Automatic Voltage Regulation
Automatic Voltage Regulation (AVR) in line interactive UPS systems stabilizes the incoming AC signal to maintain output power at a nominal 120 volts by controlling high and low voltages without resorting to battery power. This significantly increases battery life and lessens the likelihood of data loss, memory freezes, and system crashes.
How AVR Works in a Line Interactive UPS
A line interactive UPS includes an AVR autotransformer a special type of transformer designed to switch between powered coils of wire in response to variances in utility power input, thereby increasing or decreasing the magnetic field and the resulting output voltage to connected equipment.
This type of UPS tolerates undervoltage brownouts and overvoltage surges without consuming backup battery power by automatically selecting different power taps on the AVR autotransformer. During normal operation, incoming AC power bypasses the autotransformer (where voltage highs and lows are controlled) while also charging the battery. When the incoming voltage falls below the AVR range, the UPS switches to battery backup, and the DC-AC inverter circuitry is engaged. Power will continue to be supplied by the battery-inverter circuit until incoming voltage returns to the range manageable by the AVR.