A Ampere Hour (Ah) Automatic Voltage Regulation (AVR) Autonomy Time Auto Restart B Battery Battery Back Up Boost Circuit Buck Circuit C Continuous Power Supply I Inverter L Line Interactive UPS System O Offline UPS System Online UPS System P Pseudo Sine Wave Inverter Pure Power R Rectifier RMS (Root Mean Square) Runtime S Sine Wave Inverter Square Wave Inverter Standby UPS System U Uninterrupted Power Supply Uninterruptible Power Supply UPS System