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 con-
duit pipes that is grounded on both ends or in steel-
reinforced concrete cable trunks with continuously con-
nected reinforcing.
– Signal lines should be protected against overvoltage 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 indi-
vidual 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.
Screening is one method commonly used to reduce (attenuate) the
interference pick-up from magnetic, electrical or electromagnetic
fields.
Lightning protection
Equipotential bonding
Rules for equipotential
bonding
Screening of lines and
cables
VIPA HMI Touch Panel
Installation Guidelines
EMC-equitable cabling
HB160 | TP-ECO | 62P-NHC0 | GB | 13-45
47
