SENSITRON
A Halma Company
MT4731
SMART3-R
Manual (EN)
P. 21/26
3.1
CONNECTION RELAYS OUTPUTS
To connect relays, see the board layout described in Figure 3. It’s important
to consider these explanations: NC stays for normally closed, NO indicates a
contact normally open and COM is the common contact.
3.2
CONNECTION SERIAL LINE RS485
The connection of SMART3-R to RS485 bus lines should be performed by using a
4-wire cable, 1 pair for the RS485 bus and 1 for the power supply. It is also necessary
that:
I
Wiring between the detectors and the control panel should be made
by using connection cable EIA RS485: 2 core wires with section 0.22 /
0.35 mm2 and shield (twisted pair). Nominal capacity between the wires
<50pF/m, nominal impedance 120 Ω. These features can be found in
BELDEN cable 9842 or similar (data transmission cable in EIA RS485).
II
Using this wiring, the total length of the line should not exceed 1000 m.
III
Detectors are to be wired in daisy chain mode. We recommend avoiding
star or tree mode connection as interference immunity would be reduced.
IV
Make sure that each multi-polar wire includes just one RS485.
V
Make sure that a 120 Ω end line resistor is placed at the beginning and at
the end (on the last detector) of the bus line.
VI
For the detectors’ power supply connection, we recommend using a
2-wire cable with suitable section according to the distance and number of
detectors.
VII
Once the installation has been completed, verify that each detector
reaches at least 12 Vdc.
3.3
CONNECTION ANALOGUE OUTPUT (ONLY IN 12-24 VDC VERSION)
The default configuration provides a 4-20 mA proportional output. Wiring between
the detector and the control panel should be carried out taking into account the
following:
I
Use shielded cables.
II
Wires’ cross section depends on the distance between the control panel
and the detector: for a distance up to m 100 we advise a 3-core wire
with cross section area of 0.75 mm2; for a distance between m 100 and
200 we recommend a 3-core wire with cross section of 1.0 mm2; for a
distance between m 200 and 300 we recommend a 3-core wire with
cross section 1.5 mm2.
III
Should any junctions be necessary on wires, please make sure there is
no interruption on the shield.
VI
Please remember that the shield is to be grounded from the control
panel side only. Also remember never to connect the shield to the
detectors.
V
Ensure the wire connections, either clutching or crimping type, are
properly carried out with terminals that do not oxidise or loosen. We
recommend having them soldered.
VI
The SMART3-R gas detectors can be connected to control panels
available on the market having 4-20mA input signals.
3.4
REMOTE HEAD CONNECTION
The remote head is supplied with the 6-conductor cable already crimped, it
must be connected to the base-board of the SMART 3-R detector. Open the
detector box by unscrewing the 4 screws on the front side and connect the
6-conductor cable to the connector shown in Figure 4. Pass the cable through
the cable gland in the caseunderside.
