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Siemens S5-135U/155U User Manual

Page 50

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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