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3.3.7.1
The influence of power distribution systems (EN 501742, 6.4.4.2)
Planning the electrical installations
To avoid the power distribution system affecting sensitive devices, the following points must
be taken into account when planning the electrical installation:
● Possible sources of interference, for example voltage distributors, voltage transformers,
● Metal pipes (for example for water, gas, heating) and cables should enter the building at
● The metal surfaces, shields, metal pipes, and connections of such conduits must be
● Using a common cable route for lowvoltage cable and signal cables with adequate
● The use of either a single multicore cable for all power supplies or (in the case of higher
3.3.7.2
Cable categories and clearances
Fiberoptic cables
When using fiberoptic cables, mechanical protection is necessary, however the EMC rules
do not apply.
Grouping in categories
It is useful to group wires and cables into various categories according to the signals they
carry, possible interference signals, and their sensitivity to interference. Minimum clearances
can be specified for these categories so that interferencefree operation can be expected
under normal operating conditions if the clearance is adhered to.
Constraints
Grouping cables according to voltage classes assumes that the interference voltages relate
directly to the power supply voltage conducted (the lower the supply voltage, the lower the
interference voltage). Remember, however, that DC or 50 Hz power supply voltages do not
represent any danger to Industrial Ethernet bus cables. The critical interference voltages in
the kHz to MHz frequency range are created by the consumers connected to the cable. A 24
V DC cable with which a relay is switched regularly has a far more critical interference range
than a 230 V cable supplying a lightbulb.
Passive network components
System Manual, 02/2013, C79000-G8976-C282-01
3.3 Guidelines for setting up networked automation systems in buildings
elevators, high currents in power supply bars, must be located at a suitable distance from
sensitive devices;
the same point;
connected with lowresistance conductors to the main bonding conductor of the building;
separation (either by clearance or shielding) between the two to avoid large induction
loops that are created by the different lowvoltage cabling;
power requirements) of conductor bars with weak magnetic fields.
Installing network components in cabinets
97
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