Parallel Connection Of Basic Line Modules - Siemens SINAMICS S120 Function Manual

Function modules
8.10 Parallel connection of power units
8.10.1.1

Parallel connection of Basic Line Modules

Features of Basic Line Modules:
● The DC-link voltage is greater than the rms value of the line rated voltage by a factor of
1.35.
● They are used in cases where regenerative feedback capability is not required.
● If regenerative operating states occur in the drive line-up, Braking Modules that convert
the excess energy to heat in braking resistors must be used.
Basic Line Modules in chassis format are available for the following voltages and power
ratings:
Table 8- 9
Line supply voltage
380 to 480 V 3 phase AC
500 to 690 V 3-phase AC
The following rules must be observed when connecting Basic Line Modules in parallel:
● Up to four identical Basic Line Modules can be connected in parallel.
● A common Control Unit must always be used to implement the parallel connection.
● Special Line Connection Modules are available for the parallel connection.
● With multiple infeeds, power must be supplied to the systems from a common infeed
point (i.e. the modules cannot be operated on different line supplies).
● A current reduction (derating) of 7.5% must be taken into consideration, regardless of the
number of modules connected in parallel.
As Basic Line Modules have no current compensation control, the three-winding transformer,
power cabling and line reactors must meet the following requirements in order to provide a
balanced current:
● Three-winding transformer must be symmetrical, recommended vector groups Dy5d0 or
Dy11d0.
● 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
(cables of identical type with the same cross-section and length)
● Using line reactors that match the Basic Line Modules
Line reactors can be omitted if a double-tier transformer is used and only one Basic Line
Module is connected to each secondary winding of the transformer.
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.
564
Basic Line Modules
Rated power
200 ... 710 kW
250 ... 1100 kW
≥ 4%.
k
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
≤ 5%.
k
Drive functions