EP0022269A1 - Current conductor with transposed partial conductors - Google Patents

Abstract

The invention relates to a current conductor (1) for electrical power engineering, which, in order to reduce power losses as a result of current displacement during alternating current operation, is divided into parallel-connected partial conductors (2,2') running alongside one another and insulated with respect to one another and carried in an alternately interchanged position with respect to one another, the partial conductors (2,2') consisting of coaxially arranged rod sections (3,3') of various widths, the ends of which are connected to one another by crossings (4). <IMAGE>

Description

The invention relates to a current conductor for reducing the line loss due to current displacement in AC operation in parallel, side by side continuous and insulated from each other and alternately b _e - guided conductor züglich its opposite sides location interchanged is divided.

The proposed conductor is used in high-voltage technology and, in particular, in cables, in switchgear, as a connection between generators and transformers or as a busbar, where it is used to conduct alternating currents of 1000 amperes and more, and in high-frequency technology.

When transferring and distributing electrical energy, the basic task is to keep the electrical resistance of all current-carrying conductors as low as is economically justifiable, so that energy losses and heating are kept small. It is known that the pure ohmic resistance of the entire conductor is for the transmission of a direct current cross-section is decisive, while with alternating current the cross-sectional area effective for the current supply is considerably reduced by the current displacement (the "skin effect"), so that with a solid conductor of circular cross-section only a small ring zone near the surface takes over the power line; As a result, the conductor resistance effective in AC operation becomes considerably larger than that in operation with DC.

Measures to suppress current displacement have been known in electrical engineering for almost 100 years. At high currents, the conductors of a winding are divided into parallel, insulated individual conductors to avoid additional losses due to the skin effect. The first composite conductor rod was probably already known in 1886 by the British patent specification 12 880, where two copper strips lying one above the other in the groove of an electrical machine were interlocked in the middle of the groove. In the meantime, a large number of conductors with a rectangular cross-section have been developed, which are composed of several partial conductors lying in layers, which change their position cyclically within the overall cross-section. A disadvantage of these rectangular conductors - of which the best known is the so-called "Roebel rod" - is the fact that the position of the partial conductors is only exchanged in one direction because of the interlinking with the magnetic field, which is admittedly advantageous for use in electrical machines , however, a possible use in cables or switchgear makes so little sense that such has apparently not yet taken place. Current conductors with reduced current displacement, which have a cylindrical cross section and in which there is a radially symmetrical interchange of the partial conductors, have hitherto not been disclosed.

The object of the invention is to design a current conductor which is subdivided into partial conductors in order to reduce line losses as a result of current displacement and which has a cylindrical cross section for the purpose of opening up new fields of application in the case of radially symmetrical interchanging of its partial conductors.

To solve this problem, a current conductor of the type described in the introduction is used and the object is achieved in that the partial conductors consist of coaxially arranged pipe sections of different widths, the ends of which are connected to one another by transitions. In the case of a current conductor composed in this way, the necessary interchanging takes place in that the innermost partial conductor is led outward at certain intervals by means of a transition and thereby becomes the outermost partial conductor, and at the same point the position of the other partial conductor is also changed by other transitions. As a result, all the partial conductors have the same AC resistance after a few such exchanges and they carry the same partial current. The result of this uniform current distribution is that the skin effect results in a current displacement in the individual partial conductor, but not in the overall cross section. For this reason, the generally usable cylindrical current conductor according to the invention has a particularly low effective resistance with alternating current.

The transitions can be either radial or conical.

In a preferred embodiment of the invention, each partial conductor consists of at least two identically designed ones and successively connected conductor elements made of at least two pipe sections of different widths which are connected to one another by means of recesses, which are arranged coaxially and are pushed into one another in such a way that the pipe sections of larger diameter are above those of smaller diameter and the free end of each pipe section with the smallest width is connected to the free start of the pipe section are connected to the largest width of the adjacent conductor element through the recesses connecting pieces. Such a conductor can be manufactured relatively easily because it is composed of nothing but the same components.

