Public-supply-system distortion and unbalance from single-phase a.c. traction

A.C. traction loads cause the public supply voltage to be unbalanced on the three phases and distorted in waveform. These effects are potentially harmful, and it is necessary to understand and limit them in the interests of other parties. For this purpose, a method of prediction has been devised using the well known harmonic and phase-sequence components to make the calculation practicable. Although the manipulation of these components for single-phase traction supplies is complicated, prone to error and full of pitfalls, a simple method of calculation is illustrated.