1680 A at 40 °C — sizing the main power path and the bypass
The 3RW4458-6BC36: At 50 °C the rating drops to 1472 A, and at 60 °C it falls to 1316 A — the derating curve matters if the soft starter lives inside a closed panel near a furnace line or a hot-strip mill stand. The integrated bypass contact system eliminates the need for an external bypass contactor, saving panel space and reducing the wiring count — the thyristors are shorted out after the start, so the heat load in steady state is just the bypass contact resistance. Inside-delta circuit capability means the motor windings can be configured in delta and the soft starter connected in series with each winding, reducing the current through the soft starter to 58% of the line current — useful when the motor FLA exceeds the soft starter's rating.
Termination and cable entry — what fits the lugs
The main current circuit terminates via busbar connection; the power cable lugs accept stranded copper from 70 to 240 mm² and finely stranded from 50 to 240 mm². For US wire gauge equivalents, the main contacts accept 2/0 to 500 kcmil — covers the range from 2/0 AWG up to 500 MCM.
Mounting and clearances — fitting it into the panel
The unit measures 640 mm high by 510 mm wide by 290 mm deep and is fastened by screw fixing to a backplate — it does not snap onto a DIN rail. Mounting position allows a vertical surface with ±90° rotation and ±22.5° tilt forward or backward — useful when the panel layout forces an angled installation. Required clearances: 100 mm above, 75 mm below, and only 5 mm at the sides — the tight side clearance lets you pack units side-by-side, but the vertical clearance is non-negotiable for cable bending radius and airflow.
Protection and diagnostics — what's built in
Motor overload protection is integrated, so no separate overload relay is needed in the motor circuit — the thermal model protects the motor and the thyristors (intrinsic device protection,). Adjustable current limitation lets you set the starting torque from 8% of motor FLA (minimum load,) up to whatever the motor can handle — critical for soft-starting a loaded conveyor without tripping upstream. A display shows fault signals locally — no need to plug in a laptop to read the last trip cause. External reset input allows remote clearing of latched faults from a PLC or pushbutton station.
Environmental and compliance — industrial-grade construction
Pollution degree 3 per IEC 60947-4-2 — the soft starter is designed for conductive dust and industrial atmospheres, not just clean control rooms. Operating frequency is 50/60 Hz — the same unit works on either grid without a hardware change. Storage temperature range -25 to +80 °C; operating ambient up to 60 °C with derating starting at 40 °C.