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Siemens  Standard application AHU  CE1P3977en_02 
Building Technologies  Functions  01.02.2010 
5.4  Fan control 
This section deals with the topics fans, air flows, air pressures and associated con-
trol, such as pressure control. 
 
 
5.4.1  Configuration 
 
The main air control functions are enabled, preconfigured and the inputs/outputs 
are defined in confuration1 and configuration 2 and Configuration I/Os. Exhaustfan 
should be set to “combined” if combined outputs for the supply fan and exhaust are 
wanted, and set to “no” if no exhaust fan. 
Main Index > Configuration > Configuration 1 
Parameter  Range  Function 
TSP steps    Enable possible fan steps. 
  –  1Step  
–  2Steps 
–  3Steps 
–  Single-step fan (only one setpoint). 
–  2-step fan (two setpoints). 
–  3-step fan (three setpoints). 
Fan control mode    Select fan and control type. 
  –  Direct 
–  DirectVar 
–  FixedSpeed 
 
–  Pressure 
 
–  Flow 
 
–  SupplySlv 
 
 
 
 
–  ExhaustSlv 
–  Digitally controlled stepped fans. 
–  Digitally controlled variable speed drives.  
–  Stepped analog controlled variable speed drive with digital re-
lease [%]. 
–  Pressure-controlled plant with modulating controlled variable 
speed drive and digital release [Pa]. 
–  Volume-controlled plant with modulating controlled variable 
speed drive and digital release [l/s].  
–  One digital and analog output each for the variable speed drives 
in pressure-controlled plants where the supply air fan operates 
dependent on the exhaust fan [Pa]/[l/s]. The exhaust fan is 
pressure controlled and the exhaust flow is calculated, the 
supply fan is flow controlled to follow the exhaust flow. 
–  One digital and analog output each for the variable speed drives 
in pressure-controlled plants where the exhaust air fan operates 
dependent on the supply air fan [Pa]/[l/s]. The supply fan is 
pressure controlled and the supply flow is calculated, the 
exhaust fan is flow controlled to follow the supply flow. 
 
Main Index > Configuration > Configuration 2 
Parameter  Range  Function 
Fan steps freq conv    Activation of additional digital outputs depending on the selected 
fan type. Function available only for analog controlled variable 
speed drives (Fan control mode <> Direct or DirectVar). The switch 
does not affect air control and fan behavior. 
  –  1Step 
–  2Steps 
 
–  3Steps 
–  Enable variable speed drive (always active). 
–  Output for optional wiring depending on fan step 2. 
–  Outputs for optional wiring depending on fan step 3. 
Prerequisite 
Enable 
Configuration 
Basis Document Siemens Climatix Control System
BDCX.100820.01GB
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