Siemens Simantic ET200SP System Manual page 46

Application planning
3.4 Forming potential groups
Operating principle
1 CPU/interface module
2 BaseUnit BU...D
3 BaseUnit BU...B
4 Potential group 1
5 Potential group 2
6 Potential group 3
7 BaseUnit BU...B with dummy module
8 BaseUnit BU30-MS2
9 BaseUnit BU30-MS4
10 BaseUnit BU30-MS1
11 Potential group 4
12 BaseUnit BU30-MS4
13 Backplane bus
Figure 3-3 Placing the BaseUnits
Connecting different potentials to the AUX bus
Note
If you apply different potentials to the power or AUX bus within an ET 200SP station, you
need to separate the potential groups with a BaseUnit BU...D.
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14 Server module
15 Self-assembling voltage buses P1/P2
16 AUX bus
17 Infeed bus 500 V AC (L1, L2(N), L3, PE)
18 Supply voltage L+
19 Supply voltage L+ (3)
20 Additionally required voltage
21 Supply voltage L+ (2)
22 Protective conductor
23 Supply voltage L+ (1)
24 Supply voltage 1L+
System Manual, 12/2016, A5E03576849-AG
Distributed I/O system