Soft Starter · 25 A, 11 kW at 400 V, 200-480 V AC, screw terminals · Siemens 3RW4026-1BB14

What this product is for

This soft starter is used for controlled starting and stopping of 3-phase AC motors where reduced inrush current and lower mechanical stress are important. It is part of the Siemens SIRIUS 3RW40 series and is rated 25 A with a motor rating of 11 kW at 400 V, approximately 15 hp.

Use for

Use for pumps, fans, blowers, compressors, and conveyor drives where a smoother ramp-up helps protect belts, couplings, gearboxes, and driven equipment. It is suitable for line supplies from 200 to 480 V AC with a control supply of 110 to 230 V AC/DC.

Avoid for

Avoid using this unit where full variable speed control is required, where the motor load exceeds the starter rating, or where application duty requires features not supported by this model such as inside-delta connection. For highly dynamic speed control, a VFD is typically the better choice.

Best for

Best for standard fixed-speed motor applications that need softer starts than across-the-line starting without the added complexity of a variable frequency drive. Typical buying decision factors are motor full-load current, line voltage, enclosure design, and available panel space.

Installed in

Installed in industrial control panels, MCC sections, OEM machinery panels, pump control assemblies, and commercial mechanical systems. The compact S0 frame helps where DIN rail or panel space is limited.

Why this product exists

This product exists to limit starting current and reduce torque shock during motor starting. That can help reduce nuisance voltage dip, lower wear on mechanical components, and improve startup behaviour on equipment with frequent starts. As typical guidance, soft starters are commonly selected where reduced mechanical stress matters more than speed control. Actual performance depends on motor characteristics, load inertia, installation conditions, and local electrical code.

Compared with similar products

Compared with a contactor-only starter, a soft starter provides controlled acceleration and deceleration. Compared with a VFD, it does not provide continuous speed variation, but it is often a simpler choice for fixed-speed applications. This model includes an integrated bridging contact system and adjustable current limitation based on Siemens product data.

Specifications

• Manufacturer: Siemens
• Series: SIRIUS 3RW40
• Manufacturer part number: 3RW4026-1BB14
• Product type: Soft starter
• Frame size: S0
• Rated operational current: 25 A
• Motor rating at 400 V: 11 kW (approximately 15 hp)
• Main circuit voltage: 200-480 V AC
• Control supply voltage: 110-230 V AC/DC
• Terminal type: Screw terminals
• Integrated bypass or bridging contact: Yes
• Adjustable current limitation: Yes
• Motor overload protection: Yes
• Inside-delta connection: No
• Typical application voltage reference: 400 V, approximately 230/400 V system context depending on installation