Rectifier transformers are growing in size and complexity due to the increased prevalence of large motor drives. In order to reduce the line harmonics, rectifiers with high pulse numbers are now being used.

In this paper a 3 phase 36 pulse rectifier transformer is to find the extra winding losses produced by high radial flux concentrations between the phase breaks. Non-phase shifting transformers studied produce mostly axial flux in the window except near the ends of the winding. The size and orientation of the copper strands reduce the eddy current losses. In a rectifier transformer the field distribution is much more complex. A finite element analysis of a 3 phase transformer with a single core design using a delta primary and 18 extended delta secondaries was conducted to winding. A discussion of the effects of the harmonics in the waveform is also included. their distribution. We also identify the very large variations in eddy current losses which are necessary to determine the hot spot of the identify the losses.