The Siemens 3RW4024-1BB14 is a SIRIUS soft starter in the S0 frame size, rated 12.5 A at 40 °C with a 110–230 V DC control supply. It uses thyristor-based ramp control and includes an integrated bypass contact system that switches the thyristors out once the motor is at full speed — cuts heat dissipation in the panel and extends device life. Mounts on DIN rail or screws to a backplate (screw and snap-on mounting), so it fits into standard control cabinets without special bracketry.
The 12.5 A rating at 40 °C is the headline number, but the derating curve is where the real decision lives: at 50 °C it drops to 11 A, at 60 °C to 10 A. Minimum load is 20 % of the rated current, so a 2.5 A motor is the practical floor; smaller loads may not trigger the thyristors reliably. Control supply is 110–230 V DC, not AC — a common miss when pulling from a 120 V AC control transformer without a rectifier.
Dimensions: 45 mm wide, 125 mm high, 155 mm deep — S0 frame footprint. Clearance requirements: 60 mm above, 40 mm below, 15 mm at the sides. Main circuit uses screw-type terminals; auxiliary and control circuit also screw-type. Wire sizes for main circuit: 2 x (0.5…2.5 mm²) solid or stranded. For auxiliary contacts: 2 x (20…14 AWG). Front clamping point accepts 1 x 8 AWG or 2 x (16…10 AWG). Maximum motor cable length is 300 m — long enough for most distributed motor installations, but if you're pushing past that, factor in voltage drop on the ramp. No inside-delta circuit configuration — this is a standard in-line soft starter.