... sound every 4 seconds after utility power failsBeeping sound every second if battery approaches final dischargeOverload ProtectionContinuous beepingFaultContinuous ... %IndicatorsLCDVFD/LCD Indicator StatusInput/Output Voltage,Frequency,Output Power,Battery,Utility,Inverter,Overload,Fault,BypassCommunication PortRs232/USBInterfaceMonitor of ... 85.00 Online & Sine Wave Uninterruptible Power Supply(UPS)