MOISTURE-PROTECTED WOUND CAPACITOR VOLL AND A METHOD FOR MANUFACTURING SUCH VOLL

Abstract: The invention relates to a moisture-protected capacitor wrapping (1) together with a method and apparatus for man­ ufacturing such a wrapping. The wrapping (1) is wrapped in a manner known per se using ribbons (2, 3) laid one upon the other, of dielectric material with associated electrodes (4, 5), which between themselves define the electrically active area of the wrapping (1). In accordance with the invention this active area is caused to terminate at least one wrapping turn from the final end of the wrapping (1) to form an electrically inactive area in which a water-impermeable ribbon (6) is inserted, said ribbon (6) extending at least one turn round the wrapping (1).

Description: MOISTURE-PROTECTED CAPACITOR WRAPPING AND A METHOD AND APPARATUS FOR MANUFACTURING SUCH WRAPPING TECHNICAL FIELD The present invention relates to a moisture-protected capacitor wrapping which is wound from ribbons, wrapped one upon the other, of dielectric material with associated electrodes defining between themselves the active area of the capacitor wrapping, furthermore i relates to a method and an apparatus for manufacturing such a moisture-protected capacitor wrapping. BACKGROUND ART Moisture-protected capacitor wrappings are known, e.g. from the US Patent Cpecification 2 549 770 and the German published Specifications 12 27 558 and 12 97 231. The disadvantage with these known wrappings is that their production can not be automated, which makes their manufacture comparatively expensive. DISCLOSURE OF INVENTION The object of the present invention is to provide a moisture-protected capacitor wrapping, which can be produced automatically and which is thereby cheap to manufacture. This is obtained by the wrapping, method and apparatus in accordance with the invention being given the characterizing features disclosed in the claims. DESCRIPTION OF FIGURE The invention will now be described in detail with reference to the appended drawing, on which the sole Figure is a perspective view of an embodiment of a moisture-protected capacitor wrapping in accordance with the invention. PREFERRED EMBODIMENT A perspective view is shown in the Figure of an embodiment of a moistureprotected capacitor wrapping In accardance with the invention, generally denoted by the numeral 1. The wrapping l, which is partially unwrapped, has been wrapped round an unillustrated wrapping mandrel, using two ribbons 2, 3 laid one upon the other, the ribbons being of dielectric material, e.g. paper or plastics, and each has its associated electrode 4, 5, respectively. In the illustrated embodiment the electrodes 4 and 5 are assumed to be made from separate metal ribbons, but it is to be understood that the electrodes may be metallized coatings on the dielectric ribbons 2 and 3 instead. The number of ribbons of dielectric material and metal is naturally not limited to two but may be varied, depending on the desired performance of the capacitor. Between themselves, the electrodes 4 and 5 define the electrically active area of the capacitor wrapping. In accordance with the invention, the active area of the capacitor wrapping 1 terminates at least one wrapping turn from the final end of the wrapping 1 to form an inactive area in which a water-impermeable ribbon 6, e.g. of aluminium is inserted, said ribbon 6 extending at least one turn around the wrapping l. In the embodiment of the wrapping 1 illustrated in the Figure, the inactive area at the final end of the wrapping has been provided by both the electrodes 4 and 5 being cut at least one wrapping turn before the dielectric ribbons 2 and 3 are cut. The water-impermeable ribbon 6 has been inserted in the inactive area thus formed between the ribbons 2 and 3 and thereafter wrapped together with the dielectric ribbons 2 and 3 at least one turn round the wrapping 1. Both electrodes 4 and 3 do not of course need to be cut at the final end of the wrapping to form the electrically inactive area, and it is sufficient to cut one of the electrodes. If the water-impermeable ribbon 6 is made from an aluminium ribbon, it must however be ensured that this ribbon does not come into contact with either of the electrodes 4 and 5. In the case where the electrodes consist of a metallic coating on the dielectric ribbons 2 and 3, at least one of these ribbons must be demetallized at its final end to obtain the electrically inactive area in which the water-impermeable ribbon 6 can be inserted. Manufacturing of a moisture-protected capacitor wrapping in accordance with the invention is easily automated with the aid of means known per se for ribbon demetallizing and cutting.

Claims: CLAIMS 1. A moisture-protected capacitor wrapping (1) wrapped of ribbons (2,3) laid one upon the other, of dielectric material with associated electrodes (4,5) which consist of metal coating on the ribbons, characterized in that at least one of the ribbons is demetallized at least one turn from the final end of the wrapping. 2. Method of producing a moisture-protected capacitor wrapping (1) by wrapping ribbons of dielectric material (2,3) laid one upon the other together with associated electrodes (4,5), which consist of metallic coating on the ribbons, characterized in that at least one of the ribbons is demetallized at least one wrapping turn from its final end. 3. Apparatus for manufacturing a moisture-protected capacitor wrapping (l) wrapped of dielectric material (2,3) laid one upon the other together with associated electrodes (4,5) which consist of metallic coating on the ribbons, characterized in that it includes demetallizing means for causing at least one of the electrodes to terminate at least one wrapping from the final end of the wrapping.

Inventors: HEDQVIST, GOSTA TORBJORN, JOHANSSON, JAN-ULF ARNE, LARSSON, HANS INGE ROBERT, NILSSON, STIG KJELL RONNY, TORDSSON, HANS GORAN ROLAND, Hedqvist, Gösta Torbjörn, Tordsson, Hans Göran Roland
Applicants: TELEFONAKTIEBOLAGET L M ERICSSON
Application year: 1984
Main classification: H01G1
IPC codes: H01G13, H01G4, H01G2