JPS59127819A - Stationary induction apparatus - Google Patents

Abstract

PURPOSE:To avoid excess concentration of electric field at the end of a winding by a method wherein an insulation layer of a shield ring for electrostatic shield is formed by molding and commonly utilized as an end insulation ring. CONSTITUTION:Conductive materials 22, 30, 31, 32 are applied on core materials 1, 4, 13, 14 and their whole circumferences are formed by molding so that insulation rings 25, 26, 27, 28, which include end insulation in common, are formed. The shield ring at the end of a winding and the end insulation ring are commonly formed in one solid body and an oil wedge or a gas wedge at which concentration of electric field is most likely produced are eliminated and excess concentration of electric field at the end of the winding can be avoided. Therefore insulation distance between a high-voltage winding and a low-voltage winding and between the windings and the upper and lower yokes can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to static induction electric devices, and in particular to electrostatic shielding devices suitable for alleviating electric field concentration at the ends of windings such as 8Fa gas insulated transformers having a composite dielectric insulation structure. This invention relates to a stationary induction appliance equipped with a shield ring.

At the end of the winding, wrap the 4'#L material around the ring-shaped core material so that the corner part has an appropriate curvature diameter so that no single turn is formed, and then tape it with an insulating material from above. Sil'W formed into a ring shape! It is known that electric field concentration at the winding end can be alleviated by arranging a shielding ring and connecting it to the same potential as the winding end. However, in such conventional technology, a liquid or gaseous insulating material such as insulating oil or SFg gas is surrounded by a solid insulating material by combining an insulating cylinder or the like at the corner of the electrostatic shielding shield ring, thereby creating a minute space, i.e. A region called an oil wedge or gas wedge is formed. In general, the dielectric constant of liquid and gas insulators is 1/2 to 1/4 of that of solid dielectrics, and in particular, in the case of SF6 gas, it is about 174, so the electric field concentration due to the dielectric constant ratio becomes large, and the insulation dimension This was an obstacle to reducing the size of the

An object of the present invention is to provide a stationary induction electric appliance that avoids excessive electric field concentration at the winding ends.

The present invention has focused on the fact that in the above-mentioned prior art, a wedge portion is inevitably formed in the chamfered corner portion of the shield ring for shielding the winding, and the present invention has been developed by 1
A shield ring for shielding is provided on the entire circumference of the fIS, and a conductive layer and an insulating layer are provided in close contact with the outer periphery, and an end insulating ring is provided on the outer periphery of the shield ring. In the stationary induction electric device, the insulating layer portion of the electrostatic shielding shield ring is molded and configured to be shared with the end insulating ring, so that the electrostatic shielding shield ring and the winding or other insulating structure are combined. It is characterized by avoiding the formation of an oil wedge or a gas wedge between the material and the material.

Embodiments of the present invention will be described below with reference to the drawings, taking a transformer as an example.

Figure 1 shows an example of a conventional example, in which the low voltage winding 7
The high-voltage winding 6 is arranged concentrically on the core leg 9, and is combined with the insulating tube 22 and a plurality of linear spacers 11, 17 provided around the entire circumference. An electrostatic shielding shield ring (hereinafter simply referred to as a shield ring) A is arranged at the ends of the low voltage winding 7 and the high voltage winding 6, and the iron core yoke portion 8. End insulating rings 15, 16, 20, 21 are interposed and supported between the 10 and 10. Hereinafter, for convenience, the high voltage winding 6 side will be explained. The shield ring A is arranged at both ends of the high-voltage winding 6, and a conductive material 3 is wound around the surface of a ring-shaped core material 1 (or 13), and an insulating material 2 (or 12) is further wound with a predetermined thickness. It is wound so that it looks like this. The conductive material 3 is formed to be non-conductive at one location in the circumferential direction of the core material l (or 13) so as not to form one turn by interlinking with the magnetic flux passing through the core leg 9. The corners of the core material 1 (or 13) are chamfered with an appropriate curvature because the electric field is concentrated when the conductive material 3 of the shield ring A and the end coil are connected at the same potential. By arranging the conductive material 3 along this, the surface electric field of the insulating layer 2 wound thereon is also alleviated. However, this shield link At-attached to the end of the winding, high and low voltage windings 6 and 7
When combining, the linear spacer 11 used for the combination.
17 and end insulating rings 20, 21, 15, 16, etc., as shown in FIG. A portion 19 is formed.

At this wedge part, an electric field is concentrated according to the ratio of the dielectric constants of the high-permittivity material and the low-permittivity material, and in particular, as shown in Figures 1 and 2, the permittivity is uniform at this corner part. However, since the density of the equipotential lines shown by the dotted lines, that is, the electric field is high,
The partial number 'VL1r is likely to occur.

In particular, in the case of low-pressure gas containing 8Fa gas, if discharge starts here, it will immediately lead to total breakdown, so special care must be taken in terms of insulation. Therefore, in order to reduce the insulation dimensions, it is necessary to eliminate such locations where electric field concentration occurs.

An embodiment of the present invention is shown in FIG. Components that are the same as those in the conventional example shown in FIG. 1 are designated by the same reference numerals. In the same figure, it is the same that conductive materials 22, 30, 31° 32 are applied on the core materials 1.4, 13° 14, etc.
Instead of wrapping an insulating material around this outer periphery, the entire insulating ring 2 is molded, including the end insulation.
5°26.27.28.

Possible methods for molding include injecting and hardening epoxy resin, or forming a pipe from a material with a dielectric constant as close to that of oil or gas as the main insulating medium and fixing it to the core material. However, they can be easily formed into a shape that does not create a wedge at the boundary with other insulating materials.

According to this embodiment, the shield ring at the winding end and the end insulating ring are integrated, and the oil wedge and gas wedge that are most likely to cause electric field concentration are eliminated, and excessive electric field concentration at the winding end is prevented. This makes it possible to shorten the insulation distance between the high and low voltage windings and between the windings and the upper and lower yoke parts, which has the effect of reducing the internal dimensions and weight by about 20%.

As explained above, according to the present invention, it is possible to avoid excessive electric field concentration at the end of the winding in a stationary induction electric appliance.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing the configuration of a conventional transformer, FIG. 2 is an enlarged vertical sectional view of part B showing the wedge part of the transformer shown in FIG. 1, and FIG. 3 is an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the transformer. A... Electrostatic seeding, 1, 4, 13.14...
Core material, 22, 30, 31. 32...2!4 Electrical material, 2
5゜26.27.28...Mold insulation ring, 6.
・High -9°

Claims (1)

[Claims] 1. At the end of the winding, a shield ring for shielding static electricity is provided, in which the corners of the ring-shaped core material are chamfered over the entire circumference, and a conductive layer and an insulating layer are closely attached to the outer circumference.
A stationary induction appliance comprising an end insulating ring provided on the outer periphery of the shield ring, characterized in that the insulating layer portion of the electrostatic shielding shield ring is molded to be used in common with the end insulating ring. .