High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Housing structure
Patent
1998-02-17
1999-05-11
Friedhofer, Michael A.
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Housing structure
218 43, 218 53, 218 62, 218 63, H01H33/88
Patent
active
059029803
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an insulating component for use in high-voltage switching equipment, and more particularly for use in a gas-insulated switch gear.
BACKGROUND INFORMATION
An insulating component is described, for example, in Germany Patent No. 26 26 855. These insulating components are used, for example, as spacers or nozzles for the feeding of insulating gas in electric high-voltage switches, particularly high-voltage power switches.
Such components are used as supports for busbar conductors or leadthroughs in, for example, encapsulated high-voltage switchgear. They may, for example, consist of cast resin, an epoxy resin, polytetrafluoroethylene ("PTFE"), a ceramic, or porcelain.
Under high dielectric stresses, such as in the case of high electrical field strengths, particularly if the field strength has a component tangential to the surface of the insulating component, there is an increased probability of displacement currents on the surface of the insulating component, which may also lead to electric arcing.
In accordance with the related art, a poorly conductive fabric is embedded in the region of the surface of the component in order to discharge surface charges.
While this certainly increases the conductivity of the component, it also contributes a substantial expense to the cost of the manufacture of the component. Different structural materials are combined with each other and there is the danger that a part of the fabric is not firmly bound to the component and extends into a dielectrically highly stressed region of the high-voltage equipment.
It is known from German Patent No. 30 47 761 to embed in an insulating component a mineral filler the particles of which lie freely on the surface of the component and prevent the formation of carbon-containing, and partially electrically conductive, tracks on the surface upon discharges. Such an insulating component is difficult to manufacture.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an insulating component of the aforementioned type which permanently withstands high dielectric stresses and is economical to manufacture.
The object of the present invention is achieved by providing the surface of the component with sharp-edged grooves or ridges with a depth of roughness of at least 100 .mu.m in at least one region which is particularly strongly stressed dielectrically.
One advantageous embodiment of the invention provides that at least one particularly dielectrically stressed region of the surface has a depth of roughness of at least 200 .mu.m.
As a result of the depth of roughness, no displacement currents which could give rise to electric arcing can occur on the surface of the component.
In a cross section of the component, the latter has, in the region of its surface, sharp-edged elevations or recesses due to its surface structure. This structure leads to an improved dielectric strength since high electric field strengths occur on the tips and edges, which lead to the emission of surface charges and thus limit the potential of surface charges.
No additional material other than that of which the component is made of is necessary in order to achieve this result.
Another exemplary advantageous embodiment of the invention provides that the grooves or ridges are produced by machining.
In that case, the component, after it has been formed by casting, sintering or extrusion, can be worked further by lathe-cutting or milling in the dielectrically particularly stressed region.
A groove-depth more than 200 .mu.m has been found to be particularly advantageous.
In the case of a component with rotational symmetry, the grooves may advantageously be concentric to each other or arranged in the form of a spiral.
This is particularly advantageous when the component is part of an insulating material nozzle for a high-voltage power switch. Since such a power switch is frequently designed with rotational symmetry, the regions which are particularly highly stressed dielectrically also exhibit rotat
REFERENCES:
patent: 3789175 (1974-01-01), Beier et al.
patent: 4229627 (1980-10-01), Rostron
patent: 4289942 (1981-09-01), Milianowics
Reincke Frank
Trapp Norbert
Friedhofer Michael A.
Siemens Aktiengesellschaft
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