MX321 is a three phase sensed Automatic Voltage
Regulator and forms part of the excitation system for a
brush-less generator. Excitation power is derived from a
three-phase permanent magnet generator (PMG), to
isolate the AVR control circuits from the effects of nonlinear
loads and to reduce radio frequency interference on
the generator terminals. Sustained generator short circuit
current is another feature of the PMG system.