Converter

Abstract

To provide a method for connecting a high-pressure lead line and a high-pressure winding which can suppress increase of the electric resistance in a joint part without using a tab lead.SOLUTION: In a converter in which an aluminum strip is used for a converter winding and a copper strip is used for a high-pressure lead line 11 which connects the converter winding to a bushing, an end part of the converter winding and the high-pressure lead line 11 are joined by a connection conductor 13 formed of an aluminum conductor. The connection conductor 13 and the end part of the converter winding are joined by welding and the connection conductor 13 and the high-pressure lead line 11 are joined by a crimp terminal 16.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a technology for joining an end of a transformer winding made of an aluminum conductor to an end of a high voltage lead wire made of a copper conductor in a transformer. [Background technology]

[0002] The transformer body that constitutes a transformer consists of an iron core and a winding (transformer winding) wound around it. The transformer winding consists of a high-voltage winding and a low-voltage winding. The end of the high-voltage winding is connected to the high-voltage lead wire that constitutes the high-voltage bushing, and the low-voltage winding is connected to the low-voltage bushing via an outlet conductor.

[0003] The high-voltage lead wire is inserted through the high-voltage bushing and connected to an external electric wire or cable via the external terminal of the high-voltage bushing, while the low-voltage lead conductor is connected to an internal terminal of the low-voltage bushing, inserted through the low-voltage bushing, and connected to an external electric wire or cable via the external terminal of the low-voltage bushing.

[0004] Fig. 5 shows an example of the above-mentioned transformer. In Fig. 5, 21 denotes an iron core with transformer windings 22 wound around its legs, and the transformer windings 22 have, for example, a low-voltage winding wound on the inside and a high-voltage winding wound on the outside.

[0005] Reference numerals 23 and 24 denote clamps that clamp and fix iron core 21 from above and below, and together with transformer winding 22, constitute transformer body B. Reference numeral 25 denotes a transformer tank that houses transformer body B, and reference numeral 26 denotes insulating oil 26 that immerses transformer body B inside transformer tank 25. Reference numeral 27 denotes a transformer cover that closes the upper opening of transformer tank 25, reference numeral 28 denotes a high-voltage bushing attached to transformer cover 27, and reference numeral 29 denotes a low-voltage bushing attached to transformer cover 27.

[0006] Reference numeral 30 denotes a high-voltage lead wire that is connected to an external terminal 31 of the high-voltage bushing 28, passes through the inside of the high-voltage bushing 28, and is drawn into the transformer tank 25, and reference numeral 32 denotes an output wire of the high-voltage winding of the transformer winding 22 that is connected to the end of the high-voltage lead wire 30. The external terminal 31 of the high-voltage bushing 28 is connected to an external power distribution line, cable, or the like.

[0007] Reference numeral 32 denotes an internal terminal of the low-voltage bushing 29, and 33 denotes an output conductor connected to the low-voltage winding of the transformer winding 22. Reference numeral 34 denotes a fixing member such as a bolt or nut that connects the end of the output conductor 33 to the internal terminal 32 of the low-voltage bushing 29. Reference numeral 35 denotes an external terminal of the low-voltage bushing 29, and the external terminal 35 is connected to an external power distribution line or cable or the like.

[0008] In a transformer having the above configuration, copper wire is often used for the transformer winding 22 due to its high electrical conductivity. Accordingly, copper wire is also used for the high voltage lead wire 30 connected to the transformer winding 22.

[0009] On the other hand, aluminum wire may be used for the transformer winding 22. Although aluminum has a lower conductivity than copper, it is lightweight and can carry the same current as copper with half the weight. Aluminum also has the advantage of being cheaper than copper.

[0010] In this case, it is possible to use an aluminum conductor for the high voltage lead 30, but it is also possible to change only the transformer body from copper windings to aluminum windings, and continue to use the specifications before the change for the other components. In this case, the high voltage lead wire 30 remains a copper wire.

[0011] In this context, when copper is used for the high-voltage lead wire 30 and aluminum is used for the transformer winding 22, a known method of electrically connecting the two is to connect the transformer winding 22 and the high-voltage lead wire 30 with a crimp terminal.