The conical transitions are expediently designed as truncated cones bearing the recesses. This design allows a particularly compact, short design of the transitions.

Sleeves are advantageously used as connecting pieces and are clamped between the pipe sections by means of screw bolts passing through them.

It can be advantageous for the manufacture and assembly of the proposed current conductor if the transitions are separate components which carry pipe connections provided with connecting devices, to which the pipe sections can be attached on both sides.

In the case of highly loaded electrical conductors, it is expedient if a ventilation duct is provided in the interior of the conductor elements for the purpose of forced ventilation. If self-ventilation is preferred, the pipe sections have cross holes.

For the necessary mutual insulation of the partial conductors from one another, spacers made of insulating material are advantageously provided between the conductor elements. Such spacers hinder forced cooling of the partial conductors only very little.

• Fig. 1 einen Stromleiter mit zwei koaxialen Teilleitern in einem Längsschnitt, schematisch dargestellt;
• Fig. 2 einen Stromleiter mit drei koaxialen Teilleitern in einem Längsschnitt, schematisch dargestellt;
• Fig. 3 einen Stromleiter mit. vier koaxialen Teilleitern in einem Längsschnitt, ebenfalls schematisch dargestellt;
• Fig. 4 einen Stromleiter mit drei koaxialen Teilleitern, die aus Leiterelementen zusammengesetzt sind, in einem verkürzten Längsschnitt;
• Fig. 5 den Stromleiter nach Fig. 4 in einem Querschnitt, geschnitten entlang der Linie .V - V in Figur 4;
• Fig. 6 ein Leiterelement des Stromleiters gemäß Figur 4, in einem verkürzten Längsschnitt;
• Fig. 7. einen als gesonderten Bauteil konisch ausgebildeten Übergang in Gestalt von Kegelstümpfen, in einem Längsschnitt.

The invention is explained below with reference to the accompanying drawings. Show it:

• 1 shows a current conductor with two coaxial partial conductors in a longitudinal section, shown schematically.
• Figure 2 shows a current conductor with three coaxial partial conductors in a longitudinal section, shown schematically.
• Fig. 3 with a conductor. four coaxial partial conductors in a longitudinal section, also shown schematically;
• 4 shows a current conductor with three coaxial partial conductors, which are composed of conductor elements, in a shortened longitudinal section;
• FIG. 5 shows the current conductor according to FIG. 4 in a cross section, cut along the line .V - V in FIG. 4;
• 6 shows a conductor element of the current conductor according to FIG. 4, in a shortened longitudinal section;
• Fig. 7. a conical transition as a separate component in the form of truncated cones, in a longitudinal section.

A current conductor 1 according to the invention in its simplest embodiment - compare FIG. 1 - has two electrically connected partial conductors 2 and 2 ', which consist of coaxially arranged pipe sections 3, 3'. The ends of these pipe sections 3, 3 ', which may have a circular, elliptical or even a polygonal cross section, are connected to one another at several points by transitions 4. The partial conductors 2 and 2 'are attached to a common connection plate 5 at their beginning and at their end. The pipe sections 3,3 '...,. the transitions 4 and the connection plate 5 consist of a metal of high electrical conductivity, preferably of copper, aluminum or a suitable alloy.

The pipe sections 3,3 '... have different widths, for a current conductor 1 (FIG. 1) consisting of two partial conductors 2, 2', a number of pipe sections 3,3 'of two different widths are required. Pipe sections 3, 3 'and 3 "with three different widths are required for a current conductor 1 consisting of three partial conductors 2, 2' and 2 '' (see FIG. 2), and pipe sections with four different ones are required for a current conductor 1 consisting of four partial conductors Widths required (Fig. 3) etc.

