SX440 is a two phase sensed Automatic Voltage Regulator(AVR) and forms part of the exciation system for a brush-less generator.The AVR senses the voltage in the main generator winding and control the power fed to the exciter stator and hance the main rotor to maintain the generator output voltage within the specified limits, compensating for load sprrd,temperature and power factor of the 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..The AVR has the faclity for droop CT connection,to allow parallel running with other similarly equipped generators.