CAUTION!
Where cables and signal lines for PLC equipment are
installed outside of buildings, the conditions for internal
and external lightning protection must be satisfied.
– Exterior lines should either be installed in metallic
conduit pipes that is grounded on both ends or in
steel-reinforced concrete cable trunks with continu-
ously connected reinforcing.
– Signal lines should be protected against over-
voltage by varistors or by lightning arrester filled
with rare gas.
– Install these protective elements at the location
where the cables enter the building.
Any lightning protection system must be based on an
individual assessment of the entire plant. For questions
please contact VIPA GmbH.
Potential differences can occur between different sections when con-
trollers and peripheral equipment are connected by means of non-iso-
lated connections or the screens of screened cables are connected at
both ends and grounded on different sections of the plant. One
reason for a potential difference can be that different sections of the
plant are powered from different power sources. These potential dif-
ferences must be reduced by means of equipotential bonding conduc-
tors to ensure that the electronic equipment employed on the plant
operates properly.
n
The lower the impedance of the equipotential bonding conductor,
the higher the effectiveness of potential equalization.
n
The impedance of the equipotential bonding conductor must not
exceed 10% of the impedance of the screen where screened
signal lines are connected between the different sections of the
plant and the screening is connected to ground/neutral on both
sides.
n
The cross-sectional area of the equipotential bonding conductor
must be calculated to carry the maximum equalization current.
The following cross-sections have been successfully employed:
– 16mm
2
Cu for equipotential bonding conductors up to 200m
– 25mm
2
Cu equipotential bonding conductors exceeding 200m.
n
Use copper or galvanized steel for equipotential bonding conduc-
tors. These must be connected to ground/neutral by means of
large-surface connections that are protected from corrosion.
n
The equipotential bonding conductor should be installed in such a
manner that it includes the smallest surface between the bonding
conductor and the signal lines.
Lightning protection
Equipotential bonding
Rules for equipotential
bonding
VIPA HMI
Installation guidelines
EMC-equitable cabling
HB160 | PPC | 67K-PNL0 | GB | 16-40
57
