Current ratings that decide the motor match
The 3RW4427-1BC46: Rated 161 A at 40 °C, derating to 142 A at 50 °C and 125 A at 60 °C. The 40 °C figure is the baseline — above that, the thyristor junction temperature limits the continuous current. For a motor nameplate of 150 A FLA in a 40 °C ambient, this unit holds headroom; in a 50 °C panel, the 142 A ceiling still covers most 132 kW (400 V) machines. The 8% minimum load setting means it handles lightly loaded conveyors or pumps without dropping out.
Integrated bypass and wiring constraints
An integrated bypass contact system means the thyristors are shorted out once the motor reaches full speed — no external bypass contactor needed, and the heat load in the panel drops to near zero during run. The main circuit uses box terminals accepting stranded 4–50 mm² or solid 0.5–2.5 mm². Control and auxiliary circuits use screw-type terminals sized for 20–14 AWG. Maximum motor cable length is 500 m — beyond that, reflected wave spikes on the cable can stress the thyristor stack.
Mounting and clearance for panel layout
Screw fixing to a vertical mounting surface, with ±90° rotation and ±22.5° tilt front/back allowed. Dimensions: 170 mm wide, 192 mm high, 270 mm deep. Clearance requirements: 100 mm above, 75 mm below, 5 mm at the sides — the top clearance is the critical one for heat plume rise from the heatsink. Pollution degree 3 per IEC 60947-4-2 means it's rated for the conductive-dust environment typical of industrial panels.
Inside-delta wiring and adjustable current limit
Supports inside-delta circuit connection — the soft starter sits in the delta legs of a six-lead motor, reducing the per-phase current the thyristors carry by a factor of √3 compared to in-line wiring. Adjustable current limitation lets you set the start current between the motor's no-load and locked-rotor values, which is useful for conveyors that need a controlled acceleration ramp without tripping upstream protection. Motor overload protection is built in, so a separate overload relay is not required.
Control supply and fault indication
The unit has a display for fault signals and supports external reset — useful for remote reset in an unmanned conveyor zone. Storage temperature range is -25 to +80 °C; during operation the ambient must stay at or below 60 °C. Derating temperature threshold is 40 °C — above that, the output current must be reduced per the derating curve.