The current conductor 1 has interchanging points 6 at various periodic intervals, at which the ends of the pipe sections 3, 3 ', 3 "... are connected to one another" crosswise ", so to speak, by the transitions 4 1, each of the two subconductors 2 and 2 ', which run next to one another and are connected in parallel by the connecting plates 5, is led alternately once inwards and once outwards. With three subconductors 2, 2' and 2 " (FIG. 2), the position of the partial conductors 2, 2 ', 2 "is continuously cyclically interchanged by the transitions 4, so that the partial conductor 2 attached to the connecting plate 5, initially on the inside, in the form of the tube section 3" at the first exchange point 6 is led through the transition 4 to the outside; at the next exchange point 6, it is guided in the middle between the two other pipe sections 3 and 3 ', and at the third exchange point 6 it is led inwards again, etc. In the course of each current conductor 1, each becomes in this way three partial conductors 2, 2 ', 2 "over the total length of the current conductor 1, one third each inside, in the middle and outside, so that the current conductor 1 thus has an equivalent impedance in terms of amount and components between its two connection plates 5 in AC operation For this reason, the current flowing in it is evenly distributed over the three partial conductors 2.2 'and 2 ", so that the skin effect only to a current displacement within a single partial conductor 2.2' or 2", but not to a displacement in the entire cross section of the conductor 1 leads.

The disadvantageous effect of current displacement can be reduced even further by using four coaxial partial conductors 2.2 ', 2' 'and 2 "' (FIG. 3). A further reduction in line losses is possible by increasing the number of parallel partial conductors, however, the technical effort increases progressively There is a reasonable limit where the wall thickness of the partial conductors 2.2 '... is equal to the penetration depth of the alternating current according to the skin effect consist of two or more partial conductors constructed in accordance with FIGS. 1 or 2 or 3, main and secondary exchange points having to be provided for the cyclical exchange.

All sub-conductors 2,2 '... are electrically insulated from one another for a voltage of a few volts. The partial conductors 2 also run past one another in an electrically separated manner at the transitions 4, which is why they must be designed in a special way - in the case of a radial or conical structure.

A specific embodiment of the invention is represented by the current conductor 1 shown in FIGS. 4 to 6. Here, each of the three partial conductors 2, 2 'and 2 "consists of a number of identically arranged conductor elements 7 - see FIG. 6. Each of these conductor elements 7 consists of three pipe sections 3, 3 'and 3 "of different widths connected to one another by means of radially designed transitions. In the area of the transitions 4, four circular recesses 8 are arranged, in the area of the free start of the pipe section 3 ″ with the largest width there are four holes 9 and in the area of the free end of the pipe section 3 with the smallest width the threaded holes 10. The recesses 8, the holes 9 and the threaded holes 10 are each under central angles of 90 degrees. The pipe section 3 with the smallest width is penetrated by a ventilation duct 11, all pipe sections 3, 3 'and 3''have an annular cross section.

To form the current conductor 1 according to FIG. 4 consisting of the three partial conductors 2, 2 ', 2 ", a number of conductor elements 7 are pushed into one another in such a way that the pipe sections 3... Larger diameter are each above the smaller diameter - see FIG. 4 The free end of each conductor element 7 (or the free end of each tube section 3 with the smallest width) is with the free start of each adjacent conductor element 7 (or the free start of each tube section 3 "with the largest width of the adjacent conductor element 7) Electrically connected with the aid of connecting pieces 12 which reach through the recesses 8. These connectors 12 are sleeves 13, which are penetrated by bolts 14. The sleeves 13 are each clamped between the pipe sections 3 "with the largest width and the pipe sections 3 with the smallest width with the aid of the tightened screw bolts 14, so that they establish an electrical connection while they are electrically insulated from the recesses 8.

Mushroom-shaped spacers 15 made of an electrically non-conductive material are provided between the conductor elements 7. In their place, the conductor elements 7 can also be provided with a firmly applied insulating layer covering the entire surface or essential parts thereof. The partial conductors 2, 2 'and 2 "are at their beginning and at the end with screws 16 from a well-conductive conductive metal existing connection plates 5 screwed, with the help of the parallel connection of the three sub-conductors 2,2 ', 2 "is effected.

