JPS609333B2 - single phase transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single-phase transformer in which a plurality of unit transformers are coupled together via a duct.

In ultra-high voltage power transmission of 500 KV or more, the capacity of a single transformer becomes large, and substations installed on inner walls are generally configured with single-phase transformers due to transportation size and weight constraints.

However, due to the difficulty in securing land for these ultra-high voltage substations, transportation conditions are becoming increasingly severe, and it is expected that in the future there will be many cases where it will not be possible to construct a bank with three single-phase transformers. In that case, the single-phase transformer is divided into a plurality of units, and the unit transformers that are transported one by one are assembled on-site through an oil-submerged duct or the like to form the single-phase transformer.

For example, as shown in Fig. 1, a unit in which a high voltage winding 2 and a medium voltage winding 3, which are connected in parallel to the two main legs of a single-phase four-leg iron core 1, are wrapped and stored in a tank 4. Two transformers A and B
When connecting in parallel to configure one single-phase autotransformer, 2
Two submerged oil ducts 5a, 5b are provided, and the ducts 5a, 5
The two unit transformers A and B are connected via the duct b, and the high-voltage lead 6 and medium-voltage lead 7 are connected to each other through their respective ducts. in this case,
If the leads 6 and 7 are at high voltage, the area where the electric field is concentrated on the lead insulating surface can be reduced by covering the center conductor surface with insulating paper or the like and at the same time arranging several insulating cylinders coaxially on the outside. Efforts have been made to improve pressure resistance and stability by subdividing oil pipes. However, the duct 5a, which is the counter electrode of the lead,
, 5b has a flange for connecting the two tanks 4, 4, and it is difficult to prevent unevenness from being formed on the inner surface at this portion, and it is difficult to insulate the tank.
Therefore, in order to increase the withstand voltage between the leads and the outside of the duct, it was necessary to increase the dimensions of the duct and suppress the electric field on the duct side to a sufficiently low level. However, even with this method, the lead connection work is still done on-site, so it is difficult to maintain complete dust-proof control like in a factory, and if foreign matter gets mixed in,
There is a risk of dielectric breakdown at very low electric fields. This invention reduces the number of ducts by half, compacts the duct dimensions, and improves the reliability of lead insulation when two or more unit transformers are connected via ducts to form a unit transformer. The purpose is to provide a single-phase transformer that can

Hereinafter, the present invention will be described with reference to the drawings in the case where two unit transformers are connected in parallel. In FIGS. 2 and 3, in which the same parts as in FIG. connected. As will be described later, this duct 15 has a high voltage lead electrode 16, a medium voltage lead electrode 17, and a ground shield electrode 18 arranged in a coaxial cylindrical shape inside. Each unit transformer A, B has a high-voltage winding 2 and a medium-voltage winding 3 on two legs of a single-phase four-leg iron core 1, respectively.
A high voltage lead 6 is drawn out from approximately the center of the high voltage winding 2. These high voltage leads 6 are grouped together at a position between the two main legs for each unit transformer and are connected to the ends of high voltage lead electrodes 16 in the duct 15, respectively. The medium voltage lead 7 drawn out from the upper end of the high voltage winding 2 and the medium voltage winding 3 and the lower end of the high voltage winding 2 is passed horizontally between the upper and lower ends of the winding and the tank 4 for each unit transformer. At a position between the two main legs, the upper lead is lowered downward, the lower lead is raised upward, and each is connected to high voltage lead electrode 1.
6 are respectively connected to the ends of medium voltage lead electrodes 17 arranged outside. Further, the high voltage and medium voltage leads 6 and 7 are respectively connected to a high voltage bushing 8 and a medium voltage bushing 9 attached to one unit transformer. As shown in FIG. 4, the inside of the duct 15 has a high voltage lead electrode 1 passing through the center.
An insulating coating 12 is applied to the outer peripheral surface of the medium voltage lead electrode 1 through a plurality of cylindrical insulating barriers 13 on the outside thereof.
7 is provided coaxially with the high-voltage lead electrode 16, and a ground shield electrode 1 is connected to the outer side of the high-voltage lead electrode 16 via a plurality of insulating barriers 23.
8 is provided coaxially with high voltage and medium voltage lead electrodes 16 and 17.

