Which of the following is a common cause of control loop instability?

Control loop instability often results from incorrectly adjusted tuning parameters. Tuning parameters, such as gain, integral time, and derivative time, are critical in determining how a control system responds to changes in process variables. When these parameters are set incorrectly, the control loop may react too aggressively or too sluggishly to disturbances, leading to oscillations or divergence from the setpoint. For instance, if the gain is too high, the system may overshoot the desired value, while if it is too low, the system may respond too slowly, both scenarios contributing to instability.

In contrast, increased monitoring frequency tends to enhance the system's response and can help identify issues more effectively without necessarily causing instability. Choosing an improper system location may affect performance but doesn't typically cause instability in the control loop itself. Excessive maintenance efforts generally ensure the system operates as intended; however, if not performed correctly, they could potentially introduce variability but not directly cause inherent instability in the control loop. Hence, the most direct relationship to control loop instability is found in the adjustment of tuning parameters.