Frame Sizes R5 And R6; Calculation Example - ABB ACS800 Series Hardware Manual

110

Frame sizes R5 and R6

Choose between gG and aR fuses according to the table under
selecting between gG and aR fuses
checking that the short-circuit current of the installation is at least the value
given in the fuse table. The short-circuit current can be calculated as follows:
where

Calculation example

Drive:
• ACS800-01-0075-3
• supply voltage
Transformer:
• rated power S
• rated voltage (drive supply voltage) U
• transformer impedance z
Supply cable:
• length = 170 m
• resistance/length = 0.398 ohm/km
• reactance/length = 0.082 ohm/km.
Technical data
U
I =
k2-ph
2
R + (Z
2 ·
c
I = short-circuit current in symmetrical two-phase short-circuit
k2-ph
U = network line-to-line voltage (U)
R = cable resistance (ohm)
c
2
Z = z · U /S = transformer impedance (ohm)
k k N N
z = transformer impedance (%)
k
U = transformer rated voltage (V)
N
S = nominal apparent power of the transformer (kVA)
N
X = cable reactance (ohm).
c
= 600 kVA
N
2
U
N
·
Z = z · = 0.072
k k
S
N
ohm
m · 0.398
R = 170
c
km
ohm
m · 0.082
X = 170
c
km
on page 114, or verify the operating time by
2
+ X )
k c
= 430 V
N
= 7.2%.
k
2
(430 V)
= 22.19 mohm
600 kVA
= 67.66 mohm
= 13.94 mohm
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