The Siemens 3RV2021-1HA20 is a SIRIUS motor protection circuit breaker with CLASS 10 trip class. Rated breaking capacity is 100 kA at 400 V AC, which covers most industrial distribution fault levels without requiring an upstream current-limiting fuse or breaker for coordination. At 690 V AC the breaking capacity drops to 4 kA, so verify the available fault current at that voltage level.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. Width is 45 mm, depth 97 mm, height 119 mm. Clearance requirements: 50 mm upwards and downwards, 30 mm to the side, zero forwards or backwards. The zero forward clearance means it can be mounted flush against a panel door or backplate without additional standoffs.
Termination and environment
Main current circuit terminates via spring-loaded terminals, accepting 2× (1 to 10 mm²) solid or stranded wire. Spring-cage termination speeds panel wiring — no torque driver needed, and the connection stays vibration-resistant in a motor-starting environment. Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. The -20 °C floor means it can sit in an unheated enclosure in a northern climate without concern for the mechanism stiffening.
Protection features
Phase failure detection is built in — the breaker will trip if one phase is lost, preventing single-phasing damage to the motor. Ground fault detection is not integrated, so if ground-fault protection is required it must be added externally. Maximum switching frequency at AC-3 duty is 15 operations per hour, which suits pump, fan, and conveyor cycling but not high-speed jogging or reversing applications.