Honeywell UDC2500 - Manual (Page 118)

Monitoring and Operating the Controller
104 UDC2500 Universal Digital Controller Product Manual 4/07
4.11 Accutune III
Introduction
Accutune III (TUNE) may be used for self-regulating and single integrating processes.
This autotuning method is initiated on-demand, typically at initial start-up.
There are no other requirements necessary, such as prior knowledge to the process
dynamics or initial or post tune process line-out to setpoint or manual output.
Also, the setpoint value is not required to change in order to initiate the tuning process,
but the controller must be in the Automatic mode to start tuning. The process need not be
in a static (lined out) state and may be dynamic (changing with a steady output).
Configuration check
Make sure:
• TUNE has been enabled see to Subsection 3.6 - Accutune Set Up Group for details.
Tuning indicators
“TUNE” will flash in the upper display until tuning is completed.
Operation
The “TUNE” (Accutune II) algorithm provides user-friendly, on-demand tuning in this
controller. No knowledge of the process is required at start-up. The operator simply
initiates the tuning while in the automatic mode.
Once Accutune III has been enabled in the TUNE setup group, either “SLOW” or
“FAST” tuning may be used. Which one is used is selected via the lower display during
normal operation.
For the SLOW selection, the controller calculates conservative tuning constants with the
objective of minimizing overshoot. If the controller determines that the process has
appreciable dead time, it will automatically default to use Dahlin Tuning, which produces
very conservative tuning constants. The SLOW selection may be useful for TPSC
applications, as it reduces any “hunt” problems for the motor.
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 desireable to
enable the FUZZY tune selection. See Section 4.12. 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.
The TUNE 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. “TUNE” flashes in the upper display until tuning is
completed.