Technical data 103
Fuses
gG and aR fuses for protection against short circuit in the input power cable or drive
are listed below. Either fuse type can 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
(page 109)
,
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 (A)
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).
I
k2-ph
=
2 ·
R
c
2
+ (Z
k
+ X
c
)
2
U
To Next Page
Loading...
