Control performance monitoring is also a practical way to implement predictive maintenance, since faults in field equipment usually affect control performance. By monitoring control performance, possible problems in field equipment can be detected. Because control loop performance monitoring does not require digital fieldbus or intelligent field devices, it is an attractive approach for existing mills to implement predictive maintenance.
Control performance usually decreases over time because of several reasons, including process changes, process actuator wear, and contamination of sensors. These factors all affect the performance of the process and can be detected by continuous monitoring of control performance.