In terms of a control system, what does an actuator primarily do?

In a control system, the primary function of an actuator is to convert energy into motion, which enables a physical response in the system. Actuators take the control signal provided by the controller and translate it into mechanical action, such as moving a valve, positioning a damper, or driving a motor. This mechanical action directly influences the process variable being controlled, allowing the system to react to the changes in conditions. For example, when the control system determines that a temperature is too high, the actuator may open a cooling valve to allow chilled water to flow, thereby acting to reduce the temperature back to the set point.

While amplifying the signal, measuring variables, and adjusting loop gain are important functions within a control system, they do not define the role of an actuator. Amplification relates to signal processing, measurement pertains to sensors, and loop gain adjustments are generally associated with controllers, making them distinct from the actuator's primary job of converting energy into motion.