Heavier industrial drives put more stress on every feeder: large three-phase motors draw high starting currents, and a single stalled motor on a conveyor, crusher, or pump can trip upstream protection or damage winding insulation. Where the small S00 motor-protection breakers top out at a few amps, the Siemens SIRIUS 3RV2031-4PB10 (order number 3RV2031-4PB10) is built for the next frame up. It is a size S2 device in the SIRIUS 3RV2 family with a 28 to 36 A overload setting and a Class 20 trip characteristic. This guide sets out its verified ratings and shows how it differs from the compact S00 breakers used on smaller motors.
What Is the 3RV2031-4PB10?
The 3RV2031-4PB10 is a three-pole motor-protection circuit breaker in the SIRIUS 3RV2 generation. Like its smaller relatives, it combines a thermal overload release with an instantaneous magnetic short-circuit release in one DIN-rail unit, but its S2 frame and 36 A permanent current put it in a different power class. The 3RV2 series is the successor to the 3RV1 range, designed for IE3/IE4 premium-efficiency motors, with low heat loss, worldwide IEC and UL/CSA approval, and suitability for DC switching and hazardous-area (ATEX / IEC Ex) use.
Verified Specifications
| Parameter | Specification |
|---|---|
| Order number | 3RV2031-4PB10 |
| Product family | SIRIUS 3RV2 motor starter protectors |
| Frame size | S2 |
| Design | Circuit breaker for motor protection, 3-pole |
| Overload release setting (Ir) | 28 ... 36 A, adjustable |
| Instantaneous short-circuit release | 520 A |
| Tripping class | Class 20 |
| Rated permanent current (Iu) | 36 A |
| Typical motor power (AC-3, 400 V) | 18.5 kW |
| Typical motor power (AC-3, 230 V) | 11 kW |
| Rated operational voltage | Up to 690 V AC |
| Breaking capacity (Icu) at 400 V | 65 kA |
| Main circuit terminals | Screw terminals |
| Phase-failure sensitivity | Yes |
| Integral auxiliary switch | No (accessories available) |
| Degree of protection | IP20 |
| Dimensions (H x W x D) | 140 x 55 x 149 mm |
| Net weight | Approx. 1.1 kg |
How It Compares With the Smaller S00 Breakers
The 3RV2031-4PB10 is not a like-for-like swap for a compact S00 protector such as the 3RV1011-1GA10. The two sit several frame sizes apart:
| Feature | 3RV1011-1GA10 (S00) | 3RV2031-4PB10 (S2) |
|---|---|---|
| Frame size | S00 | S2 |
| Overload setting range | 4.5 ... 6.3 A | 28 ... 36 A |
| Short-circuit release | 82 A | 520 A |
| Tripping class | Class 10 | Class 20 |
| Typical motor power (400 V) | 2.2 kW | 18.5 kW |
| Width | 45 mm | 55 mm |
The wider gap between running current and the 520 A magnetic trip, together with the Class 20 curve, is deliberate: heavier machines often use higher-inertia loads that draw longer starting currents, and Class 20 allows a slightly longer safe stall time before the thermal element trips.
Wiring and System Integration
The S2 device mounts on a standard 35 mm DIN rail with screw terminals on the line and load sides. It can be combined with a matching SIRIUS S2 contactor to form a compact motor starter, and the SIRIUS 3RV29 infeed system reduces main-circuit wiring when several starters share a panel. Because the unit is phase-failure sensitive, single-phasing of a three-phase winding is detected and cleared. For larger breakers, pay particular attention to the short-circuit coordination with the upstream supply and to the cable cross-section, since the 65 kA breaking capacity is high but the downstream conductors must still be protected within their own short-time limits.
Typical Applications
- Conveyor drives, crushers, mills, and agitators in the 15 to 18.5 kW class at 400 V
- Pumps, fans, and compressors with high-inertia loads and long starts
- IE3 and IE4 premium-efficiency three-phase motors
- Panels built with SIRIUS modular contactors and infeed systems
- Hazardous-area installations permitted under ATEX / IEC Ex
If your motor is much smaller, a size S00 or S0 breaker is usually the more economical and compact choice; if it sits around 30 A, the S2 frame is the appropriate rating. Browse related components in our Siemens range and the motor-control collection.
Lifecycle and Spare Parts
The SIRIUS 3RV2 range is the current-generation family that succeeds the older 3RV1 breakers, and it is designed for long-term support. Nevertheless, spare parts for installed S2 feeders are worth holding, because larger motors tend to be critical assets where a trip means a full line stop. When a breaker is no longer easy to source through normal channels, our Discontinued Products range and sourcing team can help; send us the part number and we will confirm availability and compatible alternatives.
Frequently Asked Questions
What motor power is the 3RV2031-4PB10 rated for?
At 400 V it corresponds to a typical 18.5 kW three-phase motor in AC-3 duty, and about 11 kW at 230 V. Its overload dial is adjustable from 28 to 36 A to match the nameplate current.
Why is it Class 20 rather than Class 10?
Class 20 tolerates a longer stall time (up to 20 s from cold at 7.2 times rated current), which suits high-inertia loads that take longer to start without tripping the thermal overload.
Can it replace a smaller S00 breaker like the 3RV1011?
No. The S2 frame protects motors in the 28 to 36 A range, far above the 4.5 to 6.3 A S00 range. Using an oversized breaker would leave a small motor under-protected.
Does it include an auxiliary contact?
This variant does not have an integral auxiliary switch; SIRIUS auxiliary and signaling contacts can be added as accessories for remote indication of the trip state.
SHLY-PLC is an independent distributor of industrial automation parts. All brand names, model numbers, and trademarks are the property of their respective holders and are used only for identification and compatibility reference.