Siemens RDF600T Basic Documentation

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Siemens RDF300… / RDF340... / RDF400… / RDF600… Basic Documentation CE1P3076.en
Smart Infrastructure 2020-02-21
4.8 Fan control
The fan operates in automatic mode or at the selected speed with manual mode.
In automatic mode, the fan speed depends on the setpoint and the current room
temperature. When the room temperature reaches the setpoint, the control valve
closes and the fan switches off or stays at fan speed 1 (parameter P60)
Factory setting for P60,:
· RDF600... fan Off in dead zone
· RDF3..., RDF4... fan speed1 in dead zone
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 diagram below shows fan speed control for continuous PI
control.
w
XpH
Y
C
[%]
Q
Q3
Q2
Q1
Y
H
[%]
0
0
XpC
100
100
x
dz
w Room temperature setpoint
Q Fan speed
Y
H
Control demand “Heating”
Y
C
Control demand “Cooling”
XpH Proportional band “Heating”
XpC Proportional band “Cooling”
X
dz
Dead zone
Note: The diagram only shows the PI controller’s proportional part.
In applications with on/off control (2-position):
1) The switching point for low fan speed (Q1) is synchronized to the
heating/cooling output. Parameter “Switching point fan speed low” P57 is not
relevant.
2) The maximal switching range of the fan (XpH
Fan/
XpC
Fan
) is defined by the
switching differential (SDH/SDC) via a look-up table.
T[°C] Room temperature
w Room temperature setpoint
Q Fan speed
V Control command “Valve”
SDH Switching differential “Heating”
SDC Switching differential “Cooling”
X
dz
Dead zone
XpH
Fan
Switching range for fan “Heating”
XpC
Fan
Switching range for fan “Cooling”
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
The fan speed controller can control a 3-speed or single-speed fan (selected via
control parameter P53). A single-speed fan is connected to terminal Q1, a 3-speed
fan to terminals Q1, Q2 and Q3.
Fan control with
modulating control
Fan control with
on/off control
Look-up table with
on/off control
3
-
speed/1
-
speed fan

Siemens RDF600T Specifications

General

Brand	Siemens
Model	RDF600T
Category	Thermostat
Language	English