DE4100070A1 - AC high current conductor for energy distribution - has partial conductors, changing position in main conductor for current distribution equalisation - Google Patents

Abstract

The AC busbar and branch line for energy distribution or transmission is subdivided into rigid part-conductors. The latter change their position in the main conductor (busbar) such that an equalisation of the current distribution between them, or an increase of current capacity of the high current conductor, takes place. Pref. at the part-conductor intersection points, their profiles are recessed such that the intersections do not increase much the main conductor dimensions. The part-conductor profiling may be complementary, with the exception of small restrictions, to maintain the same cross section. USE/ADVANTAGE - For switchgear, outdoor conductors, installation connections etc., with current distribution equalisation.

Description

The magnetic field induces electrical alternating currents in conductors electrical field strengths that lead to a lead to uneven current distribution in the conductors. The uneven current distribution in conductors has one increased electrical resistance compared to Direct current. This means the same conductors the current carrying capacity with alternating current is smaller than with Direct current.

Conductors that carry higher currents are often in divided several sub-conductors. As the main leader is a single conductor or a composite arrangement a number of conductors that make up the total current of a Lead Stranges, designated. As a sub-leader, a Conductor of a certain part of the total current of a strand and is part of the main conductor, designated.

The reduced current carrying capacity of AC main conductors where rectangular Partial conductors are arranged in packages (see DIN 43 670 and DIN 43 671).  

The reduced current carrying capacity follows from:

• - The current displacement within the sub-conductor, as well out
• - the uneven current distribution between the Partial conductors.

In the case of rectangular partial conductors, arranged in packages the outer partial conductors are loaded more than the ones inside. It is even more pronounced uneven current distribution with concentric partial conductors, where the outermost pipe carries almost all of the current.

The aim of the present invention is an interpretation for rigid high current conductors of switchgear and Power transmission lines to find the Power distribution evened out and corresponding Show possible solutions.

An equalization of the current distribution can be realized if the position of the partial conductors along the Executive is changed. It is advantageous if the partial conductors are proportional along the main conductor go through all typical magnetic field areas. Thereby are those induced in the individual partial conductors Tension equalized and thus the subconductor about the same currents.  

In Figs. 1, 18 and 19, such conductor structures are shown.

The conductor configuration in FIG. 1 represents the smallest and simplest unit in the change in position. Such a change in position brings advantages if other main conductors or partial conductors run in parallel in the vicinity.

The solution shown in FIG. 2 can be used for the intersection at which the partial conductors swap their positions. Each of the partial conductors is provided with a recess ( FIGS. 4 and 5) and bent in an S-shape. The impact of the local cross-sectional reduction at the crossing point is negligible with regard to the current carrying capacity, since the temperatures at the screwing points and not the temperatures in the course of the conductors are relevant for the current carrying capacity (see DIN VDE 0670, Part 1000). The increased temperature in the conductors practically drops from the crossing point to the screw connection points.

To increase the mechanical strength of the The subconductors can be separated by insulating strips Intermediate pieces are mutually supported (in the Figures not shown).  

A further possible solution for carrying out the crossing without a substantial reduction in the cross section of the partial conductors is indicated in FIG. 6. In this variant too, one dimension of each partial conductor is in principle reduced, while in a second dimension (possibly laterally) the remaining cross section is thickened, so that the overall cross section of the partial conductor is not, or is not significantly, reduced. In this solution, because of the otherwise occurring contact resistances, the cross section is preferably increased by means of additional brackets by means of brazing (and not by screwing).

With concentric conductors, as shown in Fig. 19, or with arrangements that are similar to concentric conductors (as shown, for example, in Fig. 13 ), the uneven current distributions are particularly significant. Since the cladding tube or the outer partial conductors carry almost the entire current of the main conductor in these arrangements, such designs are used extremely rarely. By changing the position of the partial conductor sections in the course of the main conductor, an almost identical current distribution can be achieved. Such a solution is particularly important for versions where a higher current carrying capacity is required, but the dimensions of the main conductor cannot be increased (e.g. in gas-insulated switchgear with pipe busbars).

In the case of concentric partial conductors, a solution according to FIG. 9 can be carried out. The cladding tube and the inner conductor are slotted in opposite directions and connected by conductive intermediate pieces so that in the course of the main conductor a current transfer from the first section of the outer conductor to the second section of the inner conductor and (almost) a current transfer from the first section of the inner conductor to the second section of the outer conductor is guaranteed (see Fig. 9). As a result, each of the two partial conductors of the main conductor is implemented as an outer conductor in one section and as an inner conductor in a second section, and thus - with sections of the same length - the current distribution between the partial conductors is made more uniform.

