Siemens Simantic ET200SP System Manual page 45

AUX bus (AUX(iliary) bus)
BaseUnits with additional AUX terminals (e.g. BU15-P16+A10+2D) enable the additional
connection of a potential (up to the maximum supply voltage of the module), which is applied
via the AUX bus.
In the case of BaseUnits of motor starters, the AUX bus is interrupted to the left. An internal
24 V DC signal is output to the right.
The AUX bus can be used individually:
● As a protective conductor bar (the requirements of EN 60998-1 apply). To comply with
this standard, a maximum of 8 I/O modules may be plugged into the corresponding
potential group.
● For additionally required voltage
NOTICE
AUX bus as PE bar
If you use an AUX bus as a protective conductor bar, attach the yellow-green color
identification labels to the AUX terminals, and establish a functional connection to the
central protective conductor connection.
If you stop using the AUX bus as a protective conductor bar, make sure you remove the
yellow-green color identification labels and remove the connection to the central protective
conductor connection again.
The AUX bus is designed as follows:
● Maximum current carrying capacity (at 60 °C ambient air temperature): 10 A
● Permissible voltage: Depending on the BaseUnit type (see BaseUnit manual
(http://support.automation.siemens.com/WW/view/en/59753521))
Self-assembling voltage buses
You must feed in the supply voltage L+ via the BaseUnit BU...D, BU30-MS1 or BU30-MS3 .
Each BaseUnit BU...B allows access to the supply voltage L+ via terminals (red/blue). The
motor starter BaseUnits "BU30-MS1", "BU30-MS2", "BU30-MS3", "BU30-MS4", "BU30-MS5"
and "BU30-MS6" do not have this access.
Distributed I/O system
System Manual, 12/2016, A5E03576849-AG
Application planning
3.4 Forming potential groups
45