Rectangular tubular conductor busbar with solid core and internal heat dissipation

Abstract

Applicable to low-voltage, medium-voltage, and high-voltage power switchgear, and electrical cabinets for prefabricated wiring, a rectangular tubular conductor busbar having a solid core and internal heat dissipation, the main configuration comprising a body (1) defined by an outer wall, a substantially parallelepiped rectangular tubular busbar (P), and a solid core (2) formed by the overlapping of elements, the core being three times the thickness of the walls forming the body (1), and located between the upper and lower walls of the body (1). The rectangular tubular busbar (P) has two distinct regions: a hollow area (A1) and a solid core (2). The hollow area (A1) is defined between the rear surface of the rectangular tubular busbar (P) and the top and bottom surfaces of the rectangular busbar (P). The solid core (2) is located within the region defined by the front surface of the rectangular tubular busbar (P), the top and bottom walls of the rectangular tubular busbar (P), and the hollow area (A1).

Description

Technical Field

[0001] The present invention relates to an electrical conductor busbar, and more specifically, to low voltage, medium voltage, and high voltage power switchgear, and to electrical cabinets for prefabricated electrical wires (busways / enclosed busbars), and relates to a rectangular tubular electrical conductor busbar, also known as a flat busbar, having a solid core and internal heat dissipation.

Background Art

[0002] Low voltage, medium voltage, and high voltage power switchgear are essential for any electrical equipment in all fields of economic activity. Such assemblies are intended to be used with equipment designed for the generation, transmission, distribution, and conversion of electrical energy, and for the control of equipment that consumes electrical energy. These assemblies consist of electrical cabinets, functional units in which individual devices are installed, and busbar systems.

[0003] A busbar system is a low impedance conductor that can connect several electrical circuits separately. Its function is to conduct electrical energy between various points within the assembly, and its sizing should take into account the following factors: a) The temperature rise caused by the flow of electrons under normal operating conditions, which is related to the selection of the materials used; b) Thermal and dynamic stresses caused by abnormal situations such as voltage and current peaks, short circuits, and accidental electrical arcs; c) Leakage currents caused by the proximity between conductors, and between conductors and the metal parts of the electrical cabinet; and d) The amount and manner in which connections and branches are made.

[0004] Given these inherent properties of electric busbars, copper is almost entirely made from copper bars with a rectangular cross-section because it has good conductivity, relatively low manufacturing costs compared to other conductive materials such as silver and gold, and higher mechanical strength than aluminum, another commonly used conductor for industrial purposes.

[0005] When a conductive busbar is subjected to a high value of alternating current, it is greatly affected by the skin effect, reducing the area useful for electrical conduction. This is because the alternating current tends to concentrate around the conductor, thus decreasing the current density inside.

[0006] As a result of the skin effect, more material is used in the manufacture of solid busbars, increasing their cross-sectional area to ensure conductors with lower apparent electrical resistance, thereby reducing the negative effects of the skin effect and resulting in more effective busbars.

[0007] 1mm 2 Solid bars with a rectangular profile and low current density per unit area are almost exclusively used in copper busbar applications in electrical cabinets. This configuration is typically found in a variety of dimensions, including, among others, 100 x 10 mm, 80 x 10 mm, and 50 x 10 mm.

[0008] Other busbar shapes are also used, and examples presented in Patent Document 1, filed on September 6, 2018, aim to increase the perimeter, improve heat dissipation, reduce losses caused by the skin effect, optimize the current density in the material for high currents, and thereby allow the use of less material for its structure.

[0009] Another example of a tubular busbar known in the prior art is the subject of Patent Document 2, which presents an electrical cabinet assembly that houses a main busbar and a secondary conductor busbar constructed in a closed tubular shape, mounted within the electrical cabinet assembly, the electrical cabinet assembly also includes insulators and secondary insulators, a protection system on the main busbar, an extender assembly, and finally a branch connector.

[0010] Furthermore, another patent document relating to tubular busbars applied to electrical cabinets is the subject of Patent Document 3, which deals with electric conductor busbars, more specifically electric conductor busbars having a sinusoidal tubular shape applied to electric cabinets for low-voltage and high-voltage power switchgear and prefabricated wires. The busbar has an initial crimp tab, which connects to a first sinusoidal portion, which then connects to a joining tab, which then connects to a second sinusoidal portion, so that the first and second sinusoidal portions form a tubular region between them and there is no contact between the first and second sinusoidal portions. The second sinusoidal portion is connected to a final crimp tab, or alternatively, to a second joining tab, which connects to a third sinusoidal portion, which is connected to a final crimp tab.

