Electric control valve is an important execution unit industrial in automation controlling process. As higher and higher degree of industrial automation, it’s being used more and more in the field of all kinds of industrial production. Compared with traditional pneumatic control valve, it has obvious advantages: energy-saving (only consume electricity when at work), environmental (no carbon emissions), convenient installation (no need for complicated pneumatic pipe and pump stations). According to its functions and features valve are divided into linear features, percentage and parabolic characteristics.  Working principle Power supply：DC24V,AC220V,AC380V Input control signal ：DC4-20MA，DC1-5V Feedback control signal：DC4-20MA（load (electric) hinder below 500Ω） Automatic regulating function is realized by receiving signals (such as: 4 ~ 20 ma) from industrial automation control system to drive valve ,changing the cross-sectional area of the pipeline between valve core and valve seat ,controlling the flow rate, temperature, pressure and etc of pipeline medium. New type electric control valve’s actuator has servo function, 4-20 ma, accepts unified 4-20mA or 1-5 v DC standard signal, converts current signal to corresponding linear displacement, automatically controls valve opening, achieving continuous adjustment to the fluid’s pressure, flow, temperature, liquid level and other process parameters inside the pipeline. Electrical principle Action principle: motor power 220 VAC or 380 VAC, control signal 4 ~ 20 mA, valve has controller inside, the controller converts current signal to the angular travel signal of the stepper motor, motor rotation, the straight travel or angular travel is realized by gears, levers, or gear lever driving the stem . Feedback: motor operates through the gear running, slide rheostat outputs valve’s position signal by three joints, there are also three lines limit signals (full open and full closed. public line)