Siemens SINAMICS S120 Combi - Page 52

Line-side power components
2.8 Line connection versions
SINAMICS S120 Combi
50 Manual, Edition 07/2012, 6SL3097-4AV00-0BP3
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Note:
The system fault level (short-circuit power) at the plant connection S
K plant
plays a decisive
role in dimensioning/selecting the matching transformer.
From the rated power (S
n1
or S
n2
) calculated under a) and b), the higher value must be used
for the matching transformer.
Table 2- 7 Transformer configuration instructions
S120 Combi Power Module
P
n
Required rated power S
n
of
the isolation
transformer/autotransformer
Required short-circuit
voltage u
k
Required system fault level
S
K line
16 kW S
n
≥ 21 kVA u
k
≤ 3 % S
K line
≥ 1.12 MVA
20 kW S
n
≥ 26 kVA u
k
≤ 3 % S
K line
≥ 1.4 MVA
Note
Ask your local power utility company for the system fault level S
K line
.
Example 1
u
k
matching transformer = 3 %
S
K plant
= 50000 kVA
S
K line
= 16 kW • 70 • 0.73 = 820 kVA
According to a)
S
n1
= 1.27 • 16 kW = 21 kVA
According to b)
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S
n2
> S
n1
⇒ S
n2
is decisive
The matching transformer requires a rated power S
n
of 25 kVA for a short-circuit voltage u
k
of 3%.