EN
INSTRUCTION
CTDT2
IN20074 REV. A, 2022-09-23
C
Caauuttiioonn!! Read and understand the instruction before using the product.
C
Caauuttiioonn!! Ensure that the installation complies with local safety
regulations.
C
Caauuttiioonn!! Before installation or maintenance, the power supply should first
be disconnected. Installation or maintenance of this unit should only be
carried out by qualified personnel. The manufacturer is not responsible
for any eventual damage or injury caused by inadequate skills during instal-
lation, or through removal of or deactivation of any security devices.
Function
CTDT2 is a transmitter for measuring carbon dioxide concentration and
temperature.
The transmitter has a probe in the shape of a so-called venturi tube with
two air channels. The CO
2
sensor element is mounted in the housing and
the temperature sensor element is located inside the probe.
The air in the ventilation duct is transported to the CO
2
sensor element
through one half of the probe and then back to the duct through the
other half. The temperature sensor is located inside the probe. (see
Technical Data
Supply voltage
24 V AC ±20 %, 50…60 Hz
15…35 V DC
Power
consumption
2 VA, 15 mA, max. 0.5 A for 0.3 s
Ambient
temperature
-20…+60 °C
Storage
temperature
-20…+60 °C
Ambient humidity
0…95 % RH, non-condensing
Long-term stability
Typ. 20 ppm / year
Protection class
IP65 with probe downwards, otherwise IP20
CO
2
Output signal
0…10 V DC, -1 mA <I
L
<1 mA
4…20 mA, R
L
<500 Ω
Measurement
principle
NDIR (Non-Dispersive Infrared Technology)
Measuring range
0...2000 ppm
Accuracy (at 25 °C)
< ± (50 ppm + 2 % of the measured value)
Time constant (re-
sponse time)
< 100 s at 3 m/s air speed in the duct
Temperature
dependance
Typ. 1 ppm CO
2
/ °K (-20...+45 °C)
Warm-up time
< 5 min
Temperature
Output signal
0…10 V DC, -1 mA <I
L
<1 mA
Working range
0-10 V: 0…50 °C
PT1000: -20…+60 °C
Accuracy (at 20°C)
±0.3 °C
Time constant (re-
sponse time)
< 50 s
Installation
Mount CTDT2 at a place in the duct where it can be expected to give a
representative reading. It should be placed at least 4 duct diameters from
a bend or other obstacle, e.g. a damper, for minimal turbulence.
1. Unscrew the spring loaded screws to open the cover and access the
terminals.
2. Place the transmitter in the air flow direction of the ventilation duct
according to the marks on the cover. The air flow direction is either
from right to left (as in
) or from left to right. The hole in the
duct should measure 13 mm in diameter.
3. Connect the wires to the terminals according to the wiring diagram.
4. Screw the cover back on and ensure that it is properly fastened and
that the cable gland makes a tight seal around the cable.
Sensor element,
CO₂
Air flow direc#on
Sensor element,
temperature
Figure 1 The airflow direction is either from right to left (as in the example) or from
left to right
Wiring
1
Supply voltage 24 V AC or 15…35 V DC
2
System neutral
3
Signal neutral
4
CO
2
output 0…10 V DC or 4…20 mA
5
Temperature output 0…10 V DC
6
Temperature output PT1000
7
Temperature output PT1000
N
No
ottee!! System neutral and signal neutral are internally connected.
CTDT2
1 (6)
