Siemens S5-135U/155U appendix Controller with, An Ungrounded, Supply

Installation Guidelines

Operating a		In cases in which the higher-level power supply is not grounded, you must
Programmable		connect the programmable controller to a separate protective
Controller with		conductor/ground (e.g. foundation ground). Operation of the PLC with
Process I/Os from		non-floating power supplies is not allowed.
an Ungrounded		When connecting the power supplies, please note:
Supply
		In 3 x 230 V systems, you may connect the power supply directly to two
		phases.
	Low-Voltage Distribution,
L1	e.g. IT System (3 X 230V)
L2
L3
PE

À		Schrank			Programmable Controller
Control Power Supply
AC	L+	L+/L1
DC	L±		Uint	CPU
	L1	L±/L2
			PS 0 V
	L2			Non-Float-	Non-Float-	Floating	Floating
		PE		ing Input	ing Output	Input	Output

	PE
	Protective Conductor Bar
Protective	in Cabinet
Conductor
Grounding
￿	￿
AC
	Process I/Os
AC

￿24 to 230 V AC Load Supply for AC Modules

￿ ￿ ￿

AC

DC

￿ ￿

AC

DC

5 to 60 V DC Load Supply for Non-Floating DC Modules

￿

5 to 60 V DC Load Supply for Floating DC Modules

Figure 3-10 Operating a Programmable Controller with Process I/Os from an Ungrounded Supply

In 3 x 400 V systems, a connection between phase and neutral conductor is not allowed (excessively high voltage in the event of a ground fault). Intermediate transformers should be used in these systems.

System Manual	3-25
C79000-G8576-C199-06