SIRIUS 3RW4024-1TB04 soft starter — 12.5 A, S0 frame, integrated bypass
The Siemens 3RW4024-1TB04 is a SIRIUS soft starter in the S0 frame size, rated 12.5 A at 40 °C and 24 V control voltage (50/60 Hz). It includes an integrated bypass contact system, so once the motor is up to speed the thyristors are shorted — no heat sink derating during run, and the bypass carries the full load current. That makes it a good fit for conveyors, pumps, and fans where you want a compact starter that doesn't waste panel space on an external bypass contactor.
At 40 °C the unit delivers 12.5 A continuous. Minimum load is 20% of the rated current — below that the soft starter may not fire the thyristors reliably, so don't use it on a motor that draws less than about 2.5 A at 40 °C.
Mounts via screw or snap-on to DIN rail. The S0 frame is 45 mm wide, 125 mm tall, 155 mm deep. Keep 60 mm free above and 40 mm below for airflow; side clearance is 15 mm. Without an external fan, the mounting surface must be within ±10° of vertical; with the optional fan you can rotate ±90° and tilt ±22.5° front/back. Storage temp range is -40 to +80 °C; operating ambient is -25 to +60 °C.
Main power circuit uses screw-type terminals; auxiliary and control circuit also screw-type. Solid wire accepted: 2x (0.5... 2.5 mm²). Auxiliary contacts: 2x (20... 14 AWG). Front clamping point: 1x 8 mm² or 2x (16... 10 AWG). Maximum wire length from the starter to the motor is 300 m — beyond that, voltage drop and capacitance may cause nuisance tripping.
Protection and control features
Built-in motor overload protection and intrinsic device protection are standard. Adjustable current limitation lets you set the starting torque profile. External reset input is provided. Insulation voltage rated 600 V. A red LED indicates fault status.