Installing Electrical Connections; Connection Between Sensing Heads Polytron Se Ex Pr M* Dd Or Se Ex Lc M* Dd And Device Rack - Dräger Polytron SE Ex PR M1 DD Gebrauchsanweisung

NOTICE
Certain substances in the atmosphere to be monitored
may impair the sensitivity of the sensors which are in-
stalled in the sensing heads:
a polymerizing substances such as acrylonitrile,
butadiene and styrene,
b corrosive compounds such as halogenated
hydrocarbons (releasing halogens such as bro-
mine, chlorine or fluorine when being oxidized) and
halogen hydride acids as well as acidic gaseous
compounds such as sulphur dioxide and nitrogen
oxides,
c catalyst poisons such as sulphurous and
phosphorous compounds, silicon compounds (es-
pecially silicones), and metal-organic vapours.
The sensors used are based on measuring elements
(pellistors) which are "poison-resistant" (PR) and so
have a longer lifetime than conventional sensors if cat-
alyst poisons occur. However there is still the rule to
decrease the test or calibration intervals if catalyst poi-
sons are expected to occur in the atmosphere being
monitored.
Pay Attention to Ventilation!
Always arrange sensing head in air flow between pos-
sible leak or collection point and possible source of ig-
nition.
Pay Attention to the Density of Gas!
In case of gases, the density of which is lower than that
of air, such as hydrogen, methane or ammonia the
sensing head must be located above a possible leak or
at the highest points at which major concentrations of
gas may be found.
In case of gases and vapours with a density greater
than that of air, the sensing head must be installed be-
neath a possible leak or at the lowest points at which
such gases and vapours may be present.

Installing Electrical Connections

The wiring must conform to the national regulations
(separation of mains, low-voltage and control voltage
circuit).
– All connections are established on terminals at the
rear of the device rack.
– Connect the device rack to a central terminal strip
using flexible cables.
 Protect cables against tensile stress using the tie
bands provided.
 Connect shielding to earth of rack system or panel.
CAUTION
CAUTION
CAUTION
Connection between Sensing Heads
Polytron SE Ex PR M DD or
SE Ex LC M DD and Device Rack
Observe laws and regulations concerning electrical
equipment in potentially explosive atmospheres as
well as the approval conditions!
 With shielded 3-core cable (braided screen,
cover  80%). Outer diameter max. 12 mm.
 Connect shielding as short as possible to earth ter-
minal of rack system or panel.
 By means of the con-
necting cone within
the cable gland the
cable-screen has to
be contacted to the
internal conductive
surface of the enclo-
sure as shown.
Remarks about the cable gland
The cable gland is intended to be used for fixed instal-
lations only and suitable for cable diameters from 7 up
to 12 mm. The thread of the cable gland is M 20 x 1.5
(metric).
NOTICE
Remark concerning sensing head
Polytron SE Ex PR M2 DD and SE Ex LC M2 DD
On the bottom side this housing is equipped with a Ex-
stopping plug which can be removed to exchange it by
the cable gland if the cable shall be inserted from the
bottom side. This exchange needs to be carried out
before mounting / installation.
WARNING
~45 mm
a b
~12 mm
c d
CAUTION
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