... GNDOUTPUTVoltage220/230/240±2%VACFrequencySynchronous with Input Frequency(Utility Mode)/50±0.2%Hz(AC Frequency exceed ... 90%AudibleAlarmBattery DischargeBeeping sound every 4 seconds after utility power failsBeeping sound every second if battery approaches ... to Bypass< 4msTotal Efficiency≥90%IndicatorsLCDVFD/LCD Indicator StatusInput/Output Voltage,Frequency,Output Power,Battery,Utility,Inverter, ...