What it is and where it fits
The Siemens 3RV2031-4WB15 is a SIRIUS motor protection circuit breaker designed to protect three-phase induction motors against overload and short-circuit. It mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 60715, with any mounting position allowed — a straightforward drop into a motor control center or standalone panel.
Key ratings and what they mean for your motor
Rated at 52 A at 480 V and 52 A at 600 V, this breaker handles common North American motor sizes in those voltage classes. At 230 V it supports a 10 hp motor. The breaking capacity is 30 kA at 400 V AC, 100 kA at 240 V, and 2 kA at 690 V — so it safely interrupts fault currents up to those levels without upstream coordination issues in most industrial distribution. Trip class is CLASS 20, meaning it allows up to 20 seconds to trip under locked-rotor conditions — standard for general-purpose pumps, fans, and compressors that don't need the faster CLASS 10 protection. Maximum switching frequency is 15 operations per hour under AC-3 (motor) duty, which suits cyclic loads like conveyors or batch mixers. Phase failure detection is built in — the breaker will trip if one phase is lost, preventing single-phasing damage to the motor winding. No ground fault detection on this variant.
Physical fit and clearances
Dimensions are 55 mm wide, 140 mm high, 149 mm deep. Required clearances: 50 mm above and below for arc venting, 10 mm at the sides. Terminal capacity accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded copper. Main contact screws are M6.