Parameters
WE
Range of values
K
P
Mixed air chamber
0.5
0.1 to 99.9
T
N
Mixed air chamber
60 sec 1 to 999 sec
T
V
Mixed air chamber
– – –
– – – to 999 sec
Minimum outdoor air rate
20 %
0 to 100 %
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
P
Mixed air chamber, T
N
Mixed air chamber
and
T
V
Mixed air chamber. The parameter Minimum outdoor air rate guarantees a mini-
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
Control methods and system components
Y1
Y2
Y3
Y1
Y2
Y3
Y1
Y2
Y3
t
A
< t
Ab
t
A
> t
Ab
Fig. 15 · Various output signals, e.g. in system code number 4
Control
signal
Control
signal
Control
signal
Without outdoor air and exhaust air/
extract air temperature feedforwarding
With outdoor temperature
feedforwarding
With outdoor air and exhaust air/extract
air temperature feedforwarding
– System dev
Control variable
– System dev
Outdoor temperature
Control variable
Control variable
Outdoor temperature