1,351 A at 40°C — the number that sizes the panel
The 3RW4456-6BC45 is a SIRIUS soft starter rated 1,351 A at 40°C in standard duty (cites:). That is the continuous motor current it handles during start and, with the integrated bypass contactor closed, during run — no external bypass contactor needed (cites:). If your enclosure runs warm — common with high-current starters in compact panels — size for the derated figure, not the 40°C headline. Inside-delta wiring is supported (cites:). In that configuration the soft starter sees phase current, not line current, so a lower-rated unit can start the same motor — a panel-space and cost play worth discussing at RFQ time.
Integrated protection — one less relay to wire
Motor overload protection is built in, along with intrinsic device protection (over-temperature on the thyristors) and adjustable current limitation (cites:,). That means no separate overload relay in the power circuit — fewer terminals to torque, fewer parts to stock. The thyristor stack is rated for the full 1,351 A path (cites:). The integrated bypass contactor carries the current in steady-state, so the thyristors only dissipate heat during the start ramp — the bypass is what keeps the enclosure from cooking on a long run. Maximum motor cable length is 500 m (cites:). For remote pumps or conveyors, that is the distance limit before voltage drop or reflected-wave issues need attention — factor it into the cable sizing, not just the ampacity.
Mounting and enclosure fit
The unit measures 640 mm high by 510 mm wide by 290 mm deep (cites:,). That is a substantial footprint — plan for a 700 mm+ tall enclosure section with side clearance for the busbar connections (busbar connection is the specified main circuit termination, cites:). Mounting position is flexible: vertical surface with ±90° rotation and ±22.5° tilt front/back (cites:). Screw fixing is the fastening method (cites:). The clearance requirements are 100 mm upward, 75 mm downward, and 5 mm at the sides (cites:,) — the side gap is tight, but the top and bottom need breathing room for airflow. Power wiring accepts stranded 70–240 mm² or 2/0–500 kcmil (cites:,). The control circuit also has a motor brake output (cites:) — useful if the driven load needs a DC brake, though the brake itself is external.