Three-phase Delta-connected AC Regulator with Balanced Resistive Load
The circuit of a three-phase, delta-connected ac regulator (termed as ac to ac voltage converter) with balanced resistive load is shown in Fig. . It may be noted that the resistance connected in all three phases are equal. Two thyristors connected back to back are used per phase, thus needing a total of six thyristors. As stated earlier, the numbering scheme may be noted. It may be observed that one phase of the balanced circuit is similar to that used for single-phase ac regulator described in the previous lesson (26) of the module. Since the phase current in a balanced three-phase system is only (3/1 ) of the line current, the current rating of the thyristors would be lower than that if the thyristors are placed in the line.