Sinusoidal tubular conductive bus

Abstract

A sinusoidal tubular busbar is a busbar, more specifically, a conductor busbar having a sinusoidal tubular shape, for low and high voltage and switchgear and power control electrical cabinets for prefabricated power lines. The busbar has a starting fastening tab connected to a first sinusoidal curve which in turn is connected to a joining tab which in turn is connected to a second sinusoidal curve such that said first sinusoidal curve and said second sinusoidal curve form a tubular area between them with no contact between said first sinusoidal curve and said second sinusoidal curve. Said second sinusoidal curve is linked to a final fastening tab or to a second joining tab which is connected to a third sinusoidal curve which is linked to a final fastening tab.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electrically conductive busbar, more specifically, an electrically conductive busbar having a sinusoidal, tubular shape, which is applied to electrical cabinets for control and switching equipment assemblies for low and high voltage power and prefabricated power lines. BACKGROUND

[0002] Low and high voltage control and switching equipment assemblies are essential for any electrical installation in all sectors of economic activity. Such assemblies are intended to be used with devices designed for the control of the generation, transmission, distribution and conversion of electric power and for devices that consume electric power. These assemblies are composed of electrical cabinets, functional units in which individual devices are installed, and busbar systems.

[0003] The busbar system is a low impedance conductor to which several circuits can be connected individually. Its function is to conduct electric power between several points in the assembly, and its dimensions must be considered to perform the following:

[0004] a) the temperature rise caused by the flow of electric current in normal use conditions, where this temperature rise is related to the choice of the material used;

[0005] b) thermal and dynamic stresses caused by unusual conditions such as voltage and current spikes, short circuits and accidental arcs;

[0006] c) leakage currents caused by the proximity between conductors and between the conductors and the metal parts of the electrical cabinet; and

[0007] d) the number and way of connections and derivations.

[0008] Given these inherent characteristics of the electric busbar, it is almost entirely made of copper bars with a rectangular cross section, since copper has good electrical conductivity, with a relatively low manufacturing cost compared to other conductive materials such as silver and gold.

[0009] The conductor busbar, when subjected to higher values of alternating current, has a greater chance of suffering from the skin effect, that is, the useful area for electrical conduction is reduced, since the alternating current tends to concentrate on the outer perimeter of the conductor, thus reducing the current density inside it.

[0010] Due to this skin effect, more material is used in the production of solid busbars, thus increasing its cross-sectional area in order to ensure that the conductor has a low apparent resistance, which reduces the negative effects of the skin effect, resulting in a more efficient busbar.

[0011] Bars with a rectangular and solid cross section are practically used in all copper busbar applications in electrical cabinets, and such configurations are commonly found with sizes such as 100 x 10 mm, 80 x 10 mm, 50 x 10 mm, among others.

[0012] Other forms of busbars have also been used, one example being the busbar disclosed in document BR 10 2018068113-3, filed on September 6, 2018, whose purpose is to increase the perimeter so as to improve heat dissipation and reduce losses caused by the skin effect, aiming at the current density in the material of the high current, thus allowing the use of less material to manufacture the busbar. Despite such improvements, in this configuration and others that seek to take advantage of the gain obtained by increasing its perimeter, in systems in which two or more conductors are used per phase, losses are also generated caused by a phenomenon identical in principle to the skin effect; however, similar to the interaction that occurs between different conductors, this phenomenon is known as proximity effect.

[0013] In this way, the prior art would benefit from a profile whose embodiments allow the use of less material, presenting a shape that, by means of the transposition and inversion of the possible paths traveled by the electromagnetic field, there is attenuation of the proximity effect and, as a result, it is possible to achieve the same current capacity as these current profiles. SUMMARY

[0014] The present invention discloses a busbar constructed in a sinusoidal tubular shape, which has a disposition that has mechanical resistance compatible with solid conductive busbars, but with greater conductive efficiency when increasing the perimeter of the conductor, then obtaining a greater area for heat dissipation, in comparison with conventional systems; in conjunction with this, in addition to the space occupied by the busbar reinforcement conductor and the possibility of assembling several busbars together to increase the supported current capacity, the skin effect and proximity effect are also exploited, which results in a reduction of the section, thus increasing the current density in the conductor.

