Current derating and bypass — what drives the real rating
The 3RW4426-3BC45: Rated 133 A at 40 °C, derated to 118 A at 50 °C and 102 A at 60 °C — the ambient inside the panel sets the usable current, not the nameplate number. Integrated bypass contact system means the thyristors are shorted out once the motor is up to speed, cutting heat dissipation in the enclosure and letting the soft starter run cooler in continuous duty.
Mounting, clearances, and terminal wiring
Dimensions 170 mm wide × 192 mm high × 270 mm deep; screw fixing to the back panel, not DIN rail. Mounting position allows ±90° rotation and ±22.5° tilt front-to-back. Minimum clearance: 100 mm above, 75 mm below, 5 mm at the sides — plan the gland plate and busbar routing to keep airflow open. Main circuit uses box terminals accepting 2× (4 … 50 mm²) stranded or 2× (10 … 1/0 AWG).
Protection, control, and inside-delta wiring
Built-in motor overload protection and intrinsic device protection reduce the need for separate relays in the starter bucket. Adjustable current limitation lets you set the starting torque profile per load. Inside-delta circuit capability — for six-lead motors, the soft starter can be wired inside the delta to run at a lower current rating per phase, saving panel space and cost. Minimum load is 8 % — light-load applications like small pumps or fans need to stay above this threshold to avoid misfiring the thyristors. External reset input and a fault display simplify remote troubleshooting without opening the panel door.
Insulation, environment, and wire length
Rated insulation voltage 690 V with pollution degree 3 per IEC 60947-4-2 — suitable for industrial environments with conductive dust or condensation. Operating temperature range –25 to +60 °C during operation, storage from –25 to +80 °C. Maximum motor cable length 500 m — stay under this to avoid reflected-wave trips on long runs.