✓ Standard: 2-3 days
✓ Urgent: 24-48 hours*
✓ Service Exchange: 48-hour replacement*
✓ Spare Unit: Same unit as the original*
* Services subject to availability
The SIRIUS 3RW30 and 3RW40 are compact soft starters from the Siemens SIRIUS range. They are thyristor devices for starting three-phase asynchronous motors, and they are not variable speed drives: they ramp the motor up to speed and then hand over to bypass contacts, with no control of running speed.
Both families start on a voltage ramp: motor voltage rises from an adjustable starting voltage, settable between 40 and 100 per cent, to full mains voltage over a ramp time of 0 to 20 seconds, which limits starting current and torque shock.
The 3RW30 is soft start only, from 3.6 A to 106 A, or 1.5 kW to 55 kW at 400 V, in sizes S00 to S3. The 3RW40 covers 12.5 A to 106 A in sizes S0 to S3 and adds soft stop, adjustable current limiting and motor overload protection; its larger sizes S6 and S12 reached 432 A and 250 kW.
Voltage ramp starting, with starting voltage adjustable from 40 to 100 % and a ramp time of 0 to 20 s
Two-phase control with polarity balancing, so no direct-current component reaches the motor
Integral bypass contacts, so the thyristors carry no load current after run-up
Soft stop on the 3RW40
3RW40 adds current limiting and motor overload protection with CLASS 10, 15 or 20 trip
Optional thermistor motor protection on 3RW40 TB versions
| Manufacturer | Siemens |
|---|---|
| Series | SIRIUS 3RW30 and 3RW40 soft starters |
| 3RW30 Range | Ie 3.6 A – 106 A; Pe 1.5 kW – 55 kW at 400 V (sizes S00 to S3) |
| 3RW40 Range | Ie 12.5 A – 106 A; Pe 5.5 kW – 55 kW at 400 V (sizes S0 to S3). Sizes S6 and S12 reached 432 A and 250 kW and have been obsolete since October 2023 |
| Control Principle | Two-phase controlled, variable phase angle control with integral bypass contacts |
| Standards | Based on IEC/EN 60947-4-2 |
| Degree of Protection | IP20 on the front to IEC 60529, finger-safe from the front; open-type device for cabinet mounting |
| Normal Starting (CLASS 10) | Max ramp time 3 s, starting current 300%, 20 starts/hour, ON time 30%, standalone, up to 1000 m, ambient max 40 °C |
| Max Ramp-Up Time (3RW30) | 20 seconds |
| Installation Altitude | Up to 5000 m; derate current above 1000 m; above 2000 m the maximum operational voltage is reduced to 480 V |
| 3RW40 Protection Functions | Settable current limiting, motor overload and intrinsic device protection, optional thermistor motor protection |
| Cooling | Optional fan on 3RW40 sizes 24 to 47; integrated on 55 to 76; the 3RW30 cannot take a fan |
| Product Status | 3RW30 sizes S00 to S3 and 3RW40 sizes S0 to S3 remain current Siemens products. 3RW40 sizes S6 and S12 became obsolete on 1 October 2023 |
| Family | Size / Ie code | Rated current Ie at 400 V / 460 V |
Rated power Pe at 400 V / 460 V |
Frame size |
|---|---|---|---|---|
| 3RW30 | 13 | 3.6 A / 3 A | 1.5 kW / 1.5 hp | S00 |
| 3RW30 | 14 | 6.5 A / 4.8 A | 3 kW / 3 hp | S00 |
| 3RW30 | 16 | 9.0 A / 7.8 A | 4 kW / 5 hp | S00 |
| 3RW30 | 17 | 12.5 A / 11 A | 5.5 kW / 7.5 hp | S00 |
| 3RW30 | 18 | 17.6 A / 17 A | 7.5 kW / 10 hp | S00 |
| 3RW30 | 26 | 25 A / 23 A | 11 kW / 15 hp | S0 |
| 3RW30 | 27 | 32 A / 29 A | 15 kW / 20 hp | S0 |
| 3RW30 | 28 | 38 A / 34 A | 18.5 kW / 25 hp | S0 |
| 3RW30 | 36 | 45 A / 42 A | 22 kW / 30 hp | S2 |
| 3RW30 | 37 | 63 A / 58 A | 30 kW / 40 hp | S2 |
| 3RW30 | 38 | 72 A / 62 A | 37 kW / 40 hp | S2 |
| 3RW30 | 46 | 80 A / 73 A | 45 kW / 50 hp | S3 |
| 3RW30 | 47 | 106 A / see note * | 55 kW / 75 hp | S3 |
| 3RW40 | 24 | 12.5 A / 11 A | 5.5 kW / 7.5 hp | S0 |
| 3RW40 | 26 | 25 A / 23 A | 11 kW / 15 hp | S0 |
| 3RW40 | 27 | 32 A / 29 A | 15 kW / 20 hp | S0 |
| 3RW40 | 28 | 38 A / 34 A | 18.5 kW / 25 hp | S0 |
| 3RW40 | 36 | 45 A / 42 A | 22 kW / 30 hp | S2 |
| 3RW40 | 37 | 63 A / 58 A | 30 kW / 40 hp | S2 |
| 3RW40 | 38 | 72 A / 62 A | 37 kW / 40 hp | S2 |
| 3RW40 | 46 | 80 A / 73 A | 45 kW / 50 hp | S3 |
| 3RW40 | 47 | 106 A / 98 A | 55 kW / 75 hp | S3 |
| 3RW40 | 55 | 132 A / 117 A | 75 kW / 75 hp | S6 |
| 3RW40 | 56 | 160 A / 145 A | 90 kW / 100 hp | S6 |
| 3RW40 | 73 | 230 A / 205 A | 132 kW / 150 hp | S12 |
| 3RW40 | 74 | 280 A / 248 A | 160 kW / 200 hp | S12 |
| 3RW40 | 75 | 350 A / 315 A | 200 kW / 250 hp | S12 |
| 3RW40 | 76 | 432 A / 385 A | 250 kW / 300 hp | S12 |
Values are for normal starting (CLASS 10) as defined in the Siemens manual. * The 460 V current for the 3RW30 size 47 could not be read reliably from the source document, so we have left it out rather than print a figure we are not sure of. The equivalent 3RW40 size 47 is 98 A. Contact us and we will confirm the figure for your unit.
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