Fuses; Calculation Example - ABB ACS800 Hardware Manual

112

Fuses

gG and aR 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
between gG and aR fuses
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:
• ACS800-02-0260-3
• supply voltage U = 410 V
Transformer:
• rated power S
• rated voltage (drive supply voltage) U
• transformer impedance z
Supply cable:
• length = 170 m
• resistance/length = 0.112 ohm/km
• reactance/length = 0.0273 ohm/km.
Technical data
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
on page 116, or verify the operating time by checking
U
I =
k2-ph
2
R + (Z
2 ·
c
I = short-circuit current in symmetrical two-phase short-circuit (A)
k2-ph
U = network line-to-line voltage (V)
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
= 3000 kVA
N
= 7.2%.
k
2
U
N
·
Z = z · = 0.072
k k
S 3000 kVA
N
ohm
m · 0.112
R = 170
c
km
2
+ X )
k c
= 430 V
N
2
(430 V)
= 4.438 mohm
= 19.04 mohm
Quick guide for selecting