The control mode of the electric actuator is generally divided into two types: on/off type (open loop control) and modulating type (closed loop control).
1. On/off type (open loop control)
On/off type electric actuators generally control the opening or closing of the valve. The valve is either in the fully opened position or in the fully closed position. Such valves do not require precise control of the medium flow.
2. Modulating type (closed loop control)
The regulatedmodulating type electric actuator not only has the function of a on/off type integrated structure, but also allows precise control of the valve to precisely adjust the flow of the medium.
a) Type of control signal (current, voltage)
The control signal generally has a current signal (4~20mA, 0~10mA) or a voltage signal (0~5V, 1~5V). The type and parameters of the control signal should be specified when selecting the actuator.
b) Working form (electric opening type, electric closing type)
The working mode of the modulating electric actuator is generally electric opening type (taking 4~20mA control as an example, the electric opening type means that the 4 mA signal corresponds to the valve closing, the 20 mA corresponds to the valve opening), and the other The type is electric closing (for example, the control of 4-20 mA, the electric opening type means that the 4 mA signal corresponds to the valve opening, and the 20 mA corresponds to the valve closing).
c) Lost signal protection
Lost signal protection means that when the control signal is lost due to faults such as lines, the electric actuator will control the valve to open and close to the seted protection value. The common protection values are full opened, full closed, and keep in place. Not easy to modify afterwards.