The Frequency Converter As A Low-Frequency Source Of Interference - Siemens SINAMICS G130 Engineering Manual

EMC Installation Guideline
Engineering Information
Connection of doors, side walls, back walls, roof plates, and floor plates to the cabinet frame
The SINAMICS G150 and S150 converter cabinet units as well as the Cabinet Modules of the SINAMICS S120
modular cabinet unit system are built at the factory in such a way that they automatically comply with the interference
radiation limit values defined in category C3 of the EMC product standard EN 61800-3, when the devices are
operated with the cabinet doors closed.

The frequency converter as a low-frequency source of interference

If SINAMICS converters are connected to a supply system with a purely sinusoidal voltage (generator or
transformer), the non-linear characteristics of the components in the line-side rectifier circuits cause non-sinusoidal
supply system currents to flow, which distorts the voltage at the PCC (Point of Common Coupling). This low-
frequency, conducted effect on the line voltage is known as "Harmonic effects on the supply system" or "supply
system perturbation".
Measures for reducing low-frequency interference emissions
The supply system perturbation caused by SINAMICS converters largely depends on the type of rectifier circuit used. The
magnitude of the supply system perturbation can, therefore, be influenced by the selection of the type of rectifier and by
additional line side components such as line reactors or Line Harmonics Filters.
The highest level of supply system perturbation is generated by six-pulse rectifier circuits, which are used with
SINAMICS G130 and G150 converters as well as with S120 Basic Line Modules and Smart Line Modules.
Typical line current with 6-pulse rectifier circuits
A considerable reduction in supply system perturbation can be achieved by means of Line Harmonics Filters for
SINAMICS G130 and G150 converters or by means of 12-pulse rectifier configurations with SINAMICS S120 Basic
Line Modules and Smart Line Modules.
Typical line current of 6-pulse rectifiers with Line Harmonics Filters
The lowest levels of supply system perturbation is generated with active rectifiers, which are used with SINAMICS
S150 converters and SINAMICS S120 Active Line Modules. In this case, current and voltage are virtually sinusoidal.
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