Siemens Building Technologies QFA31 Data Sheet
1
858
QFA31…
QFA31..D QFA31… with AQF3100
AQF3150 AQF3153
Symaro™
Room sensors
QFA31…
for relative humidity (high accuracy) and temperature
1858P01
1858P02
1859P02
1859P04
• Operating voltage AC 24 V / DC 13.5...35 V
• Signal output DC 0...10 V / 4…20 mA for relative humidity and temperature
• Very high measuring accuracy across the entire measuring range
• Capacitive humidity measurement
• Function test
• Range of use −40…+70 °C / 0…100 % r. h.
with LCD display
−25…+70 °C / 0…100 % r. h.
Use
The QFA31… is for use in ventilation and air conditioning plants where high accuracy
and short response times for measuring relative humidity are required. The measuring
range covers the entire humidity range of 0…100 %.
Examples:
• Storage and production facilities in the paper, textile, pharmaceutical, food, chemical
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and electronics industry, etc.
• Laboratories
• Hospitals
• Indoor swimming-pools
• Computer and EDP centers
• Greenhouses
• With the AQF3100 accessory for outdoor use
Building Technologies
Type summary
Type
Temperature
Temperature
Humidity
Humidity
Operating
Measured
QFA3100
None
None
0...100 %
active, DC 0...10 V
AC 24 V or
No
QFA3101
None
None
0...100 %
active, 4…20 mA
DC 13,5…35 V
No
QFA3160
0...50 °C / − 40…+70 °C
active, DC 0...10 V
0...100 %
active, DC 0...10 V
AC 24 V or
No
QFA3160D
0...50 °C / − 40…+70 °C
active, DC 0...10 V
0...100 %
active, DC 0...10 V
AC 24 V or
Yes
QFA3171
0...50 °C / − 40…+70 °C
active, 4…20 mA
0...100 %
active, 4…20 mA
DC 13,5…35 V
No
QFA3171D
0...50 °C / − 40…+70 °C
active, 4…20 mA
0...100 %
active, 4…20 mA
DC 13,5…35 V
Yes
0 10 20 30 40
700
400
300
800
900
600
500
100
0
200
Burden [Ohm]
[DC V]
Operating voltage
Admissible
range
Inadmissible
range!
1858D02en
Relative humidity
Temperature
Burden diagram
reference
measuring range
/ − 35...+ 35 °C
/ − 35...+ 35 °C
/ − 35...+ 35 °C
/ − 35...+ 35 °C
Ordering and delivery
Equipment combinations
signal output
measuring range
signal output
voltage
DC 13,5…35 V
DC 13,5…35 V
DC 13,5…35 V
value dis-
play
When ordering, please give name and type reference, e.g.: Room sensor QFA3160
The outdoor mounting kit AQF3100, and the service set AQF3153 listed under “Accessories“ must be ordered as a separate item.
All systems and devices capable of acquiring and handling the sensor’s DC 0...10 V or
4...20 mA output signal.
When using the sensors for minimum or maximum selection, for averaging, or to calculate enthalpy, enthalpy difference, absolute humidity, and dew point, we recommend to
use the SEZ220 signal converter (see Data Sheet N5146).
Technical design
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The sensor acquires the relative humidity in the room or in the outer air, respectively,
via its capacitive sensing element whose capacitance varies as a function of the relative humidity of the ambient air.
An electronic circuit converts the sensor’s signal to a continuous DC 0...10 V or
4…20 mA signal, corresponding to a relative humidity of 0...100 %.
The sensor acquires the temperature in the room or in the outer air, respectively, via its
sensing element whose electrical resistance changes as a function of the temperature.
This variation is converted to an active DC 0…10 V or 4…20 mA output signal, depending on the type of sensor. The output signal corresponds to a selectable temperature
range of 0…50 °C, –35…+35 °C, or −40...+70 °C.
Output signal, terminaI I1 / I2
Mechanical design
1
2 3
1 2 3
Range
5 V
10 V
5 V
0 V
10 V
5 V
0 V
5 V
U1 U2 I1 I2
20 mA
12 mA
4 mA
12 mA
12 mA
20 mA
12 mA
4 mA
°F °C
°F °C
QFA31...D
Measuring range
Test function active
1858Z03en
Display
temperature unit
Room sensor QFA31…
Measured value display
Setting elements
Malfunction
The room sensor consists of a housing, a printed circuit board, connection terminals
and a measuring tip. The two-part housing comprises a base and a screwed removable
cover.
A rubber seal is installed between base and cover in order to satisfy the requirements
of IP 65 degree of protection.
The measuring circuit and the setting element are accommodated on the printed circuit
board inside the cover, the connection terminals in the base. Housing and measuring
tip are screwed together. The measuring tip features a degree of protection of IP40.
The sensing elements are located at the end of the measuring tip, protected by a
screw-on filter cap.
Cable entry is made via the cable entry gland M16 supplied with the sensor, which
screws into the housing.
If the sensor is used outdoors, that opening must be closed off and the prepared hole
on the opposite side of the base knocked out.
The types QFA3160D and QFA3171D provide the measured values on its LCD display.
The following measured values are displayed alternately in intervals of 5 s:
Temperature: in °C or °F
Humidity: in % r. h.
The setting elements are located inside the cover. A setting element consists of 6 pins
and a jumper. It is used for selecting the required temperature measuring range and for
activating the test function. Types with LCD display have a second setting element with
4 pins and a jumper.
The different jumper positions have the following meaning:
• For the active temperature measuring range:
Jumper in the left position (R1) = − 35...+ 35 °C,
Jumper in the middle position (R2) = 0...50 °C (factory setting)
Jumper in the right position (R3) = −40...+70 °C
• For the active test function:
Jumper in the horizontal position: The values available at the signal output are those
given in the table “Test function active“.
• For the measured value display (QFA31…D)
- Jumper vertical in the right position = °C (factory setting)
- Jumper vertical in the left position = °F
• Should the temperature sensor become faulty a voltage of 0 V (4 mA) will be applied
at signal output U2 (I2) after 60 seconds, and the humidity signal at signal output U1
(I1) will reach 10 V (20 mA).
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• Should the humidity sensor become faulty a voltage of 10 V (20 mA) will be applied at
signal output U1 (I1) after 60 seconds, and the temperature signal will remain active.
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