JPS5842610B2 - Henry Yuuki Keikiyou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a primary conductor insulating layer of a current transformer for measuring instruments, and an object of the present invention is to reduce the thickness of the insulating layer and thereby reduce the external size.

FIG. 1 shows a fractured cross-sectional view of the primary source of a high-voltage instrument current transformer insulated using a capacitor cone.

The figure shows, as an example, a case where the capacitor is composed of four layers, including conductors, 1. A t-th insulating layer 21 is provided on the outside, an electrode 31 is provided on the outside, and a second insulating layer 2 is provided on the outside in order.
2 and the electrode 32, the third insulating layer 23, the electrode 33, and the fourth electrode 32. An aR24 electrode 34 is provided.

Note that a shield ring 41 is provided at the end of each electrode.
42, 43, and 44 are arranged.

The thickness of each insulating layer of the instrument current transformer configured in this manner is determined by the insulation strength with respect to the impulse voltage.

As shown in FIG. 2, this insulating layer has conventionally been constructed by wrapping a thin tape-shaped insulating paper 5.

Kraft paper is used for this insulating paper, and the breakdown potential gradient of the kraft paper impregnated with insulating oil against impulse voltage is approximately 120 KV/lla when the density is 0.85 g/7.
Degree, 1. Approximately 150KV/y for OgZctdtv
It is about ym.

In high-voltage current transformers, the thickness of this insulating layer is quite thick, and as a result, the external dimensions of high-voltage current transformers are extremely large. there were.

The present invention aims to improve this and reduce the size of the current transformer for measuring instruments by making the insulating layer thinner.

Therefore, in the present invention, a plastic film is used as the feed line material constituting the insulating layer.

Plastic films have a high breakdown potential gradient with respect to impulse voltage; for example, the breakdown potential gradient of a high-quality nodylopyrene film impregnated with insulating oil is 20, "0 =
/'#! That's all.

However, if the insulating layer is made of only plastic film, 1. There are disadvantages such as poor impregnating properties, and voids that occur due to the plastic films sticking to each other during high-temperature vacuum drying during production, and the gas in the voids cannot be completely removed by vacuum operation, resulting in corona defects.

In the present invention, this drawback is overcome by using a plastic film in combination with the plastic film.

Figure 3 shows the structure of an insulating layer according to an embodiment of Lee's invention, where 6 (j plastic film, γ, 2 is an insulating paper wider than the above plastic film 6, and both are overlapped). A primary conductor (not shown) is wound in a lap manner.

In this case, the plastic film 6 and the insulating paper 7 may be overlapped in advance or may be used in an overlapping manner during the production of the insulating layer.

By using plastic film and insulating paper in layers in this way, the impregnation properties are much improved compared to when plastic film is used alone, and by making the width of the insulating paper wider than the plastic film, it can be used for wrapping and wrapping. In this case, the plastic films are prevented from overlapping each other, and the above-mentioned fear of voids occurring due to close contact between the films does not occur.

Therefore, the insulating layer can be made much thinner than the conventional case where only insulating paper is used.

As explained above, according to the present invention, a plastic film is used for the insulating layer of the primary conductor of a current transformer for measuring instruments to make the insulating layer thinner and smaller, and the plastic film and insulating paper are used in a stacked manner. This has advantages such as improving the impregnating properties of the plastic film, making the width of the insulating paper wider than the width of the plastic film, and preventing the generation of voids due to mutual adhesion of the plastic films when wrapped. It is particularly effective as a high voltage instrument current transformer.

[Brief explanation of the drawing]

Figure 1 is a broken cross-sectional view showing the state in which the primary conductor of a high-voltage current transformer is insulated by a capacitor cone with four layers of insulation, and Figure 2 is the structure of a conventional insulation layer made of insulating paper. FIG. 3 is a cross-sectional view schematically showing the structure of an embodiment of the insulating layer according to the present invention. 1...Primary conductor, 21, 22, 23, 24...
...Insulating layer, 31.32=,33,34...
- Electrode, 41°42.43,44...Shield ring, 5,7...Insulating paper, 6...Plastic film.

Claims (1)

[Claims] 1 A plastic film and an insulating paper that is wider than the above plastic film are overlapped, and the primary conductor is wrapped in a P! An instrument current transformer characterized by forming an edge layer.