Rated current and thermal derating — the real continuous-duty limit
The 3RW4457-2BC46: The headline rating is 1524 A at 40 °C ambient. For a panel builder sizing this into a 50 °C enclosure, the usable current is 1351 A — not the 40 °C figure. The derating temperature threshold is 40 °C, meaning above that ambient the output must be reduced per the curve. Insulation voltage is rated 690 V, covering 400/480/575 V systems with margin. Pollution degree 3 per IEC 60947-4-2 means the unit is designed for industrial environments with conductive dust or condensation — not for clean-room or climate-controlled spaces. Operating frequency is 50/60 Hz dual-rated, so the same unit works on 50 Hz or 60 Hz supplies without a hardware change. Control supply voltage is 230 V at either frequency.
Integrated bypass and inside-delta wiring
An integrated bypass contact system is built in — no external bypass contactor needed. This saves panel space, reduces wiring, and eliminates the heat load of a separate contactor coil. The thyristors are only in circuit during the start/stop ramp; the bypass carries the full load current in steady state. Inside-delta circuit wiring is supported. In an inside-delta configuration, the soft starter connects to the motor windings in a delta arrangement, reducing the current through each thyristor leg by a factor of √3 compared to standard in-line wiring. This is useful for large motors where the starter current rating would otherwise need to be oversized.
Protection features and motor brake output
Motor overload protection is built in, along with intrinsic device protection (over-temperature, phase loss, etc.). The adjustable current limitation lets you set the start current as a percentage of the motor FLA — the minimum load is 8% of the rated current, so it handles lightly loaded starts. A motor brake output is included as a product component. This is a relay output that can control an external DC injection brake or mechanical brake coil, common on hoist, crane, or conveyor applications where the load must hold after the motor stops. The fault signal is displayed on an onboard display — no separate HMI or panel indicator needed for basic fault diagnosis. External reset is supported for remote restart.
Mounting, dimensions, and termination
Dimensions are 640 mm height, 510 mm width, 290 mm depth. Fastening is by screw fixing — no DIN-rail clip. Mounting position allows vertical surface with +/-90° rotation and +/-22.5° tilt front/back, giving flexibility in panel layout. Main circuit connection is via busbar (not cable lugs), with wire sizes from 2/0 to 500 kcmil or 70 to 240 mm² stranded. The control terminals are separate from the power circuit, reducing the chance of wiring errors. Maximum motor cable length is 500 m. For long cable runs, consider the cable capacitance and potential reflected-wave issues — this is a soft starter, not a VFD, so dV/dt is lower, but runs near the limit should be checked against the motor insulation rating. Clearance requirements: 100 mm upwards, 75 mm downwards, 5 mm at the sides. Storage temperature range is -25 to +80 °C; operating ambient max is 60 °C.
Sourcing — quoted to order, active production
This 3RW4457-2BC46 is sourced through authorized distribution channels. No stock-holding claim is made; each order is quoted individually.