Siemens S7-400 - VDE Specifications for Assembling a Programmable Controller

Wiring the S7-400
4-6
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
Table 4-1 VDE Specifications for Assembling a Programmable Controller
Compare ...
Ref. to
Figure
4-1
VDE 0100 VDE 0113
Disconnection element for control
system, sensors, and actuators
 ... Part 460:
Main switches
... Part 1:
Isolating switches
Short-circuit and overload protection:
in groups for sensors and actuators
 ... Part 725:
Single-pole
protection of
circuits
... Part 1:
• With
grounded
secondary
circuit:
single-pole
protection
• Otherwise:
all-pole
protection
Load current PS for AC power circuits
with more than five items of
electromagnetic apparatus
 Isolation by
transformer is
recommended
Isolation by
transformer is
required
Rule: Grounding the Load Current Circuits
Load current circuits should be grounded.
Reliable functional safety is provided by the common reference potential (ground).
Provide a detachable connection to the protective ground conductor at the load
current power supply (Terminal L- or M) or on the isolating transformer
(Figure 4-1, ). In the event of faults in the power distribution, this will facilitate the
locating of ground faults.