SIRIUS 3RV2021-1JA20-0BA0 — motor protection circuit breaker, S0 frame
The Siemens 3RV2021-1JA20-0BA0 is a SIRIUS motor protection circuit breaker in the S0 frame size, designed for protecting three-phase motor loads. It combines a thermal-magnetic overload relay and a short-circuit trip in one device, saving panel space and wiring compared to a separate contactor-plus-overload combination. Trip Class 10 means the bimetal element trips within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal starting inrush. Breaking capacity is 100 kA at 400 V AC, which covers most industrial distribution panels fed by a transformer of that voltage. At 690 V the rating drops to 4 kA — still adequate for many 690 V motor circuits, but verify the available fault current at the panel bus. Rated motor power is 2.2 kW at 230 V. The device detects phase failure — a common cause of single-phasing damage in delta-connected motors — and trips on loss of one phase.
Mounting and wiring — DIN rail, spring terminals
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The S0 frame footprint — 45 mm wide, 119 mm tall, 97 mm deep — fits standard motor starter assemblies alongside a SIRIUS contactor of matching frame size. Clearance: 50 mm above and below, 30 mm at the sides, zero forward or backward (–). Main circuit connections use spring-loaded terminals, accepting 2× (1 to 10 mm²) solid or stranded wire. No screw torque to set — strip, insert, release. The screwdriver shaft for the terminal release is 3 mm diameter. Operating temperature range is -50 to +60 °C; storage and transport extend to -50 to +80 °C. Temperature compensation is active from -20 to +60 °C, keeping the thermal trip curve stable across the panel's ambient swing.