Mains Voltage; Protection Against External Electrical Interference - Siemens SIMATIC S7-300 Hardware And Installation Manual

Appendix

Mains voltage

The following table shows you what to watch with respect to the mains voltage.
Table 12-2
In the case of ...
For stationary systems or systems without
all-pole mains disconnect switch
For load power supplies, power supply
modules
For all circuits of the S7-300
24 VDC Power Supply
The table below shows what you must observe in connection with the 24 VDC
power supply.
Table 12-3
In the case of ...
Buildings
24 VDC power supply cables,
signal cables
24 VDC Power Supply

Protection against external electrical interference

The table below shows how you must protect your system against electrical
interference or faults.
Table 12-4
In the case of ...
all plants or system with an S7-300
installation
Supply/signal/bus cables
Signal and bus cables
Information on EMC and surge protection ...
can be found in the following Chapters.
12-2
Mains voltage
Protection against external electrical interference
Measures to take
External lightning
protection
Internal lightning
protection
Safe (electrical) extra-low voltage isolation
Protection against external electrical interference
S7-300 Programmable Controller Hardware and Installation
is ...
Installation of a mains disconnect switch or
a fuse in the building installation system.
The set rated voltage range must
correspond to the local power supply
voltage.
Rated mains voltage fluctuation/deviation
must lie within the permitted tolerance (refer
to Technical Data of S7-300 modules).
Install lightning protection
(e.g. lightning conductors).
Make sure that ...
the plant or system is connected to a
protective conductor for the suppression of
electromagnetic interference.
The conductor routing and installation is
correct.
a cable/conductor break does not result in
undefined plant or system states.
A5E00105492-02