Siemens SINAMICS G130 Engineering Manual page 20

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.
It can, however, be noted that, in some cases, motors with a low number of poles (2 or 4), whose rated power is
larger than the output power of the converter, can be operated at their rated point without overloading the converter.
In the above-mentioned example this is the case for the 2-pole motor with a rated current of 590 A and 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.
SINAMICS Engineering Manual – May 2008
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© Siemens AG
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