6.11.7 Controlling the direct expansion evaporator
In all systems with cooling coil, the binary output BA4 can be activated dependent on the
control signal Y3. The control signal Y3 is available parallely with this function.
Function
WE
Configuration
BA4 dependent on Y3
OFF
30 %
10 %
Fb12 = ON,
option:
SEQ
START (activating value) / STOP up to 100 %
STOP (deactivating value) / 0 % up to START
6.11.8 Controlling the chiller
In all systems with cooling coil (not Anl 7), a chiller can be run to overlap, i.e. parallely to
the other system elements operating in sequence. As soon as a low temperature is requested,
the chiller is activated at least for the period determined under
Minimum activated time
(START MIN). The other system elements can be requested parallely to the chiller. An excess
amount of cold air is at first compensated with HRU and heating coil. If the heating coil con-
trol signal Y1 exceeds the value
STOP (deactivation of cooling at Y1 >), the chiller is
switched off at least for the time period determined under
STOP MIN (minimum deactivated
time). When the outdoor temperature is fedforward, the chiller basically is only enabled
when the outdoor temperature is 3 °C higher than the current set point
−
with a cascade con-
trol, 3 °C higher than the current supply air set point. A chiller that is running is deactivated
when Y1 > 0 % observing the
Minimum activation time (START MIN), if the outdoor tempera-
ture is smaller than the set point; with outdoor temperatures higher than the set point de-
pending on the parameter
Deactivate cooling (STOP). The control signal Y3 is not available.
Function
WE
Configuration
Controlling the chiller
OFF
600 sec
600 sec
50 %
Fb12 = ON,
option:
PAr
START MIN (min. activation time)/ 0, 60 to 3600 sec
STOP MIN (min. deactivated time)/ 0, 60 to 3600 sec
STOP (Deactivation of cooling at Y1 >) / 0 to 100 %
EB 5477 EN
65
Control functions