Siemens SINAMICS S120, Function Manual

Page: 566 / 1094

Function modules
8.10 Parallel connection of power units
Drive functions
566
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
WARNING
Unexpected motion of individual drives
If several Motor Modules are supplied from one infeed unit, then if the V
dc_max
control is
incorrectly parameterized, individual drives can accelerate in an uncontrolled fashion -
which can lead to death or severe injury.
• Only activate the V
dc_max
control for the Motor Module whose drive has the highest
moment of inertia.
•
Inhibit this function for all other Motor Modules, or set this function to monitoring only.
8.10.1.2 Parallel connection of Smart Line Modules
Smart Line Modules are infeed/regenerative feedback units. Like the Basic Line Modules,
they supply energy to the connected Motor Modules, but unlike the Basic Line Module, they
are capable of feeding back regenerative energy to the line supply.
The DC-link voltage is greater than the rms value of the line rated voltage by a factor of 1.3.
Smart Line Modules in chassis format are suitable for connection to grounded (TN, TT) and
non-grounded (IT) supply systems. The following voltages and power ratings are available:
Table 8- 10 Smart Line Modules
Line supply voltage Rated power
380 to 480 V 3 phase AC 250 ... 800 kW
500 to 690 V 3-phase AC 450 ... 1400 kW
The following rules must be observed when connecting Smart Line Modules in parallel:
● Up to four identical Smart Line Modules can be connected in parallel.
● A common Control Unit must always be used to implement the parallel connection.
● A 4% reactor is always required upstream of each Smart Line Module for the purpose of
current balancing.
● 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 derating factor of 7.5% must be taken into consideration, regardless of the number of
modules connected in parallel.