Guidelines For Setting Up Networked Automation Systems In Buildings; General Notes On Networking Bus Cables; Protection From Electric Shock - Siemens 6GK1 901-1GB01 System Manual

3.3

Guidelines for setting up networked automation systems in buildings

3.3.1

General notes on networking bus cables

Bus cables in plants
Bus cables are important connections for communication between individual components of
an automation system. Mechanical damage or repeated electrical interference affecting
these bus connections reduces the transmission capacity of the system. In extreme cases,
such problems can lead to failure of the entire automation system. The following sections
explain how to protect cables from mechanical and electrical impairment.
Shielding and grounding concept
Bus cables connect programmable controllers. These in turn are connected to transducers,
power supply units, peripheral devices etc. over cables.
All the components together form a complex electrically networked automation system.
When connecting system components via electrical cables (in this case bus cables),
remember to take into account the requirements of the overall system structure.
Connecting cables, in particular, influence the shielding and grounding concept. Shielding
and grounding an electrical installation serves the following purposes:
● Protects both humans and animals from dangerous network voltages
● Prevents unacceptable noise emission and susceptibility to noise
● Protects the system from overvoltage (for example lightning protection)
Networking SIMATIC with SIMATIC NET
SIMATIC NET network components and SIMATIC automation components are designed to
operate together taking into account the aspects listed above. By keeping to the installation
instructions described in the system manuals and in the following sections of this book, your
automation system will meet the legal and normal industrial requirements for safety and
noise immunity.
3.3.2

Protection from electric shock

Twistedpair signal level
The signal levels on twisted pair cables are in the range of only a few volts. Correctly
installed and operated twisted-pair cables do not have dangerous electrical voltages.
Nevertheless you should remember the following rules when installing the power
supply for all components (end devices, bus components, etc.) that you want to connect to
twistedpair cable.
Passive network components
System Manual, 02/2013, C79000-G8976-C282-01
3.3 Guidelines for setting up networked automation systems in buildings
Installing network components in cabinets
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