JPH0669048A - Transformer connecting-lead-wire device - Google Patents

Abstract

PURPOSE:To reduce the temperature rise of a tubular connecting lead by a method wherein, by means of an oil-guiding tube, one part of an oil flow is guided to the tubular connecting lead from the part of a forced oil feed structure at a transformer. CONSTITUTION:In a transformer connecting-lead-wire device, at least two unit transformers 1 are connected in the horizontal direction by a connecting duct 4 in which an insulator-coated lead wire has been built, and windings 10 for the unit transformers 1 are connected electrically to a bushing 2 installed at the intermediate part of the connecting duct 4. The lead wire is formed as a hollow tubular conductor 5, and one part of the flow of a transformer insulating coil is guided to the opening on the transformer side of the tubular conductor 5 by means of an insulating tube 11. Thereby, the inside of the tubular conductor 5 is cooled forcibly. In addition, the insulating oil which flows out from the opening part on the bushing side of the tubular conductor 5 is made to flow between the insulation-coated tubular conductor 5 and the connecting duct 4 and is returned to the side of the unit transformers. Thereby, it is possible to reduce the temperature rise of the connecting lead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting lead wire device for a static induction electric transformer such as a transformer or a reactor, and more particularly to a connecting lead wire device for connecting each winding and a bushing in a plurality of divided unit transformers. .

[0002]

2. Description of the Related Art In recent years, transformers have tended to have large capacities and large sizes. For example, transformers used for 500 kV class power transmission have a unit capacity of 1500/3 MVA to 2000/3 MVA per phase. Therefore, it is composed of a unit transformer in which a single-phase device is divided into two or three parts due to size restrictions in transportation. Also, in the 1000 kV class transmission transformer planned for the next generation transmission voltage, the single unit capacity will be 3000/3 MVA or more per phase, and in this case as well, the unit divided into two or three units. It is composed of a transformer.

In a 1000 kV class transformer composed of a plurality of unit transformers as described above, the windings of the unit transformers are connected to each other by a duct containing a lead wire with an insulating coating, and this connecting duct is used. The lead wire is electrically connected to a bushing provided at an intermediate portion of the. In addition, since this lead wire has a high voltage, in order to provide electrical insulation strength, insulating paper is generally wound around the outer circumference of a solid round bar-shaped or hollow circular tube-shaped conductor, and a plurality of sheets is further provided outside the insulating paper. A multi-insulating barrier structure with an insulating barrier has been proposed. An example of these structures is disclosed in Japanese Utility Model Publication No. 52-62432 or Japanese Patent Publication No. 63-4284.
No. 1 publication.

A conventional single-phase transformer has two components as shown in FIG.
Bushing pockets 3 are arranged between the unit transformers 1 of the stand, and are connected to the unit transformers 1 via connection ducts 4. The bushing 2, the upper bushing shield 6, the lower bushing shield 7, and the bushing insulating barrier 8 are housed in the bushing pocket 3.

The output lead wire of the divided winding 10 of the unit transformer is connected to the connection lead 5 in the connection duct 4, but when the voltage applied to the lead wire reaches 1000 kV class, the lead conductor surface Since the electric field strength becomes very large, the lead insulating paper 13 is wound around the surface of the connection lead 5 so as to have a thickness as large as the outer diameter of the connection lead 5. Further, in order to increase the withstand voltage on the surface of the lead insulating paper 13, a plurality of lead insulating barriers 9 are provided coaxially with the connecting leads 5 in a cylindrical shape. The outer diameter of the connecting lead 5 is 50 mm to 10
Although it is as large as 0 mm, the current flowing through the connecting lead 5 flows only about 10 mm to 15 mm in thickness on the surface portion of the connecting lead 5 due to the skin effect due to the alternating current, and the Joule loss generated in the connecting lead is as thick as above. Since the loss is the same as that of a tubular conductor having a thickness, it is expected that the weight of the connecting lead 5 is reduced and the connecting lead has a hollow circular tubular shape.

[0006]

In the connecting lead wire device constructed as described above, the thickness of the lead insulating paper 13 wound around the connecting lead 5 is as large as 50 mm to 100 mm. Causes a high temperature rise due to Joule loss of the flowing current. That is, the connection lead 5
The temperature rise θ with respect to the surrounding refrigerant is given by the following equation. θ = K1 · I ² log (D / d) / A + K2 (I ² / A
D) ^0.8 where K1 and K2 are constants, I is the lead current, A is the conductor cross-sectional area of the connecting lead, d is the outer diameter of the connecting lead conductor, and D is the outer diameter of the connecting lead insulating paper. The first term of the above represents the temperature rise in the connecting lead insulating paper 13, and the second term represents the temperature rise in the oil film portion of the surface of the connecting lead insulating paper 13.

In the connection lead 5, the lead insulating paper 1
Since the winding thickness of 3 is very large, the temperature rise of the insulating paper layer is 20 to 30 times as large as the temperature rise in the oil film portion, and may exceed the allowable temperature rise of the connection lead 5.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a connecting lead wire device capable of reducing the temperature rise of the connecting lead below an allowable value.

[0009]

In order to achieve the above object, the present invention connects at least two unit transformers in a horizontal direction by a connecting duct containing a lead wire having an insulating coating, and the lead wire In the transformer connecting lead wire device for electrically connecting the winding of the unit transformer and the bushing installed in the intermediate portion of the connecting duct by the above, the lead wire is a hollow tubular conductor, and the tubular conductor is By guiding a part of the flow of transformer insulating oil into the opening on the transformer side by means of an insulating tube, the inside of the tubular conductor is forcibly cooled and comes out from the opening on the bushing side of the tubular conductor. The transformer insulating oil is made to flow between the insulating-coated tubular conductor and the connection duct so that the transformer insulating oil returns to the unit transformer side.

