Wiring the S7-400
4-4
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
4.3 Choosing the Load Current Power Supply
Choosing the Load Current Power Supply
The input and output circuits (load current circuits) as well as sensors and
actuators are powered by the load current power supply. Listed in the following are
the characteristics of the load current power supplies required in special
applications for choosing the load current power supplies.
Characteristics of
the Load Current
Power Supply
Required for ... Remarks
Safe isolation Modules which must be
supplied with voltages
60 VDC or 25
VAC.
The Siemens SITOP power load current
supplies have this characteristic.
24 VDC load circuits
Tolerances of the
output voltages:
20.4 V to 28.8 V
40.8 V to 57.6 V
51 V to 72 V
24 VDC load circuits
48 VDC load circuits
60 VDC load circuits
If the output voltage tolerances are
exceeded, you should provide an energy
storage capacitor. Rating: 200 µF per 1 A
load current (with bridge rectification).
Load Current Power Supplies
The DC load current power supply must meet the following requirements:
Only a safe, isolated extra-low voltage of 60 VDC may be used as the load
current supply. Isolation may be implemented according to the requirements of the
following, amongst other publications:
VDE 0100-410 / HD 384-4-41 S2 / IEC 60364-4-41
(as a functional extra-low voltage with isolation) or
VDE 0805 / EN 60950 / IEC 60950
(as a safety extra-low voltage SELV) or VDE 0106 Part 101.
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