What does "proportional band" indicate in control systems?

Proportional band measures the range of error values throughout which the control output is directly proportional to the input error. In a control system, the proportional band defines a specific range over which the controller will react to deviations from a setpoint. For example, if the proportional band is set to a narrower range, the system will respond more aggressively to changes and will work to bring the process variable back to the setpoint more quickly. Conversely, a wider proportional band results in a more gradual response.

This concept is integral to understanding how a proportional controller functions. It is crucial for maintaining control over a process while minimizing oscillations and overshoot. Essentially, the proportional band helps determine how sensitive the control system is to errors, influencing the overall stability and performance of the system.