Rated current and thermal derating — the real motor ceiling
The 3RW4457-2BC34 is rated 1,524 A at 40 °C ambient — that's the full-load current it can start and run continuously when the panel ambient stays at or below 40 °C. At 50 °C the ceiling drops to 1,351 A, and at 60 °C it's 1,200 A. If your enclosure runs hot — say a non-ventilated cabinet next to a motor — the derating curve is the number that governs the real motor size, not the 40 °C headline. The integrated bypass contact system shunts the thyristors out of the circuit once the motor reaches full speed. That means the heat dissipation in run mode is just the bypass contact resistance, not the semiconductor forward drop — so the derating matters less for continuous running than for the start cycle.
Inside-delta wiring and motor protection — what the terminals mean
This soft starter supports inside-delta circuit wiring, which connects the soft starter in series with each motor winding rather than in the supply lines. That reduces the current the soft starter sees to 58% of the line current — a 1,524 A rated unit can start a motor with a line FLA up to roughly 2,630 A when wired inside-delta. Motor overload protection and intrinsic device protection are built in — no separate overload relay needed. The adjustable current limitation lets you set the start current anywhere from 8% minimum load up to the rated ceiling, so you can tune the ramp for a soft start on a conveyor or a pump. The main circuit terminals are busbar connection, accepting stranded cable 70–240 mm² or finely stranded 50–240 mm². Auxiliary and control wiring lands on spring-loaded terminals — no screwdriver torque check needed, which saves time on a panel with dozens of control wires.
Mounting and integration into the panel
Mounting is screw fixing — not DIN-rail snap-on. The envelope is 640 mm high, 510 mm wide, 290 mm deep. Plan for 100 mm clearance above and 75 mm below for ventilation and cable bending radius; side clearance is 5 mm. The mounting position allows a vertical surface with ±90° rotation and ±22.5° tilt forward/back. That gives flexibility in a tight cabinet — you can orient the display for readability without relocating the whole assembly. Operating temperature range is 60 °C max during operation; storage range is -25 to +80 °C.