617 A at 40 °C — the motor-starting current that drives the selection
The 3RW4446-2BC45 is a SIRIUS-branded soft starter rated 617 A at 40 °C ambient. For a motor with a 500 A FLA, this unit gives headroom without oversizing the cabinet. Inside-delta wiring reduces the line current by about 42 % compared to standard-in-line connection — a 617 A unit in inside-delta mode handles the equivalent of a 1050 A motor FLA. That matters when the existing feeder cables or MCC busbars are the constraint.
Terminal sizing and busbar connection — what lands on the lugs
Main circuit terminals accept stranded 70–240 mm² or finely stranded 50–240 mm², plus AWG 2/0–500 kcmil for the main contacts. The busbar connection is standard for this current class — expect flat copper bars, not cable lugs, in the panel layout. The rear clamping point takes 250–500 kcmil; the front takes 3/0–600 kcmil. The screw fixing means no DIN-rail clip — the unit bolts directly to the backplate, so pre-drill the mounting holes to the 210 mm width and 230 mm height footprint.
Active production — no lifecycle surprises
The lifecycle stage is current — Siemens still manufactures this order code. For BOM planning, this part is a standard catalog item; the supply channel is the normal Siemens distribution network. Pollution degree 3 per IEC 60947-4-2 means the soft starter is rated for conductive dust and occasional condensation — typical for motor control centres in mills, plants, and pump houses.