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6.3
Connecting the equipotential bonding circuit
Avoiding differences in potential
Differences in potential arise between separated system parts, which in some cases leads to
high equalization currents. This situation may arise if the cable shielding is, for example,
terminated at both ends and grounded at different system parts. Potential differences can be
caused, for example, by different power inputs.
Reduce the differences in potential by laying the equipotential bonding cables in such a way
that the affected electronic components function properly. Observe with the following
guidelines when setting up equipotential bonding:
● The lower the impedance of the equipotential bonding cable, the greater the effectiveness
● When two system parts are connected by means of a shielded signal cable, and their
● Make sure that the equipotential bonding cable cross section is selected to accommodate
● Use equipotential bonding conductors made of copper or galvanized steel. Connect the
● Lay the equipotential bonding cable in such a way that the area between the equipotential
A low-impedance earth connection ensures that interference signals generated by external
power supply cables, signal cables or cables to the peripherals are safely discharged to
earth.
The connection for the equipotential bonding of the device is located at the connection
elements of the computer unit and is identified by the following symbol:
Figure 6-1
SIMATIC HMI IPC577C
Operating Instructions, 10/2010, A5E02368074-02
of the equipotential bonding.
shields are both connected to the ground or protected conductor, the following must be
observed: The impedance of the additional equipotential bonding cable amounts to 10%
of the shield impedance, at the most.
the maximum equalization current.
cables to the ground or protective conductor over a wide area. Protect the ground or
protective conductor from corrosion.
bonding cable and signal cables is as small as possible.
Equipotential bonding
6.3 Connecting the equipotential bonding circuit
Connecting
49
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