... LED Online UPS, CPU control ,IGBT , High Reliability Comprehensive Self-Protection Design, Audible AlarmHT series online UPS 6-20kVA characteristics:1. True online double conversion technology2. IGBT PFC ... percentage, battery state, utility state, inverter and bypass state, overload, system fault.Audible alarmBypass mode, battery mode, battery low, overload, faultNoise1 ...