The Metravi PRO 531 is a comprehensive test instrument carefully developed and specially designed for field test of three phases, multi-functional and intelligent, concise man-machine operation.It is easy to use with large LCD screen display, high resolution, shock-proof shell structure and so on.It can simultaneously measure the 4-channel current (ABC three phase and neutral wire current), 4-channel voltage (ABC three-phase voltage and neutral line voltage to ground), the peak value of current voltage, maximum/minimum value over a period, three-phase imbalance factor, short-time voltage flicker, transformer K factor, active power, reactive power, apparent power, power factor and displacement power factor, active power, reactive power, apparent power, total harmonic distortion and harmonic, etc; Display real-time waveform, harmonic ratio bar charts of current voltage; Dynamically capture instantaneous change of voltage current, monitoring starting current, monitoring the power parameters and generate the alarm list, generate the trend chart for a long time record test data.