Control Loop

A control loop is the complete chain of components that measures a process variable, compares it to a setpoint, and adjusts an actuator to drive the variable toward that target. It typically includes a sensor, controller, and final control element working together to maintain a desired process condition.

Control loops are classified as open-loop, which act without feedback, or closed-loop, which continuously correct based on measured results. A closed loop reads a variable such as flow or temperature, computes the error against the setpoint, and commands a valve or drive to reduce that error. Control loops are the fundamental building block of process automation, allowing plants to hold critical conditions steady despite disturbances, load changes, and equipment variation.

Where this applies

Implementing chilled water supply temperature reset · Adding flue-gas oxygen trim control · Sequencing and allocating load across multiple boilers · Optimising stack damper and furnace draught · Optimising desuperheater control