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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 se 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 80 % of maximum compensation.
= 500 + 700 * 0,8 = 500 + 560 = 1060 [Pa]
– Maximum possible setpoint = Stage3 se 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
