Equipotential Bonding System - Siemens 6GK1 901-1GB01 System Manual

3.3.6.1

Equipotential bonding system

Aims of equipotential bonding
The noise immunity of extended electronic automation systems or, in general, information
technology systems largely depends on the suitable design of the grounding and
equipotential bonding system of the building.
Equipotential bonding and grounding have two essential aims:
● Protection from the dangers of electricity
● Improvement of electromagnetic compatibility
Causes of potential differences
Wherever electric currents flow, magnetic fields are produced that in turn induce stray
currents in electrically conductive materials. Induced stray currents can therefore not be
avoided in the vicinity of electrical consumers (drives, electronic controls, lighting etc.) and
their power supply cables. They spread in all conductor loops. Conductor loops are formed
by parts of buildings such as metal banisters on staircases, water pipes or central heating
pipes as well as through the shields of electrical data cables and the protective ground
connectors of electrical devices (PE). The flow of current produces a voltage drop. This can
be measured as a potential difference between two locations within the system.
Extremely high potential differences between two grounding points result from lightning
strikes.
Effects of potential differences in information technology systems
If locations with different grounding potential are connected via cables, currents will flow. The
currents flow on all connections between these two points, for example also on the signal
cables or cable shields connecting them. Attached devices can be disturbed or even
destroyed.
The aim of a grounding and equipotential bonding system is to ensure that the currents flow
in the grounding system and not in the electronic circuits.
Passive network components
System Manual, 02/2013, C79000-G8976-C282-01
3.3 Guidelines for setting up networked automation systems in buildings
– by limiting the contact voltage and creating a fault to ground path
– by creating a reference potential and equalizing potential differences between parts of
the system
– by shielding.
Installing network components in cabinets
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