... digital, simultaneously8) With full protections (over voltage, over load, over temp, over current, short), long durable years9) ... adjustable 4763Hz (400Hz option)Fix :position switch for 50Hz220V,60Hz110V,60Hz120V settingLoad stability±1%Frequency ... Frequency, LED digitalProtections functionOver voltage, over load, over temperature Short, over current latches output OFF and alarmCooling systemForced ...