Download E5CN/E5AN/E5EN/E5GN Digital Temperature Controllers

Section 4-4
Executing Heating/Cooling Control
Dead Band
• For heating/cooling control, the dead band is set with the set point as its
center. The dead band width is the set value of the Dead Band parameter
(adjustment level). Setting a negative value produces an overlapping
band.
• If an overlapping band is set, the bumpless function may not operate
when switching between manual operation and automatic operation.
• The default is 0.0 EU for Controllers with Thermocouple/Resistance Thermometer Universal Inputs and 0.00% FS for Controllers with Analog
Inputs.
Dead band: Dead band
width = A positive value
Output
Heating
side
Heating
side
Cooling
side
PV
0
Set point
Cooling Coefficient
Overlapping dead band: Dead
band width = A negative value
Output
Cooling
side
PV
0
Set point
If the heating characteristics and cooling characteristics of the control object
are very different and good control characteristics cannot be achieved with the
same PID constants, the cooling coefficient can be used to adjust the proportional band (P) for the control output assigned to the cooling side. Use this to
achieve balanced control between the heating side and cooling side. The proportional bands (P) for the control outputs assigned to the heating/cooling
sides can be calculated using the following equations.
P for control output assigned to heating side = P
P for control output assigned to cooling side = P for control output assigned to
heating side × cooling coefficient
The cooling coefficient is multiplied by the P for the control output assigned to
the heating side to obtain control with characteristics that differ from those of
the control output assigned to the heating side.
Output
Output
P for control output
assigned to heatP for control output
ing side × 1.0
assigned to heating side × 1.0
P for control output
P for control output
P for control output
P for control output
assigned to heating side
assigned to heating side
assigned to cooling side
assigned to cooling side
PV
PV
0
0
Set point
Set point
P for control output assigned to
P for control output assigned to
heating side × 1.5
heating side × 0.8
Automatic Cooling
Coefficient Adjustment
By executing AT during heating/cooling control, the cooling coefficient can be
automatically calculated along with the PID parameters.
Parameter name
Automatic Cooling
Coefficient Adjustment
Note
Setting rage
OFF: Disabled, ON: Enabled
Default
OFF
If there is strong non-linear gain for the cooling characteristics, such as when
cooling water boils for cooling control, it may not be possible to obtain the optimum cooling coefficient at the Controller, and control may take the form of
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