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User manual - ATR144- 25

8.9 Dual Action (Heating-Cooling)

ATR144 is suitable also for systems requiring a combined

heating-cooling action.

The command output has to be conﬁgured as PID for Heating

(Par. 19 a c . t .1 = Heat and P. b . 1 greater than 0), and one of the

alarms (A L.1 . F. or A L.5 . F.) has to be conﬁgured as co o L.

The command output must be connected to the actuator

responsible for heating, while the alarm will control cooling

action.

Parameters to be conﬁgured for the heating PID are:

a c . t .1 = Heat Command output action type (Heating);

P. b. 1 or p. b . 2: Heating proportional band;

i . t. 1 or i . t. 2: Integral time of heating and cooling;

d . t. 1 or d . t. 2: Derivative time of heating and cooling;

c. t. 1 or c. t. 2: Heating time cycle.

Parameters to be conﬁgured for the cooling PID related to

regulation loop 1 and alarm 1 are:

A L .1 . F. = co o L. Alarm 1 selection (Cooling);

p.b.m.1: Proportional band multiplier;

o.d.b.1: Overlapping / Dead band;

c. c. t.1: Cooling time cycle.

Par. p.b.m.1 (that renges from 1.00 to 5.00) determines the

proportional band of

cooling action basing on the formula:

Proportional band for cooling action = p. b . 1 x p.b.m.1.

This gives a proportional band for cooling which will be the

same as heating band if p.b.m.1 = 1.00, or 5 times greater if

p.b.m.1 = 5.00.

Integral and derivative time are the same for both actions.

Par. o.d.b.1 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 (o.d.b.1 ≤ 0), must be conﬁgured, vice versa you can

conﬁgure an overlapping (o.d.b.1 > 0).

The following ﬁgure shows an example of dual action PID

(heating-cooling) with i. t. 1 = 0 e d . t. 1 = 0.

Pixsys ATR144 User Manual

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