3RW4447-6BC44 Siemens Soft Starter for Pumps, Fans, Compressors

Product Description / Overview

The Siemens 3RW4447‑6BC44 is a new SIRIUS soft starter designed for high-power three-phase motors.
It ensures smooth motor acceleration and deceleration, minimizing mechanical stress on shafts, belts, and couplings.

Moreover, the SIRIUS 3RW44 series integrates bypass contactors, motor overload protection, and thermistor evaluation functions.
This model also includes current limitation, inside-delta connection support, and a motor brake output for advanced control.

In addition, it is engineered for heavy-duty industrial applications such as pumps, compressors, fans, conveyors, and large machinery.
Therefore, it provides reliable operation under continuous load conditions while maintaining energy efficiency.

Technical Data / Specifications

Product Type: Soft Starter
Series: SIRIUS 3RW44
Manufacturer: Siemens AG

Rated Operational Voltage (Ue): 200–460 V AC, 3-phase
Rated Motor Power: Up to 400 kW (at 400 V, AC‑53b duty)
Rated Operational Current (Ie): 820 A

Control Supply Voltage (Us): 110–250 V AC/DC
Starting Method: Voltage ramp with adjustable start/stop parameters
Integrated Bypass: Yes

Protection Functions:

• Motor overload protection

• Thermistor motor evaluation

• Intrinsic device protection

Special Features:

• Current limitation

• Inside-delta connection capability

• Motor brake output

• External reset option

Insulation Voltage (Ui): 690 V
Pollution Degree: 3 (IEC 60947‑4‑2)
Utilization Category: AC‑53b (IEC soft starter duty)

Operating Temperature: –25 °C to +60 °C
Storage Temperature: –40 °C to +80 °C

Mounting Type: Panel mounting
Protection Class: IP20 (open type, requires enclosure)

Dimensions (H × W × D):  470 × 320 × 250 mm
Weight: 4kg

Status: Phased-out product
Recommended Successor: SIRIUS 3RW5 series

FAQ

Is the Siemens 3RW4447-6BC44 compatible with thermistor-protected motors?
Yes, it supports direct thermistor motor protection evaluation for precise temperature monitoring.

What is the recommended replacement for new installations?
Siemens recommends the SIRIUS 3RW5 series as the successor platform for future-proof installations.

Does this soft starter include an integrated bypass?
Yes, it includes bypass contactors to reduce heat losses during normal operation.

Can it operate in inside-delta motor configurations?
Yes, inside-delta connections are supported to optimize current utilization and reduce device size.

What is the maximum motor power supported at 400 V?
This model supports motors up to 400 kW at 400 V with AC‑53b duty classification.