Siemens SINAMICS S120 Function Manual page 325

● Three-winding transformer must be symmetrical, recommended vector groups Dy5d0 or
● Relative short-circuit voltage of three-winding transformer u
● Difference between relative short-circuit voltages of secondary windings Δu
● Difference between no-load voltages of secondary windings ΔU ≤ 0.5 %.
● Use of symmetrical power cabling between the transformer and the Basic Line Modules
● Use of suitable line reactors for the Basic Line Modules. Line reactors can be omitted if a
A double-tier transformer is generally the only means of meeting the requirements of a three-
winding transformer for this application. Line reactors must always be installed if other types
of three-winding transformer are used. Alternative solutions for obtaining a phase
displacement of 30 °, such as two separate transformers with different vector groups, cannot
be used due to the inadmissibly high tolerances involved.
Drive functions
Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5
Dy11d0.
(cables of identical type with the same cross-section and length)
double-tier transformer is used and only one Basic Line Module is connected to each
secondary winding of the transformer.
Function modules
7.11 Parallel connection of power units
≥ 4%.
k
≤ 5%.
k
325