing device housing a disconnector or the like within a tank and the tank opposing the conductor part.SOLUTION: Between an end portion including a conductor part curved surface 1a to which a high voltage is being applied and a tank 3 opposing a conductor part 1, a circular insulation material is inserted as a circular uneven barrier 2. In the barrier 2, a surface shape opposing the conductor part 1 has a concave or convex apex at a position of a center axis of the conductor part 1, and unevenness is repeated radially from the center axis. A height of the convex part is fixed or made higher gradually as it is separated from the center axis, the convex part does not touch the conductor part 1, the surface shape opposing the tank 3 is made smooth and an end portion has a curved surface.

Description

  The present invention relates to an insulating structure of an electric device.

  An example of the internal structure of the gas insulated switchgear will be described. The gas-insulated switchgear shown in FIG. 5 is connected to the power system via a cable head 12, and a disconnector 8, a breaker 9, a ground switch 10, a lightning arrester 11, etc. are arranged and stored in the tank 3. . As the insulating medium in the tank 3, SF6 gas, which is an inert gas, is mainly used.

  However, SF6 gas has a global warming potential approximately 23900 times higher than CO2. Therefore, the insulating medium of the switchgear is being replaced with an insulating gas having a low environmental load such as dry air.

  Under atmospheric pressure, switchgear using dry air as insulation medium has insulation performance about 1/3 that of SF6 gas compared to switchgear using SF6 gas as insulation medium. It is necessary to increase the insulation distance between the conductor portion such as the vessel 9 and the tank 3. As a result, the volume of the tank 3 of the gas insulated switchgear becomes large.

  If the volume of the gas-insulated switchgear is increased, extra costs and land are required. Therefore, in order to suppress an increase in the volume of the gas insulated switchgear, the pressure of an insulating gas such as dry air sealed in the tank 3 is increased, or the conductor part and the tank as disclosed in Patent Document 1 are used. Although an attempt is made to reduce the insulation distance by inserting an insulating barrier that covers the conductor portion between them, it is not easy to realize in terms of processing and cost.

Patent No. 4632959

  A high voltage is applied to conductors such as a disconnector and a circuit breaker disposed and accommodated in the tank. When the tip of the conductor portion to which a high voltage is applied is a curved surface and the tank on the ground side facing it is flat, the electric field is often unequal compared to the case where they face each other in a spherical shape.

  In general, the surface area of the conductor part where the electric field strength is 90% or more and 100% or less of the maximum electric field strength, which is the weak point where dielectric breakdown occurs (S90). Moon) etc.) is so wide that the space near the surface of the conductor portion becomes an unequal electric field.

  In addition, when an insulating barrier is inserted between the conductor and the tank, depending on the shape of the barrier, insulation performance may be reduced due to creepage damage on the barrier or concentration of the electric field on parts other than the barrier, such as the tank and other conductors. In some cases, it may cause a decrease.

  Therefore, when the barrier is inserted, the area of the conductor portion where the electric field intensity is 90% or more and 100% or less of the maximum electric field intensity is reduced, and in addition, the creeping path on the barrier is extended to improve the insulation performance. Provide an insulating structure for electrical equipment that can be used.

  A circle with a concavity and convexity on the surface facing the conductor part between the curved end of the conductor part such as a disconnector to which a high voltage is applied and the plane inside the tank on the ground side facing the conductor part A shaped insulating material is inserted as a barrier.

  The surface shape facing the conductor portion of the barrier has a vertex of either the unevenness at the position of the central axis of the conductor portion, and the unevenness is repeated radially from the central axis. The end of the barrier has a curved surface. The height of the convex portion is constant or is increased as the distance from the central axis increases. However, the convex part of the barrier does not touch the conductor part. The surface of the barrier facing the tank is smooth.

  The distance in parallel with the tank inner ground plane from the vertex of the barrier convex portion to the adjacent vertex is about the radius of the conductor portion. The barrier surface irregularities are repeated two or more times, and the radius of the barrier should be about 1.1 to less than twice the radius of the conductor. Hereinafter, this shape of the barrier is referred to as a circular uneven barrier. The relative dielectric constant of this circular uneven barrier is about 2 to 6.

  In the method of attaching the circular concavo-convex barrier, screw hole processing is performed on the central axis of the tank facing the conductor portion, and the tank is fixed to the tank using an insulating stud extending from the center of the smooth surface of the barrier. The length of the stud is changed depending on the insertion position of the circular uneven barrier. The studs are threaded so as not to penetrate the thickness of the circular uneven barrier so that the stud can be removed from the circular uneven barrier.

  According to the present invention, by attaching a circular uneven barrier between the end of the conductor part and the plane inside the tank on the ground side facing the conductor part, 90% of the maximum electric field on the surface of the conductor part serving as the weak point part The surface area at which the electric field strength is 100% or less can be reduced as compared with the surface of the conductor portion without the barrier.

  In addition, since the surface of the circular concavo-convex barrier has a concavo-convex surface shape, an effect of extending the creeping fracture distance can be expected.

  Therefore, the insulation performance between the conductive part and the tank can be improved, and the distance for insulation between the conductive part and the tank can be shortened.

It is a barrier attachment side surface sectional view of conductor parts, such as a disconnector in an embodiment of the present invention. It is explanatory drawing of the barrier in embodiment of this invention. It is explanatory drawing of the barrier attachment method in embodiment of this invention. It is explanatory drawing of the electric field distribution in embodiment of this invention. It is a tank internal structure figure of the conventional gas insulation apparatus. It is explanatory drawing of the electric field distribution in conventional embodiment.

