Siemens SINAMICS Series Operating Instructions Manual page 107

The fundamental component of current I
following formula
I = g × 0.817 × I
1
where I
where g is the fundamental factor (see previous table)
The harmonic currents calculated according to the previous table only apply for:
I.) Short-circuit power S
S = U
K
with
X = X
N
and
U
v0
I Direct current of the operating point examined in A
d
f Line frequency in Hz
N
L Inductance of the commutating reactors used in H
D
X Impedance of the commutating reactor
D
X Impedance of the line
N
X Impedance at the unit terminals
K
II.) Armature inductance L
L = 0.0488 × U
a
If the actual values for the short-circuit power S
the values calculated using the previous formulas, a separate calculation procedure will need
to be carried out.
Example:
Let us assume a drive with the following data:
U
v0
I = 150 A
d
f = 50 Hz
N
L = 0.169 mH (4EU2421-7AA10 with I
D
With
X = 0.03536 × 400 / 150 - 2π × 50 × 0.169 × 10
N
the network short-circuit power at the converter unit terminal is as follows:
S = 400
K
and the armature inductance of the motor is as follows:
L = 0.0488 × 400 / (50 × 150) = 2.60 mH
a
The harmonic currents I
can be taken from the tables, only apply for the values S
in this way. If the actual values deviate from these, a separate calculation will have to be
made.
SINAMICS DCM DC Converter
Operating Instructions, 12/2018, A5E34763375A
d
is the DC current of the operating point under investigation and
d
at the location where the converter is connected
K
/ X (VA)
2 v0
N
- X = 0.03526 × U
K D
No-load voltage on the power unit terminal V
a
/ (f × I ) (H)
v0 N d
= 400 V
/ 0.0412 = 3.88 MVA
2
(with I
ν
6.1 Instructions for EMC-compliant drive installation
as a reference variable is calculated using the
1
/ I - 2πf × L (Ω)
v0 d N D
and/or armature inductance L
K
= 125 A)
Ln
-3
= g × 0.817 × I for firing angles α = 20° and α = 60°) that
1 d
= 0.0412 Ω
and L that have been calculated
K a
Connecting
deviate from
a
105