User Manual
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Siemens Building Technologies Room sensor QFA65.1 CM1N1850E
HVAC Products 14.07.2003
Mode of operation
The sensor acquires the relative humidity with the help of a capacitive humidity sensor
whose electrical capacity changes in function of the relative humidity of the ambient air.
An electronic circuit converts the sensor's signal into a continuous DC 0...10 V signal,
which represents 0...100 % relative humidity.
The sensor acquires the temperature with a nickel sensing element (LG-Ni 1000)
whose electrical resistance changes in function of the temperature of the ambient air.
Mechanical design
The room sensor has been designed for wall mounting. It is suitable for use with most
commercially available recessed conduit boxes. The cables can be introduced from the
rear (concealed wiring) or from below or above (surface-run wires) through knockout
openings.
All terminals are protected against false wiring.
The unit consists of two major sections: Casing and baseplate. Both snap together but
can be detached again. The casing accommodates the temperature and humidity
sensing elements. The baseplate carries the connecting terminals.
Engineering notes
The transformer used must be suitable for safety extra low voltage (SELV). It must
have separate windings and be suited for 100 % duty.
The transformer must be sized and fused in compliance with local safety regulations.
When sizing the transformer, the power consumption of the QFA65.1 must be taken
into account.
For the connection of the sensor, refer to the data sheets of the units with which the
sensor is used. The maximum permissible line lengths should be observed.
• UNIGYR
®
/VISONIK
®
The humidity sensor must be connected to a measured value input (U...) of the
measured value module (PTM1.2U10)
The temperature sensor must be connected to a measured value input (B...) of the
measured value module (PTM1.2K1K or PTM1.4R1K).
Fitting notes
Location:
On an inner wall of the space to be air conditioned. Not in recesseds, shelves, not
behind curtains, not opposite or near heat sources.
The unit must not be exposed to spot lights or direct solar radiation.
The end of the conduit at the sensor must be sealed to prevent false measurements
due to draughts through the conduit.
Installation instructions are printed on the packing.
Relative humidity
Temperature