Cabling Requirement - Crowcon Xgard IR Instructions D'installation, D'utilisation Et D'entretien

2.Installation
2.2 Mounting
Xgard IR should be installed at the designated location with the sensor pointing down.
This ensures that dust or water will not collect on the sensor and stop gas entering the
cell. The mounting detail is shown in Diagram 2. Care should be taken when installing
the detector to avoid damaging the painted surface and screw threads of the junction
box and sensor retainer.

2.3 Cabling requirement

Cabling to Xgard IR must be in accordance with the recognised standards of the
appropriate authority in the country concerned and meet the electrical requirements
of the detector.
Crowcon recommend the use of steel wire armoured (SWA) cable and suitable explo-
sion proof glands must be used. Alternative cabling techniques, such as steel conduit,
may be acceptable provided appropriate standards are met.
Xgard IR requires a dc supply of 10-30 V, at up to 100 mA. Ensure there is a minimum
of 10 V at the detector, taking into account the voltage drop due to cable resistance. For
example, a nominal dc supply at the control panel of 24 V has a guaranteed minimum
supply of 18 V. The maximum voltage drop is therefore 8 V. Xgard IR can demand up
to 100 mA and so the maximum loop resistance allowed is 80 Ohms.
A 1.5 mm 2 cable will typically allow cable runs up to 3.3 km. Table 1 below shows the
maximum cable distances given typical cable parameters.
C.S.A.
mm 2
1.0
1.5
2.5
Table 1: maximum cable distances for typical cables
The acceptable cross sectional area of cable used is 0.5 to 2.5 mm
table is provided for guidance only, actual cable parameters for each application
should be used to calculate maximum cable distances.
14
Resistance (Ohms per km)
Awg Cable
17 18.1
15 12.1
13 7.4
Max. Distance
Loop
36.2
24.2
14.8
2 (20 to 13awg). The
Xgard IR
(km)
2.2
3.3
5.4