Installing An S7-300 With Grounded Reference Potential; Table 4-7 Vde Specifications For The Installation Of A Plc System - Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual

Configuring
4.9 Electrical assembly, protective measures and grounding
Specified components and protective measures
A number of components and protective measures are prescribed for plant installations. The
type of components and the degree of compulsion pertaining to the protective measures will
depend on the VDE specification applicable to your particular plant.
The table below shows components and protective measures.
Table 4-7
Compare ...
Disconnect devices for control
systems, signal generators and
final control elements
Short-circuit / overload
protection:
In groups for signal generators
and final control elements
Load power supply for AC load
circuits with more than five
electromagnetic devices
1) This column refers to the indexes of the figure in the chapter Overview: Grounding.
Reference
For further information on protective measures, refer to the Appendix.
4.9.2

Installing an S7-300 with grounded reference potential

Introduction
During installation of an S7-300 with grounded reference potential interference current is
discharged to the ground conductor / to earth. A grounding slide contact is used for this
except with CPU 31xC.
Note
Your CPU is supplied with grounded reference potential. Therefore, if you wish to install an
S7-300 with grounded reference potential, you do not need to modify your CPU!
4-16
VDE specifications for the installation of a PLC system
1)
(1)
(2)
(3)
VDE 0100
...Part 460:
Master switch
...Part 725:
Single-pole fusing of
circuits
Galvanic isolation by
transformer
recommended
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
VDE 0113
... Part 1:
Load disconnect switch
... Part 1:
With grounded secondary
•
power circuit: single-pole
fusing
Otherwise: fusing of all poles
•
Electrical isolation by transformer
mandatory