3RW4445-6BC44 313A Soft Starter | Siemens SIRIUS

Introduction to the Siemens 3RW4445-6BC44 Soft Starter

When motor starting demands precise control and robust performance, the 3RW4445-6BC44 from Siemens SIRIUS series stands ready. This soft starter is engineered for high-feature applications, offering a rated operating current of 313 A at 40 °C in standard circuit. With an operating voltage range of 200-460 V AC, it adapts to diverse industrial power systems. The 3RW4445-6BC44 integrates bridging contacts and thyristors to ensure smooth acceleration and deceleration, reducing mechanical stress on driven equipment.

For applications requiring higher starting torque, the inside-delta circuit configuration provides a rated current of 542 A at 40 °C. This flexibility makes the 3RW4445-6BC44 a versatile choice for three-phase squirrel-cage motors. The device supports a control supply voltage of 230 V AC at both 50 Hz and 60 Hz, with tolerances of -15% to +10%. Its screw terminals for auxiliary and control circuits simplify wiring, while the main circuit uses busbar connections for high-current handling.

Key Features and Technical Specifications

The 3RW4445-6BC44 is packed with features that enhance motor protection and operational efficiency. Below are the core specifications extracted from the official datasheet:

• Rated operating current (standard circuit): 313 A at 40 °C
• Rated operating current (inside-delta circuit): 542 A at 40 °C
• Operating voltage: 200-460 V AC (standard and inside-delta)
• Control supply voltage: 230 V AC (50/60 Hz)
• Operating frequency: 50-60 Hz (±10%)
• Mechanical power output: 160 kW at 400 V (standard), 315 kW at 400 V (inside-delta)
• Ambient temperature: up to 60 °C during operation
• Protection class: IP00
• Dimensions (W x H x D): 210 mm x 230 mm x 298 mm
• Mounting: Screw fixing, rotatable ±90°

One distinctive feature is the adjustable current limitation, which allows precise control of starting current to protect both motor and supply network. Additionally, the device includes motor overload protection and evaluation of thermal resistor motor protection, ensuring comprehensive safeguarding. The integrated bridging contact system reduces power loss during continuous operation, with typical active power loss of 145 W at 40 °C.

Applications and Use Cases

The 3RW4445-6BC44 is ideal for heavy-duty industrial applications where controlled starting is critical. Common use cases include conveyors, pumps, fans, and compressors. In conveyor systems, the soft starter minimizes belt stress and prevents material spillage during start-up. For pump applications, it reduces water hammer by gradually ramping up the motor speed. The inside-delta circuit configuration is particularly beneficial for high-inertia loads, such as large centrifugal fans or crushers, where starting torque must be carefully managed.

Furthermore, the device's wide voltage range (200-460 V AC) makes it suitable for global installations. Its ability to operate at altitudes up to 5,000 meters above sea level expands its applicability in mining and high-altitude facilities. The 3RW4445-6BC44 also supports reset external, allowing remote reset from a control room, which enhances operational convenience.

Installation and Setup

Proper installation is essential for optimal performance. The 3RW4445-6BC44 features screw fixing for mounting, with a mounting position that can be rotated ±90° on a vertical plane and tilted ±22.5° forward/backward. Maintain the following clearances to adjacent components: 100 mm upwards, 5 mm sidewards, and 75 mm downwards. These distances ensure adequate ventilation and prevent overheating.

Electrical connections for the main circuit use busbar connections, capable of accepting conductor cross-sections from 70 to 240 mm² (finely stranded) or 95 to 300 mm² (stranded). For auxiliary circuits, screw-type terminals accept solid conductors from 2x (0.5 to 2.5 mm²) or finely stranded with end processing from 2x (0.5 to 1.5 mm²). Ensure all connections are torqued to the manufacturer's specifications to avoid loose connections.

Maintenance and Reliability

Routine maintenance ensures long-term reliability. The 3RW4445-6BC44 is designed for minimal upkeep, but periodic inspection is recommended. Check the tightness of all electrical connections, especially after initial installation and during thermal cycling. Verify that the ambient temperature does not exceed 60 °C, as derating occurs above 40 °C. The device's IP00 protection class means it is not sealed against dust or moisture, so install it in a clean, dry enclosure.

Given the soft starter's solid-state design, there are no moving parts to wear out, reducing maintenance frequency. However, the cooling fans (if present) should be checked for dust accumulation. Follow the manufacturer's manual for any specific maintenance procedures.

Comparison with Similar Soft Starters

When comparing the 3RW4445-6BC44 with other soft starters in the SIRIUS series, several differences emerge:

• Current ratings: The 3RW4445-6BC44 offers 313 A standard and 542 A inside-delta, whereas smaller models like the 3RW4425 provide lower currents (e.g., 200 A).
• Voltage range: This model supports 200-460 V AC, while some variants are limited to 400 V or 690 V.
• Control voltage: The 230 V AC control supply is standard, but other models may use 24 V DC.
• Features: The 3RW4445-6BC44 includes integrated bridging, overload protection, and thermal resistor evaluation, which may not be present in basic models.

These differences make the 3RW4445-6BC44 a high-performance choice for demanding applications.

Support and Availability

The Siemens 3RW4445-6BC44 is available through AutoDCSTech. We stock this soft starter and can ship promptly. For detailed technical documentation or assistance with your specific application, contact our team. We are here to help you integrate this reliable soft starter into your system.