Harmonics and Load Balance of Multiphase Rectifiers Considerations in the Selection of the Number of Rectifier Phases

This paper analyzes the operating characteristics of multiphase power rectifiers from the standpoint of harmonics, load balance, and their interrelation, and their effects on the apparatus and circuits to which they may be connected. These factors are considered in connection with selection of the number of rectifier phases, which varies from six (four for very small sizes) to combinations of six-phase units to form a much larger number, such as 36, 72, or even 108 phases. More specifically, the problems of harmonics, load balance, and number of phases are considered from the standpoint of the effects on 1. Apparatus, particularly turbine generators and capacitors. 2. The wave-shape distortion on circuits that may be important in inductive co-ordination. 3. The possibility of resonance being encountered in the supply system to amplify one or more of the rectifier harmonics. These problems have increased greatly because of the great number and large size of rectifier installations made in connection with the war.