50 A at 40 °C — what that means for the motor circuit
The 3RW4422-3BC34: The integrated bypass contactor pulls the thyristors out of the circuit once the motor is up to speed — that means no continuous heat sink load from the SCRs during run, and the bypass carries the full motor current without the semiconductor voltage drop.
Mounting, wiring, and panel fit
Screw fixing to the mounting plate — 170 mm wide, 192 mm tall, 270 mm deep. Clearance needs: 100 mm above, 75 mm below, 5 mm at the sides. The mounting position allows vertical surface with ±90° rotation and ±22.5° tilt front-to-back, so it fits in tight enclosures as long as the airflow path stays clear. Main circuit uses box terminals accepting 10 AWG to 2/0 AWG (stranded 4 to 50 mm²). Control and auxiliary circuits use spring-loaded terminals for 24 to 16 AWG solid (0.25 to 1.5 mm²). The spring-clamp on the control side saves time on the wireway — no torquing small screws.
Protection, control, and field wiring limits
Built-in motor overload protection and intrinsic device protection — the soft starter monitors both the motor and its own thyristor junction temperature. Adjustable current limitation lets you set the start current below the supply transformer or generator capacity. Minimum load is 8 % of the rated current, so it handles unloaded starts on conveyors or pumps without nuisance tripping. Maximum motor cable length is 500 m — beyond that, cable charging current can interfere with the zero-cross detection on the SCR firing. External reset input allows remote restart after a fault; the display shows the fault code for troubleshooting. Pollution degree 3 per IEC 60947-4-2 means it's rated for industrial environments with conductive dust or condensation. Inside-delta wiring is supported — that connects the soft starter in the delta legs of a six-lead motor, reducing the current through the thyristors by 58 % compared to in-line connection. Useful for larger motors where the 50 A frame would otherwise be undersized.