Siemens RDG100KN Basic Documentation page 69

Synchronization
PWM control
(RDG100KN only)
Note
PWM for thermal
valve actuators
Notes
PWM for electric heaters
Note
DC 0...10 V control
DC 0...10 V
for valve actuators
Note
DC 0...10 V
for electric heaters
Siemens
Building Technologies
adjusted via P44 (Y1 and Y2) or P45 (Y3 and Y4).
The parameters are only displayed if 3-position is selected via DIP switches 4 and
5.
1. When the thermostat is powered up, a closing command for the actuator
running time + 150% is provided to ensure that the actuator fully closes and
synchronizes to the control algorithm.
2. When the thermostat calculates the positions "fully close" or "fully open", the
actuator's running time is extended + 150% to ensure the right actuator
position is synchronized to the control algorithm.
3. After the actuator reaches the position calculated by the thermostat, a waiting
time of 30 seconds is applied to stabilize the outputs.
The demand calculated from the current room temperature and setpoint is provided
via Y1 and Y3 to the valve actuator as a PWM (pulse width modulation) signal for
thermal actuators. The control output is activated for a period proportional to the
heating/cooling demand and then switched off for the rest of the PWM interval.
The actuator running time is 150 seconds (factory setting). It can be adjusted via
P44 (Y1) or P45 (Y3). These parameters are only displayed if On/Off is selected
via DIP switches 4 and 5 and if PWM is selected via P46 and P47.
For a more accurate control temperature with PWM signals, the integral action
time (P35) must be set to 0 (Proportional control).
For thermal valve actuators, set the running time to 240 seconds.
· Never apply PWM to a motorized actuator
· It is impossible to ensure exact parallel running of 2 or more thermal valve
actuators. Motorized actuators with On/Off or 3-position control take
precedence if several fan coil systems are controlled by the same room
thermostat.
For electric heaters, set the running time to 90 seconds.
To avoid burn-off of mechanical contacts by frequent switching, use a current valve
in place of a relay or contactor.
For PWM, the integral action time (P35) must be set to 0.
This function is available with RDG16..KN only.
The demand calculated by PI control from the current room temperature and
setpoint is provided via Y10 and Y20 to the valve actuator as a continuous
DC 0...10 V signal.
Parameter P78 (RDG160KN SW version
when PICV is installed in heating and cooling systems at output Y10. See 3.5.
· The demand calculated by PI control from the current room temperature and
setpoint is provided via Y20 as a continuous DC 0...10 V signal
· The signal converter (SEM61.4) converts the DC 0...10 V signal to AC 24 V
PDM pulses for the current valve
· The current valve (SEA45.1) supplies the electric heater with pulsed current
RDG100KN, RDG160KN, RDG165KN Basic Documentation
2.04) sets the heating flow limitation
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CE1P3191en
2018-07-03