3RW4455-6BC44 710 kW Siemens SIRIUS Soft Starter

Key Features and Technical Specifications

• Rated current: 693 A at 40 °C (standard circuit), 1,200 A at 40 °C (inside-delta).
• Operating voltage: 200–460 V AC (standard and inside-delta).
• Control supply voltage: 230 V AC at 50/60 Hz.
• Operating frequency: 50–60 Hz with ±10% tolerance.
• Adjustable rated current range: from 138 A (minimum) for motor overload protection.
• Continuous operating current: 115% of I_e at 40 °C.
• Active power loss: 220 W typical at operating current.
• Integrated bridging contact system: Yes.
• Motor overload protection: Yes.
• Inside-delta circuit: Yes.
• Protection class: IP00.

These specifications make the 3RW4455-6BC44 a versatile choice for applications requiring high current and power handling. The adjustable current limitation and external reset functionality provide flexibility in various control schemes.

Applications and Use Cases

This soft starter is well-suited for industries such as mining, water treatment, and manufacturing, where large motors drive critical processes. For example, a conveyor system in a mining operation benefits from the reduced inrush current and smooth acceleration, minimizing belt stress and mechanical wear. Similarly, a water pumping station can rely on the 3RW4455-6BC44 to prevent pressure surges and extend pump life.

Because the device supports inside-delta wiring, it can handle higher currents than standard configurations, making it ideal for retrofit projects where space is limited. The adjustable current limitation allows fine-tuning to match motor characteristics, optimizing performance and energy efficiency.

Installation and Mounting Considerations

Proper installation is critical for safe and reliable operation. The 3RW4455-6BC44 features screw fixing and can be mounted in various orientations, including ±90° rotation on a vertical plane and ±22.5° tilt forward/backward. Maintain the required clearances: 100 mm above, 5 mm to the sides, and 75 mm below for adequate airflow.

The main circuit connections use busbar connections, while auxiliary and control circuits use screw terminals. Connectable conductor cross-sections range from 50–240 mm² (finely stranded) for main contacts, and for auxiliary contacts, 2x (0.5–2.5 mm²) solid or 2x (0.5–1.5 mm²) finely stranded. For AWG, main contacts accept 2/0–500 kcmil, and auxiliary contacts accept 2x (20–14).

Ensure the control supply voltage is 230 V AC at 50 or 60 Hz, with tolerances of -15%/+10%. The operating frequency tolerance is ±10%, and the installation altitude can be up to 5,000 m above sea level. Maximum cable length is 500 m.

Maintenance and Reliability

Regular inspection is essential to maintain performance and longevity. Check all electrical connections periodically to ensure they remain tight and free of corrosion. Verify that the ambient temperature stays within the rated limits (up to 60 °C during operation, storage from -25 °C to +80 °C). The device is designed for continuous operation at 115% of rated current at 40 °C, but derating is required at higher temperatures (e.g., 615 A at 50 °C and 551 A at 60 °C).

The integrated bridging contact system reduces wear by bypassing the thyristors after start-up, lowering power loss and heat generation. This extends the life of the power electronics and reduces maintenance frequency. For any issues, refer to the official Siemens manual or contact AutoDCSTech for support.

Troubleshooting Common Issues

If the soft starter fails to start, check the control supply voltage and ensure it is within the specified range. Verify that the motor overload protection settings are correctly adjusted. If the device trips frequently, inspect the load for mechanical jams or excessive current draw. The built-in fault display provides diagnostic information; refer to the manual for detailed fault codes.

Another common issue is overheating. Ensure proper ventilation and maintain the required clearances. If the ambient temperature exceeds 40 °C, derate the operating current accordingly. For persistent problems, contact AutoDCSTech for expert assistance.

Availability and Support

The Siemens 3RW4455-6BC44 is available from AutoDCSTech. Contact us for current pricing and lead times. Our team can assist with technical questions and ensure you select the right soft starter for your application.