Glossary · Control theory and process control
Continuous control
Also known as: Continuous process control, Regulatory control
German: Kontinuierliche Regelung
In process automation, continuous control is the control of process variables that are measured and adjusted continuously, typically with closed control loops that keep a steadily running process at its setpoints.
- Control theory
- Process industry
In one sentence
Continuous control keeps continuously measured process variables at their setpoints, usually with closed loops such as PID controllers.
Example
In a water treatment plant, continuous control keeps the chlorine dosing proportional to flow and measured residual chlorine around the clock.
How it applies
- Engineering: Continuous control is the domain of PID controller loops, ratio, cascade and override structures. In digital systems, the loop is executed cyclically, so the cycle time must be short compared with the process dynamics.
- Operation: Operators supervise continuous control through trends and faceplates and intervene by changing setpoints or switching loops to manual.
- Documentation: Describe each loop with its tag, measured variable, manipulated variable, setpoint range and normal mode. A loop list or control narrative is the usual format and should stay aligned with the tags in the HMI.
Continuous control vs. discrete control
Continuous control acts on analog variables such as temperature and flow. Discrete (sequential) control switches states and steps, as in machine sequences. Many plants combine both, for example a sequence that starts a continuously controlled heating phase.