What happens when you decrease the percentage of proportional band in a control system?

When the percentage of proportional band in a control system is decreased, the system becomes more sensitive to changes in the process variable. The proportional control strategy works by adjusting the output in relation to the error—the difference between the desired set point and the current process variable.

By reducing the proportional band, which is the range of error over which the controller will respond, the system is now configured to react more sharply to small discrepancies. This means that even minor deviations from the set point will elicit a stronger response. Therefore, a smaller proportional band heightens the system's sensitivity, making it better equipped to maintain the desired level of control by minimizing the error more effectively.

This heightened sensitivity can lead to quicker correction of any deviation from the set point, improving the overall performance of the control system in reacting to disturbances or changes in the conditions.