Siemens S5-135U/155U appendix Equipotential Bonding

Installation Guidelines

3.3.2Equipotential Bonding

Between separate sections of an installation, potential differences can develop if

Sprogrammable controllers and I/O devices are connected via a non-floating link, or

Scable shields are connected at both ends and are grounded at different parts of the system.

Different AC supplies, for example, can cause potential differences. These differences must be reduced by installing equipotential bonding conductors to ensure functioning of the electronic components.

The following points must be observed for equipotential bonding:

SThe lower the impedance of the equipotential bonding conductor, the greater is the effectiveness of equipotential bonding.

SWhere shielded signal lines are laid between the relevant sections of the system and connected at both ends to the ground/protective conductor, the impedance of the additional equipotential bonding conductor must not exceed 10 % of the shield impedance.

SThe cross-section of the equipotential bonding conductor must be rated for the maximum circulating current. The following cross-sections of copper have proved to be satisfactory in practice:

±16 mm@ of copper for equipotential bonding conductors of up to 200 m in length

±25 mm@ of copper for equipotential bonding conductors of more than 200 m in length.

SUse copper or zinc-plated steel for equipotential bonding conductors. They must be given a large-area connection to the ground/protective conductor and protect it from corrosion.

SThe equipotential bonding conductor should be laid so that the smallest possible areas are enclosed between the equipotential bonding conductor and signal lines.

Signal Line

Equipotential Bonding Conductor

Figure 3-4 Routing of Equipotential Bonding Conductor and Signal Line

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	C79000-G8576-C199-06