4 Setting Up
4.5 Installation
20
Version 2.4 04/07
Interference suppression of switched inductances
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Suppressing switched inductances with fuses:
Switching inductances, e.g. in relays and fans,
generates interference voltages which are many
times higher than the switched operating voltage.
These interference voltages can affect electronic
devices.
The interference voltages of inductances must be
limited at their source of emission by means of
fuses (by connecting diodes or RC elements). Only
use interference suppressors which are intended
for the used relays and fans.
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Cabinet lighting:
Use filament lamps (e.g. LINESTRA lamps) for the
cabinet lighting. Do not use fluorescent lamps
because they generate interference fields. If the
use of fluorescent lamps cannot be avoided, the
interference suppression measures shown in Fig. 6
must be implemented.
4.5.1 Installation guidelines
Electromagnetic compatibility (EMC)
Electromagnetic compatibility (EMC) covers all aspects
regarding the effects of radiated and received electrical,
magnetic, and electromagnetic emissions.
In order to prevent interference in electrical systems,
these effects must be reduced to a minimum.
The structural design and correct connection of bus lines
as well as the interference suppression of switched
inductances play a major role in limiting interference.
4.5 Installation
Shield grid
over lamp
Shielded cable
Metal-encased
switch
Mains filter or
shielded mains cable
Fig. 6: Interference suppression of fluorescent lamps in cabinet
Arrangement of devices and cables
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Reducing interference by providing adequate
space:
A simple yet effective way of reducing interference
is to separate devices and cables causing inter-
ference from those affected by interference.
Inductive and capacitive interference injection
decreases by the square of the distance between
the elements concerned. This means that doubling
the distance reduces the interference by a factor of 4.
If the arrangement of the various elements in a
building or in the switch cabinet is taken into con-
sideration at the planning stage, the cost of the
necessary interference suppression measures is
generally very low.
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Please note:
Between an OZD Profi 12M … and a power switching
element (e.g. contactor, relay, temperature regulator,
switch, etc.) a minimum separation of 15 cm is to
be maintained.
This minimum separation is to be measured bet-
ween the outer edges of the components and in all
directions around an OZD Profi 12M ….
The power supply wires (+24 V DC and
) for the
OZD Profi 12M … must not be laid in the same
cable duct as cables for load circuits.
The wires (+24V DC and
) should be twisted
together.
