Calculating The Short-Circuit Current Of The Installation; Calculation Example - ABB ACS580 Series Hardware Manual

296 Technical data
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Calculating the short-circuit current of the installation

Make sure that the short-circuit current of the installation is at least the value
given in the fuse table.
The short-circuit current of the installation can be calculated as follows:
I =
k2-ph
2
2 · R
c
where
I k2-ph Short-circuit current in symmetrical two-phase short-circuit
U Network line-to-line voltage (V)
R c Cable resistance (ohm)
Z k = z k · U n 2 / S n = transformer impedance (ohm)
Z k
z k
Transformer impedance (%)
U n
Transformer rated voltage (V)
S n
Nominal apparent power of the transformer (kVA)
X c
Cable reactance (ohm)

Calculation example

Drive:
• ACS580-01-145A-4
• supply voltage = 410 V
Transformer:
• rated power S
rated secondary voltage (supply for drive supply) U
•
• transformer impedance z
Supply cable:
• length = 170 m
• resistance/length = 0.398 ohm/km
• reactance/length = 0.082 ohm/km.
U
2
+ (Z + X )
k c
= 600 kVA
n
= 7.2%
k
= 430 V
n