Siemens Simatic S7-400, Installation Manual, Page: 74 / 228

Wiring the S7-400
4-14
Automation System S7-400 Hardware and Installation
A5E00850741-01
Connecting the Load Voltage Ground
Many output modules require an additional load voltage to switch the actuators.
Two different modes are possible for this load voltage:
•
Non-isolated operation
•
Floating operation
The following table shows how the load voltage ground is connected in the
individual modes.
Table 4-3 Grounded connection load voltage
Mode Connection of Load Voltage
Non-isolated operation
• Grounded configuration
• Ungrounded configuration
to the reference point of the rack; metallic connection
between frame element and chassis ground must be
fitted.
to the reference point of the rack; metallic connection
between frame element and chassis ground must be
fitted.
Floating operation
•
Grounded and ungrounded
configuration
Left open or to any point, but not to protective ground
or reference potential M of operating voltages
The following figure shows how the load voltage ground is connected for
non-isolated operation.
Metallic connection, remove for
ungrounded configuration
Ground terminal for
load voltage
Figure 4-7 Grounded connection load voltage