NO121549B - - Google Patents

Description

Plant for alternating current supply to a

moving device along a path.

The present invention relates to a plant for supplying alternating current to a device which moves along a path, for example to an electrically driven crane.

In general, the power supply to such devices is ! along rails mounted along the track, and a corresponding number of current collectors with spring-loaded sliding contacts mounted on the device. Each of the current rails has an uninsulated contact surface that provides electrical contact with the current collector when it slides along the rail.

As similar tracks can be very long, up to several hundred metres, the contact rails are usually divided into sections, usually approx. 7 to 14 m long. There were as few business connections as possible, but on that Kfr. 35b-9/14 on the other hand, the sections should not be too long for appropriate handling. Necessary movement must be ensured during thermal expansion and contraction of the rails, which is why a number of expansion joints are often arranged in these rails.

For installations of this kind, for practical reasons, it is mostly advised to mount the contact rails with a relatively large distance between them, usually approx. 0.20 - 0.40 m. In the case of alternating current systems and long raceways, this means that the rail system has high reactance. As it often involves large currents, e.g. of 2,000 A or more, this means that there are significant voltage drops up to the consumer site. In order to reduce the voltage drop to acceptable values, it is necessary to use relatively large conductor cross-sections, and often

therefore, several rail feeders in parallel, at the same time as, as a rule, provision must be made for feeding at several places along the rail system.

The present invention aims to remedy this and primarily involves arranging a so-called compensated wiring for the individual contact rails by laying conductors along and at a small distance from each contact rail with largely equivalent cross-sections and in a number corresponding to to the number of the remaining contact rails as well as conductors connected to each of these at locations distributed along the track.

In this way, it can be achieved that the reactance in the busbar system becomes negligible. This of course applies regardless of the number of phases and thus of contact rails.

The necessary cross connections can most practically be arranged at the busbars' work locations, where the conductors can be accessible. The additional conductors can be laid isolated from each other and from the adjacent

contact rail in any way,, but. for ..rational production, it is preferred to place them isolated together with the respective adjacent contact rail..

A composite conductor section which is suitable for use in the plant will thus appropriately consist of a contact rail partly 'surrounded by insulation, and a or. several;,^ equivalent cross section and completely surrounded by insulation.

In the drawing, the invention is a schematic three-phase system, as the most common method of the type in question is to use a three-phase power supply. •• = • -• ..

Fig. 1 shows a schematic cross-section of the string rail system with cross connections drawn in, and- • ?'; '■■ >*■

figo 2 is an overview link core for the facility..

For the sake of simplicity, only one motor M, connected to pantographs 15 - 17, is indicated in the drawing as a consumption unit on the moving device (the crane).

As shown, along and at a small distance from the contact rails 1,

2 and 3 corresponding to the phases R, S and T, respectively, two conductors 4 and 5, resp. 6 and 7, resp. 8 and 9. The two conductors located near a contact rail are each connected to the other two phases in the three-phase system. Each rail unit thus contains the three phases R, S and T

in a three-phase system, but the phases are cyclically exchanged in the three rail units. At certain intervals along the rail system, the three conductors of the same phase are then connected via cross connections, as in fig. 1 is denoted by 10, 11 and 12. The insulation in each rail unit is in the form of stuffed insulating material as indicated by 13, 14 and 15 respectively on

fig. I. The distance a (fig. l) between the current rails is electrically indifferent with this rail arrangement, but can be as usual, i.e. e.g. 0.20 - 0.40 rn. Likewise, the length b of the rail sections can be as usual, i.e. approx. 7 - 14 m, and the transverse connections are laid at the work sites.

Under the assumption that all conductors from 1 to 9 have equivalent conductor cross-sections, the currents will be distributed among the three conductors of the same phase by currents flowing in the cross connections near the tapping point as indicated in the diagram in fig. 2. G-through the essential part of the rail connection between feed point A and drain point B

there will be a balance between the currents in each rail unit, respectively Ir/3» -J-s/3 and ^T/30 Man ^ T al-ts^ as a result three three-phase conductors up to the tapping point, each with negligible reactance.

As practically only ohmic voltage drop occurs with this system, a single feed point will be sufficient to cover several hundred meters of busbars.

For economic reasons, aluminum is preferred as the conductor material in the additional conductors 4-9. However, aluminum is not suitable as a sliding surface material against the sliding contacts, so the contact rails 1, 2, 3 must in any case have a sliding surface of another material, e.g. copper or stainless steel, In the part of the cross-section that does not form a sliding surface, aluminum can of course also be used.•

In addition to efficient utilization of the conductor cross-section, a current supply system of this kind will provide a better power factor compared to previously known current busbar systems for the same purpose.

In the case of a single-phase system, two contact rails will be used, each with a conductor at a small distance from the rail and connected to the other phase in the system. As with a three-phase system, the conductors of the same phase are connected by a number of cross connections, also here with distances of approx. 7 - 14 m.

Although in this presentation everywhere it is said that a conductor for each of the other phases in the system must be arranged near each contact rail, it will of course be understood that each such additional conductor can be composed of several conductor strings connected in parallel.

Claims (2)

1. Installation for alternating current supply to a device moving along a path, e.g. an electrically powered crane, via contact rails of different potential, arranged along the movement path and arranged for interaction with strain gauges on the device, characterized in that along and at a small distance from each contact rail are laid conductors with largely equivalent cross-sections and in a number corresponding to the number of the other contact rails as well as conductors connected to each of these at locations distributed along the track. 2. Installation as specified in claim 1, characterized in that the additional conductors are isolated and joined with the respective adjacent contact rail. 3= Installation as specified in claim 2, characterized by one composite conductor section consisting of a contact rail partially surrounded by insulation, and one or more additional conductors with approximately equivalent cross-section and completely surrounded by insulation.