[0011] Another technical problem present in literature cited as an example of prior art concerns the heat dissipation of busbars, because conductivity fluctuates with temperature, and in some cases, due to the skin effect, the contact area between the walls of tubular electric busbars tends to experience a substantial rise in temperature, which can affect their performance in certain applications.

[0012] Furthermore, another technical problem present in the literature cited as an example of prior art is that the tubular busbar has a different shape configuration than conventional busbars, making it difficult to easily replace conventional busbars with the tubular busbar within an electrical cabinet.

[0013] Therefore, the prior art benefits from rectangular tubular busbars having similar dimensions to conventional solid busbars, making it easier to swap one with the other within an electrical cabinet. Furthermore, solutions prioritizing internal heat exchange and the resulting reduction of the temperature rise of the rectangular tubular busbar are advantageous, allowing the busbar to operate for longer periods at temperatures that enable better conductivity, especially in the case of high currents. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Brazilian Patent Application No. 102018068113-3 [Patent Document 2] Brazilian Patent Application No. 102017019384-5 [Patent Document 3] Brazilian Patent Application No. 102020003216-0 [Overview of the Initiative]

[0015] The present invention provides a busbar constructed in a rectangular tubular shape with a solid core, characterized by improved conductivity efficiency by reducing the amount of material used compared to conventional systems, and superior mechanical resistance compared to solid conductor busbars. Furthermore, it includes an internal air passage for heat dissipation, utilizing the skin effect. This results in a reduction in cross-sectional area, an increase in current density within the conductor, optimization of material use and space, and simplification of the assembly of multiple busbars, thereby improving current capacity.

[0016] The object of the present invention is to provide a busbar that can carry a higher current with less material by varying, increasing, or decreasing the size of the solid and hollow portions, thereby optimizing the amount of material appropriate for the desired capacity and contributing to sustainability with respect to the materials used.

[0017] Another object of the present invention is to provide a rectangular tubular busbar having an internal air passageway, which reduces the temperature rise due to heat dissipation of the conductor under high current.

[0018] It is also an object of the present invention to provide a busbar that improves the utilization of the skin effect by using a tubular shape having less material within the internal area of the conductor.

[0019] Another object of the present invention is to provide a structurally reinforced busbar having a rectangular tubular shape formed by a sequence of at least 10 bending sections, which can withstand the dynamic forces and vibrations that the busbar experiences in both normal operating conditions and stress situations such as during a short circuit.

[0020] It is also an object of the present invention to provide a busbar that enables internal heat dissipation through an air passageway and improves its electrical conductivity.

[0021] Another object of the present invention is to provide a rectangular tubular conductor busbar made of copper, aluminum, or a bimetal material.

[0022] Finally, an object of the present invention is to provide a busbar that has structural characteristics different from those of a conventional solid busbar, but has the same dimensions as a conventional solid busbar and enables one to be exchanged with the other within various electrical cabinets.

