The difference between a switch-type electric actuator and a regulated electric actuator

If the electric valve can be divided into electric switch valve and electric regulating valve according to the control mode, the main difference is in the  electric actuator, the valve is generally the same, the Electric Actuator is divided into two categories according to the different control modes of switch type (open loop control) and regulation type (closed-loop control). So what are the characteristics and differences between switching Electric Actuators and regulating electric actuators?

1. Switch-type Electric Actuator (open-loop control)
Switching electric actuators generally realize the opening or closing control of the valve, the valve is either in the fully open position or in the fully closed position, such valves do not need to accurately control the flow of the medium, nor can the opening control of the valve. Switching electric actuators can also be divided into split structure and integrated structure due to different structural forms. This must be explained when selecting the model, otherwise it will often occur in the field installation and other mismatch phenomena such as conflicts with the control system. 

a) Split structure (usually called ordinary type): the control unit is separated from the electric actuator, the electric actuator can not realize the control of the valve alone, and the external control unit must be added to achieve the control, and the controller or control cabinet is generally used externally to match. The disadvantage of this structure is that it is not convenient for the overall installation of the system, increases the wiring and installation costs, and is prone to failure, and is not convenient for diagnosis and maintenance when the fault occurs, and the cost performance is not ideal.

b) Integrated structure (usually called integral type): the control unit and the electric actuator are packaged as a whole, and can be operated on the spot without an external control unit, and can be operated remotely by simply outputting relevant control information. The advantages of this structure are that it is convenient for the overall installation of the system, reduces wiring and installation costs, and is easy to diagnose and troubleshoot. However, the traditional integrated structure products also have many imperfections, so the intelligent electric actuator has been produced, and the intelligent electric actuator will be explained later.

The main users of on-off electric actuators are on-off electric ball valves, Electric Butterfly Valves, electric gate valves, electric globe valves, etc

2. Regulating type (closed-loop control) 
Regulating electric actuators not only have the function of an integrated on-off electric actuator, but also can precisely control the valve, control the opening of the valve, and thus accurately adjust the temperature, flow, or pressure of the medium. There are mainly the following forms.

1). Control signal type (current signal, voltage signal)
The control signal of the regulated electric actuator generally has a current signal (4~20mA, 0~10mA) or a voltage signal (0~5V, 1~5V), and the type and parameters of the control signal should be clarified when selecting the type.

2). Working form (electric open type, electric off type) 
The working mode of the regulating electric actuator is generally electric open type (taking 4~20mA control as an example, electric open type means that the 4mA signal corresponds to the valve close, and 20mA corresponds to the valve open), and the other is the electric close type (taking the control of 4-20mA as an example, the electric open type means that the 4mA signal corresponds to the valve open, and the 20mA corresponds to the valve close). 

3). Loss of signal protection 
Loss of signal protection refers to the loss of control signals due to line and other faults, the  electric actuator  will open and close the Control Valve to the set protection value, the common protection value is fully open, fully closed, keep in place three situations, the user generally needs to confirm when selecting, and it is not easy to modify after leaving the factory.