... constants of watt-hour meter; 2, Real-time field measurement three-phase voltage, current, active power, reactive power, phase, power ... , Divided into direct measurement and current clamp measurement, good stability, safety and reliability; 7, Optional 5 A, 20 A, 100 A ... ≤20ppm/HzPulse interface TTL level * 6 Communication interface RS232 Power supplies 1 Line voltage power supply 40 ~ 450 V AC, 10 ...