ATR243 - User manual -
23
7.12 Dual Action Heating-Cooling
ATR243 is suitable also for systems requiring a combined heating-cooling action.
Command output must be configured as Heating P.I.D. (
Act.t.
=
HEAT
and with a
P.b.
greater than 0), and one of the alarms (
AL.1
,
AL. 2
or
AL. 3
) must be configured as
cooL.
Command output must be connected to the actuator responsible for heat, while the
alarm will control cooling action.
Parameters to configure for the Heating P.I.D. are:
Act.t.
=
HEAT
Command output type (Heating);
P.b.
: Heating proportional band;
t.i
: Integral time heating and cooling;
t.d.
: Derivative time heating and cooling;
t.c.
: Heating time cycle.
Parameters to configure for the Cooling P.I.D. are the following (ex: action associated to
alarm 1):
AL.1
=
cooL
Alarm 1 selection (Cooling);
P.b.M.
: Proportional band multiplier;
ou.d.b.
: Overlapping / Dead band;
co.t.c.
: Cooling time cycle.
Parameter
p.b.m.
(that ranges from 1.00 to 5.00) determines the proportional band of
cooling basing on the formula:
Cooling proportional band
=
P.b.
x
P.b.M.
This gives a proportional band for cooling which will be the same as heating band if
P.b.M.
= 1.00, or 5 times greater if
P.b.M.
= 5.00.
Integral
and
derivative time
are the same for both actions.
Parameter
ou.d.b.
determines the percentage overlapping between the two actions. For
systems in which the heating and cooling output must never be simultaneously active a
dead band (
ou.d.b.
≤ 0) can be configured, and vice versa an overlapping (
ou.d.b.
> 0).
The following figure shows an example of dual action P.I.D. (heating-cooling) with
t.i.
=
0 and
t.d.
= 0.
1
ACTIVE
ACTIVE
SPV
PV
x
=
COOL
x
=
COOL
x
=
COOL
<
0
=
0
>
0
(
HEAT
)
(
HEAT
)
(
HEAT
)
COMMAND OUTPUT (
HEAT
)
ALARM OUTPUT (
COOL
)
COMMAND OUTPUT (
HEAT
)
ALARM OUTPUT (
COOL
)
COMMAND OUTPUT (
HEAT
)
ALARM OUTPUT (
COOL
)
SPV
PV
ACTIVE
ACTIVE
SPV
PV
ACTIVE
ACTIVE