JP3326782B2 - Gas insulated transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas insulated transformer, and more particularly to a winding structure equipped with an electrostatic ring.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional gas insulated transformer comprises a low voltage winding 2 concentrically wound around an iron core 7 and a high voltage winding 1 wound outside the low voltage winding 2. At the upper and lower ends of the high-voltage winding 1, an electrostatic ring 4 made of a conductive material for reducing the electric field at the end of the winding is attached.
These electrostatic rings 4 are formed to have the same dimensions as the outer diameter and inner diameter of the winding. Furthermore, in order to secure a vertical insulation distance between the high-voltage winding 1, the low-voltage winding 2 and the iron core 7 and a gas passage, a duct pipe made of an insulating material having the same width as the radial winding width of the low-voltage winding 2 is used. The low-voltage winding 2 is provided with a plurality of radially arranged windings 16 on the upper and lower end surfaces of the low-voltage winding 2. Several places are arranged radially via the ring 4. A high-voltage winding 1 and a low-voltage winding 2 are placed above and below the duct pieces 16 and 17, respectively.
And a high-voltage winding 1 and a low-voltage winding 2 are fixed from above and below by disposing an insulating ring 18 having a radial width sufficient to fix the same from above and below. The core 7 and the low-voltage winding 2
The insulating gasket 19 and the duct piece 20 are provided in the gas path between the high-voltage windings 1 and the low-voltage winding 2 in the gas path. It is configured to secure the insulation distance by laminating.

[0003]

However, in the conventional gas insulated transformer, since the inner peripheral portion of the electrostatic ring 4 comes into contact with the duct piece 9, a minute gas gap as shown in FIG. Eleven had occurred. By the way, in a portion where such an insulating gas comes into contact with a solid insulator such as the duct piece 9 or the insulating cylinder 10, the electric field strength on the insulating gas side is expressed by the following equation. E ₁ = V / {D−t (1−ε ₁ / ε ₂ )} [kV / mm] V: potential difference between windings [kV] D: distance between windings [mm] t: solid insulator Thickness [mm] ε ₁ : relative permittivity of insulating gas ε ₂ : relative permittivity of solid insulator Further, there is no solid insulator between the windings, and the relative permittivity is 1.0.
The electric field strength when only the insulating gas is used is expressed by the following equation. E ₀ = V / D Therefore, by disposing the solid insulator having the thickness t between the windings, the electric field intensity shared by the insulating gas becomes E ₁ / E ₀
Double. For example, when a solid insulator having a relative dielectric constant of 3.3 is arranged, E ₁ / E ₀ = D / {D−t (1-1 / 3.3)} = D / (D−0.7t) . Here, the high-voltage winding 1 and the low-voltage winding 2 are connected by a solid insulator such as a duct piece 9 and an insulating cylinder 10 (t ≒ D), and the duct piece 9 and the electrostatic ring are further connected. If there is a small gas gap 11 that is negligible in terms of dimensions between the four, the small gas gap portion will have E ₁ / E ₀ ≒ D / (D−0.7D) = D / 0.3D = 3 The electric field intensity in the portion of the minute gas gap 11 is twice the dielectric constant of the solid insulator, and an extremely large electric field is applied compared to the electric field intensity of the insulating gas in the portion without the duct piece 9. As described above, the dielectric strength is remarkably reduced in a portion where a large electric field is applied, and the inner peripheral portion of the electrostatic ring 4 is a portion where the electric field is concentrated most, so that it is the weakest point on the insulation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas-insulated transformer which can reduce the electric field concentration caused by using an electrostatic ring and a duct piece for the winding and improve the dielectric strength to improve the reliability of the gas. To provide an insulating transformer.

[0005]

Means for Solving the Problems To achieve the above object, according to the present invention, a low voltage winding wound around an iron core and a high voltage winding wound outside the low voltage winding are provided. And an upper electrostatic ring disposed on the upper end surface of the high-voltage winding and a lower electrostatic ring disposed on the lower end surface, and disposed between the low-voltage winding and the high-voltage winding. A solid insulator that forms a gas passage while maintaining an insulation distance, and has an inner diameter of the lower electrostatic ring that is equal to that of the high-voltage winding.
By making it smaller than the inside diameter, the inside diameter side from the high voltage winding
A protruding portion that protrudes into the high-voltage winding.
The position of the upper end face of the solid insulator is the position of the upper end face of the high-voltage winding.
The solid insulator inscribed in the high-voltage winding
A diagonal notch is provided at the lower part of the
It is supported on the upper surface of the projection of the lower electrostatic ring. Further, in the present invention described in claim 2, a low-voltage winding wound around an iron core, a high-voltage winding wound outside the low-voltage winding, and an upper portion disposed on an upper end surface of the high-voltage winding. An electrostatic ring and a lower electrostatic ring arranged on the lower end surface, and a solid insulator which is arranged between the low-voltage winding and the high-voltage winding, maintains an insulation distance between both windings, and forms a gas passage. An upper part of the upper electrostatic ring, and a lower electrostatic ring.
Place an insulation material with a T-shaped cross section at the bottom of the
The outer peripheral side of the ring is fixed to the right-angled portion of the insulating material having the T-shaped cross section.
A continuous space is formed between the inner peripheral surfaces of the upper and lower electrostatic rings and the solid insulator in the circumferential direction.

