CN110914935A

CN110914935A - Lead wire outlet assembly

Info

Publication number: CN110914935A
Application number: CN201780093509.7A
Authority: CN
Inventors: D.W.赖特; I.马克瓦那; W.杨
Original assignee: General Electric Technology GmbH
Current assignee: General Electric Technology GmbH
Priority date: 2017-07-31
Filing date: 2017-07-31
Publication date: 2020-03-24
Also published as: BR112020001296A2; WO2019024977A1

Abstract

The invention relates to a lead wire outlet assembly (1) for a high voltage transformer/reactor (20), comprising an elongated bushing (2) having a bushing axis (B), a stress shield (5) at a base (6) of the bushing (2) for receiving a winding lead wire (7) from the transformer (20) and accommodating a connection between the winding lead wire (7) and the base (6) of the bushing (2), the stress shield (5) being configured to receive the winding lead wire (7) in an off-axis direction with respect to the bushing axis (B).

Description

Lead wire outlet assembly

Technical Field

The present invention relates to a lead-out assembly for a High Voltage (HV) transformer or reactor (reactor). The invention also relates to a transformer or reactor with the lead wire outlet assembly. The invention also relates to a distribution network comprising said transformer or reactor.

Background

Transformers or reactors typically include an inductive element, such as a winding, mounted within a tank or housing. The lead exit assembly provides an internal inductive element that is externally connected to a transformer or reactor. The lead exit assembly typically includes a bushing (bushing) and associated electrostatic shielding and insulation. The bushing carries a conductor which is connected at one end to the inductive element by a winding lead and at the other end provides a terminal (terminal) of the transformer. The terminals allow for example an external device or a distribution network to be connected to the transformer.

At high pressures, the bushings are typically mounted in a tower (turret) that extends from the outer surface of the transformer housing. The tower supports the liner and houses connections between the liner and winding leads that extend from the windings, through holes in the housing and into the tower. A shield and insulation, called stress shield, surrounds the connection between the bushing and the winding lead in the tower.

The tower and bushings are often disassembled after manufacture and testing for transport of the transformer. Therefore, the transformer must be carefully reassembled in the field. Care must be taken to ensure that the device is restored to the same conditions as it was tested in the factory. When replacing the tower and liner, the stress shield must be carefully positioned to ensure its insulating integrity. The tower is typically also filled with an insulating fluid, such as oil, and the insulation is adjusted accordingly. The need to disassemble the tower for shipping can extend the time that the moisture-absorbing insulation of the lead exit assembly is exposed to the environment, which can increase the risk of contamination.

Disclosure of Invention

According to a first aspect of the present invention there is provided a lead outlet assembly for a high voltage transformer/reactor comprising an elongate bushing having a bushing axis, a stress shield at a base of the bushing for receiving winding leads from the transformer/reactor and accommodating a connection between the winding leads and the base of the bushing, the stress shield being configured to receive the winding leads in a direction off-axis with respect to the bushing axis.

Thus, the stress shield is configured such that the bushing extends out of the stress shield along the bushing axis and the winding lead extends into the stress shield along the second axis or direction, the angle between the bushing axis and the second axis being less than 180 °. It has been found that constructing the stress shield in such a way that it does not have to receive the winding leads along the bushing axis allows for a more compact design and may eliminate the need for the tower and thus any disassembly of the tower during transport.

The stress shield may be configured such that an angle between the winding lead and the bushing axis at a connection point between the winding lead and the base of the bushing is less than 180 °. The angle may be less than 170 ° or less than 150 ° or less than 120 °. The angle at which the stress shield receives the winding lead relative to the bushing axis and the angle at which the connection is made between these two components is important because it allows the lead outlet assembly to be compact.

The lead outlet assembly may form part of a transformer or a reactor. The transformer/reactor may comprise an Ultra High Voltage (UHVAC) transformer/reactor. The transformer/reactor may include an inductive element mounted within the tank. The stress shield may be mounted within the canister. This is advantageous since the tower is no longer required, since the stress shield, which is accommodated in the connection between the bushing and the winding lead, is mounted inside the tank, rather than outside the tank inside the tower structure. A transformer/reactor may form an aspect of the invention having an inductive element mounted in a tank, wherein a stress shield forms an insulating structure around a connection between a lead wire of the transformer/reactor and a bushing.

The liner may be arranged such that it extends through the aperture in the tank.

The tank may be configured to support the liner at the point where the liner extends through the tank.

The liner may include a first end received within the stress shield and a second end opposite the first end forming a terminal of the transformer/reactor, the first and second ends separated by an intermediate section, wherein the tank is configured to engage and support the liner through the intermediate section of the liner.

