Current rating and thermal derating
The 3RW4446-2BC44: The thyristor-based output handles the full motor start cycle without mechanical contacts, and the inside-delta wiring option reduces line current by 58 % compared to standard in-line connection — useful for retrofitting into existing cable runs without upsizing the supply feeder. Minimum load is 8 % of the rated current — below that the soft starter may not trigger reliably, so confirm the motor magnetising current exceeds this floor before committing the BOM line.
Mounting, clearance, and wiring constraints
Envelope is 298 mm deep, 210 mm wide, 230 mm high — screw-fixing to the back panel, not DIN-rail snap-on, so factor in drill-and-tap or through-hole mounting during panel layout. Clearance requirements: 100 mm above, 75 mm below, 5 mm at the sides — the vertical gap is the main space driver; stacking multiple units in a row needs the full 100 mm top clearance for airflow and service access. Main circuit connection is busbar only — no cable lugs on the power terminals. Stranded cable range is 70 to 240 mm² (or 2/0 to 500 kcmil using both clamping points), with the front clamp accepting up to 600 kcmil and the back clamp 250 to 500 kcmil. Mounting position is flexible: vertical surface with ±90° rotation and ±22.5° tilt forward/backward — useful for tight enclosures where the unit must be angled to clear gland plates or busbars.
Protection, control, and environment
Motor overload protection and intrinsic device protection are built in — no separate overload relay needed for the soft starter itself. Adjustable current limitation lets you set the start current between the minimum load threshold and the unit's full rating. External reset input and a fault-signal display (text/graphic, not just LEDs) simplify remote diagnostics — the display shows the fault code directly, which speeds troubleshooting on a line-down call. Operating temperature limit is 60 °C during operation; storage range is -25 to +80 °C. The derating temperature threshold is 40 °C — above that, use the derating curves in the manual, not the nameplate rating.