Siemens RDF400 User Manual

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Siemens RDF300…/RDF340.../RDF400… Basic Documentation CE1P3076en
Building Technologies 4BFunctions 28 Aug 2008
The diagram below shows the control sequence for continuous PI control.
Heating mode Cooling mode
XpH
100
0
w
Y [%]
3076D03
T[°C]
Y1
XpC
Y [%]
100
0
w
3076D04
T[°C]
Y1
T[°C] Room temperature XpH Proportional band “Heating”
w Room temperature setpoint XpC Proportional band “Cooling”
Y1 Control command “Valve”
The diagrams only show the PI controller’s proportional part
4.6.2 2-pipe fan coil unit with electrical heater
In 2-pipe applications with electrical heater, the controller controls a valve in
heating/cooling mode with changeover, heating only mode, or cooling only mode
plus auxiliary electrical heater. Cooling only is factory set (P01=1) with enabled
electrical heater (P13).
In cooling mode, the valve receives an OPEN command if the acquired
temperature is above the setpoint. The electrical heater receives an ON command
if the acquired room temperature drops below “setpoint” – “dead zone” (=“setpoint
for electrical heater”) while the electrical heater is enabled (parameter P13).
Note: “Setpoint for electrical heater” is limited by parameter “Maximum heating
setpoint” (P10).
In heating mode, the valve receives an OPEN command if the acquired
temperature is below the setpoint. The electric heater is used as additional heating
source when the heating energy controlled by the valve is insufficient. The
electrical heater receives an ON command, if the temperature is below “setpoint” –
“setpoint differential” (=setpoint for electrical heater).
The electrical heater is active in heating mode only and the control output for the
valve is permanently disabled when manual changeover is selected (P01=2).
Remote enabling/disabling of the electrical heater is possible via digital input X1/X2
for tariff regulations, energy saving etc.
Input X1 or X2 must be commissioned accordingly. See section 4.9 “Multifunctional
input”.
Control se
quence
modulating output
Note
Heating or cooling with
auxiliary heater
Electrical heating,
active in cooling mode
Electrical heating in
heating mode
Electrical heating, and
manual changeover
Digital input “Enable
electrical heater”

Siemens RDF400 Specifications

General

Brand	Siemens
Model	RDF400
Category	Temperature Controller
Language	English