Current rating that governs the real operating envelope
The 3RW4456-2BC36: The headline 1351 A at 40 °C is the rating at the manufacturer's derating temperature threshold — above that, the available current drops to 1200 A at 50 °C and 1065 A at 60 °C.
Integrated bypass — one less contactor in the BOM
The 3RW4456-2BC36 carries an integrated bypass contact system, meaning the thyristors are shorted out once the motor reaches full speed. This eliminates the external bypass contactor that a standard soft starter topology requires — saves one panel-mounted device, reduces wiring, and cuts the heat load inside the enclosure because the bypass carries the full-load current with negligible losses.
Inside-delta wiring cuts line current by 42 %
This soft starter supports inside-delta circuit connection, which places the thyristors in the motor delta legs rather than the supply lines. The line current seen by the upstream breaker and cable is 58 % of the motor FLA — a 1351 A motor draws roughly 784 A from the supply in inside-delta mode. That difference can drop the feeder cable by two AWG sizes and may keep the installation within an existing MCC bucket rating without a bus upgrade.
Pollution degree 3 — built for the panel floor, not the clean room
Rated pollution degree 3 per IEC 60947-4-2, the creepage distances and clearance are designed for conductive dust, humidity, and the general industrial atmosphere you find on a motor control centre floor. This is not a clean-room device; it holds the unit on the grid in the same environment where the MCC sees grinding dust and coolant mist, provided the enclosure keeps the internal ambient within the derating curve.
Protection set — three functions, one device
Motor overload protection, intrinsic device protection for the thyristor junction temperature, and adjustable current limitation are all integrated. The current limitation sets a ceiling on the starting inrush — useful when starting into a weak supply or when the upstream protection is coordinated for a specific let-through. The motor overload replaces a separate thermal overload relay in the line, provided the application is within the soft starter's operating range.
Control wiring — spring terminals, no torque driver needed
The spring clamp holds the conductor without periodic re-torquing — one less maintenance item on the PM schedule. Main circuit connections are busbar with stranded cable range 70... 240 mm² and finely stranded 50... 240 mm², or 2/0... 500 kcmil for the North American install.
Mounting position and cooling clearances
Mounting position allows vertical surface orientation with ±90° rotation and ±22.5° tilt front-to-back. The cooling clearances are 100 mm upwards, 75 mm downwards, and 5 mm at the sides — the side clearance is tight, so the real thermal bottleneck is the vertical air path. Stacking units without the vertical clearance will force the upper unit to operate on the 50 °C or 60 °C derating curve even if the room ambient is 40 °C.