Siemens SINAMICS G130 Engineering Manual page 162

Fundamental Principles and System Description
Engineering Information
Depending on whether it is only necessary to prevent the intervention by the thermal monitoring model at occasional
overloads or whether the lifetime of the IGBTs has to be taken in account when the sum of the overload periods
corresponds to more than about 2 % of the total operating time, different measures are required.
1.12.3.2.1 Operation with high overload with occasional periods of low output frequencies < 10 Hz
In this case, the drive must only be configured to ensure that no overload reaction is initiated by the thermal
monitoring model. The effect on the lifetime of the IGBTs is negligible and need not be taken into account.
If the converter occasionally has to operate without triggering an overload reaction for a period corresponding to less
than approx. 1 % to max. 2 % of its total operating time at output frequencies of less than 10 Hz with a short-time
current of I = 1.5 • I
ShortTime
the associated base load current I
accordance with the following derating characteristic (precondition: Overload reaction parameter is set to p290 = 1).
Permissible short-time current and permissible base load current with occasional
high overload as a function of the output frequency and the overload period t
Note:
As the derating curve indicates, high current loads for brief periods at low output frequencies, such as those which
might occur during occasional starting and braking, can be ignored provided that they do not last longer than 0.5 s in
each case and the total high-load period equals less than 1 % to max. 2 % of the total operating time.
As an example, the hoisting drive for a container crane is normally accelerated or braked at high current several
times within a period of 1 minute. However, since the operating conditions - which involve low output frequencies and
high output currents - normally last only for a period of fractions of a second and do not typically total more than
approximately 1 % to max. 2 % of the total operating time of the hoisting drive, no derating needs to be applied when
drives of this type are configured.
1.12.3.2.2 Operation with high 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 frequently has to operate without triggering an overload reaction and without risk of premature IGBT
failure for a period corresponding to more than approximately 1 % to max. 2 % of its total operating time or
permanently at output frequencies of less than 10 Hz with a short-time current of I
load duty cycle "high overload", then the short-time currrent I
be reduced depending on the output frequency in accordance eith the following derating characteristic.
SINAMICS Engineering Manual – November 2015
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Ó Siemens AG
according to the load duty cycle "high overload", then the short-time current I
H
must be reduced depending on the output frequency and the overload period t in
H
ShortTime
and the associated base load current I
ShortTime
and
ShortTime
= 1,5 • I according to the
H
must
H