Actuators: Valves, Dampers, VFDs

If sensors are a control system's senses, actuators are its muscles: the valves, dampers and drives that turn a controller's decision into a physical change in flow. A loop with perfect sensing and a perfect algorithm still controls badly if its actuator is the wrong type, poorly sized, or mechanically bound. The subtlest and most common of these faults is a valve with the wrong authority, which makes an otherwise sound loop sluggish and unstable. This lesson covers actuator types and the authority concept that governs valve control.