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3RW3 semiconductor motor control unit
SIRIUS System Manual
GWA 4NEB 430 0999-02b
8-15
SIKOSTART 3RW34
The SIKOSTART 3RW34 is suitable for drives with low demands in terms of
the functionality of the soft starter. The SIKOSTART 3RW34 is very similar to
the SIRIUS 3RW3 soft starter in terms of its operation and configuration. It
covers a power range of up to 1000 kW (400 V).
The functions of the 3RW34 are as follows:
• Soft starting and soft coasting down
• 2 circuit variants: standard and root 3 circuits
• Three-phase control
• Optional AS-i bus control
You will find the technical specifications and a detailed description of the
3RW34 in the document describing SIKOSTART 3RW22/3RW34 solid-state
motor controllers (order no.: E20001-A200-P302).
SIRIUS 3RW3 soft
starter
The SIRIUS 3RW3 soft starter covers the power range from 1.5 kW to
45 kW.
Power semiconductors always exhibit power loss. This manifests itself in
heat generation. In order to keep this power loss as low as possible, the
semiconductors are bypassed by relay contacts after the motor has started
up. The device's heat sink and its dimensions can thus be smaller than they
otherwise would be. In addition, it is necessary to use a bypass contactor,
which bypasses the line semiconductors in the conventional configuration.
For further processing in the system controller, the device offers two relay
outputs:
• "ON" contact (terminals 13/14), which can be used, for example, to control
the soft starter by button (locking)
• "BYPASSED" contact (terminals 23/24), which signals the completion of
startup (e.g. in order to switch a solenoid valve after a soft-started pump
has started up)
For drives in this power range, good motor startups can be achieved with a
two-phase controller.
In the case of a two-phase controller, semiconductor elements are only
used in two phases in order to reduce motor current and motor voltage in all
three phases. The third phase is bypassed internally in the soft starter.