Siemens SINAMICS G130 Engineering Manual page 374

SINAMICS S120
Engineering Information
Three identical braking resistors R
a motor. These resistors form a symmetrical resistive load. They can be built as three individual resistors in separate
housings or as a symmetrical 3-phase resistor in one housing. It is not permissible to use asymmetrical or single-
phase resistor arrangements.
The temperature switches (NC contacts) for monitoring the temperature of the three braking resistors must be
connected in series.
The minimum cable length to the braking resistors is 10 m. If this arrangement is not feasible, a motor reactor must
be employed.
The maximum cable length is 300 m with shielded cables and 450 m with unshielded cables, corresponding to the
maximum cable lengths for Motor Modules used for their standard purpose. The recommended cable types and
recommended, maximum connectable cable cross-sections are the same as those specified for S120 Motor Modules
used for their standard purpose.
Selection of Motor Modules
The output currents of SINAMICS S120 Motor Modules employed as 3-phase Braking Modules are in some cases
lower than those of Motor Modules used for the standard purpose.
The reason for this reduction in output current is that the MoMo output power is pure active power when it is
employed as a Braking Module. By contrast with the standard application in which the output power includes a
reactive component delivered by the DC link capacitors of the MoMo, a MoMo working as a Braking Module draws its
entire output power via the DC busbar, causing an increase in the input current across the DC fuses. The DC fuses
provided in air-cooled Motor Modules and the DC fuses recommended for liquid-cooled Motor Modules constitute a
unit-specific limit to the application as a Braking Module and thus necessitate a current reduction of up to 12 %
specific to the unit type.
The permissible output currents for application as Braking Modules (continuous braking current I
braking currents I and I
L-Brake
specific technical data on the next page.
As regards load duty cycles, the definitions, charts and calculation formulae contained in section "Load duty cycles" in
chapter "Fundamental Principles and System Description" apply, in which the quantities I
substituted in each case by I
The braking power P
Brake
during braking. This response threshold V
specified in the table below for the relevant line connection voltage.
On the one hand, the response threshold V
voltage to be expected in motor operation (including line voltage tolerances) in order to ensure that the Braking
Module will operate only when the drive is working in generator mode.
On the other hand, the upper value in the table must not be exceeded so as to reliably prevent tripping of the Motor
Module as a result of DC link overvoltage.
Line supply voltage
380 V – 480 V 3AC
500 V – 600 V 3AC
660 V – 690 V 3AC
Range of programmable response thresholds
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Ó Siemens AG
in a star connection are connected to the output of the Motor Module instead of
BR
, and the maximum braking current I
H-Brake
, I , I and I
rated-Brake L-Brake H-Brake
of a Motor Module working as a Braking Module is proportional to the DC link voltage
can be programmed freely, but should be limited to the range
DC-Brake
must be at least 50 V to 70 V higher than the maximum DC link
DC-Brake
Range of programmable response threshold V
673 V - 774 V
841 V - 967 V
1070 V - 1158 V
can be found in the table of unit-
max-Brake
.
max-Brake
DC-Brake
, base load
rated-Brake
I , I and I must be
rated, L H max