Siemens SINAMICS S120 - Page 191

Fundamental Principles and System Description
Engineering Information
SINAMICS Engineering Manual – November 2015
Ó Siemens AG
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The charts below show the partial-load efficiency of SINAMICS S150 converters for drives with quadratic load
characteristic M~n
2
. The calculations are based on a typical efficiency at full load of 96 %. The efficiency is
represented in three different ways. In one chart, the efficiency is shown as a function of the output frequency, in the
second chart, as a function of the output current, and in the third chart, as a function of the active output power.
Figure 2a) shows the characteristic curve of the efficiency for drives with quadratic load characteristic as a function of
the output frequency ratio f
Out
/f
Out-rated
which is proportional to the motor speed ratio n/n
rated
.
Converter efficiency in %
Figure 2a)
Efficiency of SINAMICS S150 converters in drives with quadratic load characteristic
as a function of the output frequency ratio in %
Figure 2b) shows the characteristic curve of the efficiency for drives with quadratic load characteristic as a function of
the output current ratio I
Out
/I
Out-rated
which is proportional to the motor torque ratio M/M
rated
.
Figure 2b)
Efficiency of SINAMICS S150 converters in drives with quadratic load characteristic
as a function of the output current ratio in %