... ~54Hz or 50Hz ± 0.2Hz (Line mode)50Hz ± 0.2Hz ( Battery mode)Voltage stabilityWithin 1%(static load)Crest factor3:1Wave distortionLinear ... interfaceEfficiencyabove87%(full load)ProtectionOutput short circuit, Overload, Output low voltage, Battery low voltage, Over-temperature, etc communicationRS232(Standard),USB and SNMP ...