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Siemens
RDG100.., RDG110.., RDG160T.. Basic Documentation
CE1P3181en
Building Technologies
Functions
2015-07-29
The individual switching points for
ON
of each fan stage can be adjusted via control
parameters P55…P57. The fan speed switch off point is 20% below the switch on
point. The diagrams below show fan speed control for modulating PI control.
Heating/Cooling
1-speed or
3-speed fan
Y
Q3
Q2
Q1
Off
w
Room temperature setpoint
Q
Fan speed
Y
H
Control demand "Heating"
Y
C
Control demand "Cooling"
XpH Proportional band "Heating" (P30)
XpC Proportional band "Cooling" (P31)
X
dz
Dead zone (P33)
Fan speed switching point high (P55)
Fan speed switching point med (P56)
Fan speed switching point low (P57)
The diagram only shows the PI control's proportional part.
On applications with 2-position control:
1) The switching point for low fan speed is synchronized to the heating/cooling
output. Parameter "Switching point fan speed low" P57 is not relevant.
2) The maximum switching range of the fan (XpH
Fan/
XpC
Fan
) is defined by the
switching differential (SDH/SDC) via a look-up table.
Heating/Cooling
1-speed or
3-speed fan
ECM fan
Y
Q3
Q2
Q1
T [°C]
Room temperature
w
Room temperature setpoint
Q
Fan speed
Y
Control command "Valve"
SDH
Switching differential "Heating" (P30)
SDC
Switching differential "Cooling" (P31)
Xdz
Dead zone (P33)
XpH
Fan
Switching range for fan "Heating"
(Table)
XpC
Fan
Switching range for fan "Cooling"
(Table)
Fan 3-speed switching point high (P55)
Fan 3-speed switching point med (P56)
Fan_max Max. ECM fan speed (P55)
Fan_min Min. ECM fan speed (P56)
SDH/SDC
[K]
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
>4.5
XpH
Fan
/XpC
Fan
[K]
2
3
4
5
6
7
8
9
10
3-speed fan control
with modulating
heating/cooling control
(PWM, 3-pos or
DC 0...10 V)
Note
3-speed/ECM fan
control with On/Off
heating/cooling control
Look-up table with
On/Off control