... coal mines improve continuously the degree of automation, frequency inverters, with its characteristic of energy-saving, efficiency ... AC 660V, AC 1140V;50Hz~60HzVoltage fluctuation: ±15%, frequency fluctuation: ±10%Overload capacity150%Rated current 60s; 200 ... -function 8 ICTRelay output2-way relay outputdisplayDisplay screeenSetting frequency, output frequency, current, power, motor speed, load rate, ...