... functionNice interface design, LCD display the UPS operating status.Built in control board design, have on need of any adjustment, ... 60Hz±0.5%(with battery)Output frequencystability<±0.5%(no in phase)Input frequency50Hz±5%Crest factor3:1WaveSine waveOutput waveformdistortionSine wave ... equipment, Securities electric factory ,traffic, industry and so on off-grid solar inverter 3 phase inverter 20KVA