Impregnated capacitor and method of manufacture
AssigneeJohnson & Phillips (Capacitors) Limited
InventorsJohn Edward Murfitt, Alastair Martin Pitt
Life of this patent
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Abstract
A capacitor element is made by interwinding electrode foils and non-porous dielectric films, without interposed paper wicks. The foils and films are wound at different tensions so that transverse passages are formed between adjacent surfaces within the element; when the element is subsequently impregnated with dielectric liquid, those passages facilitate entry of the liquid between the various foils and films and assist proper permeation. The dielectric film and dielectric liquid are preferably polypropylene and mineral oil respectively.
Claims16
In a method of making a capacitor element comprising the steps of
- a. interwinding electrode foils and layers of substantially non-porous dielectric film, to form a winding, and
- b. impregnating said winding with a dielectric liquid,
- the improvement according to which said foils and said layers in said winding are interwound under conditions such that the foils and films of said winding are at sufficiently different tensions that at least one of each pair of adjacent foil and film surfaces is corrugated during winding to form passages extending transversely to the lengths of said layers between said adjacent surfaces, which passages assist entry of said impregnating liquid between said foils and said layers.
A capacitor element comprising electrode foils interwound with separating layers of substantially non-porous dielectric film, the foil and layers being at different elongations and the film layers consequently having randomly arranged transverse corrugations forming passages between the layers and foils, and each layer consisting of a plurality of films, of which there are at least two at different elongations.
A method of making a capacitor, comprising the steps of
- a. forming at least one capacitor element winding by interwinding at differing tensions electrode foils and layers of substantially non-porous dielectric film, and thereby forming passages extending transversely to the lengths of said layers between adjacent foil and dielectric layer surfaces within said winding,
- b. placing said at least one capacitor element winding within an impregnation tank,
- c. subjecting the interior of said tank to an inert gas at super-atmospheric pressure, and
- d. introducing an impregnating dielectric liquid to said tank to impregnate said at least one winding, entry of said liquid into said winding being assisted by said passages.
A method of making a capacitor, comprising the steps of
- a. forming at least one capacitor element winding by interwinding at substantially the same tension electrode foils and substantially non-porous dielectric films from reels of said foils and films, on at least two of said reels said films being pretensioned at different values, and thereby forming passages extending transversely to the lengths of said foils between adjacent foil and film surfaces within said winding,
- b. placing said at least one capacitor element winding within an impregnation tank,
- c. subjecting the interior of said tank to an inert gas at super-atmospheric pressure, and
- d. introducing an impregnating dielectric liquid to said tank to impregnate said at least one winding, entry of said liquid into said winding being assisted by said passages.
Dependencies are inferred from the claim text.