JPS644661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a transformer, and more particularly to a high-voltage transformer in which the electric field at a core yoke is alleviated.

[Background of the invention]

A transformer generally has a core leg and a yoke integrally formed by laminating a plurality of silicon steel plates formed into a predetermined shape. The yoke constructed in this way is
The surrounding area is stepped, and the electric field is concentrated at the ridge. For this reason, in conventional transformers, in order to alleviate the electric field at the ridge of the core yoke facing the high voltage winding, the entire portion of the yoke facing the winding is removed as shown in Figure 1. A method of shielding is being taken.

That is, the core yoke portion 10 is formed by laminating a plurality of silicon steel plates, and is formed integrally with the core leg 12 so as to be perpendicular to the core leg 12. The core yoke part 10 includes a winding 14 wound around the core leg 12.
The surface facing the is multi-staged. An end insulator 16 is provided at the end of the winding 14, and clamping fittings 18, 18 for clamping the core yoke part 10 in the width direction are attached to the end insulator 16 by tightening bolts 17. ing. Further, a shield 20 is disposed between the core yoke portion 10 and the end insulator 16 to cover the multi-stepped surface of the core yoke portion 10, so that the electric field at the ridge portion 22 can be relaxed. It's summery. This shield 20 is made of a metal body in the form of a wire mesh, and in order to prevent the wire mesh from coming into contact with the core yoke, a piece of insulating material is placed at an appropriate distance between the wire mesh and the core yoke. Intervening (1973-
118020). On the other hand, the shield 20 may be formed in a sandwiched manner using a wire mesh made of an insulator such as a press board, and the electric field may be relaxed while avoiding contact between the wire mesh and the iron core yoke portion 10.

This means that the electric field E _n at the corner in a high electric field is generally
Average electric field E ₀ (=voltage E/distance d) and electric field concentration coefficient
Since it is expressed as the product of S _T , the idea is to cover the corners of the iron core yoke with wire mesh to bring the electric field concentration coefficient closer to a uniform electric field.

However, in such conventional shields, the wire mesh that makes up the shield 20 is made of extremely thin wires, so the wires that make up the wire mesh break during shield manufacturing or transformer assembly. There is a disadvantage that a so-called floating state occurs in which the ground is not grounded. Furthermore, since the above-described shield is a method in which a metal body is inserted between the winding 14 and the core yoke 10, the wires constituting the shield may break due to vibrations that occur during operation of the transformer.
There was a risk of it floating in the same way as above. Moreover, this type of shield has the disadvantage that it has a complicated structure and is difficult to manufacture.

[Purpose of the invention]

The present invention has been made in order to eliminate the drawbacks of the prior art, and an object of the present invention is to provide a transformer that can reliably alleviate the electric field at the ridge of the core yoke facing the winding. do.

[Summary of the invention]

The present invention provides an insulating material having an L-shaped cross section in close contact with the ridge of a core yoke facing the winding, and a boundary point of insulating oil at a point a certain distance from the ridge. The structure is such that the electric field at the boundary between the insulating oil and the insulating oil is reduced, and the electric field is relaxed.

[Embodiments of the invention]

Preferred embodiments of the transformer according to the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals are given to the parts corresponding to the parts explained in the prior art, and the explanation thereof will be omitted.

As shown in FIG. 2, an insulator 24 having an L-shaped cross section and made of kraft pulp is closely attached to the ridge (corner) 22 of the core yoke 10 facing the winding 14. It is installed. This insulator 24
As shown in FIG. 3, is attached along the longitudinal direction of the ridge part 22 of the core yoke part 10 so as to cover the entire surface of the ridge part 22. A core yoke insulating layer 26 is disposed between the core yoke 10 and the winding 14 so as to cover the multi-stepped surface of the core yoke 10. Note that the winding 14 is composed of a low voltage winding 14A and a high voltage winding 14B with an insulating layer 28 in between. The thickness t of the insulator is preferably 2 to 5 mm, but can be increased or decreased depending on the strength of the electric field.

In the embodiment configured as described above, since the insulator 24 is interposed between the insulating oil (not shown) and the ridge 22 of the core yoke 10, the electric field at the boundary of the insulating oil is It decreases by the distance between the two. Therefore, the ridge 22 of the core yoke portion 10
The electric field can be relaxed. Furthermore, since the insulator 24 is attached only to the ridge portion 22, there is no risk of blocking the cooling oil duct provided within the core. The insulator 24 has a simple structure and is easy to manufacture, which not only reduces costs, but also reduces the distance between the winding 14 and the core yoke 10, resulting in a smaller transformer. be able to.

In the above embodiment, the insulator 14 is made of kraft pulp, but it may be made of other insulators such as pressboard or laminated paper.

〔Effect of the invention〕

As explained above, according to the present invention, by closely adhering an insulator having an L-shaped cross section along the ridge of the core yoke, it is possible to reliably alleviate the electric field at the ridge. .

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a conventional transformer, FIG. 2 is a partial front sectional view of a transformer according to an embodiment of the present invention,
FIG. 3 is a partial cross-sectional plan view of the embodiment, and FIG. 4 is a perspective view of an example of the insulator used in the embodiment. 10... Iron core yoke part, 12... Iron core legs, 14...
...Winding, 20...Shield, 22...Ridge, 24
……Insulator.

Claims (1)

[Claims] 1. A plurality of core legs formed by laminating a large number of steel plates, a winding wound around these core legs, and a coil formed at both ends of the core legs to magnetically connect each core leg. 1. A transformer comprising a yoke portion, characterized in that an insulator having an L-shaped cross section is closely attached along a ridge of the yoke portion facing the winding.