[0015] The purpose of the present invention is to provide a busbar that is capable of conducting greater current with less material.

[0016] Another purpose of the present invention is to provide a busbar that makes it possible to increase the perimeter, thus improving the heat dissipation of the conductor.

[0017] The purpose of the present invention is also to provide a busbar that improves the use of the skin effect when using a tubular shape, in which the internal area of the conductor has less material.

[0018] Another purpose of the present invention is to provide a busbar that allows the assembly of systems with two or more conductors per phase, in such a way that the electromagnetic field generated by the proximity effect is attenuated, thus improving the current balance between the two conductors of the same phase.

[0019] Another object of the present invention is to provide a busbar having an excellent mechanical resistance to withstand the dynamic stresses to which the busbar is subjected in normal operating conditions or in stress conditions, for example in short circuits.

[0020] Another object of the present invention is also to provide a busbar which improves the heat exchange, enhances its cooling and therefore the electrical conductivity.

[0021] Finally, another object of the present invention is to provide a busbar which makes it possible to optimize the space occupied by it. BRIEF DESCRIPTION OF DRAWINGS

[0022] The subject matter of the present specification is best understood when considered in conjunction with the following detailed description and the accompanying drawings, of which:

[0023] - Figure 1 A side view of an embodiment of a busbar in a single folded sheet is shown, in which the initial crimping tab and the joining tab are aligned at the same plane and in which the initial crimping tab is single-layer;

[0024] - Figure 2 A side view of an embodiment of a busbar in a single folded sheet is shown, in which the initial crimping tab and the joining tab are parallel and located in different planes and the initial crimping tab is single-layer;

[0025] - Figure 3 A side view of an embodiment of a busbar in a single folded sheet is shown, in which the joining tab and the final crimping tab are aligned at the same plane, in which the initial crimping tab is double-layer and the joining tab is triple-layer;

[0026] - Figure 4 A side view of an embodiment of a busbar in a single folded sheet is shown, in which the sinusoidal curve is M-shaped, in which the joining and final crimping tabs are aligned at the same plane and in which the initial crimping tab is double-layer and the joining tab is spaced between its flanks;

[0027] - Figure 5 A side view of an embodiment of a busbar in a single folded sheet is shown, in which three M-shaped sinusoidal curves are used, in which the initial crimping tab is two-layer and two joining tabs with two layers are used;

[0028] - Figure 6 A side view of an embodiment of a busbar in a single folded sheet is shown, in which three M-shaped sinusoidal curves are used, in which the initial crimping tab is two-layer and two joining tabs with two layers are used; Figure 1 A side view of two busbar assemblies is shown as

[0029] - Figure 7 A side view of two busbar assemblies is shown as Figure 2Side view of two busbar assemblies as shown in

[0030] - Figure 8 Side view of two busbar assemblies as shown in Figure 3 where the two busbars are fixed by a final crimping tab and an initial crimping tab and the busbars are laterally displaced from each other;

[0031] - Figure 9 Side view of two busbar assemblies as shown in Figure 3 where one of the busbars is fixed by a final crimping tab and an initial crimping tab and the other busbar is fixed by a joining tab and the busbars are laterally displaced from each other;

[0032] - Figure 10 Perspective view of two busbar assemblies aligned assembled where the fixing holes and cooling holes can be observed; and

[0033] - Figure 11 Perspective view of a busbar with attached connecting elements where the fixing holes and cooling holes can be observed. DETAILED DESCRIPTION

[0034] According to the preceding figures, the present invention "sinusoidal tubular conductive busbar" consists of a busbar (B) having an initial crimping tab (1) connected to a first sinusoidal curve (10) which in turn is connected to a joining tab (2) which in turn is connected to a second sinusoidal curve (20) in such a way that said first sinusoidal curve (10) and the second sinusoidal curve (20) form a tubular region (T) therebetween, wherein there is no contact between said first sinusoidal curve (10) and the second sinusoidal curve (20). Said second sinusoidal curve (20) can be connected to a second joining tab (2b) or a final crimping tab (3).

