Siemens S5-135U/155U appendix Power Supplies for Programmable Controllers and I/Os

Installation Guidelines

3.4Power Supplies for Programmable Controllers and I/Os

This section describes:

SWhich circuits you must distinguish in the control system and which demands are made on the power supply.

SConnection and grounding concept with higher-level infeed from grounded, centrally grounded and ungrounded supplies.

SConnecting the power supply to non-isolated and isolated modules.

3.4.1Power Supplies for Control Systems with SIMATIC S5

For control systems with SIMATIC S5, you will need:

SA power supply for the internal PLC circuits (control power supply)

Sand a load power supply for the input and output circuits.

Power Supply for the PLC Circuits

Load Power Supply for the I/Os

!

The power supply for the internal PLC circuits powers the CPU and the modules used.

Note

Ensure that the control power supply is not overloaded. Make a current addition and estimate the current drawn by all modules.

The load power supply feeds the input and output circuits (load circuits) as well as sensors and actuators. Only a power supply which offers safe electrical isolation from the AC system may be used for the 24 V DC supply.

Caution

Only safety-separated low voltage DC v 60 V may be used for the 24 V DC supply. The safety separation can be implemented according to the requirements of, amongst other sources, VDE 0100, Part 410/HD

384-4-41/IEC 364-4-41 (functional extra-low voltage with safety separation) or VDE 0805/EN 60950/IEC 950 (safety extra-low voltage SELV) or VDE 0106, Part 101.

3-20	System Manual
	C79000-G8576-C199-06