Although not shown, the high voltage lead electrode 16 is connected to a high voltage lead, and the intermediate voltage lead electrode 17 is connected at its end to the intermediate voltage lead 7 lowered from the upper part and raised from the lower part. At this time, the end of the medium voltage lead electrode 17 is placed at a position where a predetermined insulation distance from the closed part of the duct 15 can be secured, and the tip is rounded with an appropriate curvature to alleviate electric field concentration. Further, an insulating coating 22 is also applied to the outer peripheral surfaces of these medium voltage leads 7 and medium voltage lead electrodes 17. The end of the ground shield electrode 18 is located at the closed part of the duct 15 and spread out in a trumpet shape to alleviate electric field concentration in that part. Note that this ground shield electrode 18 is connected to the duct 15 through a ground lead 31 at an appropriate location. In this way, the number of ducts can be halved by connecting two unit transformers to each other.

In addition, the insulation between the high and medium voltage lead electrodes 16 and 17 and between the medium voltage lead electrode 17 and the ground shield electrode 18 has a high withstand voltage because the oil passage is subdivided by a number of insulation barriers 13 and 23. As the insulation properties improve, the variation in breakdown becomes smaller and stable insulation properties can be obtained. Regarding the dimensions when two high-medium voltage leads are passed through the ground shield electrode 18, even when only the high voltage lead electrode 16 is passed through the ground shield electrode 18, there is a gap between the high voltage lead electrode 16 and the ground shield electrode 18. There must be a surface in which the voltage on the cylindrical surface of the radius in the insulating layer is the same potential as the medium voltage lead electrode 17, and if the medium voltage lead electrode 17 is placed on this surface, it becomes a ground shield electrode. High voltage lead electrode 16 inside 18
It takes up almost the same space as when passing only through it. Therefore, compared to the case where the high voltage lead electrode 16 is directly passed through the duct 15, the size can be reduced by the increase in withstand voltage due to the insulating barriers 13 and 23. Furthermore, when connecting the duct 15 on-site, the insulated structure from the high-voltage lead electrode 16 to the ground shield electrode 18 is treated as a lead wire, and even though it was assembled and tested at the factory, it was assembled and reproduced on-site as is. There is no room for foreign matter to get into the insulation structure system, and even if foreign matter gets into the duct during duct connection work, no voltage will be applied between the ground shield electrode 18 and the duct 15, so there is no need to worry about insulation. There are also effects that do not occur. Next, another embodiment of the present invention will be described with reference to FIG.

In the figure, the winding 2 is divided into two parts in series, the high voltage line end 2a is placed in one unit transformer A, the medium voltage line end 2b is placed in the other unit transformer B, and the medium voltage winding 3 is placed in two unit transformers. They are placed in unit transformers A and B of the same unit and connected in parallel. At this time, when two unit transformers A and B are connected, the high voltage lead 6a has a potential intermediate between the high voltage line end and the medium voltage line end, and the medium voltage lead 7a has the potential of the medium voltage line end. With the high voltage lead 6a as the center pole and the medium voltage lead 7a as the outer circular electrode, a coaxial oil lead including the shield electrode 18 is passed through the case of the duct 15.

In the case of such a connection, the same effect as that explained in the configuration of FIG. 2 can be obtained. In the above embodiment, the case where a single-phase transformer is divided into two and the divided unit transformer has two parallel windings is described. Alternatively, the present invention can be implemented even when the number of legs of the winding is three or more.

Furthermore, the present invention can be applied to all cases where high voltage leads and low voltage leads need to be connected between unit transformers, such as when windings wound around multiple legs are not connected in parallel. It is something. As explained above, this invention divides a single-phase transformer into a plurality of unit transformers, and when connecting these, high voltage lead electrodes, low voltage lead electrodes, and shield electrodes are arranged coaxially, and between each electrode By using an oil submerged lead in which the oil passage is subdivided by an insulating barrier, the number of ducts can be halved, the duct can be made more compact, and the reliability of IJ cord insulation can be improved.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a connection structure of a conventional unit transformer, Fig. 2 is a plan view showing a connection structure between single-phase transformers in an embodiment of a single-phase transformer according to the present invention, and Fig. 3 is a plan view showing a connection structure between single-phase transformers. 2 is a side view showing one of the unit transformers, FIG. 4 is a sectional view showing details of the duct entrance portion in FIG. 2, and FIG. 5 is a lead connection diagram showing another embodiment of the present invention. 2...High voltage winding, 3...Medium voltage winding, 4...Tank, 6,6a・
...High voltage lead, 7,7a...Medium pressure lead, 13,2
3... Insulation barrier, 15... Duct, 16...
High voltage shield electrode, 17... Medium voltage shield electrode, 18
...Grounding shield. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In a system in which a plurality of unit transformers are connected through a duct to form one unit transformer, a high voltage lead electrode, a medium voltage lead electrode, and a ground shield electrode are arranged coaxially in the duct in order from the inside. A single-phase transformer characterized in that a lead having a plurality of insulating barriers interposed between each electrode is inserted, and the unit transformers are connected to each other via the lead.