Overview; 14.2 3Rw30 - Siemens SIRIUS 3RW30 Manual

Technical data

14.2 3RW30

14.2 3RW30
14.2.1

Overview

SIRIUS 3RW30 soft starters reduce the motor voltage through variable phase angle control
and increase it from a selectable starting voltage up to the mains voltage within the ramp
time. They limit the starting current and torque, so that the shocks that occur during direct
starts or wye-delta starting are avoided. Mechanical loads and mains voltage dips can be
effectively prevented in this way.
Soft starting reduces the stress on the connected equipment, resulting in lower wear and
therefore longer periods of trouble-free production. The selectable starting voltage means
the soft starters can be individually adjusted to the requirements of the application in
question and – unlike wye-delta starters – are not restricted to two-stage starting with fixed
voltage ratios.
SIRIUS 3RW30 soft starters are characterized above all by their small space requirements.
Integral bypass contacts mean that no power loss has to be taken into account at the power
semiconductors (thyristors) after the motor has started up. This cuts down on heat losses,
enabling a more compact design and making external bypass circuits superfluous.
Soft starters rated up to 55 kW (at 400 V) can be supplied for standard applications in three-
phase systems. Extremely small sizes, low power losses and simple startup are just three of
the many advantages of this soft starter.
Note
The rated motor current is extremely important when selecting a soft starter.
Refer to the information about selecting soft starters in chapter Configuration (Page 85).
Conditions for normal starting:
Max. ramp time 3 s, starting current 300%, 20 starts/hour, ON time 30%, standalone
assembly, max. installation altitude 1000 m / 3280 ft, ambient temperature
kW 40 °C / 104 °F. In the event of deviating conditions or increased switching frequency, it
may be necessary to choose a larger device. For information about the rated currents for
ambient temperatures above 40 °C, refer to chapter 3RW30..-.BB.. power electronics
(Page 130).
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SIRIUS 3RW30 / 3RW40
Manual, 10/2018, NEB535199502000/RS-AB/005