Operating The Et 200Sp On Grounded Incoming Supply - Siemens Simantic ET200SP System Manual

Wiring

5.4 Operating the ET 200SP on grounded incoming supply

5.4 Operating the ET 200SP on grounded incoming supply
Introduction
Below you will find information on the overall configuration of an ET 200SP distributed I/O
system on a grounded incoming supply (e.g. TN-S network). The specific subjects discussed
are:
● Disconnecting devices and short-circuit and overload protection according to IEC 60364
(corresponds to DIN VDE 0100) and IEC 60204 (corresponds to DIN VDE 0113)
● Load power supplies and load circuits.
Grounded incoming supply
In the case of grounded incoming supplies (TN-S system) the neutral conductor (N) and the
protective conductor (PE) are each grounded. Both conductors form a part of the overvoltage
concept. When a plant is in operation, the current flows across the neutral conductor. When
a fault occurs, for example, a single ground fault between a live conductor and ground, the
current flows through the protective conductor.
Safe electrical isolation (SELV/PELV in accordance with IEC 60364-4-41)
Load current / power supply modules with safe electrical isolation are required for the
operation of the ET 200SP distributed I/O system. According to IEC 60364-4-41, this
protection is referred to as SELV (Safety Extra Low Voltage)/PELV (Protective Extra Low
Voltage).
The wiring of SELV/PELV circuits must either be isolated from the wiring of other circuits that
are not SELV/PELV or the insulation of all conductors must be dimensioned for the higher
voltage.
Configuration of ET 200SP with ungrounded reference potential
To conduct interference currents, the reference potential of the CPU/interface module and
the BaseUnits BU15...D is connected internally via an RC combination (IM/CPU:
R = 10 MΩ / C = 100 nF, BU15...D: R = 10 MΩ / C = 4 nF) with the mounting rail (protective
conductor).
● This configuration conducts high-frequency interference currents and prevents static
charges.
● It is always possible to configure an ungrounded setup of the ET 200SP distributed I/O
system as the ET 200SP distributed I/O system has no fixed ground connection. The
power pack/power supply module for 24 V DC must also be ungrounded and electrically
isolated.
If you want to configure the ET 200SP distributed I/O system with grounded reference
potential, connect the 1M connection of the CPU/interface module electrically with the
protective conductor.
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Distributed I/O system
System Manual, 12/2016, A5E03576849-AG