A surge in harmonics and distortion in the South Africa's electric power system has come to the fore in the early phases of integrating renewable energy resources to the national electric grid. Having said that, in this day and age a considerable number of harmonic producing apparatus are present. On the basis of their beneficial effects in efficacy and controllability, harmonic producing apparatus are presumed looking ahead to the realization of the 2030 Integrated Resource Plan (IRP 2030) to increase further. The mushroomed harmonics and distortion may drive inflated winding stray losses and many other transformer aspects covered in this book including maximum loading capacity, De-rating, peculiar temperature rise, stray gassing and Total Ownership Cost.