Siemens SINAMICS G130 Engineering Manual page 161

Fundamental Principles and System Description
Engineering Information
Permissible output current in operation without overload with occasional
periods of low output frequencies as a function of the output frequency
1.12.3.1.2 Operation without overload with frequent periods of low output frequencies < 10 Hz
In this case, the converter must be configured to ensure that the thermal monitoring model does not trigger
inappropriate overload reactions and that the lifetime of the IGBTs is not significantly reduced.
If the converter is to be operated frequently, i.e. for a period corresponding to more than approximately 1 % to max.
2 % of its total operating period, or continuously at output frequencies of less than 10 Hz without intervention of an
overload reaction and without risk of premature IGBT failure, the output current must be reduced as a function of the
output frequency according to the derating curve below.
Permissible output current in operation without overload with frequent periods
of low output frequencies as a function of the output frequency
1.12.3.2 Operation with high overload at low output frequencies < 10 Hz
As the output frequency decreases, the absolute chip temperature T reaches its limit value after ever shorter
Chip
periods of overload with the result that the thermal monitoring model might eventually intervene after very short
periods of overload. This must be taken into account at the configuring stage.
As the output frequency decreases, the temperature swing ΔT also increases continuously during the overload
Chip
period. If the periods of overload occur frequently or periodically with more than approximately 1 % to max. 2 % of the
total operating period, measures must be taken to ensure that the lifetime of the IGBTs is not reduced.
SINAMICS Engineering Manual – November 2015
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