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8.3 Dual Action Heating-Cooling
DRR245 is also suitable also for systems requiring a combined
heating-cooling action.
The command output must be configured as Heating PID
(
=
and with a
greater than 0), and one of the
alarms (
,
or
) must be configured as
.
The command output must be connected to the actuator responsible
for heat, while the alarm will control cooling action.
The parameters to configure for the Heating PID are:
=
Command output type (Heating)
: Heating proportional band
: Integral time of heating and cooling
: Derivative time of heating and cooling
: Heating time cycle
The parameters to configure for the Cooling PID are the following
(example: action associated to alarm1):
=
Alarm1 selection (cooling)
: Proportional band multiplier
: Overlapping/Dead band
: Cooling time cycle
The parameter
(that ranges from 1.00 to 5.00) determines the
proportional band of cooling basing on the formula:
Cooling proportional band =
*
This gives a proportional band for cooling which will be the same as
heating band if
= 1.00, or 5 times greater if
= 5.00.
The integral time and derivative time are the same for both actions.
The parameter
determines the percentage overlapping
between the two actions. For systems in which the heating output and
cooling output must never be simultaneously active a dead band
(
≤
0) must be configured, and vice versa you can configure an
overlapping (
> 0).
