JP2014147195A - Insulation structure of electrical machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas insulated switchgear in which a withstand voltage is improved by bringing an electric field between tanks facing an electrode of a switching device such as a disconnect switch housed in a tank close to an equal electric field.
SOLUTION: Threading is provided at the flat part of the inner surface of the opposing tank that is the same axis center as the axis of the electrode of an open / close device such as a disconnector housed in the tank, and the spherical resin is also the same size. By connecting both with a stud made of an insulating material and fixing it to the inner surface of the tank without a gap, the electric field between the flat tanks facing the electrodes is brought closer to the equal electric field from the unequal electric field, The withstand voltage is improved by reducing the area of the portion where the electric field strength is 90% or more of the maximum electric field strength at which dielectric breakdown occurs.
[Selection] Figure 1

Description

  The present invention relates to insulation of a gas insulated switchgear.

An example of the internal structure of the gas insulated switchgear will be described. The gas-insulated switchgear shown in FIG. 5 connects the power system and the cable head 9, and the tank 6 has a ground switch 10, a lightning arrester 11, a circuit breaker 12, a disconnector 13, a point connected to a transformer, and the like. Arranged and stored. In the tank 6, the inert gas SF ₆ is mainly used.

However, since SF ₆ has a global warming potential of about 23,900 times that of CO ₂ , it is changing to insulating gas such as dry air that has no environmental impact, but the insulation capacity is the same pressure as SF _6. However, since it is as low as about 1/3, it is necessary to increase the insulation distance between the charging site and the ground, and the size of the tank 6 of the gas insulated switchgear becomes large.

  For this reason, the electric field is reduced by increasing the pressure of an insulating gas such as dry air sealed in the tank 6 to increase the insulation capacity, or increasing the conductor size of the high voltage charging portion facing the grounded tank 6. The size of the gas insulated switchgear is suppressed from increasing.

JP 2007-104840

  High voltage is charged in switchgears such as disconnectors and circuit breakers housed in the tank. When the electrode terminal of the part where the high voltage is charged to the switchgear is spherical and the tank on the ground side facing it is flat, the unequal electric field is larger than when the charging side and ground side are opposed to each other in a spherical shape. Often has become. Therefore, on the electrode surface that has an unequal electric field, the area of the portion where the electric field strength is 90% or more of the maximum electric field strength is increased, which is considered to cause dielectric breakdown. It is contained more in the area than in the case where the spheres are opposed to each other.

  In addition, as shown in Patent Document 1, it is also possible to improve the dielectric strength by covering a conductor such as an electrode of a switching device such as a disconnector that is charged with a high voltage with a rectangular insulating cover. However, it takes time to manufacture and attach the insulating cover, and it is not easy to realize the improvement of the insulation strength because the cost effectiveness is not expected.

  An object of the present invention is to provide a gas-insulated switchgear which can easily improve the dielectric strength by reducing the area of the portion where the electric field strength is 90% or more of the maximum electric field strength.

  In the present invention, a spherical surface or an elliptical spherical surface made of epoxy or the like having a relative dielectric constant of 2 to 6 on the surface inside the flat tank that is on the ground side facing the electrode of a switching device such as a disconnector that is charged with a high voltage A resin having a shape (hereinafter referred to as a spherical shape) is attached.

  The diameter size of the spherical resin is smaller than the electrode diameter of a switching device such as a disconnector that is charged with a high voltage, and further has a height that is 1/2 or less of the insulation distance from the electrode surface to the tank surface.

  The position where the spherical resin is attached is a position where the central axis is the same as the electrode charged with a high voltage to the tank, but there may be an axial misalignment in relation to surrounding equipment and structures. .

  The spherical resin is attached by processing a screw hole of the same size on the tank and the spherical resin.

  Spherical resin is installed by screwing an insulating stud slightly shorter than the screw hole length on both the tank and the spherical resin into the spherical resin screw hole, and then machining the screw hole on the tank surface. The stud is screwed in to fix the spherical resin to the tank surface without any gap with the tank.

  According to the present invention, by attaching a spherical resin to the tank surface, the insulation strength between the electrode of the switchgear such as a disconnector that is easily charged with a high voltage and the tank is improved, and as a result, the insulation distance Can be shortened and the tank size can be reduced.

