SIEMENS
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Siemens IC 10 · 2017
SIRIUS 3RW Soft Starters
3RW30, 3RW40 for Standard Applications
3RW40
Accessories
6
Configuration
The solid-state 3RW soft starters are designed for easy starting
conditions. In the event of deviating conditions or increased
switching frequency, it may be necessary to choose a larger
device.
Where long starting times are involved, the integrated electronic
overload relay for heavy starting should not be disconnected.
PTC sensors are recommended. This also applies for the soft
ramp-down because during the ramp down time an additional
current loading applies in contrast to coasting down.
In the case of high switching frequencies in S4 mode, Siemens
recommends the use of PTC sensors. For corresponding device
versions with integrated thermistor motor protection or separate
thermistor evaluation devices,
see page 10/157
.
No capacitive elements are permitted in the motor feeder
between the SIRIUS 3RW soft starter and the motor (e.g. no
reactive-power compensation equipment). In addition, neither
static systems for reactive-power compensation nor dynamic
PFC (Power Factor Correction) must be operated in parallel
during starting and ramp-down of the soft starter. This is
important to prevent faults arising on the compensation
equipment and/or the soft starter.
All elements of the main circuit (such as fuses and controls)
should be dimensioned for direct starting, following the local
short-circuit conditions. Fuses, controls and overload relays
must be ordered separately. Please observe the maximum
switching frequencies specified in the technical specifications.
Note:
When three-phase motors are switched on, voltage drops occur
as a rule on starters of all types (direct-on-line starters, wye-delta
starters, soft starters). The infeed transformer must always be
dimensioned such that the voltage dip when starting the motor
remains within the permissible tolerance. If the infeed
transformer is dimensioned with only a small margin, it is best for
the control voltage to be supplied from a separate circuit
(independently of the main voltage) in order to avoid the
potential switching off of the soft starter.
Schematic circuit diagram of power electronics
A bypass contact system and electronic overload relay are already
integrated in the 3RW40 soft starter and therefore do not have to be
ordered separately.
Status graphs
Manual for SIRIUS 3RW30/40
In addition to relevant configuration, commissioning, and service
information, the manual also contains example circuits and
technical specifications for all devices,
see
.
L1
NSB0_001485a
L2
L3
T1
T2
T3
x
e
e
t
R on
t
U
U
N
U
S
t
R on
t
R off
t
R on
t
R off
ON 13/14
RUN 13/14
BYPASSED 23/24
NSB0_01486
t
t
© Siemens AG 2016