[0012] However, the output wire 32 (the end of the high-voltage winding) of the transformer winding 22 is prone to developing an oxide coating on its surface, and when it is connected to a high-voltage lead wire 30 made of a different material using a crimp terminal, there is a problem that the contact resistance of the connection increases due to the effect of the oxide coating.

[0013] There is also a known method of joining the output wire 32 and the high voltage lead wire 30 by soldering or brazing. However, even in this case, there is a possibility that poor soldering or brazing at the joint may result in high electrical resistance or insufficient strength.

[0014] Alternatively, cold rolling can be used as a method for joining dissimilar materials (aluminum and copper) while avoiding the problem of high electrical resistance at the joint. However, cold rolling is limited in the shapes that can be joined, and it is difficult to join aluminum wires and copper wires of different widths and diameters.

[0015] On the other hand, as a method for solving such problems, it is possible to connect the transformer winding 22 made of aluminum and the high-voltage lead wire 30 made of copper using a toughened wire formed by joining an aluminum wire and a copper wire by cold rolling, as described in paragraph

[0010] of the [Detailed Description of the Invention] of Patent Document 1 listed below. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Patent Publication No. 2017-60976

[0017] As described above, when a tuff lead is used to join the transformer winding 22 and the high voltage lead wire 30, as shown in FIG. 6, the aluminum wire side of the tuff lead 36 is joined to the output wire 32 of the transformer winding 22 made of aluminum with a crimp terminal, and the conductor side of the tuff lead 36 is joined to the high voltage lead wire 30 made of copper wire with a crimp terminal. Summary of the Invention [Problem to be solved by the invention]

[0018] However, as described above, the tough lead 36 requires joining an aluminum wire and a copper wire by cold rolling, and the manufacturing process of the tough lead itself requires many steps, which increases the manufacturing cost of the transformer.

[0019] Therefore, the present invention provides a method for connecting a high voltage lead wire and a high voltage winding while suppressing an increase in electrical resistance at the joint without using the above-mentioned toughened wire. [Means for solving the problem]

[0020] The invention described in claim 1 is a transformer comprising a transformer body consisting of an iron core and a winding, in which aluminum wire is used as the conductor of the winding and copper wire is used as the high-voltage lead wire connecting the winding to a bushing, and which is characterized in that the end of the winding and the high-voltage lead wire are joined by a connecting conductor.

[0021] The invention as recited in claim 2 is characterized in that the connecting conductor as recited in claim 1 is an aluminum conductor.

[0022] The invention as recited in claim 3 is characterized in that the connecting conductor as recited in claim 2 and the winding end are joined by welding.

[0023] The invention as recited in claim 4 is characterized in that the connecting conductor as recited in either claim 2 or claim 3 is joined to a crimp terminal attached to a high voltage lead wire.

[0024] The invention as recited in claim 5 is characterized in that the surface of the connecting conductor as recited in claim 4 and the surface of the crimp terminal are subjected to a surface treatment for preventing the formation of an oxide film. Effect of the Invention

[0025] According to the invention of claim 1, there is no need to connect the output wire of the transformer winding on which an oxide film has formed to the high voltage lead wire, and it is possible to prevent the electrical resistance of the joint from becoming high.

[0026] According to the invention described in claim 2, a connection conductor made of the same material as the lead wire of the high-voltage winding of the transformer winding is connected to the lead wire, so that the electrical resistance of the joint can be made constant to the electrical resistance of the lead wire and the connection conductor.

[0027] According to the invention as recited in claim 3, since the lead wire and the connecting conductor of the high voltage winding of the transformer winding, which are made of the same material, are welded together, the difficulty of welding is reduced and weldability can be improved.

[0028] According to the invention described in claim 4, the connecting conductor is connected to a crimp terminal attached to the high-voltage lead wire, so that the connecting conductor and the high-voltage lead wire can be joined without being affected by the oxide coating that is present on the output wire of the transformer winding, and an increase in the contact resistance of the joint can be prevented.

