CZ305394B6 - Grounding device for high voltage instruments - Google Patents

Abstract

The present invention relates to a grounding device for high voltage instruments, particularly for earthing switches and earthing switches disposed on a power plant disconnecting switch, consisting of a frame (1) with a drive shaft (9) bearing (3) located at the point of a central insulator (2) on the frame (1), wherein the drive shaft (9) is connected at its one end with a drive (10). Two “V” or “U” shaped grounding bars (4), being located on the drive shaft (9) are connected above with each other by a first electrically conducting cross bar (5) with electrically conducting contacts (8) that are fixedly attached at the point of insulators (2), whereby on the ground potential, both the grounding bars (4) are connected with each other by means of a second electrically conducting cross bar (11) and joined with the frame by an elastic electrically conducting coupling (6).

Description

Technical field

The invention relates to the construction of an earthing device for high voltage devices used in substations, in particular power stations.

BACKGROUND OF THE INVENTION

Until now, grounding devices for high voltage devices have been designed to include a frame located at ground potential. Three bearings with shafts mechanically connected to the drive were mounted on it. Grounding rods with contacts were mounted on the shafts. Three insulators were placed on the frame with contact heads at their ends. Each grounding rod was separately conductively connected to the frame by a flexible conductive connector. Each rod and flexible coupling were loaded with a full short-circuit current in the event of a short circuit. Therefore, they had to be rated for the full short-circuit current and the heat generated by the Joule losses. Designing for full dynamic short-circuit current and thus for full electrodynamic forces also affects the design of the earthing device itself. Since each grounding rod and each flexible conductive coupling had to be dimensioned for a full short-circuit current, they had to be constructed more robustly with a much higher consumption of conductive material. The electrodynamic forces acting in the long conducting loops of the individual phases from the contact head to the frame placed great demands on the design of the earthing rods and the drive. This has led to far greater material consumption and increased fuel costs.

A partial improvement occurred when the ground rods were connected to the contact heads of the insulators by a conductive partition with contacts. While this design has an effect on the electrodynamic forces and mechanical stresses of the entire circuit, it does not address the reduction in the number of rods, bearings, flexible conductive couplings, and therefore the simpler design of the earthing device has not been achieved.

SUMMARY OF THE INVENTION

The aforementioned drawbacks are largely eliminated by the grounding device for the high voltage devices according to the invention, consisting of a drive and a frame placed on the ground potential, on which three insulators are placed in one plane, with contact heads at their ends. One bearing with a drive shaft connected to the drive at one end is located on the frame at the central insulator. Two grounding rods are connected to the drive shaft in the "V" or "U" shape, connected by the first conductive bar at the top, where the contacts are firmly connected in the place of the insulators. At ground potential, both grounding rods are connected by a second conductive bar and connected to the frame by a flexible conductive connector.

Clarification of drawings

The earthing device for the high-voltage devices according to the invention can be seen from the enclosed figure, in which a three-pole earthing switch for a 25 kV network is shown in simplified perspective.

DETAILED DESCRIPTION OF THE INVENTION

A practical embodiment of a grounding device for high voltage devices according to the invention is shown in the attached figure.

It is a three-pole earthing switch for a 25 kV network. Three insulators 2 are mounted on the frame 1 at the ground potential, in one plane, at the ends of which there are contact heads 7. On the frame 1, there is a bearing 3 with a drive shaft 9 at one end connected to the drive 10. On the drive shaft 9, two earthing rods 4 are connected at the top by a first conductive crossbar 5, at which the contacts 8 are firmly connected at the insulators 2 at the ground. On the ground potential, both earthing rods 4 are interconnected by a second conductive crossbar. connected by a flexible conductive connector 6.

The first conductive partition 5 with the contacts 8 is as close as possible to the contact heads 7 located on the insulators 2. This creates a favorable short circuit for conducting the short-circuit current. In the case of a three-phase short-circuit, the short-circuit currents are added (subtracted) so that only a small differential current is led from the first conductive partition 5 to the earthing rods 4 and one flexible conductive coupling 6. In case of symmetrical short-circuit current, this current is almost zero. If a single-phase short-circuit occurs, the passing current is only 60% of the full three-phase short-circuit current. These facts have the effect of reducing the electrodynamic forces and mechanical stresses of the entire circuit. This also reduces stress on the drive (10) itself.

All the advantages of the design of the earthing device for high voltage devices according to the technical solution are the differences in the short-circuit circuits. In the construction according to the invention, the short-circuit is considerably shorter than the original three separate circuits consisting of three earthing rods.

This also results in savings, which are both material on the earthing rods and the savings of flexible couplings and, on the other hand, in reducing the number of mechanical parts. It is also important to use a more favorable drive and increase its reliability.

Industrial applicability

The grounding device for the medium voltage devices according to the invention can be advantageously used in all substations of the medium voltage networks, particularly in power stations, for earthing switches and earthing switches located on the disconnector.

Claims (1)

PATENT CLAIMS 1. Grounding device for medium voltage devices, consisting of a drive and a frame located at ground potential, on which three insulators are placed in one plane, the ends of which have contact heads, characterized in that on the frame (1) there is a central insulator (2) a single bearing (3) with a drive shaft (9) coupled at one end to the drive (10) is located on which two "V" or "U" grounding rods (4) are connected at the top by a first conductive bar ( 5), in which the contacts (8) are firmly connected in the place of the insulators (2), the grounding rods (4) are connected to the ground conductor (4) by a second conductive bar (11) and connected to the frame (1) by a flexible conductive connector (6) .