The inductive element may comprise one or two (or more) coils or windings mounted side by side and said stress shield of the lead exit assembly may be mounted at least partially between said coils. This may result in a particularly compact design, since the stress shield may occupy the space between the sides of the two substantially cylindrical coils and may fit within a linear circumference extending between the outer edges of the coils.

The stress shield may be mounted to and supported by an insulating support structure extending within the tank.

The tank may contain an insulating fluid and the fluid may submerge the stress shield and the inductive element.

The stress shield may be configured to receive more than one winding lead. Another winding lead may also be received into the stress shield in a direction other than along the liner axis.

According to a second aspect of the invention, there is provided a method of assembling a lead outlet assembly for an HV transformer/reactor, the transformer/reactor comprising a tank configured to receive an inductive element of the transformer/reactor, the method comprising:

a) installing a stress shield within the canister;

b) mounting a base of an elongated bushing in the stress shield, the bushing extending along a bushing axis;

c) mounting winding leads from the inductive element to the base of the bushing, the winding leads being received into the stress shield in an off-axis direction relative to the bushing axis.

According to a third aspect of the invention, there is provided an electrical distribution network comprising a transformer/reactor having the lead outlet assembly of the first aspect of the invention.

Drawings

Preferred embodiments of the present invention will now be briefly described, by way of non-limiting examples, with reference to the following drawings, in which:

FIG. 1 shows a plan view of a transformer including a lead outlet assembly with a bushing shown transparently therein;

FIG. 2 shows a front view of the transformer shown in FIG. 2;

fig. 3 shows a side view of the transformer shown in fig. 2 and 3; and

fig. 4 shows a flow chart illustrating a method of assembling a lead outlet assembly in a transformer.

Detailed Description

Fig. 1 to 3 show a lead outlet assembly 1 of an extra high voltage transformer 20. It should be understood that the lead exit assembly is equally applicable to a reactor, although for brevity the following example will only refer to a transformer. The lead wire exit assembly includes an elongated bushing 2 (shown in fig. 3) having a bushing axis B. The bushing 2 comprises an insulated conductor 4 (shown schematically in fig. 2) which provides an electrical connection to the transformer 20. The assembly 1 further comprises a stress shield 5 at the base 6 of the bushing 2 for receiving the winding leads 7 from the transformer 20 and accommodating electrical connections 8 between the winding leads 7 and the base 6 of the bushing 2. The stress shield 5 is configured to receive the winding lead 7 in an off-axis direction with respect to the bushing axis B. The stress shield 5 provides an insulating function around the joint between the winding lead and the bushing.

The winding lead 7 comprises an electrical conductor which extends from the inductive element of the transformer 20 comprising the winding 10. In this example, the winding 10 is arranged as two

coils

11 and 12. The winding leads 7 thus provide an electrical connection between the

coils

11, 12 and the liner 2. In the embodiment shown here, two winding leads 7a and 7b are received by the stress shield 5, one from each of the

coils

11, 12. It should be understood that the stress shield 5 may be configured to receive only one lead, two leads, or more leads.

The

coils

11 and 12 are of generally cylindrical construction with insulation around them and are mounted side by side with their axes parallel to each other as is conventional. The stress shield 5 and the connection 8 are mounted in the gap 22 between the two

coils

11, 12. This is possible because the stress shield 5 receives the winding lead 7 at an angle relative to the bushing axis.

The

inductive elements

11, 12 of the transformer 20 are mounted together with a tank 21, the tank 21 forming a housing for the

coils

11, 12. The stress shielding part 5 and the connecting part 8 are also mounted in the tank 21.

The tank 21 further comprises a support structure 23 to which the stress shield 5 is mounted. The stress shield 5 is located in the space defined by the gap 22 and the can 21. The tank 21 also includes an aperture 24 in the upper surface which allows the liner 2 to extend out of the tank.

The bushing 2 comprises a first end 13 at which the connection 8 is formed and which is received in the stress shield 5. The bushing also has a second end 14 opposite the first end 13, which includes a terminal 15 that provides an electrical connection to the transformer 20. The terminal 15 includes an end (terminal end) of the conductor 4 extending through the bushing 2. The first end 13 comprises the base 6 of the liner 2. The first end 13 and the second end 14 are separated by an intermediate section 16. The assembly 1 is configured such that the middle section 16 of the liner 2 extends through the aperture 24. The intermediate section 16 may comprise a flange 17 arranged to be connected to a tank 21. The canister 21 may include an annular ring 25 adapted to engage the flange 17. Thus, the tank supports the liner 2 by its middle section when the liner extends beyond the wall of the tank 21.

The stress shield 5 comprises a substantially spherical or ovoid conductor with an insulating wall accommodating the connection 8. The stress shield 5 is supported by an insulating support structure 18 mounted within a tank 21.