  As shown in FIG. 5, the gas-insulated switchgear that cuts off the accident current and the like is provided with a disconnector 8, a breaker 9, a ground switch 10, a lightning arrester 11, a cable head 12, and the like to insulate dry air or the like. Sexual gas is enclosed.

  A high voltage is applied to the conductor portion 1 disposed and housed in the tank 3 of the gas insulated switchgear, and a certain insulation distance is provided between the conductor portion 1 to which the high voltage is applied and the grounded tank 3. The tank 3 is filled with an insulating gas, such as dry air, that is separated by a gap between the two.

  Since the vicinity of the conductor curved surface 1a, which is the end of the conductor 1 such as a disconnector to which a high voltage is applied as shown in FIG. 1, is a high electric field, there is a gap between the tip of the conductor curved surface 1a and the tank 3 on the ground side. In order not to break down the insulation.

  Therefore, a circular uneven barrier 2 is attached between the conductor portion 1 and the tank 3. The surface shape facing the conductor portion of the circular uneven barrier 2 has a concave vertex at the position of the central axis of the conductor portion 1 as shown in 2a of FIG. Repeated irregularities radially. The end of the circular uneven barrier 2 has a curved surface. The height of the convex portion is constant or is increased as the distance from the central axis increases. However, the convex part of the circular uneven barrier 2 does not touch the conductor part 1. The surface shape of the circular uneven barrier 2 facing the tank 3 is smooth.

  As shown in FIG. 2, the distance x in the direction parallel to the ground plane from the apex of the convex portion of the circular uneven barrier 2 to the adjacent apex is about the radius of the conductor portion 1. The unevenness on the surface of the circular uneven barrier 2 is repeated twice or more, and the radius φA of the circular uneven barrier 2 is 1.1 times or more and less than 2 times the radius of the conductor portion 1. The relative dielectric constant of this circular uneven barrier is about 2 to 6.

  A method for attaching the circular uneven barrier 2 will be described below. As shown in FIG. 3, a threaded hole is formed in the tank 3 facing the central axis of the conductor portion 1 to provide a female screw 5. A screw hole is machined in the center of the smooth surface 2b of the circular uneven barrier 2 to provide a female screw 5. The circular uneven barrier 2 and the tank 3 are fixed using an insulating stud 6. The length of the stud 6 is changed depending on the insertion position of the circular uneven barrier 2. The insertion position of the circular uneven barrier 2 is preferably in the middle of the conductor portion 1 and the tank 3, but may be other than the middle. A screw hole is processed so as not to penetrate the thickness of the circular uneven barrier 2.

  When only an insulating gas exists between the conductor 1 and the tank 3 as in the prior art, when a voltage is applied to the conductor 1, the electric field distribution between the conductor 1 and the tank 3 as shown in FIG. It becomes. FIG. 6 is axisymmetric.

  On the other hand, when the circular uneven barrier 2 is inserted between the conductor 1 and the tank 3, when a voltage is applied to the conductor 1, the electric field distribution between the conductor 1 and the tank 3 is as shown in FIG. FIG. 4 is axisymmetric.

  As an example, the analysis results of FIGS. 4 and 6 are shown. Between the end of the conductor part 1 such as a disconnector to which 1000 kV is applied and the plane inside the tank 3 on the ground side facing the conductor part 1, the center axis has a concave part, and the number of concave and convex repetitions is The simulation was performed under the condition that the circular uneven barrier 2 having a relative dielectric constant of 2 was inserted 2.5 times. As a result, the maximum electric field strength 13 increases by about 9% from 28.8 kV / mm to 31.4 kV / mm, but the surface area 4 has an electric field strength of 90% or more and 100% or less of the maximum electric field on the surface of the conductor portion 1 which is the weak point. However, it was reduced by about 34% from the surface of the conductor part 1 in the state without a barrier.

  In addition, by making the circular concavo-convex barrier 2 have a concavo-convex surface shape, there is an effect that the creeping fracture distance is extended by the concavo-convex portion and the insulation performance is improved.

DESCRIPTION OF SYMBOLS 1 Conductor part 1a Conductor part curved surface 2 Circular uneven surface 2a Surface which repeats unevenness radially 2b Smooth surface 3 Tank 4 Surface area which becomes electric field strength 90% or more and 100% or less of the maximum electric field 5 Female screw 6 Stud 7 Electric field strength 8 Disconnector 9 Circuit Breaker 10 Ground Switch 11 Arrester 12 Cable Head 13 Maximum Electric Field Strength Generator

Claims (4)

Between the end portion of the conductor portion having a curved surface and the plane inside the tank facing the conductor portion, the surface facing the conductor portion has irregularities, and the apex of the irregularities at the position of the central axis of the conductor portion An insulating structure for an electrical device, comprising: a circular barrier having a flat surface and a flat surface facing the tank, the surface being opposed to the tank. 2. The insulating structure for an electric device according to claim 1, wherein the height of the convex portion of the barrier is constant or increases as the distance from the central axis increases, but does not touch the conductor portion. The distance in the direction parallel to the ground plane from the vertex of the convex portion of the barrier to the adjacent vertex is about the radius of the conductor portion, the surface irregularities are repeated twice or more, and the radius of the barrier is the radius of the conductor portion. The insulation structure for an electrical device according to claim 1 or 2, wherein the insulation structure is 1.1 times or more and less than 2 times. 4. The insulating structure for an electric device according to claim 1, wherein the relative dielectric constant of the barrier is in the range of 2 to 6.