3RW4445-2BC36
screw fixing
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Siemens 3RW4 Series
528 variants · Siemens
Siemens 3RW4 — SIRIUS Soft Starter, Legacy Series for Motor Starting
The Siemens 3RW4 series with over 470 variants is the previous-generation SIRIUS soft starter covering 3kW to 250kW at 400V. The 3RW4 is the predecessor to the current 3RW5 series — still widely deployed in existing installations and supported with spare parts availability.
3RW4 vs 3RW5
| Feature | 3RW4 (Previous) | 3RW5 (Current) |
|---|---|---|
| Current range | Up to 250kW at 400V | Up to 1200kW at 400V |
| Parameter setting | DIP switches + potentiometer | Display + keypad or software |
| Communication | Optional PROFIBUS module | Integrated PROFINET |
| Status | Mature / supported | Active production |
For new projects, Siemens recommends 3RW5 for full feature set and long-term availability. 3RW4 remains available for direct replacement in existing installations.
Availability
3RW4: limited production, available through Siemens distributors.
About the Siemens 3RW4 Series
The Siemens 3RW4 Series series groups 528 related part numbers, each listed with full specifications, a datasheet where available, and an RFQ option. Variants differ by depth, height and mounting, so you can match the exact depth your application requires using the selection guide below.
Select a variant by
- Depth
- 155 mm · 170 mm · 250 mm · 278 mm · 290 mm · 298 mm
- Height
- 150 mm · 160 mm · 198 mm · 230 mm · 640 mm
- Mounting
- screw and snap-on mounting · screw fixing
- Width
- 45 mm · 55 mm · 120 mm · 160 mm · 210 mm · 510 mm
Variant comparison
| Parameter | 3RW4055-2BB34 | 3RW4075-2BB44 | 3RW4457-2BC44 | 3RW4056-6BB35 | 3RW4456-2BC45 | 3RW4056-2BB44 |
|---|---|---|---|---|---|---|
| Depth | 250 mm | 278 mm | 290 mm | 250 mm | 290 mm | 250 mm |
| Height | 198 mm | 230 mm | 640 mm | 198 mm | 640 mm | 198 mm |
| Mounting | screw fixing | screw fixing | screw fixing | screw fixing | screw fixing | screw fixing |
| Width | 120 mm | 160 mm | 510 mm | 120 mm | 510 mm | 120 mm |
Request a quote on any Siemens 3RW4 Series part number and we confirm price, availability and lead time per line — including end-of-life and allocation-constrained variants.
