SIEMENS Sirius softstarter 30 kW 400 V 24 V AC/DC 3RW4037-1 (3RW40371BB04)

Motor starting often causes high inrush currents and mechanical stress, leading to voltage dips and increased wear. The SIEMENS Sirius 3RW4037-1 soft starter addresses this by providing a smooth voltage ramp-up, reducing starting current and torque peaks. This protects both the motor and the driven machinery, extending service life and improving power quality.

Who is it for

This soft starter is intended for industrial applications where three-phase motors up to 30 kW (at 400 V) need controlled starting and stopping. It suits conveyor systems, pumps, fans, compressors, and other machinery where abrupt starts can cause damage or process disruption. Engineers and panel builders will appreciate its compact design and integrated bypass, which simplifies installation and reduces heat dissipation.

Main features

• Soft start with adjustable voltage ramp, reducing mechanical stress and current peaks.
• Integrated bypass contacts for energy-efficient operation after motor reaches full speed.
• Solid-state motor overload protection, adjustable to match motor characteristics.
• Control supply voltage of 24 V AC/DC for flexible integration.
• Adjustable ramp-up and ramp-down times from 0 to 20 seconds.
• Current limitation function to prevent excessive starting current.
• Screw terminals for secure wiring.
• Mounting on DIN rail or screw mounting for easy installation.

Specifications

• Motor power (standard connection): 30 kW at 400 V
• Motor power (in-line circuit): 55 kW at 400 V
• Operating voltage (main circuit): 400 V AC
• Control supply voltage: 24 V AC/DC
• Operating current at 40°C: 65 A
• Number of phases: 3-phase
• Ramp-up time: 0 to 20 s adjustable
• Ramp-down time: 0 to 20 s adjustable
• Integrated bypass: Yes
• Overload protection: Integrated solid-state motor protection
• Current limitation: Adjustable
• Terminal type: Screw terminals
• Mounting type: DIN rail or screw mounting
• Degree of protection (main circuit): IP00
• Degree of protection (terminals): IP20
• Ambient operating temperature: -25 to +60 °C (derating above 40°C)
• Rated insulation voltage: 690 V

Tips

For optimal performance, ensure the control supply voltage is stable and within the specified range. When selecting the soft starter, consider the motor's starting duty and ambient temperature; derating may be necessary above 40°C. Proper ventilation is required due to the IP00 rating of the main circuit.