Omron E5CN User Manual page 110

Executing Heating/Cooling Control
Dead Band
Output
Heating
side
0
Set point
Cooling Coefficient
Output
P for control output
assigned to heating side
0
P for control output assigned to
heating side × 0.8
Automatic Cooling
Coefficient Adjustment
Note
• 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 Ther-
mometer Universal Inputs and 0.00% FS for Controllers with Analog
Inputs.
Dead band: Dead band
width = A positive value
Cooling
side
PV
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 propor-
tional 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 pro-
portional 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.
P for control output
assigned to heat-
ing side × 1.0
P for control output
assigned to cooling side
PV
Set point
By executing AT during heating/cooling control, the cooling coefficient can be
automatically calculated along with the PID parameters.
Parameter name
Automatic Cooling
Coefficient Adjust-
ment
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 opti-
mum cooling coefficient at the Controller, and control may take the form of
Overlapping dead band: Dead
Output
band width = A negative value
Heating Cooling
side side
0
Set point
Output
P for control output
assigned to heat-
ing side × 1.0
P for control output
assigned to heating side
0
P for control output assigned to
heating side × 1.5
Setting rage
OFF: Disabled, ON: Enabled
Section 4-4
PV
P for control output
assigned to cooling side
PV
Default
OFF
85