Omron E5ZE, Operation Manual

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38
Operation during Auto-tuning
•
Auto-tuning cannot be executed when the E5ZE operation is stopped or it is
being operated manually.
•
The auto-tuning execution time may be extended depending on the controlled
object. In such a case, the time required for auto-tuning to be completed may
be reduced if the proportional band (P constant) is set to 0.0. The E5ZE goes
into ON/OFF operation with oscillations increasing.
•
If the optimum PID constants have not been obtained for the controlled object,
set them manually.
•
Hunting will occur during auto-tuning. If hunting is undesirable, set the PID
constants manually.
•
The HB and HS alarms will not operate for the control point during auto-tuning.
•
If the power is turned OFF during auto-tuning, the E5ZE will stop auto-tuning.
•
The auto-tuning function will not operate properly if the controlled object (load)
is not connected to the E5ZE.
PID Constants
•
The following table shows the relationship between the PID constants and the
set point responses for the temperature being controlled. Refer to this table
when setting PID constants manually.
PID constant
Set point response
Excessive
value
Oscillation Time
Proportional Larger Decreases Decreases Long
band
Smaller Increases Increases Short
Integral time
Larger Decreases Decreases Long
Smaller Increases Increases Short
Derivative time
Larger Decreases Increases Long
Smaller Increases Decreases Short
Excessive value: Overshooting or undershooting
Oscillation: Hunting
The fuzzy control function is used when there is external disturbance, to sup-
press overshooting or undershooting the temperature being controlled by the
E5ZE and stabilize the set point within a short period.
•
The fuzzy constants are automatically adjusted when the PID constants are
changed.
•
If automatic adjustment of fuzzy constants is unsatisfactory, adjust them
manually referring to the following table.
Fuzzy constant
External disturbance response
Excessive
value
Oscillation Time
Fuzzy strength Large Decreases Increases ---
Small Increases Decreases
Fuzzy scale 1 Large Increases Decreases Long
and fuzzy
scale 2
Small Decreases Increases Short
Fuzzy Constants
Control Adjustments
Section 3-7