Omron E5ZE Operation Manual page 71

Manually Setting PID Constants
Derivative Time (D Constant)
Derivative operation is used to quickly return the temperature to its original value by providing a large output value
even if there is radical external disturbance.
Do not set the derivative time to be too long, otherwise a large temperature output value will continue to be output
and the temperature will not be stabilized. At this time, hunting of the temperature, with a cycle shorter than hunting
caused by incorrect proportional band or integral time values, will result.
Adjustment
Adjust the value of the derivative time from the larger value (longer time) to a smaller value (shorter time) to find the
optimum derivative time.
If there is hunting of the temperature with a short cycle, the derivative time may be set too long and the temperature
control response may be too fast.
Output value (%)
Short derivative
time is set.
Fuzzy Constants
Fuzzy constants are normally adjusted automatically. If, however, the results of automatic adjustment are not sat-
isfactory, or the response to external disturbance needs further improvement, the fuzzy constants can be manually
adjusted. The following flowchart shows how to manually adjust fuzzy constants.
Adjust fuzzy scale 2 only when fuzzy strength and fuzzy scale 1 adjustments are unsatisfactory.
68
Long derivative time is set.
Adjustment complete
Temperature
Set point
Time
Check external distur-
bance response
Adjust fuzzy strength and
fuzzy scale 1
Check adjustment
results
Adjust fuzzy scale 2
Appendix C
Short derivative time is set.
Long derivative time is set.
Time