It is a resin attachment side surface cross-section figure of switchgear, such as a disconnector in an embodiment of the present invention. It is explanatory drawing of the resin attachment position in embodiment of this invention. It is explanatory drawing of the resin 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 the conventional embodiment which does not attach the spherical resin of this invention.

  As shown in FIG. 5, the gas-insulated switchgear that cuts off the accident current and the like is provided with a cable head 9, a grounding switch 10, a lightning arrester 11, a circuit breaker 12, a disconnector 13, and a portion to be connected to the transformer. Insulating gas such as dry air is enclosed.

  High voltage is charged in the equipment placed and housed in the tank 6 of the gas-insulated switchgear, and the charged equipment and the tank 6 that is grounded are separated by a certain insulation distance and insulated between them. The tank 6 is filled with an insulating gas such as dry air.

  Since the vicinity of the electrode 1 serving as a terminal of the switchgear 3 such as a disconnector charged with a high voltage shown in FIG. 1 has a high electric field, it is necessary to prevent dielectric breakdown between the tanks 6 on the ground side.

  Therefore, as shown in FIG. 2, a spherical resin 2 having a relative dielectric constant in the range of 2 to 6 is attached to the inner surface of the tank 6 facing the electrode 1. The diameter φB of the spherical resin 2 is smaller than φA of the electrode 1 and the height L2 of the spherical resin 2 is smaller than 1/2 of the insulation dimension L1 between the surface of the electrode 1 and the tank 6.

  The spherical resin 2 is fixed by aligning the central axis with the electrode 1 charged with a high voltage to the tank 6 as shown in FIG. A threaded portion 15 is provided at a flat portion where the spherical resin 2 faces the tank 6, and a threaded portion 15 of the same size is also provided at a location where the tank 6 is attached. In order to fix the spherical resin 2 to the tank 6, the spherical resin 2 is connected to the tank 6 using an insulating stud 5 and fixed to the inner surface of the tank 6 without a gap.

  Thus, when the electrode 1 is charged with a high voltage, an electric field distribution as shown in FIG. 4 is formed between the electrode 1 and the tank 6. The length of the electric field strength magnitude 7 indicates the strength of the electric field strength. The electric field strength 7 is distributed on the surface of the electrode 1, and the portion where the shortest distance between the electrode 1 and the tank 6 becomes the maximum electric field strength 14. The presence of the spherical resin 2 having a relative dielectric constant range of 2 to 6 on the surface of the tank 6 causes the electric field distribution in the vicinity of the tank 6 facing the electrode 1 to rise along the spherical resin 2. This is the potential line 4.

  FIG. 4 shows the electric field distribution in the present invention. By attaching the spherical resin 2 to the surface of the tank 6, the equipotential line 4 rises and approaches the equal electric field from the non-uniform electric field as shown in FIG. The area 8 is reduced, and by reducing the area, the number of defective portions that affect dielectric breakdown is reduced, and the dielectric strength can be improved.

In this example, as a result of the numerical calculation, the maximum electric field strength 14 is increased by about 5% from 49.5 kV / mm to 51.9 kV / mm, but more than 90% of the maximum electric field strength at the beginning of dielectric breakdown. It can be seen that the area 8 of the portion where the electric field strength is reduced by 26% from 1235 mm ² to 911 mm ² , improving the dielectric strength.

DESCRIPTION OF SYMBOLS 1 Electrode 2 Spherical resin 3 Switchgear such as disconnect switch 4 Equipotential line 5 Stud 6 Tank 7 Electric field strength 8 Area of electric field strength more than 90% of maximum electric field strength 9 Cable head 10 Ground switching Device 11 Lightning Arrestor 12 Breaker 13 Disconnector 14 Maximum Electric Field Strength 15 Thread Cutting

Claims (3)

  In a gas-insulated switchgear in which switchgear is housed in a tank and filled with insulating gas, the relative permittivity is 2-6 at the position where the electrode of the switchgear and other switchgear and the central axis of the flat inner surface of the tank are aligned. A gas-insulated switchgear comprising a resin having a spherical shape or a part of an elliptical spherical surface.   The height of the resin in the shape of a part of the spherical surface or the elliptical spherical surface is smaller than ½ of the dimension between the surface of the electrode of the switchgear and the tank, and the diameter is smaller than the diameter of the electrode. The gas insulated switchgear according to claim 1, wherein   The gas insulated switchgear according to claim 1 or 2, wherein the insulating gas is dry air.