Honeywell UDC3500 Product Manual page 222

Monitoring and Operating the Controller
Position Proportional applications, as it reduces "hunt" problems for the motor. This
selection is also recommended for applications that have significant deadtimes.
For the FAST selection, the controller calculates aggressive tuning constants with the
objective of producing quarter-damped response. Depending upon the process, this
selection will usually result in some overshoot. For this reason, it may be desirable to
enable the FUZZY tune selection. See Section 4.11. When Fuzzy tune is enabled, it will
work to suppress or eliminate any overshoot that may occur as a result of the calculated
tuning parameters as the PV approaches the setpoint. This selection is best suited for
processes with a single lag or for those that do not have any appreciable deadtime.
FUZZY tuning does not work well for processes that have appreciable deadtime.
The Accutune III tuning process will cycle the controller's output two full cycles
between the low and high output limits while allowing only a very small Process
Variable change above and below the SP during each cycle. A "T" shows in the upper
display until tuning is completed.
At the end of the tuning process, the controller immediately calculates the tuning
constants and enters them into the Tuning group, and begins PID control with the correct
tuning parameters. This works with any process, including integrating type processes,
and allows retuning at a fixed setpoint.
206 UDC3500 Universal Digital Controller Product Manual 3/07