Operating Instructions

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Siemens RXB (KNX) application library RXB Description of functions for FC-10, FC-11, FC-12, FC-13 CM110385en_08
Building Technologies Fan control 2013-06-17
9.3 Description DC 0...10 V fan (RXB39.1)
The fan coil applications with RXB39.1 incorporate continuous automatic fan control
(DC 0…10 V). In addition the fan can be enabled and disabled via a volt-free relay
contact.
Controller
Outputs
RXB39.1
G0 / YC3 DC 0…10 V signal for the fan
Q33 / Q34 Enable relay for the fan
The output characteristic of the fan signal (0…10V) is defined via parameters
P150 and P151.
Output signal YC3
10 V
8 V
2 V
0 V
E.g. 1: Pos. signal min . = 2 V
Pos. signal max. = 8 V
E.g. 2 Pos. signal min . = 8 V
Pos. signal max. = 0 V
Heat demand (from controller)
The relay is activated when the fan speed demand exceeds 4% and it is deactivated
when the demand is 0% (hysteresis). In addition the relay can be enabled and disabled
via parameter P173.
9.3.1 Automatic mode (FNC02 / 03 / 04 only)
Two control strategies are available:
Fan in sequence (fan speed is only increased when an offset to the room
temperature setpoint is exceeded AND the valve is fully open)
Fan in parallel (fan speed parallel to the positioning signal of the valve or el. reheater
when the start demand is exceeded)
The strategy can be selected via parameters P160 and P161:
Parameter
Description
P160
(Valve position for) Fan start heating demand
100%
Control Strategy fan in sequence is active for heating
<100% Control Strategy fan in parallel is active for heating
(Recommended value: 20...40%)
P161
(Valve position for) Fan start cooling demand
100%
Control Strategy fan in sequence is active for cooling
<100% Control Strategy fan in parallel is active for cooling
(Recommended value: 20...40%)
Controller outputs
(fan)
Output characteristic
Fan enable relay
2 strategies