S+S Regeltechnik AERASGARD ACO2 Notice D'instruction page 7

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Mounting and Installation
ATTENTION!
The minimum CO concentration of outdoor air amounts to ca. 350 ppm (output voltage = 1.75 V) in leafy, hardly industrialized areas. A sensor
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self-test is initiated by above-atmospheric or below-atmospheric pressure or by exposure of the sensor to more than 5000 ppm CO
voltage (CO output) amounts to ca. 0.2 Volt during the self-test. Gas inter-exchange in the sensor element happens by diffusion. Depending on
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changes in the CO concentration and flow velocity of the air surrounding the sensor, the reaction of the device to changes in CO
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appear with a delay. It is absolutely necessary to choose the device mounting position so that the air stream "presses" into the duct tube. Otherwise,
below-atmospheric pressure will develop in the duct tube that may cause a substantial slow down of gas exchange or even prevent it.
Automatic calibration of carbon dioxide measurement (default)
The device calibrates itself at an interval of 7 days. To ensure this function, the device needs to be supplied with fresh air (CO
400 ppm) at least for 10 minutes during each 7-day period. For self-calibration, the devices memorises device-internally the CO
value measured during a 7-day period. After 7 days, this minimum value is standardised to 350 ppm CO
ingly. The maximum amount of correction is here limited to 40 ppm ⁄ interval.
Manual calibration of carbon dioxide measurement
Manual calibration can be started independently from the position of jumper J3 by pushing the button. After connecting the device, a period of at
least 10 minutes of continuous operation of the device at fresh air (CO
the output signal to 1.75 V (350 ppm = zero-point) is started by pressing the button "Manual calibration CO
calibration is indicated by a blinking LED. Setting the output to 1.75 V at actual ambient conditions follows automatically thereafter. During this phase,
the LED is permanently activated. After calibration is completed, the LED is deactivated.
Putting in operation
After switching on the device, a self-test and tempering period follows. This procedure takes 3 to 5 minutes, depending on ambient conditions. During
this time, the output analog voltage differs from the actual measured value.
SUPPLY VOLTAGE:
For operating voltage reverse polarity protection, a one-way rectifier or
reverse polarity protection diode is integrated in this device variant.
This internal one-way rectifier also allows operating 0 – 10 V devices on
AC supply voltage.
The output signal is to be tapped by a measuring instrument. Output
voltage is measured her against zero potential (O V) of the input voltage!
When this device is operated on DC supply voltage, the operating volt-
age input UB+ is to be used for 15...36 V DC supply and UB – or GND for
ground wire!
When several devices are supplied by one 24 V AC voltage supply, it is
to be ensured that all "positive" operating voltage input terminals (+) of
the field devices are connected with each other and all "negative" opera-
ting voltage input terminals (–) (= reference potential) are connected
together (in-phase connection of field devices). All outputs of field de-
vices must be referenced to the same potential!
In case of reversed polarity at one field device, a supply voltage short-
circuit would be caused by that device. The consequential short-circuit
current flowing through this field device may cause damage to it.
Therefore, pay attention to correct wiring!
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content 300 ppm ... 400 ppm) is to be ensured. Manual calibration of
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Connecting scheme
Power supply
AC 24V~ 0V
DC 15-36V = GND
Connecting scheme
Power supply
AC 24V~ 0V
DC 15-36V = GND
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concentration may
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content 300 ppm...
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content minimum
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and the output signal is corrected accord-
" (for ca. 5 seconds). Preparing for
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Individual operation
Circuitry
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Parallel operation
Circuitry Circuitry
. The output