3RW4028-1BB14, Soft Starter, 18.5 kW, 38 A, 200 to 480V AC

Siemens 3RW40 Soft Starter Series – Overview

Siemens 3RW40 soft starters are advanced compact motor starting solutions designed for smooth starting and stopping of three-phase asynchronous motors in industrial applications. The 3RW40 series focuses on reducing mechanical stress, limiting inrush current, and providing enhanced motor protection compared to basic soft starters. With integrated bypass functionality and flexible configuration options, Siemens 3RW40 soft starters are well suited for pumps, fans, compressors, conveyors, and general industrial machinery requiring reliable and efficient motor starting.

Product Description: 3RW4028-1BB14

The Siemens 3RW4028-1BB14 is a SIRIUS 3RW40 soft starter rated for 38 A (operating current) and a motor power rating of 18.5 kW at 400 V. It is designed for use on three-phase systems with a main supply voltage range of 200 to 480 V AC, making it suitable across common industrial voltage classes. Typical motor compatibility includes medium-duty asynchronous motors in the approximate 15–22 kW range at 400 V (catalogued as 18.5 kW), which covers many pumps, fans, compressors and small conveyor drives.

This model uses two-phase control with adjustable start parameters — start voltage can be set (typical 40–100% of supply) and current limiting is available — allowing controlled torque build-up and reduced mechanical stress during acceleration. An integrated bypass contactor removes the semiconductor power loss after the motor reaches running speed, lowering heat in the control cabinet and improving efficiency. The 3RW4028-1BB14 accepts common auxiliary/control voltages used in industrial panels (catalog documentation lists AC/DC control possibilities) and is supplied in a compact IP20 enclosure suitable for cabinet mounting.

Use cases where the 3RW4028-1BB14 is especially effective include centrifugal pump installations that benefit from reduced water hammer, belt conveyors where gentle torque reduces belt slip and wear, and fan or blower applications where soft stopping reduces process disturbance. For procurement and engineering teams, this model is a space-saving alternative to star-delta starters, provides built-in motor overload and adjustable current limiting, and simplifies wiring with its compact form factor and integrated bypass.

Key Soft Starter Attributes