Active production, current rating that drives the selection
The 3RW4458-6BC34: Rated 1680 A at 40 °C, it handles heavy motor loads. Derate to 1472 A at 50 °C and 1316 A at 60 °C — the thermal ceiling is 60 °C during operation, so a panel with marginal airflow pushes the usable current down. The derating temperature threshold is 40 °C, meaning full rating only holds below that ambient.
Bypass, inside-delta, and wiring constraints
Integrated bypass contact system means the thyristors are shorted out once the motor is up to speed — no external bypass contactor needed, and the heat load on the panel drops after start. Inside-delta circuit connection is supported — this reduces the current through each thyristor leg to 58% of the line current, effectively extending the rating range for a given soft starter frame. Confirm the motor winding configuration before wiring. Main current circuit connection is busbar; the main conductor range accepts stranded 70–240 mm² and finely stranded 50–240 mm², or 2/0–500 kcmil.
Mounting, clearance, and environmental fit
Degree of pollution 3 per IEC 60947-4-2 — this is the industrial environment rating (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation). No additional conformal coating required for typical factory-floor panels, but outdoor or washdown cabinets need a higher enclosure rating. Storage temperature range is -25 to +80 °C — the unit can sit in an unheated warehouse through most climates without damage.
Protection, diagnostics, and commissioning notes
Motor overload protection and intrinsic device protection (thyristor overtemperature, phase imbalance, etc.) are built in — no separate overload relay needed for most applications. Adjustable current limitation lets you set the start current between 8% and the rated value, which helps on weak supply networks or mechanically sensitive loads. Fault signal display is on the unit itself — a local readout shows the fault code without needing a connected HMI or PLC. External reset input allows remote clearing of latched faults from the control room. Maximum motor cable length is 500 m — beyond that, capacitive charging current from the cable can interfere with the thyristor gating. For long cable runs, consider an output reactor. A motor brake output is included as a component — useful for applications that need a DC injection brake after the soft starter ramps down.