Pulsafeeder MPC Vector - Manual (Page 69)

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Once you see the oscillation, back the integral gain down by 0.05 – 0.1. Start the pump again and make sure
that the flow rate does not overshoot the setpoint significantly.
Note: you may want to use a stopwatch to time how long it takes to get to 80% of the setpoint, especially if you are
using the Pulsaguard pump protection. Pulsaguard will stop the pump if the minimum flow is not reached within the
timeout limit. In any case the pump should be able to get to at least 90% of the given flow setpoint within 25 seconds.
Step 5 – Tune the derivative gain
The derivative gain is not required under all circumstances. In many cases, a PI controller alone is sufficient to
control the pump flow. If derivative gain is added, start with a low setting (0.05 or so) and keep adjusting in
0.05 increments until desired settling time is met.
21.5 Troubleshooting
My flow rate is never reached. How can I fix it?
If the flow rate is never reached you have what is called an over-damped system. Try increasing the Integral
gain to help pull the setpoint up higher. Also, make sure your flow rates and units match. If you are trying to
set a flow higher than the pump can provide, you’ll never reach it!
My flow goes past the setpoint and back below again and oscillates a long time. How can I fix it?
Some oscillation is natural in many PID controlled systems. To minimize it you need to decrease the
Proportional and/or Integral gains to slow the system down a bit.