What does putting a controller on manual control mean?

When a controller is set to manual control, it signifies that the operator takes direct control of the final control element within a system. This means that instead of the automated control system making adjustments based on feedback from the process variable, the operator actively adjusts the settings or parameters needed to maintain the desired state of the process.

In manual control mode, the operator typically has access to various controls that allow for the fine-tuning of the equipment or process being managed. This direct intervention enables operators to respond to immediate conditions and requirements that may not be accurately captured by an automatic system.

Other options do not fully represent the essence of manual control. For instance, while the output may indeed respond to the process variable under normal circumstances, in manual mode, it is the operator making the adjustments rather than the controller automatically responding. The concept of losing control of the final control element does not align with the principle of manual control, as the operator assumes that role instead. Finally, while an operator may adjust process variables, the key aspect of manual control is the direct engagement with the final control element, rather than just changing signals.