... 4.pure sine waveform 5.OEM service offered Feature:*IGBT/SPWM,small volume,lower noise,high reliability*double ... isolation of the input and output ,safe and reliable*output the pure sine wave,low ... state )Altitude:1500mprotection:Overcurrent, overvoltage, overheat,overload protection and automatic warning devicescooling system:Forced fan cooling 3KVA 400HZ frequency ...