Omron E5ZN - Page 189

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Temperature Control Errors Section 8-4
Overshooting or Undershooting
Hunting
For troubleshooting problems with connections and settings, refer to the same
probable causes and remedies as provided for overshooting and undershoot-
ing.
Operation Controlled object is radiating heat. Execute heating and cooling control.
Controlled object is influenced by large over-
shooting.
Refer to the following table regarding overshoot-
ing and undershooting for appropriate trouble-
shooting.
Probable cause Remedy
Connections PV of the E5ZN is abnormal. Refer to 8-3 Temperature Sensing Errors for
appropriate troubleshooting.
General-purpose temperature sensor with slow
thermal response characteristics is being used to
sense a controlled object with quick thermal
response characteristics.
Change to a sheath-type temperature sensor.
Settings E5ZN has a narrow proportional band and small P
constant.
• Increase the P constant keeping within the
range where the response delay caused by the
P constant can be allowed.
• Execute autotuning.
E5ZN has a short integral time or small I constant. • Increase the I constant keeping within the
range where the response delay caused by the
I constant can be allowed.
• Execute autotuning.
E5ZN has a short derivative time or small D con-
stant.
• Increase the D constant keeping within the
range where the D constant will not have an
undesirable influence on temperature stability.
• Execute autotuning.
E5ZN is executing ON and OFF control. Execute P or PID control.
Control period is too long when the E5ZN controls
the temperature of an object with quick thermal
response characteristics.
Shorten the control period.
Dead band instead of an overlap band is set with
the E5ZN in heating and cooling control opera-
tion.
Set the overlap band of the E5ZN.
Probable cause Remedy
Probable cause Remedy
Operation Heat capacity of a heater controlling the tempera-
ture of an object is too large for the object.
Use a heater with a heat capacity suited to the
object.
Heat capacity of a controlled object changes due
to periodical external disturbances.
Take appropriate measures to prevent the period-
ical external disturbances.
E5ZN is executing autotuning. Hunting will not occur if autotuning is completed.