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3RW3 semiconductor motor control unit
SIRIUS System Manual
8-18
GWA 4NEB 430 0999-02b
8.3 Application and use
8.3.1 Areas of application and criteria for selection
The SIRIUS 3RW3 soft starters offer an alternative to star-delta starters (see
Section 8.2.4 for a comparison and the advantages).
The most important advantages are soft starting and soft coasting-down,
interruption-free switching without current spikes that could interfere with
the supply system, and compact dimensions.
Many drives that needed frequency converters in the past can be changed
to soft-start operation with the 3RW3, if the applications do not call for vari-
ations in speed.
Applications
Typical applications include, for example:
Conveyor belts, conveyor systems:
• Smooth starting
• Smooth slowing
• Use of better-value conveyor material
Rotary pumps, piston-type pumps
• Avoidance of pressure surges
• Extended service life of the piping system
Agitators, mixers:
• Reduced starting current
Fans:
• Less strain on gearing and drive belts
Cooling time
Note:
The cooling time must be taken into consideration in the starting frequency.
8.3.2 Installation guidelines
On account of the heat generated, certain installation guidelines must be
adhered to when combining 3RW30/31 soft starters with other SIRIUS
switching devices.
Stand-alone installa-
tion
Stand-alone installation is when minimum vertical
and
lateral clearances
between the mounted devices are not violated. This applies both to indivi-
dual devices and complete load feeders.
The following minimum clearances must be adhered to in stand-alone instal-
lation (these minimum clearances depend on the frame size):
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