[0035] The initial crimping tab (1) is a flat portion connected to the first sinusoidal curve (10) and can also comprise a single layer (as seen in Figure 1 and Figure 2 ) or multiple layers, so that there is one or more 180° folds, according to Figure 3 , Figure 4 and Figure 5 where examples of the initial crimping tab (1) can be observed with 180° folds forming two layers.

[0036] The joining tab (2) connects the first sinusoidal curve (10) to the second sinusoidal curve (20). The joining tab (2) mentioned has two or more flat areas and can have one or more 180° folds.Figure 1 and Figure 2 An example of a joining tab (2) with two layers of 180° folds is visible in Figure 3 In Figure 4 , it is possible to notice a joining tab with three 180° folds forming four layers. Moreover, this joining tab (2) can have its layers separated, as shown in Figure 5 , where two layers of joining tab (2) are shown spaced between the layers. For a conductor busbar (B) with three or more sinusoidal curves, more than one joining tab (2) is used, as shown in ,

[0037] This final crimp tab (3) closes the section and can enclose the initial crimp tab (1) or the joining tab (2). Figures 1 to 4 An example of a final crimp tab (3) enclosing the initial crimp tab (1) is shown, and Figure 5 An example of a final crimp tab (3) enclosing the joining tab (2a) is shown.

[0038] The surfaces of the joining tab (2) and the final crimp tab (3) can be aligned, i.e. on the same plane. They can be in parallel planes, i.e. not aligned, or they can also be in orthogonal planes, in order to facilitate assembly in specific cases. Figure 1 , Figure 3 , Figure 4 and Figure 5 An example of aligned joining tab (2) and final crimp tab (3) is shown, and Figure 2 and Figure 7 An example is shown where the tabs are in parallel planes.

[0039] The first sinusoidal curve (10) and the second sinusoidal curve (20) form a tubular region (T) which is generated by the separation of two sinusoids which do not touch each other. In addition, there can be more than two sinusoidal curves, as shown in Figure 5 , where there is a third sinusoidal curve (30) which forms two tubular regions (Ta and Tb). The sinusoidal curves form a curved region of the conductor busbar (B) and can have a shape close to the sinusoidal curve itself, as shown in Figure 1 , Figure 2 and Figure 3 , or a different wave shape. Figure 4 and Figure 5 A sinusoidal shape similar to the letter "M" is shown.

[0040] The busbar (B) can comprise fixing holes (4) along the initial crimping tab (1), the final crimping tab (3) and the joining tab (2). Such holes help in the assembly, eliminate extra weight and save material.

[0041] Cooling holes (5) can be inserted along the sinusoidal curve, where said holes help the air circulation into the tubular region (T), thus helping the cooling of the busbar (B). The hot air convection that contacts the busbar enhances the air exchange with the busbar (B), helping.

[0042] For installations that require a current greater than the conducting capacity of the busbar (B), it can be assembled with multiple busbars (B). Figure 6 、 Figure 7 and Figure 10 Assemblies are shown in which the busbar (B) is aligned transversely, in this type of assembly the busbar (B) can be spaced apart, as seen in Figure 6 , or it can still be in contact, as seen in Figure 7 and Figure 10 . In addition, the busbar (B) can be installed without displacement, as shown in Figure 8 and Figure 9 .

[0043] In the preferred embodiment, the busbar (B) is made of a single folded sheet without welding.

[0044] The multilayer region should preferably comprise an electrical insulator between them to prevent the formation of an electric arc due to the small distance that can occur between the layers.

