Siemens SIRIUS 3RW3028-1BB14 Soft Starter, 18.5 kW at 400 V, 38 A, 200-460 V AC, 24 V AC Control

Motor starting often causes mechanical stress and high inrush currents that can trip breakers and wear down equipment. The Siemens SIRIUS 3RW3028-1BB14 soft starter eliminates these problems by ramping up voltage smoothly, reducing peak current and torque during start-up. This protects your motor, gearbox, and driven machinery while ensuring a stable power supply.

Who is it for

This soft starter is ideal for plant engineers, panel builders, and maintenance teams who need reliable starting for three-phase motors up to 18.5 kW at 400 V. It suits applications like pumps, fans, compressors, and small conveyor systems where direct-on-line starting is too harsh. With its compact design and simple wiring, it fits easily into motor control centers and industrial cabinets.

Main features

• Rated for 38 A continuous current at 40°C, handling motors up to 18.5 kW at 400 V or 11 kW at 230 V.
• Wide operating voltage range from 200 to 460 V AC, 50/60 Hz, for flexible integration.
• Integrated bypass contacts reduce heat generation and energy loss after motor reaches full speed.
• Adjustable starting voltage and ramp time allow fine-tuning for smooth acceleration.
• Compact IP00 housing mounts on DIN rail or with screws, saving panel space.
• 24 V AC control supply for safe, low-voltage operation.
• Starting current limitation up to 300% of rated motor current prevents voltage dips.

Specifications

• Product type: Soft starter
• Series: SIRIUS 3RW30
• Rated operating current at 40°C: 38 A
• Motor power at 400 V, 40°C: 18.5 kW
• Motor power at 230 V, 40°C: 11 kW
• Operating voltage range: 200 - 460 V AC
• Control supply voltage: 24 V AC
• Number of phases: 3
• Integrated bypass: Yes
• Overload protection: No (external required)
• Starting current limitation: 300% of rated motor current
• Mounting type: DIN rail / screw mounting
• Degree of protection: IP00
• Ambient operating temperature: -25 to +60 °C
• Main circuit connection: Screw terminals
• Control circuit connection: Screw terminals

Tips

Always install an external motor overload relay or circuit breaker downstream of the soft starter to protect against overcurrent. Ensure adequate ventilation in the enclosure because the IP00 design requires protection from dust and moisture. For frequent starts, check the duty cycle to avoid overheating.