Since with this arrangement the cooling conditions of the Inner conductor are significantly worse than that of the Cladding tube, measures to improve the Heat emission (gaps in the cladding tube or the like) can be provided.  

With an appropriate choice of the cross sections of the Cladding tube and the inner conductor and at appropriate Cooling measures can be taken with such an arrangement Current carrying capacity of a pipeline significantly increased will.

In further development of this idea, e.g. For example, an arrangement according to FIG. 12 could also be chosen, the cooling being improved and the uniform current distribution between the partial conductors taken into account.

Current conduction according to FIG. 14 is ensured by conductive intermediate pieces (designated Z in the figures). A high mechanical strength is achieved by insulating intermediate pieces (designated P in the figures). The current transfer via the conductive intermediate pieces can be ensured by brazing or by screwing (screwed connections are indicated in FIGS. 15 to 17, for example). With screw connections, make sure that there is no relevant shunt of the current flow through the screw shaft (if necessary, appropriate distances and insulating inserts must be provided).

In Figs. 18 and 19 several conductor configurations are shown for example, in which the conductor elements different positions undergo. It is assumed that with a package arrangement of 3 rectangular partial conductors, according to an arrangement according to DIN 43 671, Table 1, number of rails 3, the outer conductors pass through the same magnetic fields, ie conductors other than the three partial conductors shown are at a very great distance, or are arranged without much influence on the three conductors shown (e.g. one below the other). Under these circumstances, a change in position according to FIG. 18 can lead to an equal current distribution over the three conductors (the outer conductors also cyclically passing through the middle position).

With a package arrangement of 4 partial conductors of rectangular shape (see DIN 43 671, Table 1, 4 partial conductors), the 2 inner partial conductors are loaded approximately the same and the 2 outer conductors are equally loaded without changing their position. A comparison of the current distribution over all partial conductors can be achieved by the arrangement shown in FIG. 19.

In FIG. 18 and in FIG. 19 it is shown that the current distribution is made more uniform if the current supply and discharge lines take place at the ends, ie if there are crossings between them.

It is also entirely possible to carry out the crossings directly on the field-wise supports, with current discharges or feeds taking place at the supports if these current leads lead to small currents. In Fig. 20, currents I72 «I71, I73« I71, I74 «I71. The current carrying capacity of the main conductor is hardly influenced by the current draw of small currents at the crossing points.

In further development of the specified solution for Evening out the power distribution seems sensible the main ladder towards a higher number of sub-ladders subdivide, the positions of the partial conductors in Main leaders are changed. This creates the skin effect in the partial conductors themselves (current displacement in the individual partial conductors) and between the Partial conductors realized a uniform current distribution.

This proposed solution is also important for round or semi-round conductor bundles (as shown in Fig. 13), which can be used for gas-insulated switchgear.

Reference numerals

Kn . . Kn crossing point in variant n
Pn1. . . Pn4 insulating spacers in variant n, No. 1. . . 4th
In1. . . In4 electricity in variant n, No. 1. . . 4th
Tn1. . . Tn4 partial conductor in variant n, No. 1. . . 4th
Zn1. . . Zn6 conductive intermediate pieces in variant n, No. 1. . .

Claims (5)

1. AC high-current conductor of energy distribution or energy transmission (busbars and busbar branches of switchgear, exits or discharges to switchgear or electrical devices, connecting lines between electrical devices, etc.), which is divided into rigid partial conductors, characterized in that the partial conductors their position Change in the main conductor so that an equalization of the current distribution between the sub-conductors, or an increase in the current carrying capacity of the high-current conductor is achieved. 2. Claim according to point 1, characterized, that the profiles at the intersections of the partial conductors the sub-conductor are recessed symmetrically, and so the Partial conductor without, or without substantial increase in Cross the dimensions of the main conductor. 3. Claim according to point 1, characterized, that at the intersection one dimension of Ladder is reduced to about half a second dimension doubled at the same time will be the partial conductors that cross each other - if necessary with the exception of small bottlenecks - about the same Maintain cross section.   4. Claim according to point 1, characterized, that with concentric or concentric-like Partial conductor sections the crossing through the transition partial conductor sections arranged from the inside to the outside arranged partial conductor sections or from the outside arranged partial conductor sections in arranged Subconductor sections are made. 5. Claim according to point 1, characterized, that to further even out the current distribution the main leaders divided into 2 or more sub-leaders will.