Which type of control system is characterized by manual operation?

The type of control system characterized by manual operation is manual on/off control. In this system, the operator directly influences the process by turning equipment or processes on and off as needed. This can be essential in situations where precise control is not required, and adjustments can be made based on observation or specific conditions.

Manual on/off control is straightforward and relies on human intervention, making it distinct from other control types that typically use automated feedback mechanisms or continuous adjustments based on system variables. Such manual systems might be used in small-scale operations or when the technology to automate the process is unavailable or unnecessary.

Proportional control, ratio control, and feedback control all involve automated systems that use sensors and algorithms to maintain desired operating conditions without requiring direct human control for each adjustment, which differentiates them from manual on/off control.