Integrated bypass and inside-delta wiring — two features that change the install
The 3RW4466-6BC44: The integrated bypass contact system shorts the thyristors after the motor reaches full speed, eliminating the 1-2 V forward drop per device and the associated heat load — the soft starter runs cool in bypass mode, so the enclosure ventilation requirement drops. Inside-delta circuit wiring connects the soft starter in the delta legs of a six-lead motor, reducing the current per phase to 58% of the line current — a 2103 A line-rated unit in inside-delta handles a motor up to about 3600 A full-load current, effectively stepping the frame size down one bracket. Adjustable current limitation sets the start current between 0 and 100% of the rated current — paired with the minimum load of 8%, this covers light-load starts on conveyors through high-inertia fans without a separate current-limiting reactor.
Mounting, clearance, and termination — what fits in the panel
Dimensions are 575 mm wide x 780 mm high x 292 mm deep — the depth is the critical dimension for shallow back-panel enclosures. Mounting is screw-fixing with a vertical mounting surface, rotatable ±90° and tiltable ±22.5° front/back, so the unit can be oriented to match existing busbar runs. Clearance requirements: 100 mm upwards, 75 mm downwards, 5 mm at the sides — the tight side clearance allows adjacent units to be packed closely, but the vertical clearance must be maintained for airflow through the heatsink fins. Main current circuit termination is busbar connection accepting 2/0 to 500 kcmil or stranded 70-240 mm² and finely stranded 50-240 mm². Auxiliary and control circuits use screw-type terminals for 2x (20-14 AWG) and solid 2x (0.5-2.5 mm²).
Protection, diagnostics, and auxiliary functions
A display for fault signals provides on-unit diagnostics — the display shows the last fault code, which speeds troubleshooting on a line-down event without needing a laptop. External reset input allows remote clearing of a tripped fault condition from a PLC or pushbutton station. A motor brake output is included for motors with DC injection brakes, saving a separate brake contactor. Maximum motor cable length is 500 m — for runs longer than that, output dV/dt filters or a sine-wave filter should be considered to prevent reflected-wave voltage spikes from damaging the motor winding insulation.
The kit includes the soft starter unit; confirm the busbar kit and any external bypass contactor if the application requires a separate bypass path.