Siemens SINAMICS G130 Engineering Manual page 168

Fundamental Principles and System Description
Engineering Information
2
The I t value, averaged over a load duty cycle duration T of max. 300 s, must not exceed the 100 % value. The
exeptions are stated in the table.
For the following SINAMICS converters or Motor Modules the permissible I
100 % with load duty cycles:
Converter Line
or volt-
Motor Module age
SINAMICS G and S 400 V
SINAMICS G and S 400 V
SINAMICS G and S 400 V
SINAMICS G and S 400 V
SINAMICS G and S 400 V
SINAMICS S 4AS3 400 V
2
The I t value is the criterion for losses and temperature rise in the power unit during the load duty cycle and is defined
as follows:
Key to equation:
·
I(t) RMS value of the output current of the converter or inverter as a function of time
(In the case of parallel connections of S120 Motor Modules, I(t) is the RMS value of the output
current of a partial inverter resp. one Motor Module.)
·
I Rated output current of the converter or inverter
Rated
(In the case of parallel connections of S120 Motor Modules, I
partial inverter resp. one Motor Module, not taking into account the derating factor for parallel
operation.)
·
k Current derating factor (total derating factor; see above for definition)
D
·
T Load duty cycle duration which must not exceed the 300 s value for the standard load duty cycle
For the practical calculation of the I
current in each case as an approximate substitute to the output current time characteristic required by the application.
This simplifies the calculation as the integration is replaced by a simple summation.
1
2 =
t I value
T
i.e. the sum of all phases T
below illustrates the correlations.
Approximation of the current characteristic over time using time phases with constant current
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Ó Siemens AG
Permissible
Output Output
2
I t value
rat- current
with load
ing
duty cycles
110 kW 210 A 90 %
315 kW 605 A 72 %
400 kW 745 A 73 %
450 kW 840 A 87 %
560 kW 985 A 95 %
800 kW 1330 A 93 %
1
2 = ×
t I value
T
2
t value, it is generally helpful to apply a finite number m of phases of constant
é
2
æ ö æ
I
ç ç ÷ ÷ ç ç
ê
× × +
1 T
1
×
I k I
ê
è ø è
ë
Rated D Rated
where
to T equals the load duty cycle duration T, where T must be ≤ 300 s. The diagram
1 m
2
t value is limited to values of less than
Converter Line
or volt-
Motor Module age
SINAMICS G 400 V
SINAMICS G 400 V
SINAMICS G 400 V
SINAMICS G + S 500 V
SINAMICS G + S 690 V
SINAMICS S LC 690 V
2
æ ö
T
t I ) (
ò
ç ç ÷ ÷
dt
• 100 %
×
I k
è ø
Rated D
0
Rated
2
ö æ
I
÷ ÷ ç ç
× + +
2 T ......
2
×
k I
ø è
D
m
å
=
T T
,
m
1
Output Output
rat- current
ing
630 kW 1120 A
710 kW 1380 A
900 kW 1560 A
200 kW 330 A
315 kW 330 A
1500kW 1560 A
is the rated output current of a
ù
2
ö
I
÷ ÷
ú
× •
n
T
100 %
m
×
k
ú
ø
û
Rated D
Permissible
2
I t value
with load
duty cycles
72 %
73 %
86 %
90 %
90 %
85 %