Siemens SINAMICS S120 Combi Manual page 57

An isolating transformer must have the following properties:
● The transformer secondary must be in the star connection (a delta connection is not
permissible!).
● The neutral conductor must be brought out. It must be connected with the PE of the line
filter, line reactor and S120 Combi (infeed).
Comment: If the neutral conductor is not brought out and/or not connected, then all of the
restrictions of an IT line supply apply!
Figure 3-11
SINAMICS S120 Combi
Manual, 11/2017, 6SL3097-4AV00-0BP7
Operation via an isolation transformer
Line-side power components
3.8 Line connection versions
57