Siemens SINAMICS G130 Engineering Manual page 34

Fundamental Principles and System Description
Engineering Information
The output power of the above-mentioned converter for low overload, on the basis of the base load current I
400 V 3AC/50 Hz, is defined as the the rated power of the largest, 6-pole asynchronous motor for 400V/50 Hz
operation, the rated current of which does not exceed the base load current I
this definition the converter has the output power of 315 kW at 400 V on the basis of I
The output power of the converter, which, as the rated power of the motor, is given in kW, offers the possibility of a
very simple and safe coordination between the power of the converter and the motor, without having to take into
consideration other details such as current, power factor and efficiency. If the output power of the converter is chosen
at least as big as the rated power of the motor, it is always safe to operate 2, 4 and 6-pole motors at full load with the
selected converter.
The example above also demonstrates, however, that it is quite possible in individual cases to operate motors with a
small number of poles (2 to 4), whose rated power exceeds the output power of the converter, continuously at their
nominal working point without overloading the converter. In the chosen example above, this applies to the 2-pole
motor with a rated power of 355 kW.
Therefore on the one hand, the output power of the converter offers and extremely simple and safe way of
coordinating the power of a converter and a motor. On the other hand, however, this coordination can lead to an
overdimensioning of the converter in combination with motors with a low number of poles. If you want to achieve
optimum coordination between the converter and the motor, you must choose the more complicated method involving
the currents.
Note:
If the converters and inverters in this engineering manual are characterized according to their output power, which is
true in many tables in this document, then the output power is always referred to the base load current I
frequency 50 Hz and to line supply voltage 400 V or 500 V or 690 V.
SINAMICS Engineering Manual – November 2015
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Ó Siemens AG
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