Siemens S5-135U/155U - Manual (Page 50)

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