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Siemens IC 10 · 2017
SIRIUS 3RW Soft Starters
3RW44 for High Feature Applications
Accessories
6
Circuit concept
The SIRIUS 3RW44 soft starters can be operated in two different
types of circuit:
•
Inline circuit:
The controls for isolating and protecting the motor are simply
connected in series with the soft starter. The motor is
connected to the soft starter with three leads.
•
Inside-delta circuit:
The wiring is similar to that of wye-delta starters. The phases
of the soft starter are connected in series with the individual
motor windings. The soft starter then only has to carry the
phase current, amounting to about 58 % of the rated motor
current (conductor current).
Comparison of the types of circuit:
Inline circuit:
Rated current
I
e
corresponds to the rated motor current
I
n
,
three cables to the motor
Inside-delta circuit:
Rated current
I
e
corresponds to approx. 58 % of the rated motor current
I
n
, six cables to motor (as for wye-delta starters)
Which circuit?
Using the inline circuit involves the lowest wiring outlay. If the soft
starter to motor connections are long, this circuit is preferable.
The wiring complexity is twice as high when using the inside-
delta circuit, but a smaller device can be used with the same
rating. Thanks to the choice of operating mode between the
inline circuit and inside-delta circuit, it is always possible to
select the most favorable solution.
The braking function is possible only in the inline circuit.
Configuration
The solid-state 3RW44 soft starters are designed for normal
starting. In case of heavy starting or increased starting
frequency, a larger device must be selected.
3RW44 soft starters may be used in isolated supply networks
(IT systems) up to 600 V AC.
For long starting times it is recommended to have a PTC sensor
in the motor. This also applies for the ramp-down modes torque
control, pump stop and DC braking, because during the ramp-
down time in these modes, an additional current loading applies
in contrast to free ramp-down.
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.
A bypass contact system and electronic overload relay are
already integrated in the 3RW44 soft starter and therefore do not
have to be ordered separately.
The harmonic component load for starting currents must be
taken into consideration for the selection of motor starter
protectors (selection of release).
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.
For dimensioning soft starters, we recommend our Simulation Tool
for Soft Starters (STS):
or our Technical Assistance: Tel.: +49 (0) 911-895-5900,
e-mail:
technical-assistance@siemens.com
.
Device interface, PROFIBUS DP/PROFINET communication
module, Soft Starter ES parameterizing and operating
software
The solid-state 3RW44 soft starters have a PC interface for
communicating with the Soft Starter ES software or for
connecting the external display and operator module. If the
optional PROFIBUS/PROFINET communication module is used,
the 3RW44 soft starter can be integrated in the
PROFIBUS/PROFINET network and communicate using the
GSD file or Soft Starter ES Premium software.
SIRIUS 3RW44 soft starter block library for SIMATIC PCS 7
The SIRIUS 3RW44 Soft Starter PCS 7 block library can be used
for simple and easy integration of SIRIUS 3RW44 soft starters
into the SIMATIC PCS 7 process control system. The SIRIUS
3RW44 soft starter PCS 7 block library contains the diagnostics
and driver blocks corresponding with the SIMATIC PCS 7
diagnostics and driver concept as well as the elements (symbols
and faceplates) required for operator control and process
monitoring.
Manual for SIRIUS 3RW44
In addition to relevant configuration, commissioning, and service
information, the manual also contains example circuits and
technical specifications for all devices:
.
NSB0_00424
L1
L2
L3
N
PE
NSB0_00425
L1
L2
L3
N
PE
W2
W1
T3
L3
V1
V2
L2
T2
U2
U1
T1
L1
© Siemens AG 2016