Siemens 6SN1123-1AA00-0DA2 Configuration Manual page 213

7 Line Supply Connection
7.2 Voltage matching
S calculation of
n
the matching
transformer for an
NE module
Note:
Examples
7-212
S
Condition a)
The rated power (Sn) of the matching transformer must be:
w 1.27  Pn (I/R module [kW])
S
n1
Example: The minimum rated power of a matching transformer
for I/R module 16/21 is 21 kVA.
S
Condition b)
In order to avoid faults and disturbances at the other loads, that are con-
nected to the secondary side of the matching transformer, the sum of the
system fault level (short–circuit power) of the plant connection and that of
the matching transformer at the connection point (S
tain at least the values shown in Table 7-1, Chapter C.1.3. Depending on the
vector group of the transformers, e.g. YYn0, asymmetric loading of the N/MP
may not be permitted.
Consequently, the required rated power S
culated.
 S
S
+
K plant K line
S
n2
(S – S
K plant
This means:
Sn1, Sn2 Calculated rated power of the matching transformer
uk Short–circuit voltage of the matching transformer as % (see Table 7-2)
S Short–circuit power.
K
S if necessary, consult the utility company
K plant
S = at least the value contained in Chapter C.1.3,Table 7-1
K line
The system fault level at the plant connection S
dimensioning/selecting the matching transformer.
From the rated power (Sn
be used for the matching transformer.
Matching transformer for 16/21 kW I/R module sinusoidal current:
uk matching transformer = 3%; S
sinusoidal current according to Table 7-1: S
= 1.27  16 kW = 21 kVA
based on a) S
n1
based on b) Calculation of Sn2
Case 1:
+
S
n2
S > S
n2 n1
The matching transformer requires a rated power S
at a uk of 3%.
Case 2:
If the uk of the matching transformer is less than, e.g. uk=1%
for otherwise unchanged conditions for Case 1:
+
S
n2
S > S
n1 n2
The matching transformer requires an Sn rated power of 21 kVA
at a uk of 1%.
SIMODRIVE 611 Configuration Manual (PJU) – 02/2012 Edition
[kVA]
of the matching transformer is cal-
n2
 uk
[kVA]
)  100
K line
plant plays a decisive role in
K
or S ) calculated under a) and b), the higher must
1 n2
= 50000 kVA ; S
K plant
= 1120  0.73 = 820 kVA
K line
50000  820  3
= 25 kVA
(50000 – 820)  100
⇒ S
is decisive
n2
50000  820  1
= 8.3 kVA
(50000 – 820)  100
⇒ S
is decisive
n1
© Siemens AG 2012 All Rights Reserved
05.08
05.01
line supply) must con-
K
for I/R 16/21 kW
K line
of 25 kVA
n