Power chokes
Instruction handbook
b maXX
5000
Document No.: 5.09021.16
Baumüller Nürnberg GmbH
276
11.5
Example:
A transformer with a u
k
value of 5%, 400 V rated voltage and 500 kVA output is operated
in a 50 Hz mains. A device with the corresponding three-phase power choke, with 4 % u
k
,
is connected to this mains.
Thus, the transformer has an inductance of
L
transformer
u
k
U
N
2
2
f S
N
-----------------------------
0 05 400
2
V
2
2
50Hz 500kVA
--------------------------------------------------------
51
H
=
=
=
The inductance of the power choke is then calculated at
L
choke
u
k
U
N
3 I
N
2
f
--------------------------------------
400V 0 04
3 164A 2
50Hz
-------------------------------------------------------------
179
H
=
=
=
Thus, the effective inductance for the device is
L
Total
= L
Transformer
+ L
Choke
= 230 µH,
This corresponds to a u
k
value for the device of 5.13% relative to the phase voltage.
Power choke
type key
