... Advanced battery management High frequency online UPSKey FeaturesTrue on-line double conversion technology with advanced microprocessor controlWide input ... ± 2%Frequency46~54Hz or 50Hz ± 0.2Hz (Line mode)50Hz ± 0.2Hz ( Battery mode)WaveformSine WaveDistortion3 ... , Utility Power, Inverter, Bypass, Overload, FaultAudible AlarmBypass, On battery mode, Battery low, Overload, FaultAcoustic NoiseAt 1 meter ...