4.1 Installation guidelines
19
4 Setting Up
Version 04 05/2014
4 Setting Up
Interference suppression of switched inductances
䊳
Suppressing switched inductances with fuses:
Switching inductances, e.g. in relays and fans, gene-
rates 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.
䊳
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 fluores-
cent lamps cannot be avoided, the interference
suppression measures shown in Fig. 5 must be
implemented.
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.
4.1 Installation guidelines
Shield grid
over lamp
Shielded cable
Metal-encased
switch
Mains filter or
shielded mains cable
Fig. 5: Interference suppression of fluorescent lamps in cabinet
Arrangement of devices and cables
䊳
Reducing interference by providing adequate
space:
A simple yet effective way of reducing interference is
to separate devices and cables causing interference
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 consideration at the
planning stage, the cost of the necessary interference
suppression measures is generally very low.
䊳
Please note:
Between an OZD Profi 12M … PRO 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 between
the outer edges of the components and in all direc-
tions around an OZD Profi 12M … PRO.
The power supply wires (+24 V DC and 0 V) for the
OZD Profi OZD Profi 12M … PRO must not be laid in
the same cable duct as cables for load circuits.
The wires (+24V DC and 0 V) should be twisted
together.