Carel Sonde DP, User Manual

Page: 43 / 60

ENG
Cod. +030220660 DP Sensors Rel. 2.1 10/09/10 13
4.6
4.6 4.6
4.6 Power supply connection
Power supply connection Power supply connection
Power supply connection
For alternating current power supply
For alternating current power supply For alternating current power supply
For alternating current power supply (12 to 24 Vac), just one transformer can be used, connected to G-G0 on all the sensors with G0 to earth, paying
special care to observe the polarity by connecting together the terminals with the same name, or alternatively using an isolating transformer for each
individual sensor.
For the serial sensors, the type of power supply depends on the model of sensor used:
sensors with optical isolation can be powered with one power supply, G-G0, for all the sensors as well as for the controller. In this case, make sure that
the cable shield on the controller side is connected to EARTH, directly or via the G0-Earth connection on the controller.
Sensors that are NOT isolated: for short distances, these can be powered with one power supply, for distances over 10 m, an isolating transformer may
be required for each sensor.
4.7
4.7 4.7
4.7 Wiring
Wiring Wiring
Wiring
For wiring a shielded multicore cable with 3 to 5 wires, depending on the model.
The maximum cross-section of the wires allowable for the terminals is 1.5 mm
2
. In versions DPP* and DPD*, the maximum inside diameter of the cable
gland is 8 mm.
Serial version with RS485 output
Serial version with RS485 output Serial version with RS485 output
Serial version with RS485 output
For sensors with serial connection, the cable use must have the following characteristics:
−
twisted pair;
−
shielded, preferably with earth wire;
−
size AWG20 (diam. 0.7 to 0.8 mm; area 0.39 to 0.5 mm²) or AWG22 (diam. 0.55 to 0.65 mm; area 0.24 to 0.33 mm²);
−
rated capacitance between the wires <100 pF/m.
An An An Analogue version with 0 to 1 Vdc or alogue version with 0 to 1 Vdc or alogue version with 0 to 1 Vdc or alogue version with 0 to 1 Vdc or ----0.5 to 1Vdc 0.5 to 1Vdc 0.5 to 1Vdc 0.5 to 1Vdc output signal output signal output signal output signal
On the models with active outputs (not NTC res.) configured for voltage signals, the voltage drop over the cables must be kept in mind: the effect of the
drop over 1 mm
2 in cross-section means a variation of 0.015 °C for each metre of cable (0.015 °C m/mm²) in the temperature measurement, and a
variation of 0.015% rH for each metre of cable (0.015% rH m/mm2) in the humidity measurement.
Below is an example that shows the calculation of the variations that cause temperature and humidity errors.
Example: Example: Example: Example:
Cable length Cable length Cable length Cable length Cable cross Cable cross Cable cross Cable cross----section section section section Temperature error Temperature error Temperature error Temperature error Humidity error Humidity error Humidity error Humidity error
30 m 0.5 mm
2
0.9 °C 0.9% rH
30 m 1.5 mm
2
0.3 °C 0.3% rH
To avoid measurement errors due to the supply current, an additional power supply from an external transformer can be used (CAREL transformer
codes TRA12VDE00 or TRA2400001), to be connected as shown in the figure (2’ with transf.). With this configuration the maximum distance is 100 m.
The transformer must not be earthed and can be installed in the panel together with the controller. The connection cable must be multicore with 4 or 5
wires. In this situation, no supply current runs through connection M(G0). In installations with multiple sensors, use a transformer for each sensor to
avoid measurement errors.
Analogue version with
Analogue version with Analogue version with
Analogue version with 4 to 20 mA output signal
4 to 20 mA output signal 4 to 20 mA output signal
4 to 20 mA output signal
For distances over 30 m, the current output should be selected, if the system allows. The maximum installation distance for the current output is 200 m.
In the case of AC power supply, the wires used must have a cross-section of 1.5 mm
2
to reduce noise due to the supply current. Such noise may, in
some cases, cause instability in the measurement, which can be eliminated using a DC power supply or with an additional power supply, as shown in
the figure (2’ with trasf.).