Electromagnetic Compatibility (EMC)
Installation Manual PSSuniversal
21262-EN-07
12
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Cables of the same group can be laid within the same cable duct.
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Cables from group 1 and group 2 should be laid in separate groups or in cable ducts
which are at least 10 cm apart.
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Cables from group 1 and group 3 should be laid in separate groups or in cable ducts
which are at least 50 cm apart.
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Data and signal lines should be laid as close as possible to an earthed surface.
Cabling to open air systems
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As far as possible use metal conduits. These should be electrically connected and
earthed.
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Ensure there is sufficient protection against lightning by using metal conduits earthed at
both ends, or concrete cable ducts with reinforcements connected across the joints.
3.2.3
Connecting the fieldbuses
Please note:
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SafetyNET p
See System Description PSS 4000
INFORMATION
To connect the available fieldbus systems, please refer to the operating
manual for the respective head module and the guidelines published by the
user group or manufacturer.
3.2.4
Equipotential bonding
Potential differences may occur if the PSSu system and its periphery devices are connec-
ted to different earth connections. Equalising currents can flow through cable shields that
are connected at either end and have different earth connections. These equalising cur-
rents can cause interference or destroy the cable shield. In order to avoid interference,
equipotential bonding cables must be installed. Please note:
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Select a low impedance equipotential bonding cable.
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Select the following as standard values for the cross section of the equipotential bond-
ing cables:
– 16 mm
2
for equipotential bonding cable up to 200 m in length
– 25 mm
2
for equipotential bonding cable over 200 m in length
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If the PSSu system and periphery devices are connected with shielded signal cables
which are earthed at either end, the impedance is calculated as follows:
– Impedance equipotential bonding cable = 10 % of shield impedance
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Use copper or galvanised steel equipotential bonding cable.
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Connect equipotential bonding cables to the earth bar over as wide a surface area as
possible.
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As short a distance as possible should be kept between the equipotential bonding cable
and signal cable.