[0045] The sinusoidal tubular of the busbar (B) reduces the occurrence of the skin effect and makes the apparent current reached in the busbar (B) closer to the rated current calculated for a busbar in the same cross-sectional area.

[0046] When the busbar (B) has aligned initial crimping tabs (1) and joining tabs (2), it is possible to install the busbar assembly (B) without the fixing screws exceeding the area occupied by the busbar (B), as seen in Figure 6 , helping to save space inside the electrical cabinet that assembles the busbar (B).

[0047] The busbar (B) stands out from other electrical busbars disclosed in the prior art, mainly due to the fact that it has a sinusoidal tubular assembly, while the other busbars have a solid or closed tubular assembly. Thus, the busbar (B) provides a significant saving of conductive material in its assembly, thus reducing its production costs and the impact on the natural reserves of the elements used in its assembly, such as copper, aluminum, gold and silver.

[0048] Another advantage of the busbar (B) relates to its high mechanical strength, compared to solid rectangular busbars, as it has an assembly of curved walls that increase the mechanical strength, providing minimal deformation when exposed to high level short circuit circuit tests.

[0049] Finally, another advantage of the busbar (B) is that it is substantially easier to assemble in the busbar application, compared to solid busbars, as it has a series of hole options that facilitate the fixing, extension and bypass operations.

[0050] It is to be understood that the present description is not meant to limit the present application to the details described herein, and that the present application can have other embodiments and should be practiced or being executed in various ways within the scope of the claims. Although specific terms have been employed, they should be interpreted in the broadest and descriptive sense rather than for limitation.

Claims

1. A sinusoidal tubular conductive busbar for use in electrical cabinets of control and switching equipment assemblies for low and high voltage power and prefabricated power lines, characterized in that, The busbar has an initial crimp tab connected to a first sinusoidal curve, which in turn is connected to a joining tab, which in turn is connected to a second sinusoidal curve, forming a tubular region between the first and second sinusoidal curves; and the second sinusoidal curve is connected to a final crimp tab, wherein the joining tab has two layers, and there is a gap between the layers of the joining tab.

2. The busbar of claim 1, wherein The second sinusoidal curve is connected to a second joining tab, which in turn is connected to a third sinusoidal curve, forming a tubular region between the first and third sinusoidal curves; the third sinusoidal curve is connected to the final crimp tab.

3. The busbar of claim 1 or 2, characterized in that The initial crimp tab has a single layer.

4. The busbar of claim 1 or 2, characterized in that The initial crimp tab has two or more layers.

5. The busbar of claim 1 or 2, wherein The initial crimp tab is flat.

6. The busbar of claim 1, wherein, The layers of the joining tab are to be joined.

7. The busbar of claim 1 or 2, wherein The final crimp tab encloses the initial crimp tab.

8. The busbar of claim 1 or 2, wherein The final crimp tab encloses one of the joining tabs.

9. The busbar of claim 1 or 2, wherein, The surface of the joining tab and the surface of the final crimp tab are in the same plane.

10. The busbar of claim 1 or 2, wherein The surface of the joining tab and the surface of the final crimp tab are in parallel planes.

11. The busbar of claim 1 or 2, wherein The surfaces of both the joining tab and the final crimp tab are in a secant plane.

12. The busbar of claim 1 or 2, wherein, The first and second sinusoidal curves have a sinusoidal wave shape.

13. The busbar of claim 1 or 2, wherein, The first and second sinusoidal curves have an "M" shape.

14. The busbar of claim 1 or 2, wherein, The busbar has a securing hole along at least one outer edge.

15. The busbar of claim 1 or 2, wherein, The busbar has a cooling hole along at least one of the first, second, and third sinusoidal curves.

16. The busbar of claim 1 or 2, wherein, The busbar is made from a single folded, solderless sheet.

17. The busbar of claim 1 or 2, wherein, The busbar includes an electrical insulator between components having more than one layer.

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