3 - Installation
17
(2) for resistance calculations, the assumed load is 120
Ω
for 4-20 Ma, and a 300
Ω
Zener
blocking diode.
Warning: all wiring should meet the installation standards and should be described in a system
document for SI installations
The cable must have a braided screen to reduce the influence of electrical and
radio-frequency interference. A cable such as
AFNOR M 87-202 01-IT-09-EG-FA
(Nexans) may be used. It shall be selected according to the type of detector and
in accordance with the table shown hereinabove. Below are further examples of
suitable cables:
Non ATEX zone: CNOMO FRN05 VC4V5-F
ATEX zone: GEUELYON (U 1000RHC1)
ATEX zone: GVCSTV RH (U 1000)
ATEX zone: xx-xx-09/15- EG-SF or EG-FA or EG-PF (U 300 compatible with
M87202)
The maximum permissible length will depend on the cross-section of the cable
conductors (see table) and on the minimum supply voltage.
Cable connection
Switch off line power supply
On the central unit:
1. Inhibit any installation alarms to avoid unexpected triggering during operation.
2. In accordance with the manufacturer’s instructions, switch off the power to the
module in order to be connected to the detector.
Cable preparation
The cable shall be taken from the central unit (measurement and automation) to
the point of measurement (see Figure 8). The passage, support, and protection of
the cable shall be according to best practice
Cable passage
It is essential that the instructions provided by the manufacturer of the
compression gland are followed and the braided screen is correctly connected.