Operation of a 3-phase a.c. thyristor-regulator feeding an R or RL or RC balanced load

When a 6 -thyristor a.c. regulator feeds a balanced load characterised by constants R or RL or RC, three distinct operating modes can successively be found when delay angle increases: (a) 3 or 2 conducting rectifiers, (b) 2 conducting rectifiers, (c) 2 or 0 conducting rectifiers. In the paper we define the areas corresponding to these three operating modes.