Operation - Helios AIR1/KWL-CO2 0-10V Installation And Operating Instructions Manual

Installation and operating instructions
EN
CHAPTER 4

OPERATION

Room sensor AIR1/KWL-CO2 0-10V
The minimum CO2 concentration of outside air in leafy, hardly industrialised areas is
approx. 350 ppm (output voltage = 1.75 V with MR = 0...2000 ppm or 0.7 V with MR =
0...5000 ppm). The gas inter-exchange in the sensor element happens by diffusion. De-
pending on the changes to the concentration and the flow velocity of the air surrounding
the sensor, the reaction of the device to the change of concentration may take place
with a delay.
It is essential to choose an installation location for the device in which the air stream
flows around the sensor. Otherwise the gas exchange may be considerably delayed or
prevented.
4.1 Automatic calibration of the carbon dioxide measurement – (default)
The automatic background logic is a self-calibrating mechanism that is suitable for use in
applications in which the CO2 concentration regularly drops to fresh air level (350 - 400
ppm). This should typically happen attimes during which the rooms are unoccupied. The
sensor reaches its normal accuracy after 24 hours of continuous operation in an environ-
ment which has been exposed to a fresh air supply of 400 ppm CO2. The deviation error
remains minimal with at least 4 cases of sensor exposure to fresh air within 21 days. The
device needs continuous operating cycles of more than 24 hours to operate correctly
4.2 Manual calibration of carbon dioxide measurement
Manual calibration can be carried out independently of the DIP switch position.
Sufficient fresh air (CO2 content ≤ 500 ppm) must be provided before and after the ca-
libration procedure! The calibration procedure is started by pressing the „ZERO" button
(for approx. five seconds). This is signalled via the flashing LED.
Then calibration takes place. During this phase, the LED is continuously active and a 600
second countdown runs. The LED is deactivated after successful calibration.
4.3 Putting in operation
After switching on the device, a self-test and tempering period follows. This procedure
takes 30 - 50 minutes depending on ambient conditions.
Manual calibration can then be performed as an option. Make sure that no harmful
substances influence the calibration process and that the sensor is operated in fresh air.
4.4 Switching point setting
A potential-free changeover contact is available as a switch output.
A switching point between 10 % and 95 % of the measuring range can be selected using
the SET potentiometer.
The 10 % value is added to the fresh air limit of 400 ppm for CO2.
4.5 Offset
Each measuring channel has a separate offset potentiometer for subsequent adjustment
of the measurement.
The adjusting range is ± 10 % of the measuring range.
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