The Siemens SIRIUS 3RW4423-1BC36 is a soft starter rated 62 A at 40 °C, with an insulation voltage of 690 V and an operating frequency of 50 to 60 Hz. It includes an integrated bypass contact system and adjustable current limitation, plus motor overload and intrinsic device protection.
Above 40 °C, derate to 55 A at 50 °C and 50 A at 60 °C — plan your enclosure cooling if the ambient exceeds 40 °C. The 690 V insulation voltage (pollution degree 3 per IEC 60947-4-2) means it can be used on 400 V and 480 V systems with margin, but verify the line-to-line voltage does not exceed 690 V. The integrated bypass contact system eliminates the need for an external bypass contactor, reducing panel wiring and heat dissipation during run. Adjustable current limitation lets you set the starting current between 8% and 100% of the rated motor current — useful for soft-starting loads that need a controlled ramp. Mounting is screw fixing with a vertical surface orientation; the unit can be rotated ±90° or tilted ±22.5° front/back. Clearance requirements: 100 mm above, 75 mm below, 5 mm at the sides — tight side clearance helps in dense panels.
Wiring and connections
Main current circuit uses box terminals accepting stranded wire 2x (4 to 50 mm²) or solid 2x (0.5 to 2.5 mm²). Auxiliary and control circuits use screw-type terminals for 2x (20 to 14 AWG). Maximum wire length from the soft starter to the motor is 500 m — sufficient for most industrial layouts but check if your run exceeds that. The inside-delta circuit configuration is supported, which can reduce the starter's current rating requirement for six-lead motors.
Protection and diagnostics
Motor overload protection is built in, along with intrinsic device protection (e.g., thyristor overtemperature). An external reset input allows remote fault reset. A display provides fault signal indication — no need to add a separate annunciator.