Lenze Inverter EMC - Manual (Page 23)

Leakage current for portable systems
21
l
EDBEMV EN 1.3
11 Leakage current for portable systems
Frequency inverters with internal or external radio interference suppression filters usually feature a
leakage current to the PE potential, higher than AC 3.5 mA or DC 10 mA.
This requires solid connection for protection (refer EN 50178/5.2.11.1) and must be specified in the
operating documentation.
Where a solid connection is not realistic in the case of a portable consumer although the leakage
current to the PE potential is above AC 3.5 mA or DC 10 mA, a suitable countermeasure would be
the installation of an additional two-winding transformer (isolating transformer) into the power
supply, with the PE conductor being connected to the drive’s PE’s (filter, inverter, motor, shields) and
also to one pole of the secondary winding of the isolating transformer.
For 3-phase-supplied units, select a suitable isolating transformer with secondary star connection,
with the star point being connected to the PE conductor.
L1
L1
N
N
L2
N1 N2
L
M
3~
PE
primary
secon-
dary
Filter Inverter
U
V
W
Fig. 12 Installation of a two-winding transformer (isolating transformer)
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