there would normally be a large unbalance in the current in separate parallel winding parts for example this could occur in a six high low design fig5 balanced impedances yield balanced currents in the parallel parts of windings such as the tertiary voltage coil in fig5 and the low voltage coil in fig5 balanced currents yield minimum losses the invention is a transformer phase having suitable magnetic material placed between the windings as shown in the winding cross section in fig1 the magnetic material is used to adjust the impedance the impedance of such a winding can be calculated by where k is an empirical constant depending on the transformer power rating frequency and winding geometry vt is the volts per turn amt is the average mean turn u03b1 is the core opening width u03bc is the relative permeability of the magnetic material b 1 is the magnetic material thickness b 2 is greater than or equal to the high low space a is the average length of a low voltage group and c is the average length of a high voltage group for a standard design b 1 is zero i e no magnetic material is placed in the high low space the magnetic material assembly must be placed at every cross section of the winding but must not represent a complete conducting path around the core this assembly must be properly insulated electrically and may be shielded with conducting materials and connected electrically to the winding to act as a static plate the magnetic material should be laminated or made of small insulated chopped laminations microlaminations to reduce losses and heating in conclusion the invention can be used in core or.