WIKA A2G-85 Mode D'emploi page 11

6. Commissioning, operation
direct connection to a DDC or a monitoring system analogue 0 ... 10 V
outputs are available.
ABCLogic™ - self-calibration feature
GB
The outside levels of CO are generally very low at 400 to 500 ppm.
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Inside buildings people are the major source of CO . When a building
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is unoccupied for 4 to 8 hours, CO levels will tend to drop to outside
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background levels. This is especially the case when the building opera-
tional schedule includes a pre-occupancy purge of fresh air into the
building prior to the start of the day.
ABCLogic™, which stands for "Automatic Background Calibration",
uses the computing power in the sensor's on-board microprocessor
to remember the lowest CO concentration that takes place every
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24 hours. The sensor assumes that this low point is the value of the
outside level. The sensor is also smart enough to discount periodically
elevated display values, which might occur if, for example, a room was
used 24 hours a day. When the sensor has collected 14 days worth
of low concentration values, it performs a statistical analysis to see if
there have been any small changes in the sensor display regarding
background levels that could be attributable to sensor drifts. If the analy-
sis concludes that there is drift, a small correction factor is made to the
sensor calibration to adjust this deviation.
Commissioning of the sensors with ABCLogic™
When CO sensors with ABCLogic™ are installed, they will use the first
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14 days of operation to calibrate themselves to the local background
levels. Each sensor will calibrate itself to its environment over the first
14 days of operation.
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WIKA operating instructions air2guide model A2G-85