Siemens SIMATIC ET 200AL, System Manual

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Connecting
5.6 Connecting cables for ET 200AL
Distributed I/O system
50
System Manual, 08/2021, A5E31861578-AJ
5.6 Connecting cables for ET 200AL
Impact of cable length on the supply voltage
When wiring your configuration, you must take into account the impact of the cable length
on the supply voltage of the ET 200AL distributed I/O system.
CAUTION
Pay attention to maximum incoming currents
For each power supply (1L+, 2L+), you can feed in a maximum of 4A.
If you exceed the maximum incoming currents and do not comply with the required cable
cross sections, an increased incoming current could lead to overheating of the cable
insulation and the contacts. This could result in damage to the modules.
The figure below shows the voltage drop depending on the cable length for 4 current
strengths, using the example of a copper cable with ∅ 0.5 mm
2
.
Figure 5-8 Voltage drop with a cable cross-section of 0.5 mm 2
To estimate the voltage drop in your ET 200AL distributed I/O system, you must add the
voltage drops of the different cables. For every module used, you must add an additional
voltage drop of around 0.1 V.
Example
If you have a 7 m power supply cable with ∅ 0.5 mm
2
, the voltage drop is around 1.5 V with
a load of 3 A.