3RW4073-6BB44 230A Soft Starter 132kW/400V

Introduction to the Siemens 3RW4073-6BB44 Soft Starter

When motor starting stress leads to downtime, the 3RW4073-6BB44 provides a controlled ramp-up that protects both the motor and the driven equipment. This SIRIUS soft starter is engineered for three-phase motors in industrial applications where reliability and performance are non-negotiable.

With an operational current of 230 A at 40 °C, the 3RW4073-6BB44 handles demanding loads while maintaining precise control. It supports a rated operational voltage of 200–460 V AC, making it versatile across global installations.

Key Features and Technical Specifications

The 3RW4073-6BB44 integrates essential protective functions that reduce the risk of motor damage and unplanned stoppages.

• Rated operational current: 230 A at 40 °C; derates to 205 A at 50 °C and 180 A at 60 °C.
• Rated operational voltage: 200–460 V AC (standard circuit).
• Mechanical performance: 132 kW at 400 V (standard circuit, 40 °C); 75 kW at 230 V.
• Integrated bypass contact system: reduces heat dissipation and energy losses during continuous running.
• Thyristor-based power control: ensures smooth, adjustable current limitation.
• Motor overload protection: built-in, with adjustable motor current from 80 A minimum.
• External reset: supported for convenient fault recovery.
• Control supply voltage: 230 V AC at 50/60 Hz.

The device also features a red fault signal display, making status identification straightforward. Its insulation voltage is rated at 600 V, and it meets degree of pollution 3 per IEC 60947-4-2.

Applications and Use Cases

This soft starter suits conveyors, pumps, fans, and compressors where controlled acceleration extends equipment life. For example, in a pumping station, the 3RW4073-6BB44 reduces water hammer by gradually increasing torque. Similarly, on a conveyor line, it prevents belt slippage and mechanical shock during startup.

Its adjustable current limitation allows tuning to match specific load characteristics, improving process consistency. The integrated bypass further enhances energy efficiency, especially in applications with long run times.

Installation and Mounting Guidance

Proper installation ensures reliable operation and thermal management. The 3RW4073-6BB44 uses screw fixing and can be mounted on a vertical surface. With an additional fan, the unit allows ±90° rotation and ±22.5° tilt; without a fan, rotation is limited to ±10°.

Maintain required clearances: 100 mm above, 5 mm at the side, and 75 mm below for side-by-side mounting. The maximum wire length is 300 m, which should be considered when planning control wiring.

For main circuit connections, busbar connections are standard, while auxiliary and control circuits use screw terminals. Conductor cross-sections range from 70 to 240 mm² (finely stranded) or 95 to 300 mm² (stranded) at the front clamping point.

Maintenance and Reliability

Regular inspection of the soft starter and its connections helps maintain performance. Because the unit includes an integrated bypass, the thyristors are only active during start and stop, reducing thermal stress and extending service life.

Check the ambient temperature: the device operates from -25 °C to +60 °C, with derating starting at 40 °C. Ensure ventilation is unobstructed to avoid overheating. Periodically verify that all terminal screws remain tight, as vibration can loosen them over time.

Compatibility and Integration

The 3RW4073-6BB44 is part of the SIRIUS family, designed for seamless integration into motor control centers and switchgear. It accepts a 230 V AC control supply at 50 or 60 Hz, with tolerances of -15%/+10%.

It provides two NO auxiliary contacts and one CO contact for status feedback. The device supports external reset, enabling remote or automated restart after a fault. Its compact size (160 mm width, 230 mm height, 278 mm depth) fits standard enclosures.

Troubleshooting Common Issues

If the soft starter fails to start, check the control supply voltage and frequency. Verify that the motor current setting is above the minimum of 80 A and within the adjustable range. If the unit trips on overload, confirm the motor is not mechanically jammed.

For fault indication, the red LED provides a clear signal. Use the external reset to clear faults after resolving the root cause. If issues persist, consult the Siemens documentation or contact AutoDCSTech for support.

Product Support and Availability

The Siemens 3RW4073-6BB44 is available from AutoDCSTech. Please verify current lifecycle status and availability before ordering, as this product is phased out. Contact AutoDCSTech for pricing and delivery options.