Patent EA-001636-B1 (EA)
Title: A mechanically supported winding
Inventor: BERGGREN SOREN
IPC: H01F27/28
Filed: 1998-02-02
Abstract: 1. A power transformer (1) or a reactor comprising a winding (3) formed as a winding coil (2) having concentrically arranged winding turns, characterized in that at least one winding turn is formed by a high voltage cable (111) provided with an outer semiconducting layer (115) and that the winding (3) is provided with winding separating spacers (8, 9), arranged axially between each winding turn, arranged to hold the winding (3) axially together. 2. A device according to claim 1, characterized in that the spacers (8, 9) are arranged to cooperate with support means (4, 11) extending radially on both sides of the winding coil (2) in order to form a mechanical winding structure having concentrically arranged windings in a cage like construction. 3. A device according to claim 2, characterized in that a supporting means (4, 11) is formed as an upper end plate (11) provided with openings (16) through which spacers (8, 9) are extended whereby the spacers (8, 9) are arranged to be axially tightened against the upper end plate (11). 4. A device according to claim 3, characterized in that the upper end plate (11) extends radially, from the innermost winding turn (5) to the outermost winding turn, over the entire winding coil. 5. A device according to claim 4, characterized in that a number of supporting means (4, 11) are arranged radially, over at least one entire side of the winding coil (2), forming a spoke formed support side. 6. A device according to any one of claims 2 - 5, characterized in that one supporting means (4, 11) is formed as a lower end plate (4) to which the spacers (8, 9) are clamped or that the lower end plate (4) is provided with openings (16) through which the spacers (8, 9) extend whereby the spacers are arranged to be axially tightened against the upper end plate (11). 7. A device according to claim 6, characterized in that a plurality of lower endplates (4) are arranged radially, on the entire side of the winding coil (2) forming a spoke formed lower support side. 8. A device according to claim 7, characterized in that the outer semiconducting layer (115) is earthed. 9. A device as claimed in any of claims 1-8, characterized in that the winding is flexible and composed of an electrically conducting core surrounded by an inner semiconducting layer (113), an insulating layer (114) of solid material surrounding the inner semiconducting layer (113), and an outer semiconducting layer (115) surrounding the insulating layer (114), said layers (113,114,115) being adhered to each other. 10. A device as claimed in any of claims 1-9, characterized in that said layers (113,114,115) are of materials having such elasticity and such coefficient of thermal expansion that the changes in volume in the layers (113,114,115) caused by temperature fluctuations during operation are absorbed by the elasticity of the material, the layers (113,114,115) thus retaining their adhesion to each other upon the temperature fluctuations that occur during operation. 11. A device as claimed in any of claims 1-10, characterized in that the material in said layers (113,114,115) has high elasticity, preferably with a modulus of elasticity less than 500 MPa, preferably less than 200 MPa. 12. A device as claimed in any of claims 1-11, characterized in that the coefficients of thermal expansion for the materials in said layers (113,114,115) are substantially the same. 13. A device as claimed in any of claims 1-12, characterized in that the adhesion between layers (113,114,115) is of at least the same magnitude as in the weakest of the materials. 14. A device as claimed in any of claims 1-13, characterized in that each of the semiconducting layers (113,115) essentially constitutes one equipotential surface.