Motor protection circuit breaker, SIRIUS series — 3RV2021-1GA25
The Siemens 3RV2021-1GA25 is a SIRIUS series motor protection circuit breaker designed for motor protection. It carries a rated current of 6.3 A at both 480 V and 600 V, with a massive 100 kA breaking capacity at 400 V, 480 V, and 500 V — that means it can safely interrupt a fault current up to 100,000 A without welding contacts or cascading damage upstream. The CLASS 10 trip characteristic ensures it rides through normal motor inrush (typically 6–8x FLA for a few seconds) but trips fast enough to protect the motor winding from sustained overload.
Termination and mounting
Main circuit connections use spring-loaded terminals, accepting 2x (0.5... 2.5 mm²) solid or stranded wire — no screw torque to verify, just strip and insert. Mounting is screw and snap-on onto 35 mm DIN rail per DIN EN 60715, with any mounting position allowed. The 45 mm width (three TE on a DIN rail) and 97 mm depth fit standard panel layouts; allow 50 mm clearance above and below for airflow and arc quenching.
Protection features and ratings
Phase failure detection is built in — critical for three-phase motor protection where a lost phase can draw locked-rotor current on the remaining phases without tripping a standard thermal. Ground fault detection is not included, so pair this breaker with a separate ground-fault relay if that's required. Rated operational voltage spans 20... 690 V. Ambient operating range is -20 to +60 °C; storage and transport range is -50 to +80 °C.