Siemens 3RW4446-6BC44 Soft Starter 617A 355kW

3RW4446-6BC44 SIRIUS Soft Starter for High-Power Motors

The 3RW4446-6BC44 comes from Siemens’ trusted SIRIUS product line. You can use this soft starter for demanding industrial motor starting applications. It significantly reduces inrush current and mechanical shock during startup. Furthermore, it provides complete motor overload protection and thermal monitoring.

Key Electrical Parameters of the 3RW4446-6BC44

This soft starter operates at a rated voltage of 200–460V AC. For standard three-phase circuits, the operating current reaches 356A at 40°C. In inside-delta configuration, it delivers an impressive 617A at the same temperature.

The mechanical power output is equally robust. At 400V with standard switching, you get 200kW. When you use the inside-delta circuit, power output jumps to 355kW at 400V. Additionally, at 230V, standard switching provides 110kW while inside-delta gives 200kW.

Frequency support covers 50–60 Hz with ±10% tolerance. The adjustable motor current ranges from 71A up to the full rated value. Continuous operating current reaches 115% of Ie at 40°C without issues.

Control Supply and Protection Functions

The 3RW4446-6BC44 requires a 230V AC control supply at either 50 Hz or 60 Hz. Voltage tolerance sits at -15% to +10%. This flexibility makes installation in different regions straightforward.

Built-in protection features are comprehensive. The unit includes intrinsic device protection and motor overload protection. It also evaluates thermistor inputs for precise motor temperature monitoring. Moreover, you get an external reset function, adjustable current limitation, and full inside-delta circuit support.

A motor brake output comes standard with this model. The insulation voltage rating is 690V with pollution degree 3 according to IEC 60947-4-2.

Mechanical Dimensions and Installation Requirements

The 3RW4446-6BC44 measures 210 mm wide, 230 mm high, and 298 mm deep. Protection class is IP00 on the front, though it reaches IP20 when you add the box terminal cover.

Mounting uses screw fixing. You can rotate the unit ±90° on a vertical surface. Tilting ±22.5° forward or backward is also acceptable.

Required spacing includes 100 mm upward, only 5 mm sideways, and 75 mm downward. Maximum cable length reaches 500 meters. Installation altitude goes up to 5,000 meters above sea level.

Temperature Ratings and Derating Information

Operating temperature ranges from -25°C to 60°C. However, derating begins at 40°C. Therefore, at 50°C the standard current drops to 315A. At 60°C it reduces further to 280A.

For inside-delta operation at 50°C, current becomes 546A. At 60°C, it decreases to 485A. Storage temperature spans -25°C to +80°C, giving you good flexibility for inventory management.

Terminal Connections and Wiring Options

Main current circuit connections use busbar terminals. For the front clamping point, finely stranded wires with end processing require 70–240 mm². Stranded wires accept 95–300 mm².

The back clamping point works with 120–185 mm² for finely stranded wires. Stranded wires there take 120–240 mm². When using both clamping points, you can connect two conductors from 2x 50 mm² up to 2x 185 mm².

AWG conductors for main contacts range from 2/0 to 500 kcmil. For the front clamping point specifically, AWG 3/0 to 600 kcmil works well. Auxiliary contacts accept solid wires of 2x (0.5–2.5 mm²) or finely stranded 2x (0.5–1.5 mm²).

This model provides three normally open auxiliary contacts and one changeover contact. It includes no normally closed contacts.

Frequently Asked Questions (FAQ)

1. What is the maximum motor power the 3RW4446-6BC44 can handle?
In standard circuit at 400V, it handles 200kW. In inside-delta circuit at 400V, it handles 355kW. For 230V applications, inside-delta reaches 200kW.

2. How does inside-delta connection benefit my application?
Inside-delta reduces the current through each thyristor by approximately 42%. This allows the 3RW4446-6BC44 to control a higher power motor without increasing its physical size or thermal load.

3. Can I use this soft starter at 60°C ambient temperature?
Yes, but current derating applies. Standard current drops to 280A at 60°C. Inside-delta current drops to 485A at the same temperature. Plan your installation accordingly.

4. What type of motor protection does the 3RW4446-6BC44 include?
The unit provides motor overload protection, thermistor (PTC) evaluation, adjustable current limitation, and intrinsic device protection. An external reset function is also available.

5. What is the required clearance around this device?
You need 100 mm above, 75 mm below, and only 5 mm on each side. This compact spacing makes panel mounting very efficient for multiple units.