User Manual

SIRIUS 3RW30 / 3RW40
Manual, 10/2010, 535199502000 DS 03
127
Technical data
13
13.1 3RW30
13.1.1 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.