Siemens SIMATIC ET 200S Manual page 108

Wiring and Fitting
5.2 Operating the ET 200S on a grounded supply
In this section, you will find information on the overall setup of an ET 200S
distributed I/O system on a grounded supply (TN-S system). The specific subjects
discussed are:
• Circuit-breaking devices, short-circuit and overload protection in accordance
with DIN VDE 0100 and DIN VDE 0113
• Load power supplies and load circuits
Definition: Grounded supply
In a grounded supply, the neutral conductor of the system is grounded. A mere
ground fault between a live conductor and ground or a grounded section of the
plant causes the protective devices to trip.
Components and protective measures
Various components and protective measures are prescribed when setting up an
entire plant. The types of component and the degree to which the protective
measures are binding depend on the DIN VDE regulation that applies to your plant
setup. The following table refers to Figure 5-1.
Compare ...
Circuit-breaking device
for PLC, sensors and ac-
tuators
Short-circuit and overload
protection:
Grouped for sensors and
actuators
Load power supply for
AC load circuits with
more than five electroma-
gnetic devices
Safe electrical isolation
Safe electrical isolation must be provided for:
• Modules that must be supplied with v60 VDC or v25 VAC
• 24 VDC load circuits
5-4
Refer to DIN VDE 0100
Fig. 5-1
... Part 460:


Main switch
... Part 725:

Single-pole pro-
tection of circuits

 Isolation by trans-
former recom-
mended

DIN VDE 0113
... Part 1:
Disconnector
... Part 1:
•
With a grounded
secondary circuit:
single-pole protection
•
In all other cases: all-pole
protection
Isolation by transformer re-
commended
ET 200S Distributed I/O System
EWA-4NEB780602402-09