Which of the following best describes how integral control works?

Integral control is a crucial concept in control systems, particularly in Proportional-Integral-Derivative (PID) controllers. It functions by accumulating the error over time, which allows the system to adjust not only for the current deviation from the setpoint but also for the historical discrepancies.

Choosing the correct answer emphasizes that integral control considers both the time the error has been present and the magnitude of the deviation from the desired value. This means that if there is a persistent error, integral control will continue to make adjustments until the error is eliminated. This characteristic helps eliminate steady-state errors that might be missed by other control actions that do not consider past errors.

This approach contrasts with methods that adjust based solely on past errors or current changes alone, as those may not adequately address the cumulative effect of prolonged deviation. Additionally, fixing setpoints constantly does not align with how integral control functions, as it requires the system to actively compensate for ongoing deviations rather than remaining static. Thus, the comprehensive view of both time and deviation makes this option the most accurate description of integral control.