[0029] According to the invention described in claim 5, the surface of the connecting conductor and the surface of the crimp terminal are subjected to a surface treatment to prevent the formation of an oxide film, thereby preventing the occurrence of a problem in which an oxide film forms on the surfaces of the connecting conductor and the crimp terminal, increasing electrical resistance. [Brief description of the drawings]

[0030] [Figure 1] 1 is a vertical cross-sectional view showing an example of a transformer to which the present invention is applied. [Diagram 2] 2 is an enlarged view of a main portion showing a connection state between one output wire of a transformer winding and a connecting conductor that constitutes the transformer of the present invention. FIG. [Diagram 3] 2 is an enlarged view of a main portion showing the connection state of two output wires of a transformer winding and a connecting conductor that constitute the transformer of the present invention. FIG. [Figure 4] 4 is an enlarged view of a main portion showing a connected state between a connecting conductor and a high-voltage lead wire according to the present invention. FIG. [Diagram 5] FIG. 2 is a vertical cross-sectional view showing an example of a connection state between a transformer winding and a bushing that constitute a transformer. [Figure 6] 1 is a longitudinal sectional view showing an example of a connection state between a transformer winding and a bushing that constitute a transformer. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] An embodiment of a transformer according to the present invention will be described below with reference to Fig. 1 to Fig. 4. Fig. 1 shows a left side view and a vertical cross section of the transformer shown in Fig. 5 or Fig. 6. In Fig. 1, 1 indicates an iron core (three-legged iron core), and 2 indicates windings (transformer windings) wound around each leg of the iron core 1.

[0032] Clamps 3 and 4 are arranged above and below the transformer winding 2 to clamp and secure the winding 2 from above and below, and together with the iron core 1 and the winding 2, constitute the transformer body A. 5 is a transformer tank that houses the transformer body A, and 6 is insulating oil that immerses the transformer body A inside the transformer tank 5.

[0033] Reference numeral 7 denotes a transformer cover that closes the top of the transformer tank 5, and reference numeral 8 denotes a high-voltage bushing attached to the transformer cover 7. Note that a low-voltage bushing is also attached to the transformer cover 7, but this is not shown in the drawing for convenience of illustration.

[0034] Reference numeral 9 denotes an output wire derived from the high-voltage winding that constitutes winding 2, and constitutes the end of the high-voltage winding. Reference numeral 10 denotes an output wire derived from the low-voltage winding that constitutes winding 2, and is output from the opposite side (the back side of the page) to the output wire 9 of the high-voltage winding, and constitutes the end of the low-voltage winding. Reference numeral 11 denotes a high-voltage lead wire that is connected to external terminal 12 of high-voltage bushing 8, passes through high-voltage bushing 8, and is drawn into transformer tank 5.

[0035] Reference numeral 13 denotes a connecting conductor which constitutes the essential part of the present invention and connects between the high-voltage winding output wire 9 and the high-voltage lead wire 11. Note that while Fig. 1 illustrates a case in which the three-phase high-voltage windings are delta-connected, this connection method (delta connection) is illustrated only as one example that can be adopted, and connection methods other than delta connection, such as Y connection or V connection, may also be used.

[0036] Although the lead conductor connecting the lead wire 10 of the low-voltage winding and the low-voltage bushing is not shown in the diagram for convenience of illustration, any connection method may be used for the low-voltage winding as well, such as a delta connection, a Y connection, a V connection, etc. Typically, the delta-delta connection, a YY connection, a delta-Y connection, and a VV connection are representative.

[0037] 1, winding 2 is made of aluminum wire, and lead wire 9, which is the end of the high-voltage winding of winding 2, is also made of aluminum wire. On the other hand, high-voltage lead wire 11 is made of copper wire, so connecting conductor 13 connecting lead wire 9 and high-voltage lead wire 11 connects dissimilar materials.

[0038] Figure 2 shows a method of connecting the lead wire 9 of the high-voltage winding shown in Figure 1 to the connecting conductor 13. The lead wire 9 shown in Figure 2 is the paper-wrapped rectangular aluminum wire of the high-voltage winding drawn out to the outside of the winding, and is joined to the connecting conductor 13 after the coating (wrapping paper) at the end of the lead wire 9 is removed.