Brief Description of the Drawings

[0023] The subject matter of this specification will be fully understood in its technical aspects through the following detailed description based on the related drawings. [Figure 1] A front perspective view of a rectangular tubular conductor busbar in its main structure is shown, featuring an internal core, a tubular area, and internal air passage grooves passing horizontally through the core. [Figure 2] A top view of the rectangular tubular conductor busbar in its main structure is shown. [Figure 3]This is a left side view of the rectangular tubular busbar in the main structure, allowing us to observe the tubular profile including its internal core, which is formed by the joint of three overlapping walls embedded between the upper and lower walls of the main body. [Figure 4] A front perspective view shows a detailed profile of the rectangular tubular conductor busbar in the main structure, allowing for the installation and assembly details, as well as observation of the lateral air inlet and outlet holes. [Figure 5] A cross-sectional view of the rectangular tubular busbar in the main structure is shown in a front perspective view. This busbar, which, through a synergistic effect with the internal air passage groove running through the core, enables observation and identification of the lateral air inlet and outlet holes. [Figure 6] A perspective view of a rectangular tubular conductor busbar in its main modification, which has an internal core and through holes and internal air passage grooves in the lateral direction, is shown. [Figure 7] The top view of the rectangular tubular conductor busbar in the main variant is shown. [Figure 8] A side view of a rectangular tubular conductor busbar in its main modification is shown, allowing observation of the tubular profile including its internal core formed by the joints of three overlapping walls. [Figure 9] A front perspective view shows details of the profile of the rectangular tubular conductor busbar in its main modification, allowing observation of its mounting and assembly details, as well as the lateral air inlet and outlet holes aligned with the internal air passage grooves through the core. [Figure 10] A cross-sectional view of a rectangular tubular conductor busbar in its main modification is shown, from a viewpoint that allows observation and identification of lateral cooling holes due to the synergistic effect with the internal cooling grooves present in the core. [Figure 11] This shows a front perspective view of a rectangular tubular conductor busbar in a second structural modification thereof, which has an internal core with through holes aligned in a single row parallel to each other. [Figure 12] This shows a top view of the rectangular tubular conductor busbar in the second structural modification. [Figure 13]This shows a side view of a rectangular tubular conductor busbar in a second structural modification, where it is possible to observe the tubular profile including its internal core, which is formed by the joints of three overlapping walls located between the upper and lower walls of the main body. [Figure 14] The front perspective view of the second structural modification shows the details of the profile of the rectangular tubular conductor busbar, which allows observation of its internal details and the vertical air passage holes for heat dissipation. [Figure 15] This shows a front perspective view of a rectangular tubular conductor busbar in a third structural modification, which has an internal core with through-holes aligned in two parallel rows. [Figure 16] This shows a top view of the rectangular tubular conductor busbar in the third structural modification. [Figure 17] This shows a side view of a rectangular tubular conductor busbar in a third structural modification, where it is possible to observe the tubular profile including its internal core, which is formed by the joints of three overlapping walls located between the upper and lower walls of the main body. [Figure 18] The front perspective view of the third structural modification shows the details of the profile of the rectangular tubular conductor busbar, which allows observation of its internal details and the vertical air passage holes for heat dissipation. [Figure 19] An example of a rectangular tubular conductor busbar, illustrating an embodiment using two conductor materials, is shown in a front perspective view. [Figure 20] A perspective side view of a rectangular tubular conductor busbar is shown to better demonstrate the air passage groove. [Figure 21] This shows a set of three images with lateral cutouts, intended to demonstrate the structure of the air passage grooves inside a rectangular tubular conductor busbar. [Modes for carrying out the invention]

[0024] As shown in the above-mentioned figure, the present invention, "Rectangular tubular conductor busbar having a solid core and internal heat dissipation," comprises a substantially parallelepiped rectangular tubular busbar (P) which is a body (1) defined by an outer wall, and a solid core (2) formed by overlapping elements, the core being three times the thickness of the wall forming the body (1).

[0025] The rectangular tubular busbar (P) is designed for use in electrical cabinets, specifically in low-voltage, medium-voltage, and high-voltage power switchgear, as well as in prefabricated wiring. Its shape is substantially identical and equivalent to that of conventional solid electrical busbars, allowing for easy replacement of one with the other within the electrical cabinet without requiring complex adjustments or modifications. Furthermore, it allows for the use of insulators and other elements common to both rectangular tubular busbars (P) and conventional solid busbars.

[0026] In the rectangular tubular busbar (P) described above, the element that defines its substantially parallelepiped shape is its main body (1), which is formed by an outer wall divided into a front wall, an upper wall, a rear wall, and a lower wall. The main body (1) itself has two separate regions, a hollow area (A1) and a solid core (2). The region of the hollow area (A1) is defined between the rear surface of the rectangular tubular busbar (P), the upper and lower surfaces of the rectangular busbar (P), and the solid core (2).

[0027] As seen in Figures 3 and 4, the solid core (2) is located within the region defined by the front surface of the rectangular tubular busbar (P), the upper and lower walls of the rectangular tubular busbar (P), and the hollow area (A1).

[0028] The rectangular tubular busbar (P) also has air inlet holes (9) distributed across the entire front surface of the rectangular tubular busbar (P). These air inlet holes (9) are substantially rectangular in shape and penetrate the thickness of the wall of the main body (1).

[0029] The air inlet holes (9) of the tubular busbar (P) function as air inlets for internal heat dissipation of the rectangular tubular busbar (P) itself. These air inlet holes (9) form air passage grooves (4) that penetrate the solid core (2), establishing a continuous air passage between the external region of the rectangular tubular busbar (P) and the hollow area (A1).

[0030] Within the hollow area (A1), specifically on the rear wall of the body (1) of the rectangular tubular busbar (P), air inlet and outlet holes (3) are arranged along its entire length. These holes are aligned and equidistant from one another and serve to provide outlets for air entering the rectangular tubular busbar (P) through the air passage groove (4) in the solid core (2).

