Installing/Mounting
4.2 Electrical Installation
Power Modules PM240
Hardware Installation Manual, 2006-04-04, A5E00807525B AA
4-7
TT Power System
PE
L1
L2
L3
N
L1 L2 L3
Exposed Conductive Parts
Figure 4-5 TT power system
A TT power system has one point directly grounded, the exposed conductive parts of the
installation being connected to a ground, which is electrically independent of the ground of
the power system.
IT Power System
PE
L1
L2
L3
N
L1 L2 L3
Exposed Conductive Parts
Figure 4-6 IT power system
An IT power system has no direct connection to ground - instead the exposed parts of the
electrical installation are grounded.
It will be necessary to provide a mechanism for disconnecting the "DC link midpoint to
ground" capacitor.
Note
TT-/IT power systems can only be used with unfiltered drives.
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