Electricity: circuit makers and breakers – Multiple circuit control – Pivoted contact
Patent
1995-01-03
1996-06-04
Scott, J. R.
Electricity: circuit makers and breakers
Multiple circuit control
Pivoted contact
200 18, H01H 1912, H01H 1954, H01F 2902
Patent
active
055235352
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an on-load tap changer for regulating the voltage on a transformer while energized or on load which is of the type that includes a tap selector and a diverter switch. The central part of the tap selector includes support means for movable selector contacts for providing a connection between fixed contacts mounted in a circle on outer support means and current collector rings which are electrically connected to the diverter switch and which surround the central support means. The fixed contacts are arranged in through-holes in the outer support means such that both end portions of each contact extend on both sides of the support means, one end portion forming a contact part for cooperation with one of the movable contacts, the other end portion constituting a terminal intended to be electrically connected to one tap of a regulating transformer winding.
2. The Prior Art
From German Patent Document 2 945 724 an on-load tap changer that includes a tap selector and a diverter switch is previously known, in which the support means for the movable contacts of the tap selector consists of two parallel rods of insulating material which are placed inside the current collector rings of the tap selector. The fixed contacts of the tap selector are mounted on insulating bars which are arranged in parallel with and in a circle around the common axis of rotation of the two inner rods. The fixed contacts are fixed to the insulating bars by forming the end portion of the respective contact, after the contact has been placed in a through-hole in the bar, by transversal upsetting into a flat connection member which projects in the radial direction outside the hole.
From German Patent Document 2 105 604 an off-circuit tapping switch is previously known, in which the fixed contacts are fixed by upsetting to a cylindrical tube provided with mounting and inspection openings.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a tap selector which has better electrical and mechanical properties than the above-mentioned design but which, in spite of this, is simpler and less expensive to manufacture.
In a selector of the above-mentioned kind with given radial dimensions, it is advantageous for the dielectric strength between the fixed contacts and the current collector rings if these rings can be made with as small a diameter as possible. To achieve this, the two selector shafts, which in a tap selector according to the invention are placed inside the current collector rings, must at the same time be made as rigid as possible, both with respect to bending and torsion. This is achieved according to the invention by constructing the selector shafts from a metallic material, for example steel or aluminium. A sufficient electrical insulation (corresponding to one regulating step, i.e., the voltage between two adjacent tappings of the regulating winding) between the current collector ring and the selector shafts is achieved with the aid of an intermediate insulating ring and with contact holders of insulating material.
By fixing the fixed contacts by upsetting in the axial direction, a more reliable mounting is achieved than with the above-mentioned attachment by transversal upsetting without any extra fixing components being needed.
By using as support member for the fixed contacts a circular insulating cylinder with a closed circumference (i.e. not axially divided), a high rigidity with respect to bending and torsion is achieved with a moderate thickness of the material in the cylinder wall. The current requirements that the contacts shall be capable of being inspected are fulfilled by providing relatively large holes in the cylinder wall. By these holes, the mounting of certain components included in the selector is also facilitated.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in greater detail by describing an embodiment with reference to the accompanying drawings.
FIG. 1 shows in side view the l
REFERENCES:
patent: 2717296 (1955-09-01), Foley et al.
patent: 3176089 (1965-03-01), Bleibtreu et al.
patent: 3632908 (1972-01-01), Bleibtreu et al.
patent: 3678237 (1972-07-01), Rickert et al.
patent: 3798395 (1974-03-01), Norman et al.
patent: 3902030 (1975-08-01), Popa
patent: 4207445 (1980-06-01), Hammar
patent: 4931599 (1990-06-01), Bleibtreu
patent: 5034578 (1991-07-01), Lauterwald
patent: 5191179 (1993-03-01), Yatchum et al.
ABB Components Catalog--"ABB Components for the Worlds Transformer Industry, Technical Guide on Load Tup Changes Type UC", published by Globe, Luduika, Sweden, 1995-03-30, Rev. 2.
Larsson Tommy
Norman Sivert
Asea Brown Boveri AB
Scott J. R.
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