[0031] The solid core (2) of the rectangular tubular busbar (P) is a solid portion designed for connection and is a mechanical structural element that provides resistance to the rectangular tubular busbar (P), enabling it to withstand potential short-circuit demand, among other conditions. In this regard, the solid core (2) of the rectangular tubular busbar (P) has a series of square structural openings (8) that allow for horizontal air circulation within the solid core (2) and allow for the attachment of secondary elements on the rectangular tubular busbar (P).

[0032] The rectangular tubular busbar (P) presents a first structural modification called a rectangular tubular busbar (B) which is substantially parallelepiped in shape, having a body (1) defined by an outer wall and a solid core (2) formed by the overlapping of elements, the core being three times the thickness of the wall forming the body (1).

[0033] In the rectangular tubular busbar (B) described above, the element that defines its substantially parallelepiped shape is its main body (1), which is formed by an outer wall divided into a front wall, an upper wall, a rear wall, and a lower wall. The rectangular tubular busbar (B) has two recessed regions (1a and 1b), the upper recessed region (1a) is located on the upper surface of the rectangular tubular busbar (B), and the lower recessed region (1b) is located on the lower surface of the rectangular tubular busbar (B), and these recessed regions (1a and 1b) are not aligned. Regarding this misalignment, as can be seen in Figure 6, and especially in Figures 8 and 9, the upper recessed region (1a) is close to the top of the rectangular tubular busbar (B), and the lower recessed region (1b) is close to the solid core (2) of the rectangular tubular busbar (B).

[0034] The rectangular tubular busbar (B) has lateral air inlet and outlet holes (3) at its front and rear ends, which allow for air circulation within the rectangular tubular busbar (B). These lateral air inlet and outlet holes (3) are interconnected by air passage grooves (4) for heat dissipation, located inside the main body (1) and passing through the solid core (2), as shown in Figure 10. The lateral air inlet and outlet holes (3) are lateral to the front and rear walls of the main body (1) of the rectangular tubular busbar (B).

[0035] With respect to the lateral air inlet and outlet holes (3), they have a rhomboid shape, and the rhomboid shape penetrates the upper and lower walls of the body (1) of the rectangular tubular busbar (B). The interconnection between these upper and lower lateral air inlet and outlet holes (3) is achieved by air passage grooves (4) for internal heat dissipation, each air passage groove being defined by an air passage region inside the body (1) and passing through the solid core (2).

[0036] The solid core (2) of the rectangular tubular busbar (B) is a solid portion designed for connection and is a mechanical structural element that provides resistance to the rectangular tubular busbar (B), enabling it to withstand potential short-circuit demand, among other conditions. In this sense, the solid core (2) is located within the central region of the rectangular tubular busbar (B), extends along its entire length, is formed by the overlapping of three sections the same width as the walls of the body (1), occupies the entire internal space of the rectangular tubular busbar (B), i.e., is in contact with both the upper and lower walls of the body (1). Furthermore, the solid core (2) of the tubular busbar (B) has a contour such that the blank ends are locked together, as can be clearly seen in Figure 8. This structure provides greater mechanical strength to the tubular busbar (B) and makes the assembly more rigid.

[0037] The rectangular tubular busbar (B) also features a series of mounting holes (5) within the core region (2), which penetrate and traverse the upper and lower walls of the body (1) and the solid core (2). The mounting holes (5) are arranged symmetrically in the solid portion of the rectangular tubular busbar (B) and are equidistant from each other, forming a row with this symmetry and equidistantness.

[0038] The presence of a solid core (2) within the rectangular tubular busbar (B) allows for the identification of two distinct areas inside the rectangular tubular busbar (B): a hollow area (A1), a hollow area (A2), and the solid core (2). Hollow area (A2) includes the space formed between the front, top, and bottom walls of the main body (1) and the solid core (2), while hollow area (A1) includes the space formed between the rear, top, and bottom walls of the main body (1) and the solid core (2). These hollow areas (A1 and A2) are connected only by an internal air passage groove (4).

[0039] The aforementioned mounting holes (5) of the rectangular tubular busbar (B) primarily serve to assist in the assembly of the rectangular tubular busbar (B) to their individual components, facilitating power distribution and the mounting of secondary elements, as well as reducing weight and saving material.

[0040] The rectangular tubular busbar (B) also features mounting grooves (6) located at the ends of the rectangular tubular busbar (B), which are formed by internal air passage grooves (4) and air inlet and outlet holes (3), and are separated near their central region as shown in Figure 9.

