Rated current and thermal derating — the real operating envelope
The 3RW4457-2BC35: Insulation voltage is rated 690 V, operating frequency 50/60 Hz, and the unit includes an integrated bypass contact system that removes the thyristors from the circuit after start, reducing heat dissipation in continuous run.
Mounting, wiring, and environmental fit
Mounting is screw fixing with a vertical surface — the unit can be rotated ±90° or tilted ±22.5° front/back. Dimensions: 640 mm high, 510 mm wide, 290 mm deep. Clearance: 100 mm above, 75 mm below, 5 mm at the sides. Main power cables: stranded 70–240 mm², finely stranded 50–240 mm², or 2/0–500 kcmil. Maximum wire length to motor is 500 m. Degree of pollution 3 per IEC 60947-4-2, storage temperature -25 to +80 °C, operation up to 60 °C. The unit includes a display for fault signals and a motor brake output component.
Protection and control features
Motor overload protection and intrinsic device protection are built in. Adjustable current limitation is available, and the minimum load is 8 % of the rated current — below that the soft starter may not detect a load. External reset is supported. Inside-delta circuit configuration is supported, which reduces the current through the thyristors by 42 % compared to standard in-line connection — useful for large motors where thyristor sizing is the constraint.