[0039] The connecting conductor 13 is made of an aluminum conductor. The shaded portion 14 in Fig. 2 is a plated portion applied to the surface of the upper end portion of the connecting conductor 13. The plated portion 14 has a first opening 14a formed therein.

[0040] 2(a) is a front view showing a state in which an I-shaped connection conductor 13 is joined to an L-shaped lead wire 9. As shown in the figure, the tip of the lead wire 9 according to the present invention, from which the coating has been removed, is joined to a portion of the connection conductor 13 where the plating portion 14 is not applied. The two are joined by welding, preferably by TIG welding.

[0041] Fig. 2(b) is a right side view showing the joined state of the lead wire 9 and the connection conductor 13. As shown in Fig. 2(b), the connection conductor 13 is joined to the lead wire 9 by welding in a state where they are overlapped with each other.

[0042] 2(c) is a right side view showing the state where an insulating tube 15 is attached to the lead wire 9 in the joined state shown in FIG. 2(b). The insulating tube 15 is intended to ensure an insulating distance between the lead wire 9 and other components of the transformer. The coating of the lead wire 9 is removed above the upper end of the insulating tube 15.

[0043] Figure 3 shows a method for connecting multiple lead wires 9 of a high-voltage winding to a connecting conductor 13. The lead wire 9 shown in Figure 3 is also the paper-wrapped rectangular aluminum wire of the high-voltage winding drawn outside the winding, and is joined to the connecting conductor 13 after the coating (wrapping paper) at the end of the lead wire 9 is removed, just like in Figure 2.

[0044] 2 in that the connecting conductor 13 is made of an aluminum conductor, the hatched portion 14 of the connecting conductor 13 is a plated portion, and the plated portion 14 has a first opening 14a formed therein.

[0045] 3(a) is a front view showing a state in which one I-shaped connecting conductor 13 is joined to two lead wires 9 drawn out in an L-shape. The ends of the two lead wires 9, from which the coating has been removed, are joined to a portion of the connecting conductor 13 where the plating portion 14 is not applied. The joining is performed by welding, preferably TIG welding.

[0046] An insulating tube 15 is attached to the two output wires 9 to ensure an insulating distance between them and other components of the transformer, and to bundle the two output wires 9 together to prevent the output wires 9 from becoming distorted.

[0047] Fig. 3(b) is a right side view showing the joined state of the two lead wires 9 and the connecting conductor 13. As shown in Fig. 3(b), the connecting conductor 13 is joined by welding in a state where it is overlapped so as to be sandwiched between the two lead wires 9. The coating of the two lead wires 9 is removed above the upper end of the insulating tube 15.

[0048] The outlet wire 9 of such a high-voltage winding is made of aluminum wire, and the connecting conductor 13 is also made of aluminum wire. Both components are made of the same material, making it easy to join them by welding. In particular, joining them by TIG welding allows for precise welding and a beautiful finish. Also, TIG welding has the advantage of reducing spatter because inert gas is used.

[0049] As described above, by joining the lead wire 9 and the connecting conductor 13 made of the same material (aluminum) by welding, unlike joining by soldering or brazing, joint failure is less likely to occur and it is possible to prevent an increase in electrical resistance at the joint and insufficient strength. In addition, by welding at a location other than the plated portion 14 of the connecting conductor 13, it is possible to prevent the plating from being damaged by heat caused by welding.

[0050] Fig. 4 is a diagram showing a method of connecting the connection conductor 13 joined to the lead wire 9 as described above to the high-voltage lead wire 11 shown in Fig. 1, Fig. 4(a) being a front view and Fig. 4(b) being a right side view. In the case of Fig. 4, a crimp terminal 16 is attached to the tip of the high-voltage lead wire 11. A second opening 16a is formed in the crimp terminal 16. As explained in Fig. 3, an insulating tube 15 is attached to the lead wire 9 to ensure an insulating distance between the lead wire 9 and other components of the transformer.

