Siemens SIMATIC NET Instrucciones de operaciones descargar pdf (Pagina 166)

Guidelines for Installing Networked Automation Systems in Buildings

7-18

SIMATIC NET Twisted-Pair and Fiber-Optic Networks

C79000-G8976-C125-02

7.4 Arrangement of Devices and Cables

Adequate Clearance to Reduce the Effects of Interference

One simple but nevertheless effective method of reducing the effects of

interference is to keep the “culprit” and “victim” devices and cables as far apart

from each other as possible. Inductive and capacative interference injection

declines in proportion to the square of the distance of the elements involved. This

means that doubling the clearance reduces the effects of interference by a factor

of four. Taking certain aspects into account during the planning phase of a building

generally incurs little extra cost and can save considerable effort later.

Standards Recommending the Spatial Arrangement of Devices and Cables

EN 50174-2 /13/ includes recommendations on the spatial arrangement of devices

and cables with the aim of achieving the lowest possible mutual interference.

7.4.1 The Influence of Power Distribution Systems (EN 50174-2,

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:

S Possible sources of interference, for example voltage distributors, voltage

transformers, elevators, high currents in power supply bars, must be located at

a suitable distance from sensitive devices:

S Metal pipes (for example for water, gas, heating) and cables should enter the

building at the same point;

S The metal surfaces, shields, metal pipes, and connections of such conduits

must be connected with low-resistance conductors to the main bonding

conductor of the building.

S Using a common cable route for low-voltage cable and signal cables with

adequate separation (either by clearance or shielding) between the two to avoid

large induction loops that are created by the different low-voltage cabling.

S The use of either a single multi-core cable for all power supplies or (in the case

of higher power requirements) of conductor bars with weak magnetic fields.

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Siemens SIMATIC NET Instrucciones de operaciones Pagina 166