JPS6065504A - Gas-insulation transformer - Google Patents

Abstract

PURPOSE:To obtain the transformer of a high economical efficiency and a high reliability by employing a nonlinear resistance element as a lightning arrester which is connected between the high-voltage part of a winding and a tank thereby achieving the protection of the winding from the invasion of a transient overvoltage such as surge voltage and the miniaturization of equipments. CONSTITUTION:A nonlinear resistance element 9 is attached between a tank 4 and a hook part 5 of a lower part of a high-voltage shiled 5 arranged on the outermost side of a high-voltage winding 3 and the element 9 supports the winding 3 through the high-voltage shiled 5. A columnar spacers 8 and the nonlinear resistance elements 9 are arranged in uniform intervals in a circumferential direction of the winding respectively. As the nonlinear resistance elements 9 are thus arranged in the position nearest the winding, the elements function effectively and restrain the enchroaching transient overvoltage such as surge voltage. Accordingly, the generation of overvoltage in the winding is minimized to protect the winding and the value of the overvoltage to be generated can be foreseen accurately so that the reliability of insulation becomes high, the reduction of winding insulation structure becomes possible and the economical efficiency is improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a gas insulated transformer in which the transformer body is installed in a tank filled with an insulating gas such as SF6 gas. This invention relates to a gas insulated transformer with improved means for protecting the windings against transient overvoltages such as 1-noge voltages that enter the lines.

[Technical cost of the invention and its problems] Conventionally, gas insulated transformers have a disadvantage of low cooling efficiency, so generally 15'1. KV, /lOM-vA
It was said that the PiI degree was the limit and could not be used in large-capacity, high-voltage transformers.
It has been used mainly for power distribution because it has excellent advantages such as low F and light weight. In such conventional small-capacity, low-voltage gas-insulated transformers, one way to protect the 18 windings from the intrusion of transient overvoltages such as surge voltages is to install a lightning arrester outside the transformer. In addition, since it was used for power distribution, there was no need to consider railway transportation limitations.

However, with recent technological advances, the cooling efficiency of gas insulated transformers has been greatly improved.
As gas-insulated transformers such as MVA class, 500 KV, 1750 MVA class, etc. have been developed and researched, the conventional method of installing lightning arresters outside the transformer is insufficient to protect the windings against transient overvoltages. I went to #1. In other words, in this class of substation transformers, in order to effectively suppress transient overvoltages such as surges, it is necessary to place the arrester as close to the trough line of the transformer as possible; It is most desirable to install it inside the By the way, in conventional transformers of this class, mineral oil-based insulating oil has been used as the insulating medium, and since insulating oil deteriorates the lightning arrester and significantly reduces its function, it is almost impossible to incorporate the lightning arrester (j). Therefore, even in gas-insulated transformers, lightning arresters are still installed externally, and as a result, the insulation of the windings is destroyed due to the intrusion of transient overvoltage, reducing the reliability of the transformer. In a structure in which lightning arresters are installed, the equipment becomes larger and there are problems in terms of economy.Furthermore, since it is used for substations, it becomes necessary to consider the limits of railway transportation. From this point of view, there is a demand for smaller transformers.

[Object of the Invention] The present invention was proposed in order to eliminate the drawbacks of the conventional gas insulated transformer as described above. The purpose of the present invention is to provide an economical and reliable gas-insulated transformer, which enables effective winding protection against the ingress of transient overvoltages and the miniaturization of equipment.

[Summary of the Invention] The gas insulated transformer of the present invention employs a non-core resistance element as a lightning arrester, and connects it between the winding high-voltage part and the tank to incorporate it into the tank of the transformer. The linear resistance element is placed as close as possible to the winding.

[Embodiments of the Invention] Although the present invention is applicable to all gas insulated transformers, in the following, the present invention is applied to all types of gas insulated transformers.
An example of a gas insulated foil-wound transformer will be described.

The gas-insulated foil-wound transformer shown in Fig. 1 has a transformer body in which low-voltage windings 2 and high-voltage windings 3 made of foil windings are wound around an iron core 1, and is wrapped with an insulating gas such as SF6 gas. It is installed in a tank 4 which is sealed with high pressure '? At the outermost side of the i-line 3, a high voltage shield 5 having U-shaped 779 portions 5a on the upper and lower sides is provided. The potential of the tank 4 is maintained at the ground potential, and a core clamp 6 for supporting the core 1 is provided between the tank 4 and the upper and lower ends of the winding.

In particular, in the present invention, such a gas insulated foil-wound transformer has the following configuration.

In FIG. 1, an insulating plate 7 is provided at the upper and lower ends of the low-voltage winding 2, and a post-shaped spacer 8 is provided between the insulating plate 7 and the iron core clamp 6.

The low voltage winding 2 is clamped and fixed from above and below by iron core clamps 6 via the insulating plate 7 and the post-shaped spacer 8. On the other hand, a non-linear resistance element 9 is hooked between the lower hook part 5a of the high voltage shield 5 installed on the outermost side of the high voltage winding 3 and the tank 4. It supports the high voltage winding 3. These post-shaped spacers 8 and non-linear resistance cords 9 are arranged at equal intervals in the circumferential direction of the winding.

