Fundamental Principles and System DescriptionEngineering InformationSINAMICS Engineering Manual – May 2008© Siemens AG42/39601020304050607080901001 3 5 7 9 11 13 15 17 19 21 23 2501020304050607080901001 3 5 7 9 11 13 15 17 19 21 23 25Typical current harmonic spectrum with Smart Infeed in Typical current harmonic spectrum with Smart Infeed inrectifier (motor) operation with a line reactor of 4 % regenerative operation with a line reactor of 4 %(specified in %) (specified in %)The 5th current harmonic, which is very strong in rectifier (motor) operation, is reduced considerably duringregenerative operation. Therefore all remaining harmonics increase slightly. Due to the considerable decrease in the5th current harmonic, there is a slightly lower Total Harmonic Distortion factor THD(I) in regenerative operation. So itis 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) operationand regenerative operation.Typical line current with Smart Infeed in rectifier operation Typical line current with Smart Infeed in regenerativeoperationHarmonic currents of 6-pulse rectifier circuits with Line Harmonics FilterA Line Harmonics Filter LHF is a passive filter that mainly absorbes the 5 th and the 7th harmonic in the line current of6-pulse rectifiers and in this way significantly reduces the harmonic effects on the supply. It is installed between theline supply connection and converter and can be used on SINAMICS G130 and G150. Line Harmonics Filter LHFrequire a line reactor with a relative short-circuit voltage of u k = 2 % to be installed in the converter. Furtherinformation about the operating principles and usage limitations of the Line Harmonics Filter can be found in thesection “Line Harmonics Filter LHF”. Here only the harmonic effects on the supply system with Line Harmonics Filtersare discussed in detail.
