Equipotential Bonding - Siemens SIMATIC S7-300 Hardware And Installation Manual

Appendix
Equipotential bonding conductor
To reduce potential differences and ensure proper functioning of your electronic
equipment, you must install equipotential bonding conductors.
Note the following points on the use of equipotential bonding conductors:
• The lower the impedance of an equipotential bonding conductor, the more
effective is equipotential bonding.
• When shielded signal cables interconnect two system components and the
shielding is connected on both ends to ground/protective conductors, the
impedance of the additional equipotential bonding conductor must not exceed
10% of the shielding impedance.
• Determine the cross-section of your equipotential bonding conductor on the
basis of the maximum equalizing current that will flow through it. The
equipotential bonding conductor cross-section that has proven best in practice
is 16 mm
• Always use equipotential bonding conductors made of copper or galvanized
steel. Always connect the cables on a large surface to the equipotential
busbar/protective conductor and protect it against corrosion.
• Route your equipotential bonding conductor to minimize the area between the
equipotential bonding conductor and signal lines as far as possible (see the
figure below).
Figure 12-5 Equipotential bonding
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S7-300 Programmable Controller Hardware and Installation
A5E00105492-02