[0051] The connecting conductor 13 is made of an aluminum wire, and the high-voltage lead wire 11 is made of a copper wire, so that the two components are made of different materials. When connecting the connecting conductor 12 and the high-voltage lead wire 11, the plated portion 14 of the connecting conductor 13 and the crimp terminal 16 are overlapped so that the position of the first opening 14a of the connecting conductor 13 shown in Figure 4(a) and the position of the second opening 16a of the crimp terminal 16 attached to the high-voltage lead wire 11 match.

[0052] Then, as shown in Fig. 1(b), bolt 17 is inserted through first opening 14a and second opening 16a, which are aligned, and they are fixed together by tightening with nut 18. As a result, high-voltage winding lead wire 9, which is made of aluminum wire, can be electrically connected to high-voltage lead wire 11, which is made of copper wire.

[0053] In this manner, the connection conductor 13 and the high voltage lead wire 11 according to the present invention are connected via the crimp terminal 16. The surface of the crimp terminal 16 is plated (e.g., tin-plated). The connection conductor 13 is made of an aluminum wire and the high voltage lead wire 11 is made of a copper wire, so that dissimilar materials are joined in the same manner as described in the prior art. However, in the present invention, the high voltage lead wire 11 is not directly connected to the lead wire 9 having an oxide film formed on its surface by the crimp terminal 16, but is connected to the connection conductor 13, which has a plating portion 14 to prevent the formation of an oxide film, by using the plated crimp terminal 16, so that an increase in contact resistance due to the formation of the oxide film does not occur.

[0054] As described above, the transformer of the present invention can connect the output wires of the high-voltage winding made of aluminum wire to the high-voltage lead wires made of copper wire without using a tough lead. Therefore, the process of joining the aluminum wire and the copper wire by cold rolling to manufacture a tough lead is unnecessary, reducing the number of steps and making it possible to suppress the manufacturing cost.

[0055] In addition, since the output wire and the high-voltage lead wire can be joined (connected) without increasing the contact resistance between them, a decrease in the electrical efficiency of the transformer can be prevented.

[0056] In the above embodiment, the transformer winding is made of aluminum wire and the high-voltage lead wire is made of copper wire, but the reverse is also possible. Also, the connection between the high-voltage winding output wire and the high-voltage lead wire has been described as an example, but the connecting conductor of the present invention may be used to connect between the low-voltage output conductor and the low-voltage bushing.

[0057] Furthermore, the crimp terminal to be connected to the connecting conductor is not limited to the shape shown in Figure 4, and may be of any shape as long as it can connect the connecting conductor and the crimp terminal attached to the high-voltage lead wire without increasing the contact resistance. [Industrial Applicability]

[0058] The present invention is applicable to situations in which conductors made of different materials are to be connected. [Explanation of symbols]

[0059] 1,21 Iron core 2,22 Winding 3,4,23,24 Clamp 5,24 Transformer tank 6,26 Insulating oil 7,27 Transformer cover 8,28 High pressure bushing 9,10,32 Outlet wire 11,30 High voltage lead wire 12,31,35 External terminals 13 Connecting conductor 14 Plating Department 14a First opening 15 Insulating tube 16 Crimp terminal 16a Second opening 17 Volts 18 Nut 34 Fixing member A, B Transformer body

Claims

1. A transformer comprising a transformer body consisting of an iron core and a winding, wherein aluminum wire is used for the conductor of the winding, and copper wire is used for the high-voltage lead wire connecting the winding to a bushing, characterized in that an end of the winding and the high-voltage lead wire are joined by a connecting conductor.

2. 2. The transformer according to claim 1, wherein the connecting conductor is an aluminum conductor.

3. 3. The transformer according to claim 2, wherein the connecting conductor and the winding end are joined by welding.

4. 4. The transformer according to claim 2, wherein the connecting conductor is joined by a crimp terminal attached to a high voltage lead wire.

5. 5. The transformer according to claim 4, wherein a surface of said connecting conductor and a surface of said crimp terminal are treated to prevent the formation of an oxide film.

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