Pixsys ATR 121, User Manual

Page: 19 / 41

User manual - ATR121/141 -
19
9.6 Dual action Heating-cooling
The ATR121/141 is suitable also for systems requiring a
combined heating-cooling action. Command output must be
configured as Heating PID (par.11
reG.
=
Hea
|
Hea t
and par. 15
p. b.
greater than 0), and one of the alarm must be configured as
cooling action (par. 19
AL.
=
co o
|
co oL
. Command output must
be connected to the actuator responsible for heating action
while the alarm output will control cooling action.
• Parameters to configure for the Heating PID are:
reG.
=
Hea
|
Hea t
Command output type (Heating)
p. b.
: Heating proportional band
t.i.
: Integral time of heating and cooling
t. d.
: Derivative time of heating and cooling
t. c.
: Heating time cycle
• Parameters to configure for the Cooling PID are:
AL.
=
co o
|
co oL
. Alarm selection as cooling
p. b. m
: Proportional band multiplier
o u. d
|
o u. d. b.
: Overlapping/Dead band
t. c.2
: Cycle time for cooling output
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.
*
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 time and derivative time are the same for both actions.
Parameter
o u. d
|
o u. d. b.
determines the overlapping
percentage between the two actions. For systems in which
the heating and cooling output must never be simultaneously
active a dead band (
o u. d
|
o u. d. b.
≤ 0), can be configured, and
viceversa an overlapping (
o u. d
|
o u. d. b.
> 0):