Abstract: A high voltage insulation system for high-voltage direct current including a bushing, a conductor, a transformer conductor, and a connection between the conductor and the transformer conductor. A conductive shielding electrode shields the connection between the bushing and transformer. A surrounding insulation system is immersed in transformer oil. The surrounding insulation system includes transformer insulation material and bushing insulation material. A cylindrical solid insulation barrier encloses the connection between the bushing conductor and transformer conductor. At least one solid insulation barrier is fastened on the outer side of the shielding electrode. The at least one solid insulation barrier extends in an axial direction outside the axial direction of the shielding electrode and forms a distance to the insulation material of the bushing and the insulation material of the transformer, whereby a moderate voltage drop over the solid insulation barrier is obtained.

Abstract: A high voltage insulation system for high-voltage direct current including a bushing, a conductor, a transformer conductor, and a connection between the conductor and the transformer conductor. A conductive shielding electrode shields the connection between the bushing and transformer. A surrounding insulation system is immersed in transformer oil. The surrounding insulation system includes transformer insulation material and bushing insulation material. A cylindrical solid insulation barrier encloses the connection between the bushing conductor and transformer conductor. At least one solid insulation barrier is fastened on the outer side of the shielding electrode. The at least one solid insulation barrier extends in an axial direction outside the axial direction of the shielding electrode and forms a distance to the insulation material of the bushing and the insulation material of the transformer, whereby a moderate voltage drop over the solid insulation barrier is obtained.

Abstract: A regulating winding for a high power transformer which includes a conductor bunch having a multiplicity of series-connected, parallel conductor loops, each loop comprising at least two parallel loop strands. The conductor bunch includes a number of radial and/or axial cooling channels, and the loop strands and the cooling channels are so arranged that the voltage difference between two loop strands located adjacent each other, and preferably positioned together between two cooling channels, is considerably higher than the voltage difference between loop strands positioned on either side of the cooling channels.