134 A at 40 °C — what it means for your motor line
The 3RW4073-6AB44: This SIRIUS soft starter is rated 134 A at 40 °C ambient, which means it handles a motor full-load current up to that figure before the internal thyristors need derating. The 230 V control supply (50/60 Hz) powers the electronics and the bypass contactor coil. The operating frequency range is 50...60 Hz, so it works on either grid without a configuration change.
Size S12 footprint and wiring constraints
Main circuit wiring accepts stranded copper from 70 to 240 mm² or busbar connection. The auxiliary control terminals take solid wire 0.5...2.5 mm² or stranded 20...14 AWG. Keep the motor cable run under 300 m to avoid voltage drop and reflected-wave issues on the thyristor stack.
Protection and adjustment — what the built-in overload covers
Motor overload protection is integrated, so you don't need a separate thermal relay in the line. The adjustable current limitation lets you set the starting current between 20% and the full rated current — useful for soft-starting conveyors or pumps that can't take a full-voltage jolt. Intrinsic device protection monitors the thyristor junction temperature and the internal supply; an external reset input allows remote restart after a fault. Pollution degree 3 per IEC 60947-4-2 means it's rated for industrial environments with conductive dust or occasional condensation.
Mounting position — the fine print that trips up installers
With the optional fan fitted, the unit can be mounted vertically with up to ±90° rotation and ±22.5° tilt front-to-back. Without the fan, the tilt range tightens to ±10° — so if you're installing in a tight cabinet without the add-on fan, keep the unit plumb or the internal cooling path won't work right. Clearance around the unit: 100 mm above, 75 mm below, 5 mm at the sides. The 100 mm upward gap is non-negotiable for natural convection — stack another device closer and the derating curve shifts.