5 Startup
5.1 Design guidelines
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OZD Profi G12D... ATEX 1 V. 03 07/2014
5.1.6 Spatial arrangement of devices and
cables
Reduce interference by distance.
Likewise a simple as well as effective alternative for
reducing interferences is in the spatial separation of
interfering and susceptible devices and cable. Inducti-
ve and capacitive interferences decrease in the qua-
drate of the distance of the involved elements. That
means, doubling the distance reduces the effects of
the interference by factor 4. If layout considerations
right in the planning phase of a building or a control
cabinet can generally be very cost-effective.
Standard recommendations for spatial arrangement of
devices and cables
Recommendations for spatial arrangement of de vices
and cables with the aim of ensuring a possibly low
mutual inter ference, includes EN 50174–2.
5.1.5 Suppression of switched inductors
Switch switched inductors with suppressors
Switching of inductors e.g in relays and fans causes
interference voltages, the amount of which is much
more than the switched operating voltage. These
interference voltages may affect electronic devices.
The interference voltages of inductors must be limited
to the emission source by switching with suppressors
(diodes or RC wiring). Use only interference suppres-
sors, which are intended for the relays or fans used by
you.
Cabinet lighting
Use bulbs for cabinet lighting, e. g. LINESTRA lamps.
Avoid using fluorescent lamps as these lamps create
interference fields. If fluorescent lamps cannot be
used, measures shown in figure 8 must be taken.
Shield grid
over the lamp
Shielded cable
metal-encased
Switch
Mains filter or
shielded mains cable
Fig. 8: Measures against suppression of fluorescent lamps in
the cabinet
5.1.4 Electromagnetic Compatibility (EMC)
The electromagnetic compatibility (EMC) comprises all
queries of the electrical, magnetic and electro magnetic
spinning and spin-off effects.
for avoiding electromagnetic interferences in electrical
systems , these effects must be restricted
to a minimum. Limitation measures mainly in clude
design and pro per connection of bus cables and the
supp ression of switched inductors.
z
Warning!
Interference suppressor must comply with the
ATEX directives in the explosive hazard area.
