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Control methods and system components
Without outdoor air and exhaust air/
Control
extract air temperature feedforwarding
signal
Y1
– System deviation +
Control
With outdoor temperature
signal
feedforwarding
Y1
– System deviation +
Fig. 15 · Various output signals, e.g. in system code number 4
Parameters
K
Mixed air chamber
P
T
Mixed air chamber
N
T
Mixed air chamber
V
Minimum outdoor air rate
Independent mixed air temperature control
The independent mixed air temperature control is implemented by a PID control algorithm
with adjustable Mixed air temperature set point. The output Y2 is adapted to the dynamics of
the mixed air chamber with the parameters K
and T
Mixed air chamber . The parameter Minimum outdoor air rate guarantees a mini-
V
mum proportion of outdoor air.
The operating action of the control output Y2 can be reversed. The default setting is an out-
door air rate of 0 to 100 % which correspond to a control signal of 0 to 10 V. By activating
the function block Fb22, the operating action is reversed: an outdoor air rate 0 to 100 %
corresponds to 10 to 0 V. On feedforwarding the outdoor temperature, the summer time op-
eration function is taken into account (–> section 6.10.3). By additionally feedforwarding the
exhaust temperature, the automatic reversal of the operating action takes effect.
46
EB 5477 EN
Y2
Y3
Control variable
Y2
Y3
Control variable
Outdoor temperature
WE
0.5
60 sec 1 to 999 sec
– – –
20 %
With outdoor air and exhaust air/extract
Control
air temperature feedforwarding
signal
Y2
Y1
t
> t
A
Ab
Range of values
0.1 to 99.9
– – – to 999 sec
0 to 100 %
Mixed air chamber , T
P
Y3
t
< t
A
Ab
Control variable
Outdoor temperature
Mixed air chamber
N
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