The 3RW4458-2BC46 is a SIRIUS soft starter rated 1680 A at 40 °C, which means it handles large induction motors — think 800+ kW on 400 V — without the mechanical shock of a direct-on-line start. The current derates to 1472 A at 50 °C and 1316 A at 60 °C, so panel ambient temperature directly sets the usable motor load; if your enclosure runs hot, size the motor to the derated figure, not the headline 1680 A. Insulation voltage is rated 690 V, and the unit operates on 50 or 60 Hz at 230 V control supply. The integrated bypass contact system means the thyristors are shorted out once the motor is up to speed — no continuous heat dissipation from the power stack, so the enclosure sees only the bypass contactor's I²R loss during run. Inside-delta wiring is supported, which lets you connect the soft starter in the delta legs of a six-lead motor. That reduces the current through each thyristor pair to 58% of the line current — effectively giving you a higher motor rating from the same starter. Useful on retrofit or space-constrained panels where upsizing the starter isn't an option.
Mounting is screw fixing with the unit oriented on a vertical surface. Clearance requirements: 100 mm above, 75 mm below, 5 mm at the sides. That 5 mm side gap is tight — plan for cable bending radius, not just the clearance number. Dimensions are 640 mm high, 510 mm wide, 290 mm deep. Main circuit connection is busbar with stranded cable 70–240 mm² or finely stranded 50–240 mm². Auxiliary and control circuits use spring-loaded terminals accepting 2x (0.25–1.5 mm²) solid or 2x (24–16 AWG). The busbar connection means you'll need a busbar kit or custom copper — not a lug-and-cable job for the main power path.
Protection and control features
Motor overload protection is built in, along with intrinsic device protection that guards the thyristors against overtemperature and phase imbalance. Adjustable current limitation lets you set the start current between 8% and 100% of the rated motor current — the 8% minimum load is the floor for the current-sensing circuit, not a recommended start setting. An external reset input allows remote fault reset from a PLC or pushbutton station. The display version shows fault codes on an integral display, so a field tech can read the trip cause without a laptop. A motor brake output is also included as a product component, which can drive a DC injection brake or mechanical brake coil directly. That's standard for most control panels, but if your site has heavy dust or humidity, the clearance and creepage distances assume PD3 — no extra derating needed.