Grounded / Ungrounded S7-400 Configurations; S7-400 Assembly With The Removable Bridge - Siemens SIMATIC S7-400 Configuration And Use Manual

6.8

Grounded / Ungrounded S7-400 Configurations

Introduction
Depending on the requirements in the plant, you can build the S7-400 with either
grounded or ungrounded reference potential.
Application
You should usually select a grounded configuration. A grounded configuration
guarantees a high degree of interference immunity. Any interference current that
occurs is discharged to building ground. In large, extensive plants, however, you
may be required to build the S7-400 ungrounded.
Connection Scheme
A removable bridge on the rack forms a galvanic connection to the building ground.
If this bridge is removed, the rack is connected to the building ground via an RC
network and therefore configured ungrounded. RF interference is discharged
through this RC network and static charges are prevented. Figure 6-7 shows the
rack and the removable bridge.
Figure 6-7
Automation System S7-400 Configuration and Use
A5E00442711-02
Removable
bridge
6.8 nF 10 MΩ
M
Connection to mounting rail
Galvanic connection
Reference potential M
Connection to building ground

S7-400 assembly with the removable bridge

Configuration Variants of the S7-400
RC network
6-15