WO2014098272A1

WO2014098272A1 - A transformer low voltage coil and a transformer thereof

Info

Publication number: WO2014098272A1
Application number: PCT/KR2012/011017
Authority: WO
Inventors: Seung-Chul Lee; Jong-Yun Lim; Chang-Hyeon Lee
Original assignee: ABB Technology AG
Current assignee: ABB Technology AG
Priority date: 2012-12-17
Filing date: 2012-12-17
Publication date: 2014-06-26
Anticipated expiration: 2015-06-17

Abstract

The present invention provides a transformer low voltage coil, which minimizes the low voltage coil and consequently minimizes the core of the transformer and saves the cost. The transformer low voltage coil comprises a low voltage coil and at least two lead bars and said at least two lead bars (211, 212) are located separately in a way that the projection towards the redial direction (118) of each of the at least two lead bars (211, 212) on the internal surface of the low voltage coil (102) are non-overlapped. The present invention also provides a triangular core transformer using such a low voltage coil. The high voltage coil further comprises a connection support for delta connection or Y connection. Each end of said low voltage coil and the high voltage coil are fixed by three coil blocks.

Description

A TRANSFORMER LOW VOLTAGE COIL AND A TRANSFORMER THEREOF

The present invention relates generally to the field of transformer technology, and in particular, relates to a low voltage coil of a transformer and also to a transformer, especially a triangular transformer using such a low voltage coil.

Triangular core transformers have many benefits such as lower losses, reduced noise level, lower weight, smaller inrush current, smaller foot print, more manageable external magnetic radiation field and lower third harmonics in a three-phase distribution system.

See FIG. 1, triangular cores for three-phase distribution transformers 100 typically consist of three core frames 101, which are essentially a group of one or more loops of magnetic steel or a similar, low magnetic reluctance material. The core frames are fit together such that when viewed from above, the core takes the form of a triangle. Each phase of the transformer fits on a single core leg, through which two of the loops pass through. The triangular cores are located in a low voltage coil 102. The low voltage coil 102 is located in a high voltage coil 103 with an air gap between them. The air gap is for electrical strength.

Also as shown in FIG. 1, the low voltage coil 102 needs two

lead bars

111, 112 for further connection to its both ends. Traditionally, the both

lead bars

111, 112 are located together as show in FIG. 1 and FIG. 2a and FIG. 2b. That means both lead bars are located at the same place on the perpendicular direction of the low voltage core axis 119.

As the transformer cores are located in the low voltage coil, low voltage mold can not collapse for low voltage lead bar 112. Therefore, low voltage coil outer diameter should be increased by low

voltage lead bars

111, 112. The low voltage coil thickness 120 is calculated by the thickest part. See FIG. 2a, that is the two-lead bar part. It increases additional High-Low air clearance.

The traditional design of low

voltage lead bars

111, 112 makes the low voltage coil very large and consequently, the High-Low air clearance large. This further makes the high voltage coil large and the triangular core large.

Thus it is needed to minimize the low voltage coil. Thus the size of the high voltage coil and the triangular core is also minimized.

Summary of The Invention

One of the objectives of the embodiments of the present invention is to provide a transformer low voltage coil, which at least minimizes the low voltage coil and consequently minimizes the core of the transformer and saves the cost.

In one aspect of the present invention, there is provided a transformer low voltage coil. It comprises a low voltage coil and at least two lead bars and said at least two lead bars are located separately in a way that the projection towards the redial direction of each of the at least two lead bars on the internal surface of the low voltage coil are non-overlapped.

In one of the embodiments of the present invention, the transformer low voltage coil further comprises a triangular core.

In one of the embodiments of the present invention, the transformer low voltage is dry type. Said low voltage coil is located in a high voltage coil, and the high voltage coil further comprises a connection support for delta connection or Y connection.

In one of the embodiments of the present invention, each end of said low voltage coil and high voltage coil are fixed by three coil blocks. Comparing with using four coil blocks in the prior art, this can also save cost. By reducing one block in the center position of the delta core transformer, the heat dissipating efficiency is highly increased.

In another aspect of the present invention, there is provided a triangular core transformer. It comprises a triangular core, a low voltage coil and a high voltage coil, wherein the low voltage coil further comprises two lead bars which are located separately in perpendicular direction to the axial of the low voltage coil.

