The Siemens 3RV2042-4MA10 is a SIRIUS motor protection circuit breaker designed for motor protection, with CLASS 10 trip characteristic meaning it will trip within 10 seconds at 7.2x the thermal setting — fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal starts. Breaking capacity is 100 kA at 400 V AC and 100 kA at 240 V AC, which means this breaker can safely interrupt fault currents up to 100,000 amps at those voltages — sufficient for high-fault panels downstream of large transformers without needing a current-limiting upstream device. Motor horsepower ratings span from 7.5 hp at 110/120 V up to 100 hp at 575/600 V, covering a wide range of industrial motor sizes.
Any mounting position allowed. Dimensions 70 mm wide x 165 mm high x 176 mm deep — the 176 mm depth is the key dimension for enclosure depth clearance; ensure your panel has at least 180 mm usable depth to allow wiring space behind the breaker. Screw-type terminals for the main circuit accept 2x (2.5...16 mm²) solid or stranded, or 1x (10...70 mm²) for larger feeds — flexible enough for both panel internal wiring and incoming supply cables.
Lifecycle stage is current production — this is an active, non-obsolete part in the Siemens SIRIUS catalog, not a phase-out or NRND item. Rated insulation voltage 20...690 V covers standard low-voltage networks up to 690 V phase-to-phase. Maximum switching frequency at AC-3 duty is 15 operations per hour — sufficient for motor starting duty but not for high-speed jogging or frequent cycling applications.