Integral action is sometimes known as “Reset” or “Automatic Reset” because it automatically compensates for process load variations by biasing the control output when a deviation error occurs. Proportional outputs are biased over time until the error is reduced to zero.
To achieve optimal control, the integral action must be tuned to match the conditions in the application. When tuning a controller, decreasing the integral time constant increases the integral action to remove the error more quickly but if set too short, instability will be introduced into the process.