Johnson Controls SCD E00-00 Serie Installationsanleitung Seite 2

Build-up of Self-Heating by Electrical Dissipative Power
Temperature sensors with electronic components always have a dissipative power, which affects the temperature
measurement of the ambient air. The dissipation in active temperature sensors shows a linear increase with rising
operating voltage. This dissipative power has to be considered when measuring temperature. In case of a fixed
operating voltage (±0,2 V) this is normally done by adding or reducing a constant offset value. As JCI transducers
work with a variable operating voltage, only one operating voltage can be taken into consideration, for reasons of
production engineering. Transducers 0..10 V / 4..20 mA have a standard setting at an operating voltage of 24 V =.
That means, that at this voltage, the expected measuring error of the output signal will be the least. For other
operating voltages, the offset error will be increased by a changing power loss of the sensor electronics.
Remark: Occurring draft leads to a better carrying-off of dissipative power at the sensor. Thus temporally limited
fluctuations might occur upon temperature measurement.
Application Notice for Humidity Sensors
Refrain from touching the sensitive humidity sensor/element. Touching the sensitive surface will void warranty.
For standard environmental conditions re-calibration is recommended once a year to maintain the specified
accuracy.
When exposed to high ambient temperature and/or high levels of humidity or presence of aggressive gases (i.e.
chlorine, ozone, ammonia) the sensor element may be affected and re-calibration may be required sooner than
specified. Re-calibration and deterioration of the humidity sensor due to environmental conditions are not subject
of the general warranty.
Information about Indoor Air Quality CO2
The EN 16798 defines several categories for indoor air quality:
Category CO content exceeding natural CO2 levels in ppm
2
Typical range
IDA1 <400 ppm
IDA2 400.. 600 ppm
IDA3 600..1.000 ppm
IDA4 >1.000 ppm
Information about Self-Calibration Feature CO2
Virtually all gas sensors are subject to some sort of drift. The degree of drift is partially dependent on the use of
high-quality components and design. However, even with high-quality components and a proper design, a small
amount of drift can still occur in the sensor that may ultimately result in the need to recalibrate a sensor.
The natural drift of the sensor is mainly caused by:
• Dust/dirt • Aggressive chemicals absorbed inside chamber / optical elements • Corrosion inside chamber (high
rh, condensation) • Temperature cycles causing mechanical stress • Electron/hole migration in the photo
detector's semiconductor • Drift of photo amplifiers • External mechanical stress on chamber • Light source
wear-off
Most of the effects listed above are compensated by the automatic self-calibration of the sensor's dual channel
technology. In contrast to ABC-Logic, self-calibrating sensors with dual channel technology are suitable for all
applications including those operating 24 hours, 7 days a week, for example hospitals.
However, some effects cannot be compensated automatically and may result in a very gradual natural drift of a
few ppm per month. This natural drift is not covered by the warranty.
Standard value
350 ppm
500 ppm
800 ppm
1.200 ppm
SCD-xxx-E00-00 Room climate sensor
2
Description
Good indoor air quality
Standard indoor air quality
Moderate indoor air quality
Poor indoor air quality