Condenser bushing

An electrical insulation system comprising:

• an active part comprising a conductor;
• a condenser bushing disposed around the conductor, the condenser bushing comprising:
• a condenser core and electrically conductive field-grading layers, which are embedded in insulating material of the condenser core and arranged around a central channel for a conductor extending along an axis defining an axial direction, an electric connection being provided to at least one of the field-grading layers,
• pairs of neighbouring field-grading layers with the insulation material between them forming sections of the condenser core of axial lengths L1 through Ln and with capacitances C1 through Cn,
• a shape of at least one of the field-grading layers deviating from cylindricality to reduce non-uniformity of electric field stress of the condenser bushing compared to a corresponding condenser bushing with the cylindrical field-grading layers forming corresponding sections of the axial lengths L1 through Ln and with capacitances C1 through Cn, and
• at least one of the field-grading layers being shaped such that the diameter of said field-grading layer varies along the axial direction, the diameter of said field grading layer having at least one maximum between the edges of the field-grading layer, wherein the maximums of the field-grading layers increase in amplitude along a radial direction, but narrower in width along the axial direction, with increasing distance from the condenser core, wherein the terminating ends of each of the field-grading layers are straight in the axial direction.