Patent EA-001634-B1 (EA)
Title: Power transformer/inductor
Inventor: FROMM UDO
IPC: H01F27/28
Filed: 1998-02-02
Abstract: 1. A power transformer/inductor comprising at least one winding, characterized in that the winding / windings are composed of a high-voltage cable (10), comprising an electric conductor, and around the conductor there is arranged a first semiconducting layer (14), around the first semiconducting layer (19) there is arranged an insulating layer (16) and around the insulating layer (16) there is arranged a second semiconducting layer (18), whereby the second semiconducting layer (18) is directly earthed at both ends of each winding (221, 222) and that at least one point between both the ends is indirectly earthed. 2. A power transformer/inductor according to claim 1, characterized in that the high-voltage cable (10) is manufactured with a conductor area of between 80 and 3000 mm<2> and with an outer cable diameter of between 20 and 250 mm. 3. A power transformer/inductor according to any one of claims 1 - 2, characterized in that the direct earthing (36) is performed by means of galvanic connection to earth. 4. A power transformer/inductor according to any one of claims 1 - 3, characterized in that indirect earthing is performed by means of a capacitor (32; 321 - 323) inserted between earth and the second semiconducting layer 18). 5. A power transformer/inductor according to any one of claims 1 - 3, characterized in that indirect earthing is performed by means of an element (34) with non- linear voltage-current characteristic inserted between the second semiconducting layer (18) and earth. 6. A power transformer/inductor according to any one of claims 1 - 3, characterized in that the indirect earthing is performed by means of a circuit inserted between the second semiconducting layer (18) and earth, the circuit comprising an element with non-linear voltage-current characteristic in parallel to a capacitor (40). 7. A power transformer/inductor according to claim 6 characterized in that indirect earthing is performed by means a combination of alternatives according to claims 4 - 6. 8. A power transformer/inductor according to any one of claims 1 - 7, characterized in that the element with non-linear voltage-current characteristic constitutes a spark gap (36), a gas-filled diode, a Zener-diode or a varistor. 9. A power transformer/inductor according to any one of claims 1 - 8 , characterized in that the power transformer / inductor comprises a magnetizable core. 10. A power transformer/inductor according to any one of claims 1 - 8 , trans- the power transformer / inductor is built without a magnetizable core. 11. A power transformer/inductor according to claim 1, characterized in that the winding / windings are flexible (a) and in that said layers adhere to each other. 12. A power transformer/inductor according to claim 11, characterized in that said layers are of a material with such an elasticity and with such a relation between the coefficients of thermal expansion of the material that during operation changes in volume, due to temperature variations, are able to be absorbed by the elasticity of the material such that the layers retain their adherence to each other during the temperature variations that appear during operation. 13. A power transformer/inductor according to claim 12, characterized in that the materials in the said layers have a high elasticity, preferably with an E-module less than 500 MPa and most preferably less than 200 MPa. 14. A power transformer/inductor according to claim 12, characterized in that the coefficients of thermal expansion in the materials of the said layers are substantially equal. 15. A power transformer/inductor according to claim 12, characterized in that the adherence between layers is at least of the same rating as in the weakest of the materials. 16. A power transformer/inductor according to claim 11, or 12, characterized in that each semiconducting layer constitutes substantially an equipotential surface.