Tt Line System; It System - Siemens SINAMICS G120 Hardware Installation Manual

5.1.2

TT line system

In a TT line system, the transformer grounding
and the installation grounding are independ‐
ent of one another.
There are TT line supplies where the neutral
conductor N is either transferred – or not.
Inverter operated on a TT line system
● Inverter with integrated or external line filter:
– Operation on TT line systems with grounded neutral point permissible.
– Operation on TT line systems without grounded neutral point not permissible.
● Inverter without line filter:
– Operation on all TT line systems permissible.
● For installations in compliance with IEC, operation on a TT line system is permissible. For
installations in compliance with UL, operation on a TT line system is not permissible.
5.1.3

IT system

In an IT line system, all of the conductors are
insulated with respect to the PE protective
conductor – or connected to the PE protective
conductor through an impedance.
There are IT systems with and without transfer
of the neutral conductor N.
Inverter operated on an IT line system
● Inverters with integrated line filter:
– Operation on IT line systems not permissible.
● Inverter without line filter:
– Operation on all IT line systems permissible.
PM240P-2 Power Modules
Hardware Installation Manual, 11/2016, A5E37800827C AB
Connecting-up
5.1 Permissible line supplies
41