The Siemens 3RW4422-1BC46 is a SIRIUS-brand soft starter rated 50 A at 40 °C, stepping down to 45 A at 50 °C and 40 A at 60 °C — the 40 °C figure is the one to size your motor against unless the cabinet runs cooler. It switches via thyristors and includes an integrated bypass contact system, which means once the motor is up to speed, the thyristors are shorted out and the current runs through the bypass contacts. That cuts heat dissipation in the panel and extends the life of the semiconductor stack. The insulation voltage is rated 690 V, giving headroom for 400 V systems and some 480 V installations. Operating frequency covers 50 to 60 Hz at 230 V. Minimum load is 8% of the rated current, so it handles lightly loaded conveyors or pumps without dropping out.
Mounting and wiring — what fits in the enclosure
The unit measures 170 mm wide, 192 mm high, 270 mm deep. Mounting is screw fixing on a vertical surface, rotatable ±90° or tiltable ±22.5° front-to-back. Clearance requirements: 100 mm above, 75 mm below, 5 mm at the sides — the side gap is tight enough that adjacent devices can sit close. Main circuit terminals are box terminals. Stranded wire: 2x 4 to 50 mm². Solid wire: 2x 0.5 to 2.5 mm². Auxiliary and control circuit wiring uses screw-type terminals sized for 2x 20 to 14 AWG. Maximum motor cable length is 500 m — beyond that, reflected wave spikes at the motor terminals become a concern even with a soft starter.