The following are questions and answers posted on the Emerson Exchange 365 Mentoring Discussion website as part of the ISA Mentor program.
DANACA JORDAN’S QUESTION ON TUNING USUALLY INACTIVE LOOPS
I am trying to improve the control of a differential pressure controller (PDIC) that is only turned on when things go wrong on a particular product, so it is only active a couple unplanned hours at a time. Any suggestions for using limited historian or Insight data to improve tuning?
GREG MCMILLAN’S ANSWER
You can estimate the dead time from the time it takes the proportional-integral-derivative controller (PID) process variable (PV) to change direction after a change in PID output direction when the PDIC is active. For a large ...