Line-R, Back-UPS, Back-UPS PRO, Smart-UPS and APC AV.
Cause / Resolution:
AVR is a feature of Line Interactive Topology. With AVR Technology, instead of going to battery during high or low input voltages, the unit will increase (BOOST) or reduce (TRIM) the voltage to a safe operating range. This is achieved by re-routing the input voltage through the internal Automatic Voltage Regulating transformer, all without running off of the internal battery. The main advantage of this is that it helps to prolong the life of the battery and extends the operating range in which the UPS can operate online.