In one of the embodiments of the present invention, each end of said low voltage coil and the high voltage coil are fixed by three coil blocks. The high voltage coil further comprises a high voltage connection support for delta connection or Y connection.

In one of the embodiments of the present invention, the high voltage coil is made by foil disc winding.

In one of the embodiments of the present invention, the high voltage coil is made by horizontally casting a high voltage coil disc winding.

Having thus described the example embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 is a triangular core transformer with a prior low voltage coil;

FIG. 2a is a sectional view of a prior low voltage coil; Fig. 2b is a sectional view of a prior low voltage coil with a triangular core;

FIG. 3a is a sectional view of a low voltage coil according to a preferred embodiment of the present invention; Fig. 3b is a sectional view of a low voltage coil with triangular core according to a preferred embodiment of the present invention;

FIGs. 4a-4b show the longest semi-diameter comparison between the a prior low voltage coil and a low voltage coil according to a preferred embodiment of the present invention; FIGs. 4c-4d show the triangular core length comparison and the High-Low gap comparison between the a prior low voltage coil and a low voltage coil according to a preferred embodiment of the present invention;

FIG. 5 is a perspective view of a triangular core transformer with a low voltage coil according to the present invention and only three coil blocks;

FIG.6 is a front view of a triangular core transformer with a low voltage coil of the present invention and a high voltage connection support.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

The present invention will be described in more details by a triangular transformer, but the design and the improvement according to the present invention is applicable to all types of transformers.

FIG. 1 shows structure of a triangular core transformer. The triangular cores are located in a low voltage coil 102. The low voltage coil 102 is located in a high voltage coil 103 with an air gap between them. As described above in the background, the low voltage coil outer diameter is increased by low

voltage lead bars

111, 112. See FIG. 2a, the low voltage coil thickness 120 is calculated by the thickest part.

According to a preferred embodiment of the present invention, the transformer low voltage coil comprises a low voltage coil 102 and at least two

lead bars

211, 212, wherein said at least two

lead bars

211, 212 are located separately in a way that the projection towards the radial direction 118 of each of the at least two

lead bars

211, 212 on the internal surface of the low voltage coil 102 are non-overlapped. Here the radial direction 118 means a direction perpendicular to and towards the axial 119 of the low voltage coil 102. See FIGs. 2a and 3a.

According to a preferred embodiment of the present invention, the two

lead bars

211, 212 are preferred to be separated in an angle of 90°-120° to the axial 119 of the low voltage coil. But the separated angle is not limited to above scope. The preferred angle of 90°-120° is easy for assembling. But any angle which can separate the two

lead bars

211, 212 in perpendicular direction 118 to the axial 119 of the low voltage coil is applicable.

By separating two

lead bars

211, 212 in perpendicular direction 118 to the axial 119, the prior thickest part 120, as shown in FIG. 2a, can be reduced to the thickest part 220 according to the present invention. By this, the thickest part of the low voltage coil can reduce from a thickness of a

lead bar

211 or 212. See FIG. 3a.

Consequently, as shown in FIG. 2b and FIG. 3b, the high voltage coil can reduce a semi-diameter of the thickness of a

lead bar

211 or 212, and each frame of the delta core 101 can reduce a length of twice thickness of a

lead bar

211 or 212.

FIG. 4a shows the comparison between the prior transformer low voltage coil and the transformer low voltage coil of the present invention. Take a triangular transformer of 1MVA, 22.9kV/0.38kV as example, all distances in FIG. 4a and FIG. 4b are shown in the following chart. The dimension of a lead bar is 100mm in length and 12mm in thickness.

See FIG. 4a, by using prior lead bars, the longest distance D11 for Bended & Trimmed Bar or Bended & non-Trimmed Bar are both 183 mm. The longest distance D13 for Flat & non-Trimmed Bar is 189 mm. In the figures, the distance of D12 is 177mm, D14 is 159mm.

See FIG. 4b, by using lead bars of the present invention, the longest distance D21 for Bended & Trimmed Bar or Bended & non-Trimmed Bar are both 171 mm. The longest distance D23 for Flat & non-Trimmed Bar is 179 mm. In the figures, the distance of D22 is 165mm, D24 is 178mm.

