The circuitry of the R448 Automatic Voltage Regulator (AVR) provides closed loop control of the alternator output voltage by regulating the exciter field current. The primary winding has a voltage in ratio to that of the alternator (characteristic shunt), the next has a voltage in proportion to the stator current (compound characteristic: booster effect). Which is powered by two auxiliary windings which are independent of the voltage equal circuit. The power supply voltage is rectified and filtered before being used by the AVR monitoring transistor. With PMG excitatioin, a permanent magnet generator (PMG) added to the alternator supplies the AVR with voltage which is free of the main alternator winding. This is built-in at the rear of the machine and connected to the R448 AVR, and the ST9 jumper must be disconnected.    

*Quadrature droop adjustment

*AVR Voltage adjustment

*Stability adjustment

*LAM Threshold (underspeed) adjustment

*Excitation ceiling adjustment

*Selection of single phase or three phase*

*voltage sensing

*Selection of normal or rapid response time

*50 Hz or 60 Hz frequency option

*Remote voltage adjustment option

*LAM enable/disable option

*Alternator frame selection

*Excitation system selection

Specificaion

Input voltage: 70-140V AC, (PMG, or auxiliary
winding, single, three phases)
Reaction is measured : 90-480V AC
MAX. output :DC 10A 125V
Function: Built-in low-speed , over excitation
LAM,
REGULATION: +/-0.5%