Siemens RDG200KN Basic Documentation page 79

Electric heater control
signal (On/Off)
Note
3-position
control signal
(RDG200KN only)
Synchronization
PWM control
(RDG200KN only)
Note
PWM for valve actuators
(RDG200KN)
Note
PWM for electric heaters
(RDG200KN)
A6V11545892_en--_a
The electric heater receives an On command via the auxiliary heating control
output (RDG260KN: Q2, RDG200KN: Y2 or Y3, see Mounting Instructions [➙ 5] [1]
& [2]), if
1. The acquired room temperature is below the "Setpoint for electric heater",
2. The electric heater is switched off for at least 1 minute.
The Off command for the electric heater is output, if
1. The acquired room temperature is above the setpoint (electric heater),
2. The electric heater is switched on for at least 1 minute.
CAUTION! A safety limit thermostat (to prevent overtemperature) must be
provided externally.
The electric heater can be controlled via the On/Off control output (RDG260KN:
Q2, RDG200KN: Y2 or Y3) by setting P203 or P204 to 4. For adaptive temperature
compensation (P217: RDG260KN): see 2-pipe fan coil unit with electric heater
[➙ 60], 4-pipe fan coil unit with electric heater [➙ 69].
Heating: Output Y1 provides the Open command, and Y3 the Close command to
the 3-position actuator. Cooling: Same with Y2 and Y4.
The factory setting for the actuator run time is 150 seconds. It can be adjusted via
P214 (Y1 and Y3) or P215 (Y2 and Y4).
The parameters are displayed only, if 3-position is selected via DIP switches 7 and
8.
1. When the thermostat is powered up, a close command for the actuator run time
by + 150 % is issued to ensure the actuator closes fully and synchronizes to
the control algorithm.
2. When the thermostat calculates the positions "fully close" or "fully open", the
actuator run time is extended by + 150 % to ensure the correct 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 supplied
via Y1, Y2 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 PWM algorithm cycle time is 1200 seconds (factory setting). It can be adjusted
via P206 (Y1), P207 (Y2) or P208 (Y3). These parameters are only displayed if
PWM is selected via DIP switches 7 and 8 and if PWM is selected via P201, P203,
P204.
● For a more accurate control temperature with PWM signals, the integral action
time (P057 and P058) must be set to 0 (Proportional control).
● For P-band (P050, P052, P054), see Control sequences [➙ 56].
For thermal valve actuators (STA, STP), set the PWM algorithm cycle (P206, P207,
P208) to 1200 seconds. Proposed setting range for optimization: 900 to 1800
seconds.
● 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.
To control electrical equipment, we recommend using a suitable external switching
element to switch the maximum current.
If output Y2 controls external mechanical relays, the optimal run time (P207)
depends on the technical characteristics of the equipment.
Functions
4
Control outputs
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