[0006] In the gas insulating transformer of the present invention configured as described above, the inner peripheral portion of the electrostatic ring where the electric field concentrates most is formed with a sufficient space from the solid insulator, so that the electric field concentrator is formed. Is alleviated.

[0007]

FIG. 1 shows an embodiment of a gas-insulated transformer according to the present invention. In FIG. 1, the length of a duct piece 6 of an insulating material inscribed in the high-voltage winding 1 is the same as the length of the high-voltage winding 1 in the axial direction. A T-shaped cross-section duct piece 5 of insulating material is arranged below the electrostatic ring 3 at the lower end of the high-voltage winding.
The outer peripheral side is fixed by a convex portion of a T-shaped duct piece 5 so that the 4 does not shift in the radial direction. The inner diameter of the electrostatic ring 3 at the lower end of the high-voltage winding 1 is made smaller than the inner diameter of the high-voltage winding 1 in order to prevent the duct piece 6 inscribed in the high-voltage winding 1 from falling. A duct piece 6 which projects from the pressure winding 1 to the inner diameter side and which is inscribed in the high voltage winding 1 on the upper surface of this projection.
To receive. The duct piece 6 has a notch 14 formed diagonally so as not to form a small gas gap between the duct ring 6 and a curved portion of the inner surface of the electrostatic ring 3. With such a configuration, a portion of the electrostatic rings 3 and 4 facing the low-voltage winding 2 where the electric field is most concentrated forms a continuous space 12 in the circumferential direction between the portion and the solid insulator. Therefore, a minute gas gap does not occur, and the electric field concentration is reduced.

FIG. 2 shows another embodiment of the present invention. In FIG. 2, the upper part of the electrostatic ring 4 at the upper end of the high-voltage winding 1 and
A T-shaped duct piece 5 is arranged below the electrostatic ring 4 at the lower end of the high-voltage winding 1, and the outer periphery is formed by a convex portion of the T-shaped duct piece 5 so that the electrostatic ring 4 does not shift in the radial direction. Fix it. The duct piece 8 made of insulating material inscribed in the high-voltage winding 1 has the same height in the axial direction as the height of the upper end of the high-voltage winding 1. The notch 15 is made so that it may become L-shaped. With such a configuration, a space 13 that is continuous in the circumferential direction is formed between the electrostatic ring 4 and the solid insulator at a portion facing the low-voltage winding 2 where the electric field is most concentrated. Therefore, a minute gas gap does not occur, and the electric field concentration is reduced.

[0009]

According to the present invention, a small gas gap does not occur in the portion of the electrostatic ring facing the low voltage winding where the electric field is concentrated most, and the electric field concentration is reduced, so that the dielectric strength is improved,
A highly reliable gas-insulated transformer can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a winding part showing one embodiment of a gas-insulated transformer of the present invention.

FIG. 2 is a sectional view of a winding part showing another embodiment of the gas-insulated transformer of the present invention.

FIG. 3 is a sectional view of a winding part of a conventional gas-insulated transformer.

FIG. 4 is an enlarged view of a winding end of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-voltage winding 2 Low-voltage winding 3, 4 Electrostatic ring 5 T-shaped duct piece 6 Duct piece 7 Iron core 8, 9 Duct piece 10 Insulation cylinder 11 Micro gas gap 12, 13 Vacancy 14, 15 Notch 16 , 17 Duct piece 18 Ring 19 Insulation cylinder 20 Duct piece

Claims (2)

(57) [Claims] 1. A low-voltage winding wound around an iron core, a high-voltage winding wound outside the low-voltage winding, an upper electrostatic ring disposed on an upper end surface of the high-voltage winding, and disposed on a lower end surface. a lower static ring which is disposed between the low voltage winding and high voltage winding, holds the insulation distance between the windings, and a solid insulator that forms the gas passage, the lower static Electric phosphorus
The inner diameter of the coil is smaller than the inner diameter of the high-voltage winding.
And a projection protruding from the high-voltage winding to the inner diameter side.
The position of the upper end surface of the solid insulator inscribed in the high-voltage winding
The same position as the upper end surface of the high-voltage winding;
An oblique notch is made at the bottom of the solid insulator inscribed in
The lower end of this notch to the protrusion of the lower electrostatic ring.
A gas-insulated transformer characterized by being supported on an upper surface . 2. A low-voltage winding wound on an iron core, a high-voltage winding wound outside the low-voltage winding, an upper electrostatic ring disposed on an upper end surface of the high-voltage winding, and disposed on a lower end surface. a lower static ring which is disposed between the low voltage winding and high voltage winding, holds the insulation distance between the windings, and a solid insulator that forms the gas passage, wherein the upper static Electric phosphorus
The upper part of the ring and the lower part of the lower electrostatic ring have a T-shaped cross section.
Place the edge material and cut the outer peripheral side of each electrostatic ring as described above.
It is fixed to a right-angled portion of the surface T-shaped insulating material, and a circumferentially continuous space is formed between the inner peripheral surface of the upper electrostatic ring and the lower electrostatic ring and the solid insulator. Gas-insulated transformer.