The transition 4 shown in FIG. 7 for a current conductor 1 consisting of three partial conductors 2, 2 'and 2 "is a separate component on which the three coaxial, equally long pipe sections 3, 3' and 3" are connected on both sides by means of connecting devices 17 (in the form of External threads) can be attached. This transition 4 consists of a total of six pipe sections 18 a - f with three different widths corresponding to the pipe sections 3, 3 ', 3 ". The connection of the middle inlet pipe section 18 b to the inner outlet pipe section 18 d and that of the outer entrance -Tube piece 18 c with the middle outlet pipe piece 18 e happens through truncated cones 19, which carry recesses 8. Four connecting pieces 12, distributed uniformly over the circumference, consisting of a sleeve 13, through which a screw bolt 14 passes, provide the electrical connection between the inner inlet pipe section 18 a and the outer outlet pipe section 18 f. The external threads on the ends of the pipe sections 18 a - f enable the pipe sections 3, 3 'and 3 "to be screwed on. Instead of these threads e.g. also plug connections with contact fingers.

The ventilation duct 11 is used for the forced cooling of the inner partial conductors with the aid of a gaseous or liquid cooling medium flowing through the current conductor 1 in the longitudinal direction. An improvement in the heat dissipation of the inner partial conductors can also be achieved by transverse bores 20 (see FIGS. 4 and 6), which penetrate all partial conductors 2, 2 ', 2 "at certain points in such a way that they are perpendicular in the later installation position natural convection can develop.

Compilation of the reference numbers used

• 1 conductor
• 2,2 '.. partial conductor
• 3,3 '.. pipe section
• 4 transition
• 5 connection plate
• 6 Exchange office
• 7 conductor element
• 8 recess
• 9 holes
• 10 threaded hole
• 11 ventilation duct
• 12 connector
• 13 sleeve
• 14 bolts
• 15 spacers
• 16 screws
• 17 connecting devices
• 18 a - f pipe section
• 19 truncated cone
• 20 cross hole

Claims (10)

1. Conductor, which is subdivided to reduce the line losses due to current displacement in AC operation in parallel-connected, side-by-side and insulated from one another and alternately guided with respect to their mutual position, characterized in that the partial conductors (2,2 '...) from coaxial arranged pipe sections (3,3 '...) of different widths exist, the ends of which are connected by transitions (4). 2. Current conductor according to claim 1, characterized in that the transitions (4) are formed radially. 3. Current conductor according to claim 1, characterized in that the transitions (4) are conical. 4. Current conductor according to one of claims 1 to 3, characterized in that each partial conductor (2,2 '...) of at least two identically designed and connected in series, from at least two by means of recesses (8) having transitions (4) connected to each other Pipe sections (3,3 '...) of different widths made conductor elements (7), which are arranged coaxially and pushed into each other so that the pipe sections of larger diameter are above those of smaller diameter and the free The end of each tube section with the smallest width is connected to the free start of the tube section with the largest width of the adjacent conductor element through the connecting pieces (12) passing through the recesses (8). 5. Current conductor according to one of claims 3 or 4, characterized in that the transitions (4) as the recesses (8) bearing truncated cones (19) are formed. 6. Current conductor according to one of claims 1 to 5, characterized in that sleeves (13) serve as connecting pieces (12) which are clamped between them through the screw bolts (14) between the pipe sections (3, 3 '...). 7. Current conductor according to one of claims 1 to 6, d a - durc h characterized in that the transitions (4) with connecting devices (17) provided, pipe sections (18a - f) are structural components. 8. Current conductor according to one of claims 4 to 7, characterized in that a ventilation duct (11) is provided in the interior of the conductor elements (7). 9. Current conductor according to one of claims 1 to 8, characterized in that the tube sections (3, 3 '...) have transverse bores (20). 10. Current conductor according to one of claims 4 to 9, characterized in that spacers (15) made of insulating material are provided between the conductor elements (7).

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