[0010]

The excessive rise in temperature of the connecting lead is because the thermal resistance of the lead insulating paper portion outside the connecting lead is large, although the loss of the connecting lead is small. In the present invention, the inside of the connection lead can be effectively cooled by forcibly sending a part of the oil flow to the inside of the connection lead by the oil guide tube, so that the temperature rise of the connection lead can be significantly reduced.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the present invention. As shown in the figure, a bushing pocket 3 is arranged between two unit transformers 1 and is connected to the unit transformer 1 via a connection duct 4. The bushing 2, the upper bushing shield 6, the lower bushing shield 7, and the bushing insulating barrier 8 are housed in the bushing pocket 3. Further, the lead wires 12, 12 of the divided winding 10 of the unit transformer 1 are connected to the hollow-cylindrical connecting lead 5, but the connecting lead 5 has a high potential voltage, and the connecting lead surface The lead insulating paper 13 is wound thick to protect the sheet. Further, in order to increase the withstand voltage on the surface of the lead insulating paper 13, a plurality of lead insulating barriers 9 are provided coaxially with the connecting leads 5 in a cylindrical shape. This connecting lead 5 has a horizontal structure, and insulating oil as a cooling medium is retained inside the tubular connecting lead. The insulating oil guide tube 11 made of, for example, fluororesin is inserted into the winding side inlet of the connection lead 5 from the forced oil feeding structure portion (not shown) of the transformer winding or the iron core to reduce the oil flow. Oil the parts.

In the connection lead wire device thus constructed, the oil introduced into the connection lead 5 comes out from the opening on the side of the bushing 2 and the gap between the bushing 2 and the upper bushing shield 6 or the connection lead 5. There is a gap between the upper bushing shield 6 and the upper bushing shield 6, and after passing through the gap between the connecting lead 5 and the lower bushing shield 7, a unit transformer divided through a large gap between the connecting lead 5 and the connecting duct 4 is formed. And go back.

The loss that occurs in the connecting lead 5 is very small from the beginning, and if there is no thick lead insulating paper 13, it is 2 ° C.
Since the amount of heat is equivalent to a temperature rise of about 3 ° C., the amount of oil that needs to be guided by the oil guiding tube 11 may be small. Therefore, oil guiding by the oil guiding tube 11 can be achieved by a simple method in which the end portion which is the oil intake port of the oil guiding tube 11 is installed in the forced oil feeding structure portion of the transformer in parallel with the oil flow, The temperature rise of the connecting lead 5 can be easily reduced.

FIG. 2 is a sectional view of another embodiment of the present invention. This embodiment is different from the above-mentioned embodiment in that after connecting the lead wires 12, 12 from the windings, a connecting wire 5 having a relatively small cross-sectional area is used to form a winding (not shown). The bushing 2 is connected to the circular tubular conductor 14
Is only used as the shield electrode of the connection lead 5,
Since other configurations are the same, the same components are designated by the same reference numerals and the description thereof will be omitted.

Next, the operation of the present embodiment will be described. Although no current flows through the connecting lead shield electrode 14 itself and no loss occurs, if there is no forced oil flow in the shield electrode 14. The heat generated by the loss generated in the connecting lead 5 causes the shield electrode 14 to generate heat with the same amount of loss as the connecting lead 5. Therefore, by introducing a forced oil flow into the shield electrode 14 for the connection lead by the oil guide tube 11, the shield electrode 1
It is possible to reduce the temperature rise of 4 and the connection lead 5 below the allowable value.

[0016]

As described above, according to the present invention, the oil-conducting tube guides a part of the oil flow from the forced oil-feeding structure portion of the transformer to the tubular connecting lead, so that the insulating paper thickness of the connecting lead is increased. Even if is very large, the temperature rise of the connecting lead can be easily reduced. Since the required oil flow is small, it can be effectively achieved by a simple means of installing the oil guide tube in the transformer forced oil feeding structure portion in parallel with the oil flow.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional transformer connecting lead wire device.

[Explanation of symbols]

1 ... Unit transformer tank, 2 ... Bushing, 3 ... Bushing pocket, 4 ... Connection duct, 5 ... Connection lead, 6 ... Upper bushing shield, 7 ... Lower bushing shield,
8 ... Bushing insulating barrier, 9 ... Lead insulating barrier, 10 ... Winding, 11 ... Oil guide tube, 12 ... Lead wire, 13 ... Lead insulating paper, 14 ... Connection lead shield electrode.

Claims (1)

[Claims] 1. At least two unit transformers are connected in the horizontal direction by a connecting duct containing a lead wire having an insulating coating, and the lead wire is provided between the winding of the unit transformer and the connecting duct. In a transformer connection lead wire device for electrically connecting a bushing installed in a section, the lead wire is a hollow tubular conductor, and the flow of the transformer insulating oil flows in the transformer-side opening of the tubular conductor. By partially conducting oil with an insulating tube, the inside of the tubular conductor is forcibly cooled, and transformer insulating oil that comes out from the opening on the bushing side of the tubular conductor is insulated from the tubular conductor covered with the insulation. A transformer connecting lead wire device, characterized in that the transformer insulating oil returns to the unit transformer side by flowing between it and a connecting duct.