Comparing above two figures and the related distances, for both Bended & Trimmed Bar and Bended & non-Trimmed Bar, a thickness of 12mm can be saved by separating the two lead bars in the perpendicular direction 118 to the axial 119 of the low voltage coil. Here in FIG. 3a, FIG. 3b, FIG. 4a and FIG. 4b, the perpendicular direction 118 to the axial 119 of the low voltage coil means a direction on the section view and towards the center of the low voltage coil. The saved thickness is exactly the thickness of a lead bar.

The saved thickness looks not tremendous. However, it can save a big mount of cost. See FIG. 4c and FIG. 4d, by separating the two lead bars in the perpendicular direction 118 to the axial 119 of the low voltage coil, the prior longest diameter D33 of the low voltage coil is reduced to the present longest diameter D43. Take a triangular transformer of 1MVA, 22.9kV/0.38kV as example, D33 is 340mm and D43 is 328mm. If we maintain the diameter D32 of the low voltage coil and the diameter D31 high voltage coil the same in the present invention with the prior transformers. The High-Low coil gap is increased from D34 i.e. 25mm to D44 i.e. 38mm. Here in the figures, D31 is 530mm and D32 is 220mm.

For the industry transformers, the cores are always quite huge ones. And as the coppers, silicon steel and other materials for manufacturing the cores, the high voltage coil and the low voltage coils are very expensive. Thus, even saving the diameter of the cores, the high voltage coil and the low voltage coils in millimeters, the cost saving is a big amount.

According to a preferred embodiment of the present invention, a triangular core transformer comprising a low voltage coil 102 of the present invention as described above is provided. The low voltage coil 102 comprises two

lead bars

211, 212 which are located separately in perpendicular direction 118 to the axial 119 of the low voltage coil. As shown in FIG. 3a, FIG. 3b.

According to a preferred embodiment of the present invention, the transformer is a triangular core transformer, in particular it is dry type one. But the present invention is applicable to all types of transformers and not limited to dry transformer or triangular core transformer.

See FIG. 5, according to a preferred embodiment of the present invention, each end of said low voltage coil 102 and high voltage coil 103 are fixed by three coil blocks. Comparing with using four coil blocks in the prior art, this can also save cost. By reducing one block in the center position of the delta core transformer, the heat dissipating efficiency is highly increased.

According to a preferred embodiment of the present invention, see FIG. 6, the low voltage coil 102 is located in a high voltage coil 103, and the high voltage coil 103 further comprising a connection support 109 for delta connection or Y connection. The connection support 109 makes the high voltage coil 103 easy for delta connection or Y connection.

According to a preferred embodiment of the present invention, the high voltage coil 103 is made by foil disc winding. The high voltage foil 103 is made by horizontally casting a high voltage coil disc winding.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

A transformer low voltage coil, comprising a low voltage coil (102) and at least two lead bars (211, 212), wherein said at least two lead bars (211, 212) are located separately in a way that the projection towards the radial direction (118) of each of the at least two lead bars (211, 212) on the internal surface of the low voltage coil (102) are non-overlapped.
A transformer low voltage coil of claim 1, wherein it further comprises a triangular core (101).
A transformer low voltage coil of claim 1, wherein it is dry type.
A transformer low voltage coil of any one of claims 1 to 3, wherein said low voltage coil (102) is located in a high voltage coil (103), and the high voltage coil (103) further comprises a connection support (109) for delta connection or Y connection.
A transformer low voltage coil of claim 4, wherein each end of said low voltage coil (102) and high voltage coil (103) are fixed by three coil blocks.
A triangular core transformer, comprising a triangular core (101), a low voltage coil (102) and a high voltage coil (103), wherein the low voltage coil (102) further comprises two lead bars (211, 212) which are located separately in perpendicular direction (118) to the axial (119) of the low voltage coil.
A triangular core transformer according to claim 6, wherein each end of said low voltage coil (102) and the high voltage coil (103) are fixed by three coil blocks.
A triangular core transformer according to any one of claims 6 or 7, wherein the high voltage coil (103) further comprises a high voltage connection support (109) for delta connection or Y connection.
A triangular core transformer according to claim 8, wherein the high voltage coil (103) is made by foil disc winding.
A triangular core transformer according to claim 8, wherein the high voltage coil (103) is made by horizontally casting a high voltage coil disc winding.