PROCESS CONTROL ACTUATOR

PROCESS ACTUATOR

Actuators are devices that are directly connected to control device in the field to achieve control actions. It may be coil, lamp, relay, vibrator, solenoid valves, cylinders, electric motor, pump, and so on. Another name for output devices is ACTUATOR. They are powered with any of this form of energies electrical, pneumatic and or hydraulic energy.

Some actuator performs action without given feedback to elements controlling them while some gives feedback about their current position or status of mechanism they are attached to. Some actuators make use of digital output signal to perform operations while some uses analogue signals to perform operation. Some makes use of only one source of energy to initiate control actions while some combines two sources of energy to initiate control actions such as pneumatic and electric power as in the case of pneumatic components

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Some actuator can convert mechanical rotational motion to linear motion or vice versa while some only provide mechanical displacement.

In SCADA system, it is important to know the state of field devices during operation under monitoring in order to ascertain that intended action is performed. In this case, as earlier mentioned, feedback devices such as reel switch, sensors, encoders or lamp are attached to the field driven devices in order to see reactions from the input devices during operations.

Process control actuators are the final element in a control system. They receive a low power command signal and energy input to amplify the command signal as appropriate to produce the required output. What this means is that for instance, 24V is connected to a 5W solenoid coil attached to a valve actuating a cylinder (hydraulic operating) lifting 200KG platform compressing waste piled up by earthmover into a silo.  

There are numerous applications of actuator ranges from low power switches to high power hydraulic devices, operating flaps control surfaces of aircraft, valves, car steering, process plant automation field displacement devices and more