Patent EA-001725-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 (14) 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 earthed at or in the vicinity of both ends (261, 262; 281, 282) of each winding (221, 222) and that furthermore one point between both ends (261, 262; 281, 282) is directly earthed. 2. A power transformer/inductor according to claim 1, characterized in that n points (n >=2) per at least one turn of at least one winding are directly earthed in such a way that the electric connections (341, 342,...., 34n-1) between the n earthing points divide the magnetic flux into n parts to limit the losses produced by earthing. 3. A power transformer/inductor according to claim 2, 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. 4. A power transformer/inductor according to claim 3, where the windings surround a cross-section area A and the circumference of each winding turn has a length 1, whereby the electric connections (connections (341, 342 , 34n-1) between the n earthing points divide the said cross-section area into n partial areas A1, A2 .... An so that,   and divides said length 1 into n parts l1, l2,....ln, so that,   characterized in that the electric connections (341, 342,     , 34n-1) between the n earthing points are performed in such a way that the ends of every segment li are electrically connected so that only the partial area Ai is encompassed by a coil consisting of the electric connection (34i-1) and the segment li and the condition is fulfilled &Phi i/&Phi = li/l, whereby &Phii is the magnetic flux through the partial area Ai. 5. A power transformer/inductor according to claim 4, whereby the magnetic flux density B is constant throughout the cross-section of the core, characterized in that the electric connections (341, 342,     34n-1) between the n earthing points are performed in such a way that the condition is fulfilled Ai/A = li/l. 6. A power transformer/inductor according to any one of claims 1-5, characterized in that the power transformer/inductor comprises a magnetizable core. 7. A power transformer/inductor according to any one of claims 1-5, characterized in that the power transformer/inductor is built without a magnetizable core. 8. 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. 9. A power transformer/inductor according to claim 8, 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. 10. A power transformer/inductor according to claim 9, 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. 11. A power transformer/inductor according to claim 9, characterized in that the coefficients of thermal expansion in the materials of the said layers are substantially equal. 12. A power transformer/inductor according to claim 9, characterized in that the adherence between layers is at least of the same rating as in the weakest of the materials. 13. A power transformer/inductor according to claim 8, or 9, characterized in that each semiconducting layer constitutes substantially an equipotential surface.