New Automatic Voltage Regulator AVR R438 for Leroy Somer Powered by AREP or PMG filed excitation systerm 0.5% Voltage regulation (1 sec) for 20% voltage Normal Response time Voltage sensing: 95 to 140 volts (50/60 Hz) or 170 to 260 volts (50/60 Hz) or 340 to 520 volts (50/60 Hz)