What this soft starter delivers
The Siemens SIRIUS 3RW4423-1BC45 is a soft starter rated 62 A at 40 °C, with a 230 V control supply at 50/60 Hz. It includes an integrated bypass contact system, so the thyristors are shorted out once the motor is up to speed — that drops heat dissipation in the panel and extends the life of the semiconductor stack. That gives flexibility in panel layout, but the derating curve needs attention: at 50 °C the continuous current drops to 55 A, and at 60 °C it falls to 50 A. If your motor full-load amps sit near 62 A, you need to keep ambient below 40 °C or step up a frame size.
Wiring and connections
Main current circuit uses box terminals accepting 2x (4... 50 mm²) stranded. The auxiliary and control circuit uses screw-type terminals for 2x (0.5... 2.5 mm²) solid. Maximum wire length to the motor is 500 m — beyond that you risk voltage drop on the soft-starter output during the ramp. The unit supports inside-delta circuit wiring, which lets you connect the soft starter inside the motor's delta winding. That reduces the current through the thyristors to 58% of line current, effectively giving you a higher motor rating from the same frame. Minimum load is 8% of the rated current, so it handles small motors without nuisance tripping.
Protection and control features
Motor overload protection is built in, along with intrinsic device protection. Adjustable current limitation lets you set the start current between the minimum and the unit's rated maximum. An external reset input is provided, and fault signals show on the integrated display — no separate HMI needed for diagnostics.