2
IE-SNC-T81(2)xx-01
General description
The transmitters are designed for online measurement of carbon dioxide concentration and
temperature of air in a building interiors.
device type
construction type
output
T8148
ambient air
4 – 20
mA
T8248
ambient air
0 - 10
V
Principle of CO
2
concentration measurement is based on Non-Dispersive Infrared Technology
(NDIR). It is maintenance free because of the patented autocalibration feature, compensating for the
effects of aging and therefore a guarantee for outstanding long-term stability. If the device is in
operation permanently, an auto-adjustment will start automatically after 24 hours operation each.
Measured values can be read in „SLOW mode“ (filtered, averaged) or in „FAST mode“ (current
values without averaging). SLOW mode has advantages in applications like climate control because
of filtering short time peaks. As an example exhaled air from an employee passing the sensor could
affect the climate control negatively with a short response time because the control would trigger a
change of the ventilation based on this one-time measurement. On the contrary in „FAST mode“ no
software filter is used for calculating the output value. This fact adds a noise of typ. ±30ppm which
has to be considered in terms of accuracy. Of principle measurement is the measured value of CO
2
concentration depends on the value of air pressure - altitude at the installation site. For this reason, it
is suitable for accurate measurement to set the altitude of the installation site by TSensor software -
see below.
Measured values are displayed on dual line LCD display. The visual indication of CO
2
concentration is provided by three-color LED.
After power up of the device starts internal test. During this time (about 20s) LCD display shows
(----) instead of CO
2
concentration value.
Devices with 4-20 mA outputs can be connected to circuitry by means of galvanically isolated or
galvanically non-isolated current loop. Outputs 0 - 10
V are galvanically non-isolated.
All transmitter setting is performed by means of the PC connected via the optional SP003
communication cable (not included in delivery). Program
TSensor
for transmitter setting is
available to download free
www.cometsystem.cz/products/reg-TSensor
.
Models marked T
xxxx
Z
are non-standard versions of the transmitters. Description is not
included in this manual.
Please read instruction manual before the first device connection.
