ABB ACS800 Series - Frame Sizes R5 and R6; Calculation Example

Technical data
110
Frame sizes R5 and R6
Choose between gG and aR fuses according to the table under Quick guide for
selecting between gG and aR fuses on page 114, or verify the operating time by
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
I
k2-ph
= short-circuit current in symmetrical two-phase short-circuit
U = network line-to-line voltage (U)
R
c
= cable resistance (ohm)
Z
k
= z
k
· U
N
2
/S
N
= transformer impedance (ohm)
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:
• ACS800-01-0075-3
• supply voltage
Transformer:
• rated power S
N
= 600 kVA
• rated voltage (drive supply voltage) U
N
= 430 V
• transformer impedance z
k
= 7.2%.
Supply cable:
• length = 170 m
• resistance/length = 0.398 ohm/km
• reactance/length = 0.082 ohm/km.
I
k2-ph
=
2 ·
R
c
2
+ (Z
k
+ X
c
)
2
U
·
(430 V)
2
600 kVA
= 22.19 mohm
Z
k
= z
k
·
U
N
2
S
N
= 0.072
m
·
0.398
ohm
km
= 67.66 mohm
R
c
= 170
m
·
0.082
ohm
km
= 13.94 mohm
X
c
= 170