Fig. 3 shows the angular relationship between the winding lead 7 and the bushing 2. The bushing 2 is received along a bushing axis B into the stress shield 5. Thus, the stress shield 5 comprises a hole 30 for receiving the bushing 2. The stress shield 5 also comprises lead holes 31 (two in this embodiment) for receiving the winding leads. One of the winding leads is received along axis L. The lead axis L is not along the axis B and is therefore off-axis relative to the bushing axis B. Furthermore, the axis L and the axis B are not parallel to each other. Thus, the angle C formed between axis B and axis L is less than 180 °. The angle between the bushing axis and the lead 7 at the connection 8 is also less than 180 °. Thus, the connection 8 between the lead 7 and the base of the bush forms an obtuse angle, rather than end-to-end. As seen in fig. 3, the other winding lead is also received along an axis that is arranged at a similar angle to the bushing axis B. Thus, the other winding lead has a similar angular relationship to the bushing axis B. The axis L is substantially perpendicular to the axis of the

coils

11, 12. The bush 2 thus extends directly upwards away at an acute angle and the lead(s) 7 extend at an angle substantially perpendicular to the upward direction (as in this example the coil is mounted with its axis parallel to the upward direction).

Fig. 4 shows a flow chart illustrating a method of installing a stress shield within the canister as shown in step 50. Step 51 shows installing the base of an elongated bushing in the stress shield, the bushing extending along a bushing axis. Step 52 shows mounting the winding leads from the inductive element to the base of the bushing, the winding leads being received in the stress shield in an off-axis direction relative to the bushing axis. Step 53 shows fastening the middle section of the liner to the tank at the point where it extends through the hole in the tank. Step 54 shows filling the tank with an insulating fluid and thereby submerging the stress shield and inductive element in the fluid.

Claims

1. A lead wire outlet assembly (1) for a high voltage transformer/reactor (20) comprising an elongated bushing (2) having a bushing axis (B), a stress shield (15) at a base (6) of the bushing (2) for receiving a winding lead wire (7) from a transformer/reactor (20) and accommodating a connection (8) between the winding lead wire (7) and the base (6) of the bushing (2), the stress shield (5) being configured to receive the winding lead wire (7) in an off-axis direction relative to the bushing axis (B).

2. A lead outlet assembly according to claim 1, wherein the stress shield (5) is configured such that the angle between the winding lead (7) and the bushing axis (B) at the point of electrical connection between the winding lead (7) and the base (6) of the bushing (2) is less than 180 °.

3. A transformer/reactor comprising the lead-out assembly (1) of claim 1 or claim 2.

4. A transformer/reactor as claimed in claim 3, in which the transformer/reactor (20) comprises an inductive element (11, 12) mounted in a tank (21) and the stress shield (5) is mounted in the tank (21) adjacent the inductive element (11, 12).

5. A transformer/reactor according to claim 4, in which the assembly is configured such that the bushing (2) extends through a hole (30) in the tank (21).

6. A transformer/reactor as claimed in claim 5, in which the tank (21) is configured to support the liner (2) at the point where the liner projects through the tank (21).

7. A transformer/reactor according to claim 6, wherein the bushing (2) comprises a first end (13) received within the stress shield (5) and a second end (14) opposite the first end (13) forming a terminal of the transformer/reactor (20), the first and second ends (13, 14) being separated by an intermediate section (16), wherein the tank (21) is configured to engage and support the bushing (2) through the intermediate section (16) of the bushing.

8. A transformer/reactor according to any one of claims 4-7, in which the inductive element comprises at least two coils (11, 12) mounted side by side and the stress shield (5) of the lead outlet assembly (1) is mounted at least partly between the coils (11, 12).

9. A transformer/reactor according to any one of claims 4-8, wherein the stress shield (5) is mounted to and supported by an insulating support structure (18) extending within the tank (21).

10. Transformer/reactor as claimed in any of claims 4-9, in which the tank (21) contains an insulating fluid and in which tank (21) the fluid submerges the stress shield (5) and the inductive element (11, 12).

11. A method of assembling a lead-out assembly (1) of a transformer/reactor (20), the transformer/reactor (20) comprising a tank (21) configured to receive an inductive element (11, 12) of the transformer/reactor (20), the method comprising:

a) installing a stress shield (5) within the tank (21);

b) mounting a base (6) of an elongated bushing (2) in the stress shield (5), the bushing (2) extending along a bushing axis (B);

c) -mounting a winding lead (7) from the inductive element (11, 12) to the base (6) of the bushing (2), the winding lead (7) being received in the stress shield (5) in an off-axis direction with respect to the bushing axis (B).

12. A power distribution network comprising a transformer/reactor (20) as defined in any one of claims 3 to 10.