ATTENTION!
The minimum CO
2
concentration of outdoor air amounts to approx. 350
ppm (output voltage = 1.75
V
at MR = 0...2000 ppm or 0.7 V at MR =
0...5000 ppm) in leafy, hardly industrialised areas. Gas inter-exchange in the sensor element happens by diffusion.
Depending on changes in the
concentration and flow velocity of the air surrounding the sensor, the reaction of the device to changes in CO
2
concentration may appear with a delay.
It is absolutely necessary to choose the device mounting position to ensure that the air stream “presses” into the duct tube. Otherwise, below-
atmospheric pressure will develop in the duct tube that may cause a substantial deceleration of gas exchange of even prevent it.
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 CO
2
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 environment which has been exposed to a fresh air supply of 400 ppm CO
2
. The deviation error remains
minimal with at least 4 cases of sensor exposure to fresh air within 21 days. The device requires continuous operating cycles of longer than
24 hours in order to function properly.
Manual calibration of carbon dioxide measurement
Manual calibration can be carried out regardless of the position of the DIP switch.
Before and during the calibration process, sufficient fresh air (CO
2
content = 500 ppm) must be provided.
The calibration process is started by pressing the “ZERO” button (approx. 5 seconds).
This is signalled by the flashing LED or the countdown timer on the display (
AUTO 0
).
The calibration follows. During this phase, the LED is constantly active and a 600-second countdown runs
on the display
CAL 0
). The LED is deactivated after successful calibration.
Display
The first line shows the
CO
2
measured value
in ppm.
In the second line, the
switching status of the relay
is shown on the left as a circuit
(full
●
= relay energised; empty
○
= relay de-energised)
followed by the
indicator
(
C
for CO
2
)
and the
switchpoint value
is shown on the right.
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.
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 CO
2
.
(600...1900 ppm with MR = 0...2000 ppm or 900...4700 ppm with MR = 0...5000 ppm).
Offset
Subsequent adjustment of the CO
2
measured value can be carried out using
the offset potentiometer. The adjustment range is ± 10 % of the measuring range.
DIP switch
KCO
2
- W
CO
2
content
DIP 1
0...2000 ppm (default)
OFF
0...5000 ppm
O N
CO
2
automatic zero point
DIP 3
deactivated
OFF
activated (default)
O N
Output
DIP 4
Voltage 0 -10 V (default)
OFF
Current 4...20 mA
O N
Note:
DIP 2
is not assigned!
DIP switch
KCO
2
- SD
CO
2
content
DIP 1
0...2000 ppm (default)
OFF
0...5000 ppm
O N
G
Installation and Commissioning
Rev. 2020 - V39
AERASGARD
®
KCO
2
- SD
Duct CO
2
sensors and measuring transducers, Standard
AERASGARD
®
KCO
2
- W
Duct CO
2
sensors and measuring transducers, Premium
Type ⁄ WG02
Measuring Range
CO
2
Output
CO
2
Equipment
Display
Item No.
KCO
2
- SD
(switchable)
(fixed)
IP 54
K C O2- SD -U
0...2000 ppm ⁄ 5000 ppm
0 -10 V
–
1501-3160-1001-200
KCO
2
- W
(switchable)
(switchable)
IP 65
K C O2-W
0...2000 ppm ⁄ 5000 ppm
0 -10 V ⁄ 4...20 mA
changeover contact
1501-3140-7301-200
K C O2-W DISP L AY
0...2000 ppm ⁄ 5000 ppm
0 -10 V ⁄ 4...20 mA
changeover contact, display
■
1501-3140-7321-200
Optional:
Cable connection with
M12 connector
according to DIN EN 61076-2-101 (on request)
Note:
This unit
must not
be used as safety-relevant device!