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Appendix C
Manually Setting PID Constants
Refer to the information provided here on the operation of the proportional band (P constant), integral time
(I constant), and derivative time (D constant) when setting the PID constants manually.
Proportional Band (P Constant)
If the proportional band is too wide, overshooting the set point can be suppressed but the startup time will be slow.
If the proportional band is too narrow, the startup time will be quicker but overshooting and hunting for the set point
will result.
An offset from the set point will result in P or PD control operation.
Adjustments
Adjust the width of the proportional band from a large value to a smaller value.
If there is slow temperature hunting, increase the width of the proportional band.
Output value (%)
Temperature
Set point
P: Large
P: Small
Temperature
Set point
P: Small
P: Large
Offset
Time
Integral Time (I Constant)
Integral operation is used to gradually eliminate the offset of the temperature that is caused by proportional control.
Do not set the value of the integral time to too small a value in attempt to quickly eliminate the offset of the tempera-
ture. Doing so will result in hunting of the temperature.
Adjustments
Adjust the value of the integral time from a larger value (longer time) to a smaller value (shorter time) to find the
optimum integral time.
If there is slow temperature hunting or the temperature is stabilized after repeated temperature overshooting, the
integral time of the E5ZE is too short.
Output value (%)
Short integral
time is set.
Long integral time
is set.
Time
Temperature
Short integral time is set.
Long integral time is set.
Set point
Time
