Siemens SINAMICS G130 Engineering Manual page 205

Comments on b)
The variant with the common winding system that is fully parallel-connected in the motor is also feasible for parallel
connections of converters, but has certain disadvantages as compared to variant a1):
·
Decoupling measures are required (minimum cable lengths or motor reactors).
·
Circulating currents between the parallel-connected Motor Modules cannot be eliminated completely.
·
The quality of current balance between the Motor Modules in the parallel connection is slightly poorer.
Parameter p7003 must be set to "0" during commissioning for this variant (single winding system).
Comments on c)
The variant with winding systems that are completely electrically isolated and out of phase is not suitable for parallel
connections of SINAMICS converters with firmware version 4.5 or lower, as the pulse patterns of the parallel-
connected Motor Modules are synchronized by the Control Unit and are therefore absolutely identical. With firmware
version 4.6 and higher, winding systems which are out of phase by 30° are basically possible if certain boundary
conditions are fulfilled. Further information is available on request.
These types of windings were previously used in conjunction with parallel connections of current-source DC link
converters SIMOVERT A (6-phase winding for 12-pulse operation). As a result, windings of this type may exist in
installations where older models of current-source DC link converter have to be replaced by SINAMICS, but the
motors are to be retained.
Comments on d)
This variant with separate winding systems at the input side and internally coupled neutral is essentially a hybrid of
variants a) and b). The problem with this variant is that circulating currents can develop between the systems due to
the electrically coupled neutrals. These currents increase the losses in the motor and can thus cause a significant
temperature rise in the motor under unfavorable conditions. This risk of motor overheating is the reason why this
variant cannot be used in parallel connections of SINAMICS converters.
Fundamental Principles and System Description
SINAMICS Engineering Manual – November 2015
Engineering Information
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