Siemens SINAMICS S120 Combi - Page 61

Line-side power components
3.8 Line connection versions
SINAMICS S120 Combi
Manual, (GH9), 07/2016, 6SL3097-4AV00-0BP5
61
Example 2
u
k
matching transformer = 1 %
S
K plant
= 50000 kVA
S
K line
= 16 kW • 70 • 0.73 = 820 kVA
according to a)
S
n1
= 1.27 • 16 kW = 21 kVA
According to b)
S
n1
> S
n2
⇒ S
n1
is decisive
The matching transformer requires a rated power S
n
of 21 kVA for a short-circuit voltage u
k
of 1%.
Example 3
If S
K plant
is lower, then a higher-rating transformer must be used.
u
k
matching transformer = 3 %
S
K plant
= 3000 kVA
S
K line
= 16 kW • 70 • 0.73 = 820 kVA
according to a)
S
n1
= 1.27 • 16 kW = 21 kVA
According to b)
S
n2
> S
n1
⇒ S
n2
is decisive
The matching transformer requires a rated power S
n
of 34 kVA for a short-circuit voltage uk
of 3%.
Example 4
If S
K plant
is lower, you can use, alternatively to example 3, a transformer with a lower u
k
.
u
k
matching transformer = 1 %,
S
K plant
= 3,000 kVA
S
K line
= 16 kW • 70 • 0.73 = 820 kVA
according to a)
S
n1
= 1.27 • 16 kW = 21 kVA
According to b)