Siemens simatic PC 577 Operating Instructions Manual page 55

Avoiding differences in potential
Differences in potential arise between separated system parts, which in some cases lead to
high equalization currents. This situation may arise if the cable shielding is 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 the following guidelines
when setting up equipotential bonding:
• When two system parts are connected by means of a shielded signal cable, and their
• Ensure 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
SIMATIC Panel PC 577
Operating Instructions, Release 04/2006, A5E00798484-01
shields are both connected to the ground or protective 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. The equipotential bonding conductor cross-section
that has proven best in practice is 16 mm
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.
5.6 Connecting the equipotential bonding
.
2
Connecting
5-13