JPH0457087B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas insulated instrument transformer, and more particularly to improving voltage resistance characteristics.

[Technical background of the invention and its problems]

A conventional gas-insulated instrument transformer (hereinafter abbreviated as gas PT) consists of a low-voltage coil wound around a monopod of a frame-shaped iron core, alternately wound with insulating members on the outside, and one end connected to a high-voltage terminal. It is formed by housing a high-voltage coil with the other end connected to a high-voltage ground terminal and an insulating gas inside a metal container. this gas
In order to alleviate the electric field of the high voltage coil, the PT is equipped with an annular high voltage shield with an appropriately curved end on the outside of the high voltage coil, and is further grounded on the core side to alleviate the electric field at the corner of the core. A shield was installed.

However, it is practically impossible to form both the high voltage coil and the high voltage shield in a perfect circle, and therefore, as shown in FIG. There was a part where a gap g was created. Although not shown, the high voltage shield 9 is connected to take the potential of the high voltage coil 3.

As is generally known, the breakdown voltage/time characteristic, so-called Vt characteristic, of gas insulated equipment is almost flat, and the penetration of high voltage with a high wave front steepness has been a weak point in terms of withstand voltage performance. On the other hand, for voltages with very high wavefront steepness, the high voltage coil potential distribution almost depends on the capacitance of the high voltage coil 3, so the gap g between the high voltage shield 9 and the high voltage coil 3 is Since the dielectric constant of the insulating member 4, which is approximately 3, is higher than the dielectric constant of the insulating gas, which is approximately 1, the voltage share of the gap g becomes large, resulting in high electric field stress, and the gap g is considered to be the origin of breakdown. It may happen.
In order to reduce the electric field stress in the gap g, the high voltage coil 3 is made larger, which increases the size of the entire device, resulting in an increase in cost.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and
The purpose is to provide a small, inexpensive gas-insulated voltage transformer with good withstand voltage characteristics.

[Summary of the invention]

According to the present invention, in order to achieve such an objective,
By arranging an insulating member with a specific induction of at least 3 in the gap between the high voltage coil and the high voltage shield, the shared voltage in the gap can be reduced to reduce electric field stress and withstand the intrusion of high voltage. It is characterized by improved voltage characteristics, small size, and low cost.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The same parts as in FIG. 5 are given the same reference numerals. A low-voltage coil 2 is wound around a monopod of a frame-shaped iron core 1, and an insulating member 4 is alternately wound around the outside of the low-voltage coil 2, and one end is connected to a high-voltage terminal 5, and the other end is connected to a high-voltage grounding terminal 6. A high voltage coil 3 is housed in a metal container 8 together with an insulating gas 7. In order to alleviate the electric field of the high voltage coil 3, a high voltage shield 9 with an appropriate curved surface is attached to the end of the high voltage coil 3, and a flexible thin sheet-like insulating member 10 is inserted as will be described later. Attach it to the outside of the Further, a high electronic terminal 5 is connected to the high voltage shield 9, and the high voltage terminal 5 is led out to the outside by passing through an insulating spacer 11 that is airtightly attached to the opening of the metal container 8. Further, a grounding shield 12 is attached to the iron core 1 side in order to alleviate the electric field at the corners of the iron core 1.
Note that the high voltage shield 9 is at the same potential as the high voltage coil 3. In this way, a gas insulated instrument transformer (hereinafter abbreviated as gas PT) is constructed.
As described above, the sheet-shaped insulating member 10 is inserted into the high voltage shield 9, and its state is shown in FIG. The thin sheet-shaped insulating member 10 is made of, for example, a sheet-shaped rubber member or a synthetic resin such as PVC, a so-called plastic member, and has flexibility, stretchability, and softness, and has a dielectric constant of 3 or more. It has a high dielectric strength. This sheet-like insulating member 10 is connected to a high voltage shield 9 and a high voltage coil 3.
It fills the gap formed on the surface facing the insulating member 4 and is formed so as to be in close contact with the inner surface of the high voltage shield 9 and the high voltage coil 3 and the insulating member 4 facing thereto. That is, the sheet-shaped insulating member 10 is attached to the entire inner circumference side of the high voltage shield 9 in close contact.

In this way, the gap that conventionally occurs during manufacturing is filled with a sheet-shaped insulating member 10 having a dielectric constant of 3 or more, and is formed so as to be in close contact with both sides of the gap. In the part corresponding to the conventional gap, the voltage sharing is much smaller than in the past, and the electric field stress is reduced, so this part has improved withstand voltage performance against the intrusion of high voltage with a high wave front, and the insulation This has the effect of being able to avoid being the source of destruction. Further, when attaching the high voltage shield 9 to the high voltage coil 3, the work becomes easier without having to worry about creating gaps as in the conventional case.

Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4. The same parts as in FIG. 2 are given the same reference numerals. In FIG. 3, the same effect as the present invention can be obtained by simply inserting the sheet-shaped insulating member 10a between the high voltage coil 3 and the high voltage shield 9. Also, as shown in Figure 4, the high voltage shield 9
Of course, if the whole is covered with a sheet-like insulating member 10b, the withstand voltage characteristics of the surface of the high voltage shield 9 can be improved. Also, the same effects as in the embodiments of the present invention can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to improve the dielectric strength of the high voltage coil of a gas-insulated instrument transformer against a high voltage with high steepness, and therefore it is possible to downsize the high voltage coil. Then,
Since the entire gas PT can be made smaller, it can be made inexpensive, small and lightweight. Furthermore, it is possible to provide a gas-insulated instrument transformer that facilitates the work of attaching the high-voltage shield to the high-voltage coil and shortens the construction period.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a gas-insulated instrument transformer of the present invention, FIG. 2 is a cross-sectional view showing the main parts of FIG. 1, and FIG.
4 and 4 are sectional views showing the main parts of another embodiment of the present invention, and FIG. 5 is a sectional view of the main parts of a conventional gas-insulated voltage transformer. 3... High voltage coil, 4... Insulating member, 5...
High voltage terminal, 9...High voltage shield, 10, 10
a, 10b... Sheet-shaped insulating member.

Claims (1)

[Claims] 1. A high/low voltage coil is wound around an iron core, and a high/low voltage shield is installed to alleviate the electric field caused by high voltage.
These are housed in a metal container together with an insulating gas, and a sheet-like insulating material having flexibility, stretchability, softness, and a relative permittivity of at least 3 is provided on at least the entire inner peripheral side of the high voltage shield. A gas-insulated instrument transformer characterized by having members arranged in close contact with each other.