23V Synchronizing Transformer.
The TX2 synchronizing transformer converts the supply volts to a 23V synchronized output, with inputs to the A2 control assembly shown. A 525V supply is indicated, but this can be any supply level.
The 23V (rms) synchronized supply ensures that the phase lock loop control function is in phase with the mains supply vectors. That is, the vectors in the A2 control and A1 power assembly are in synchronism, such that thyristor conduction angle () determined by the closed loop control is correctly applied to the power side.
Firing of the thyristors (angle ) must be true to the angle determined by the A2
control function.