Fundamental Principles and System Description
Engineering Information
SINAMICS Engineering Manual – November 2015
Ó Siemens AG
77/528
Typical current harmonic spectrum with Smart Infeed in Typical current harmonic spectrum with Smart Infeed in
rectifier (motor) operation with a line reactor of 4 % regenerative operation with a line reactor of 4 %
(specified in %) (specified in %)
The 5
th
current harmonic, which is very strong in rectifier (motor) operation, is reduced considerably during
regenerative operation. Therefore all remaining harmonics increase slightly. Due to the considerable decrease in the
5
th
current harmonic, there is a slightly lower Total Harmonic Distortion factor THD(I) in regenerative operation. So it
is sufficient for harmonics calculations with the SINAMICS Smart Infeed to consider only the worse rectifier (motor)
operation.
The following diagrams show the typical line side currents with SINAMICS Smart Infeed in rectifier (motor) operation
and regenerative operation.
Typical line current with Smart Infeed in rectifier operation Typical line current with Smart Infeed in regenerative
operation
1.4.3 Harmonic currents of 6-pulse rectifier circuits with Line Harmonics Filter
Line Harmonics Filter LHF are passive filters that mainly absorbe the 5
th
and the 7
th
harmonic in the line current of 6-
pulse rectifiers and in this way significantly reduce the harmonic effects on the supply. Two versions of Line
Harmonics Filter are available, i.e. LHF and LHF compact. They are installed between the mains supply and
converter and can be used with SINAMICS G130 and G150 units. When stand-alone Line Harmonics Filters (LHF)
are used, a line reactor with a relative short-circuit voltage of v
k
= 2 % must be installed at the converter input. For
Line Harmonics Filters compact (LHF compact) there is no need to install a line reactor. For further information about
the operating principle and boundary conditions relating to the use of Line Harmonics Filters, please refer to section
"Line Harmonics Filters (LHF or LHF compact)". This section of the manual will only discuss the harmonic
characteristics of the LHF and LHF compact filters.
6-pulse rectifier with line reactor and Line Harmonics Filter (LHF or LHF compact) on a three-phase supply
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