[0041] The present invention also includes a structural modification of the rectangular tubular busbar (B), shown as a rectangular tubular busbar (B'), which differs mainly in that the lateral air inlet and outlet holes (3) and internal air passage grooves (4) are replaced with air passage openings (7).

[0042] The internal air passage openings (7) are arranged perpendicular to the upper and lower walls of the main body (1) and are arranged in three rows: one row in the hollow area (A1) and two rows in the hollow area (A2). The first row in the hollow area (A2) is located between the front wall and the two recessed areas (1a and 1b), and the second row is located between the solid core (2) and the recessed areas (1a and 1b).

[0043] The internal air passage openings (7) are equidistant from each other in each of the three rows, and each internal air passage opening (7) referred to is substantially rectangular in shape and penetrates, meaning that they collide with both the front and rear walls and thus form air passages for internal heat dissipation of the rectangular tubular busbar (B').

[0044] The rectangular tubular busbar (B) includes a second structural modification shown as (B''), which features the same structure as the first structural modification (B'), but has two rows of mounting holes (5) positioned above the solid core region (2).

[0045] The rectangular tubular busbar (P), and the tubular busbar (B) and its structural variations (B' and B'') stand out from other electric busbars of the prior art by their rectangular tubular structure, which mainly has a solid core (2), whereas other busbars are characterized by a solid or closed tubular structure. As a result, the rectangular tubular busbars (P, B) offer significant material savings in their structure, reduce manufacturing costs, and lessen the impact on natural reserves of the elements used in their structure, such as copper, aluminum, gold, and silver.

[0046] Another advantage of rectangular tubular busbars (P and B) and their structural variations (B' and B'') lies in their high mechanical resistance. The curved wall-based structure improves mechanical strength compared to solid rectangular busbars, resulting in minimal deformation when subjected to high levels of short-circuit testing.

[0047] Finally, another advantage of the rectangular tubular busbars (P and B) and their structural variations (B' and B'') is the presence of lateral air inlet and outlet holes (3), internal air passage grooves (4) through the solid core (2), and internal air passage openings (7), which allow for efficient heat exchange between the busbars (P, B, B', and B'') and work to their advantage to operate within a temperature range that does not affect their conductivity.

[0048] This description is not intended to limit this application to the details described herein, and it should be understood that other embodiments are possible and that the invention can be practiced or executed in various ways within the scope of the claims. While specific terms are used, these terms should be interpreted in a general and descriptive sense, not for the purpose of limitation.

Claims

1. Applicable to low-voltage, medium-voltage, and high-voltage power switchgear, and electrical cabinets for prefabricated wiring, a rectangular tubular conductor busbar made of a conductor material or a combination of two conductor materials, in its main configuration, It has a main body (1) defined by an outer wall, and a rectangular tubular busbar (P) which is substantially parallelepiped in shape, It comprises a solid core (2) formed by the overlapping of elements, This core is three times the thickness of the wall forming the main body (1), and is located between the upper and lower walls of the main body (1). A rectangular tubular busbar (P) having two distinct regions, a hollow area (A1) and a solid core (2), wherein the region of the hollow area (A1) is defined between the rear surface of the rectangular tubular busbar (P) and the upper and lower surfaces of the rectangular tubular busbar (P), and the solid core (2) is located within the region defined by the front surface of the rectangular tubular busbar (P), the upper and lower walls of the rectangular tubular busbar (P), and the hollow area (A1).

2. In the rectangular tubular conductor busbar according to claim 1, The main body (1) is an element that defines the substantial shape of the rectangular tubular busbar (P), and is a rectangular tubular conductive busbar that is divided into a front wall, an upper wall, a rear wall, and a lower wall.

3. In the rectangular tubular conductor busbar according to claim 1 or 2, A rectangular tubular busbar (P) having an air inlet hole (9) provided across the entire front surface of the rectangular tubular busbar (P), wherein the air inlet hole (9) is substantially rectangular in shape and penetrates the thickness of the wall of the main body (1), the rectangular tubular conductor busbar.

4. In a rectangular tubular conductor busbar according to any one of claims 1 to 3, A rectangular tubular conductor busbar in which the air inlet hole (9) forms an air passage groove (4) that penetrates the solid core (2), establishing a continuous air passage between the outer region of the rectangular tubular busbar (P) and the hollow area (A1).

