ABB ACS800-U7, Hardware Manual

Page: 116 / 148

Technical data
116
Fuses
The drive is equipped with aR fuses as standard. Standard aR fuses and optional gG
fuses for protection against short-circuit in the input power cable or drive are listed
below. Either fuse type may be used if it operates rapidly enough. Choose between
gG and aR fuses according to the table under
Quick guide for selecting between gG
and aR fuses on page 120, 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 (V)
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:
•
ACS800-07-0260-3
• supply voltage U = 410 V
Transformer:
•
rated power S
N
= 3000 kVA
• rated voltage (drive supply voltage) U
N
= 430 V
• transformer impedance z
k
= 7.2%.
I
k2-ph
=
2 ·
R
c
2
+ ( Z
k
+ X
c
)
2
U