The operation of this embodiment having the above configuration is as follows.

First, since the non-linear resistance element 9 is arranged at the outermost side of the high-voltage winding 3 of the transformer, that is, at the position closest to the winding, the non-linear resistance element 9 is most effective (original). Perform the song,
Sufficiently suppress transient overvoltages such as incoming surge voltages. Therefore, the occurrence of overvoltage on the windings can be minimized to protect the windings, and the value of the overvoltage that will occur can be accurately predicted, making the insulation more reliable than with conventional gas-insulated transformers. In addition, it becomes possible to significantly reduce the winding insulation structure and improve economic efficiency.In addition, unlike when J3L is immersed in oil, in an insulating gas such as S-gas, non-linear There is no risk of deterioration or functional deterioration of the resistance element.By the way, especially in transformers with foil windings as shown here, it is necessary to support the windings in stages r or 1°. The support structure itself could have been a weak point, but in this embodiment C, the non-linear resistance element is arranged to support the winding, so the winding support has a high insulation reliability of 11. IM construction is obtained.

What is shown in FIG. 2 is a second embodiment of the present invention, in which post-shaped spacers 8 are arranged at equal intervals in the concave circular direction of the high-voltage winding 3, and a non-linear resistance is provided inside the post-shaped spacers 8. It has a built-in element 9.

Sen's 17? The J configuration is completely the same as that of the first embodiment. - In the second embodiment, which has the same configuration as described above, since the non-linear resistance element 9 is built into the post-shaped spacer 8,
Although the cost is higher than that of the first embodiment, the insulation reliability 111 is higher than that of the first embodiment at the same location.

What is shown in FIG. 3 is a third embodiment of the gas insulated transformer of the present invention. In this embodiment, a nonlinear resistance cord 9 is arranged between the outermost side of the high voltage winding 3 and the tank side wall. has been done. In addition, an insulating plate 7 through Jt is provided below the low-voltage and high-voltage windings 2.3, and a common post-shaped spacer 8 is provided between these insulating plates 7 and the core clamp 5. The low-voltage and high-voltage windings 2.3 are supported by the core clamp 6 through the insulating plate 7 and the post-shaped spacer 8.

A third embodiment having the above-described configuration is based on the first and second embodiments.
Unlike the embodiment, since the non-linear resistance element 9 was connected in the radial direction of the winding, the non-linear resistance element 9 did not function as a winding support structure, and instead, the non-linear resistance element 9 was connected to the post-shaped spacer 8. :
Since the entire winding is supported, the structure is simplified and economical while maintaining insulation reliability.

In the first embodiment, the non-linear resistance elements 9 are arranged at equal intervals in the circumferential direction of the high-voltage winding 3, but it is sufficient that at least one non-linear resistance element 9 is used, and other non-linear resistance elements 9 As for the resistor element 9, it is also possible to arrange a boss-shaped spacer 8 instead. Similarly, in the second embodiment, non-linear resistance elements 9 are provided in all the boss-type spaces 1 and 8.
The key to incorporating this is to incorporate the non-linear resistance cord 9 inside one or more of the boss-shaped spacers.

As already stated, the present invention is applicable to all gas insulated transformers and is not limited to the foil G transformer shown in this embodiment. Therefore, it can be applied to evaporatively cooled gas insulated transformers, which have recently been developed, and so-called separate type gas insulated transformers that separate insulation and cooling. You can expect good results.

31. The insulating gas is not limited to 'C-b S F6 gas, but any insulating gas can be applied to the present invention. 1. The fruit has changed 4. stomach.

[Effects of the Invention] As explained above, according to the present invention, a nonlinear resistance element is built into the tank. Insulation reliability that enables the most effective protection of the windings against the invasion of transient overvoltages such as υ-voltage and miniaturization of equipment by a simple method of connecting between the D windings and the tank. It is possible to provide a gas insulated transformer with high performance and economy.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing embodiments in which the gas insulated transformer of the present invention is applied to a foil-wound transformer. 1... Legs of iron core, 2... Low voltage winding, 3... High voltage winding;), 4... Tank, 5... High voltage shield, 5
a... U-shaped hook part, 6... Core clamp, 7.
...Insulating plate, 8...Post type spacer, 9...Nonlinear resistance element. 7317 Representative Patent Attorney Kensuke Norichika (1 person) Figure 1 8 6 Figure 2

Claims (3)

[Claims] (1) The main body of the transformer, which has low-voltage and high-voltage windings wound around the legs of the iron core, is placed in a tank filled with an insulating gas such as SF6 gas, and this tank is connected to the ground. In a gas insulated transformer maintained at
gas insulated transformer. (2) The gas insulated transformer according to claim 1, wherein the winding is a foil winding. (3) Claim 1 or 2, wherein the non-linear resistance element is provided below the winding to support the winding.
Gas insulated transformer as described in section. (/l) The winding is supported by post-shaped spacers arranged at equal intervals in the circumferential direction of the winding through an insulating plate, and a non-linear resistance element is built into one or more of the post-shaped spacers. A gas insulated transformer according to claim 3.