Abstract: A transformer apparatus for an electrical power transformation system is provided. The transformer apparatus comprises three outer transformer limbs, an inner transformer limb a transfer star, and first and second connection portions. The transfer star comprises an electromagnetic transfer core and three transfer coils. The electromagnetic transfer core extends from the inner transformer limb to each of the three outer transformer limbs at a point on each outer transformer limb between the first coil assembly and the second coil assembly. The transfer coils are wound around the electromagnetic transfer core such that each transfer coil is arranged between the inner transformer limb and a respective outer transformer limb. The transfer star is configured to allow transfer of magnetomotive force between the outer transformer limbs and the inner transformer limb of the transformer apparatus. First and second connecting portions are to allow magnetic flux to flow between the inner and outer transformer limbs.

Abstract: A three phase transformer apparatus for a three phase electrical power transformation system is provided. For each phase of the three phase transformer apparatus the three phase transformer apparatus comprises: an upper core limb having a first end and a second end, a lower core limb having a third end and a fourth end, a first coil assembly comprising a first primary coil and a first secondary coil, and a second coil assembly comprising a second secondary coil and a control coil. The first primary coil and the first secondary coil of each first coil assembly are wound concentrically around the upper core limb or the lower core limb of the respective phase. The second secondary coil and the control coil of each second coil assembly are wound concentrically around the other of the upper core limb and the lower core limb of the respective phase. The second secondary coil of each second coil assembly is connected in series to the first secondary coil of the first coil assembly of the respective phase.