Active production — what that means for your BOM line
The 3RW4424-3BC45: It belongs to the SIRIUS family, Siemens' modular platform for motor management and soft starting, which means panel builders and OEMs can rely on consistent accessory compatibility (bypass contactors, overload relays, communication modules) across the range.
Current rating and thermal derating — the real-world limit
The derating temperature is 40 °C — above that, the continuous output current drops linearly. If your panel ambient runs at 50 °C, the usable current is 73 A, not the headline 81 A. The insulation voltage is rated 690 V, and the operating frequency covers 50 to 60 Hz, so it fits standard global line voltages without a hardware change.
Integrated bypass and inside-delta — what they save you
An integrated bypass contact system means the soft starter's thyristors are shorted out after the motor reaches full speed, eliminating continuous conduction losses and the need for an external bypass contactor. This reduces heat in the panel and improves system efficiency. Inside-delta wiring capability allows the soft starter to be connected in the motor's delta loop, reducing the current through each device leg to 58% of the line current. This lets a smaller-frame soft starter handle a given motor — a cost and space advantage in high-current applications.
Protection and adjustment — motor overload and current limit
Built-in motor overload protection (electronic, adjustable) and intrinsic device protection (over-temperature, phase imbalance, thyristor fault) eliminate the need for a separate overload relay in most installations. The adjustable current limitation lets you set the starting current between 8% and 100% of the soft starter's rated current, matching the motor's acceleration profile. The minimum load of 8% means it can start lightly loaded motors without nuisance tripping — useful for pumps running dry or conveyors with minimal friction at start.
Mounting, wiring, and environmental fit
Screw fixing to a vertical mounting surface, rotatable ±90° and tiltable ±22.5° front-to-back — this gives flexibility in panel layout, but the clearance requirements are strict: 100 mm above, 75 mm below, 5 mm at the sides for airflow and service access. Main circuit uses box terminals accepting 2x (4... 50 mm²) stranded or 2x (10... 1/0 AWG) using both clamping points. The maximum wire length to the motor is 500 m — beyond that, voltage drop and cable capacitance may affect the thyristor commutation. Degree of pollution 3 per IEC 60947-4-2, operating temperature up to 60 °C, storage from -25 to +80 °C — suitable for industrial environments with conductive dust or humidity, not for clean-room or outdoor exposure without additional enclosure.
Fault indication and reset — service-friendly
A display for fault signal shows the last fault code, speeding diagnosis. External reset input allows remote clearing of faults from a PLC or pushbutton panel — no need to open the enclosure door.