Siemens S5-135U/155U System Manual page 50

Installation Guidelines
Operating a
In systems with their own transformers or generators, the PLC is connected
Programmable
to the central ground. A detachable connection should be provided so that
Controller with ground faults can be measured.
Process I/Os from
The PLC should be insulated from cabinet/protective conductor potential. To
a Centrally
maintain this isolated arrangement, all connected devices must be operated
Grounded Supply
with capacitive grounding or ungrounded. For this reason, programmers
should only be powered via an isolating transformer.
Higher-Level Supply
L1
L2
L3
Detachable Con-
nection for
Measurement
Purposes
Central Ground,
e.g. Foundation
Ground
Control Power Supply
AC
DC
AC
AC
AC
DC
AC
DC
L1 L2 L3 N
Figure 3-9 Operating a Programmable Controller with Process I/Os from a Centrally Grounded Supply
3-24
Cabinet
L+/L1
L+
L-
U
int
L–/N
L1 PS
N 0 V
PE
PE
Protective Conductor Bar in Cabinet,
Insulated Arrangement
24 to 230 V AC Load Supply for AC Modules
5 to 60 V DC Load Supply for Non-Floating DC Modules
5 to 60 V DC Load Supply for Floating DC Modules
Programmable Controller, Insulated Arrangement
CPU
Non-Float- Non-Float- Floating
ing Input ing Output Input
Process I/Os
C79000-G8576-C199-06
Floating
Output
System Manual