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Siemens Standard application AHU CE1P3977en_02
Building Technologies Functions 01.02.2010
• From fan control:
– Summer compensation [%] (if negative).
– Winter compensation [%] (if negative).
• From humidification:
– Fan compensation [%] (Decrease)
• From air quality control:
– Function inverse [%].
Fan control mode = Direct or DirectVar.
• ∑ comp up > 90% ---> If possible step-up of a stage (see Disable comp).
• ∑ comp up < 10% ---> Remove compensation stage.
• ∑ comp down > 90% ---> Step-down of a stage (Stage 1 is the minimum).
• ∑ comp down < 10% ---> The removed stage is enabled again.
Fan control mode <> Direct or DirectVar.
Calculates maximum compensation (100 % compensation):
Highest stage setpoint + Max forcing – Stage1 Setpoint with fixed minimum
limit at Stage 1 setpoint and maximum limit at Stage max + Max forcing.
∑ comp up 80%
Fan control mode Pressure
TSP steps 3
Stage1 Setpoint 500 Pa
Stage2 Setpoint 800 Pa
Stage3 Setpoint 1000 Pa
Max forcing 200 Pa
Active stage setpoint Stage1, 500 Pa
– Maximum compensation = 1000 + 200 – 500 = 700 [Pa]
– Compensation setpoint = Setpoint stage1 + 80 % of maximum compensation.
= 500 + 700 * 0,8 = 500 + 560 = 1060 [Pa]
– Maximum possible setpoint = Stage3 setpoint + max force.
= 1000 + 200 = 1200 [Pa]
∑ comp down 30%
Fan control mode Pressure
TSP steps 3
Stage1 Setpoint 500 Pa
Stage2 Setpoint 800 Pa
Stage3 Setpoint 1000 Pa
Max forcing 200 Pa
Active stage setpoint Stage2, 800 Pa
– Maximum compensation 1000 Pa + 200 Pa – 500 Pa = 700 Pa.
– Setpoint = Setpoint stage2 - 30 % of maximum compensation.
– = 800 - 700 * 0.3 = 800 - 210 = 590 [Pa]
– Minimum possible setpoint = Stage 1 setpoint = 500 Pa, since the setpoint com-
pensation is limited to this value.
Staged fans
Analog fans
Example 1
Example 2
Basis Document Siemens Climatix Control System
BDCX.100820.01GB
Page 58
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