Before you start
How these work
Each exercise puts you in front of a different process with a newly replaced controller sitting on factory defaults. Every one of the ten opens exactly the same way: the same gain, no reset, no rate, and the same acting direction — because that is what comes out of the box, not because it is right for the loop in front of you. Part of commissioning any controller is deciding whether those defaults suit the process at all.
There is no score, no pass mark, and no answer key. You judge the tuning the way a technician does: by watching the trend. Does the measurement get to setpoint promptly? Does it go sailing past and come back, or crawl up and never quite arrive? Does it sit still once it gets there? And when the load changes underneath it, does the loop recover in a way you would be happy to walk away from?
Work through them in order if you can. They build: the first four are variations on the same kind of process, and the later ones are deliberately harder.
Every loop starts balanced at setpoint, which means nothing moves until you disturb it — pressing Start on its own tells you nothing about how the controller is set. Move the setpoint, or change the load, and watch which way the measurement goes.
And do not judge the tuning on a setpoint move alone. Before you call any of these tuned, change the load and confirm the loop brings the measurement back and holds it there. A loop that looks good only when you move the setpoint is not proven.
Each page carries its own tuning ranges, sized for that loop. Do not expect a setting that worked on one exercise to be sensible on the next.
Ten exercises
The library
- 1. Level — inlet fill valve Tank level, inlet fill valve The baseline level loop: a control valve on the inlet, and a load that changes underneath you.
- 2. Level — discharge valve Tank level, discharge control valve The same tank as the first exercise, but the control valve has moved to the outlet.
- 3. Level — VFD pump on the inlet Tank level, variable-speed inlet pump No valve anywhere — the controller output is a speed command to a VFD driving the fill pump.
- 4. Level — large tank, slow valve Large tank level, slow inlet valve The same inlet-valve level loop on much bigger equipment — and therefore a different tuning job.
- 5. Flow — control valve in line Pipeline flow, in-line control valve The fastest loop in the set, on a genuinely noisy measurement.
- 6. Flow — VFD pump, no valve Pipeline flow, variable-speed pump Pump speed sets flow directly — and the disturbance changes the process gain, not just the load.
- 7. Temperature — steam coil, control valve Vessel temperature, steam-heated coil Two thermal lags in series on a clean signal — the loop where rate actually earns its keep.
- 8. Temperature — chilled water cooling coil Vessel temperature, chilled-water cooling coil The slowest loop in the set, where opening the valve makes the measurement go down.
- 9. Temperature — VFD fan, forced air Temperature, variable-speed cooling fan A middle-speed cooling loop — faster than the vessel, slower than the flow loops.
- 10. Temperature — louver / damper Enclosure temperature, cooling louver A loop whose speed changes with the operating point — the hardest one to leave a single set of numbers in.