The modulating electric actuator is the main executive part of the automatic control system. It is powered by a three-phase or single-phase AC power supply, receives standard signals (including analog and digital), and converts this signal into a corresponding mechanical displacement or angle to operate the regulating mechanism to complete the automatic adjustment task. The diagram of the modulating electric actuator system is shown in Figure 1. When the modulating electric actuator is in the automatic state, the MCU digital control module on the actuator receives the standard analog signal (4~20mA, DC) from the automatic control system, and compares it with the standard analog signal (4~20mA, DC) from the valve position transmitter on the electric actuator. If the difference between the two is greater than the dead zone set according to user requirements, the MCU digital control module sends a control signal to drive the modulating electric actuator to run in the direction of reducing the deviation between the two, until the deviation between the two is less than or equal to the dead zone set by the electric actuator, the MCU digital control module sends a control signal to stop the electric actuator. When the modulating electric actuator is in the electric manual operation state, the electric actuator can be operated by the internal jog button of the actuator.