5. In a rectangular tubular conductor busbar according to any one of claims 1 to 4, In the hollow area (A1), specifically, the rear wall of the main body (1) of the rectangular tubular busbar (P) has air inlet holes and outlet holes (3) arranged along its entire length, aligned and equidistant from each other, and has the function of providing an outlet for air entering the rectangular tubular busbar (P) through an air passage groove (4) that penetrates the solid core (2).

6. In the rectangular tubular conductor busbar according to claim 1, A rectangular tubular busbar (P) has a solid core (2) having a series of square structural openings (8), allowing for horizontal air circulation within the solid core (2) of the rectangular tubular busbar (P), and enabling fixing and mounting on the rectangular tubular busbar (P).

7. A rectangular tubular conductor busbar, in which a main modification of the rectangular tubular busbar (P) defined in any one of claims 1 to 6, It comprises a rectangular tubular busbar (B) defined by the main body (1) and formed by an outer wall divided into a front wall, an upper wall, a rear wall, and a lower wall, A rectangular tubular busbar (B) having two recessed regions (1a and 1b), the recessed region (1a) located on the upper surface of the rectangular tubular busbar (B), the recessed region (1b) located on the lower surface of the rectangular tubular busbar (B), the recessed regions (1a and 1b) not aligned, the recessed region (1a) being closer to the top of the rectangular tubular busbar (B), the recessed region (1b) being closer to the solid core (2) of the rectangular tubular busbar (B), the hollow area (A2) including the space formed between the front wall, upper wall and lower wall of the main body (1) and the solid core (2), and the hollow area (A1) including the space formed between the rear wall, upper wall and lower wall of the main body (1) and the solid core (2).

8. In the rectangular tubular conductor busbar according to claim 7, A rectangular tubular busbar (B) having lateral air inlet and outlet holes (3) that allow air circulation within the rectangular tubular busbar (B), the lateral air inlet and outlet holes (3) being interconnected by air passage grooves (4) located inside the main body (1) and passing through the solid core (2), and the lateral air inlet and outlet holes (3) being provided laterally with respect to the front and rear walls of the main body (1), wherein the rectangular tubular conductor busbar.

9. In the rectangular tubular conductor busbar according to claim 7 or 8, A rectangular tubular conductor busbar, wherein the solid core (2) is located within the central region of the rectangular tubular busbar (B), extends along its entire length, is formed by the overlapping of three sections the same width as the walls of the main body (1), and occupies the entire internal space of the rectangular tubular busbar (B) between the upper and lower walls of the main body (1).

10. In a rectangular tubular conductor busbar according to any one of claims 7 to 9, A rectangular tubular busbar (B) has a series of mounting holes (5) within a core region (2), the mounting holes (5) being through holes penetrating the upper and lower walls of the main body (1) and the solid core (2), and the mounting holes (5) being arranged symmetrically and equidistantly on the rectangular tubular busbar (B) in a straight line with symmetry and equidistantness, and a rectangular tubular conductor busbar.

11. In the rectangular tubular conductor busbar according to claim 7, A rectangular tubular conductor busbar in which hollow areas (A1 and A2) can communicate only through internal air passage grooves (4) through a solid core (2).

12. A rectangular tubular conductor busbar, in a modified example of the rectangular tubular busbar (B) defined in any one of claims 7 to 11, This modified form is a rectangular tubular busbar (B') and differs mainly in that the lateral air inlet and outlet holes (3) and the internal air passage grooves (4) that penetrate the solid core (2) are replaced with internal air passage openings (7). The internal air passage openings (7) are arranged in three rows perpendicular to the upper and lower walls of the main body (1), with one row in the hollow area (A1) and two rows in the hollow area (A2). The first row in the hollow area (A2) is located between the front wall and two recessed areas (1a and 1b), and the second row is located between the solid core (2) and the recessed areas (1a and 1b), and these are rectangular tubular conductive busbars.

13. In the rectangular tubular conductor busbar according to claim 12, A rectangular tubular conductor busbar, wherein internal air passage openings (7) are arranged at equal intervals in each of the three rows, and each internal air passage opening (7) has a substantially rectangular shape and is formed extending to both the front and rear walls, forming an air passage for cooling the rectangular tubular busbar (B').

14. A rectangular tubular conductor busbar, in a modified form of the rectangular tubular busbar (B') defined in any one of claims 12 to 13, This modified example is a rectangular tubular busbar (B''), which has the same configuration as the above modified example (B'), but has two rows of mounting holes (5) arranged on a solid core region (2), and is a rectangular tubular conductive busbar.

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