Siemens SINAMICS S120 Engineering Manual page 18

1 Engineering SINAMICS S120 Booksize
Calculating the required apparent power of the matching transformer
To determine the required apparent transformer power, it is still necessary to define the required relative short-circuit voltage of the matching
transformer:
u
k_matching transformer
DIN EN 60076-5 lists recognized minimum values according to power classes. In the typical power range for matching transformers from 25 to
630 kVA for SINAMICS S120 Booksize, the minimum value is 4%. Up to power ratings of 2500 kVA, this value increases up to 6%. This is the
Note
reason that here it is recommended to specify typical values from 4% to 6%.
The maximum permissible line impedance (from the minimum RSC and converter apparent power) and the existing impedances result in a maximum
permissible impedance of the matching transformer and thus the required minimum apparent power for a given u
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a minimum value of the transformer apparent power is obtained from the k factor for the infeed type:
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The minimum apparent power of the transformer is obtained from the maximum of the two values above:
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The minimum apparent power the matching transformer is therefore defined.
Engineering manual S120 Booksize
Entry-ID: 109808992, V1.0, 04/2022
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270.7 kVA
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18