230 A at 40 °C — motor starting duty and thermal derating
The 3RW4073-6BB45: Rated 230 A at 40 °C, this SIRIUS soft starter handles motor starting current for loads up to that full-load current, with the thyristor stack sized for the inrush duration. Derate to 205 A at 50 °C and 180 A at 60 °C — the thermal ceiling for a 40 °C enclosure ambient is the design point; above that, ventilation or a larger frame is needed to hold the continuous rating. The adjustable current limitation lets you set the starting current between 20% and the rated value, so the same unit can be tuned for different load inertias — pump, conveyor, or fan — without changing hardware. Minimum load is 20% of the rated current, which covers most motor applications except very light-duty cycles.
Size S12 frame — panel integration and wiring constraints
The Size S12 envelope (230 mm height, 160 mm width, 278 mm depth) mounts via screw fixing to a vertical surface. With the optional fan, the mounting surface can be rotated ±90° or tilted ±22.5° front-to-back; without the fan, rotation is limited to ±10°. This matters for retrofit panels where the gland plate position or cable entry direction is fixed. Main circuit wiring accepts stranded 70–240 mm² or finely stranded 50–240 mm², with busbar connection as the primary termination. The back clamping point handles 250–500 kcmil, the front clamping point 3/0–600 kcmil — enough for parallel feeds on high-current installations. Auxiliary control wiring uses 0.5–2.5 mm² solid with 20–14 AWG equivalents. Clearance requirements: 100 mm upward, 75 mm downward, 5 mm at the sides. The 5 mm side gap is tight — adjacent devices or enclosure walls must respect this for airflow and arc-flash clearance per IEC 60947-4-2.
Integrated protection and control — reducing external component count
Built-in motor overload protection and intrinsic device protection eliminate the need for a separate thermal overload relay in most installations. The external reset input allows remote fault recovery, which is standard for automated lines where manual reset at the panel is impractical. The derating temperature is 40 °C — above that, the current ratings in the spec table apply.