The Siemens 3RV1021-4AA10-ZW96 is a SIRIUS motor protection circuit breaker rated for 16 A continuous current with a CLASS 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors during a stall or locked-rotor event without nuisance tripping on normal starting inrush. This breaker includes phase failure detection, which opens the circuit if one phase drops out — critical for preventing single-phasing damage on three-phase motor loads. The front panel carries an IP20 rating, so it's touch-safe once installed in an enclosure, but not rated for washdown environments.
The screw-type terminals on the main circuit accept 2x (1... 2.5 mm²) solid or stranded, or 2x (2.5... 6 mm²) — fine for the 16 A rating with standard panel wire. Auxiliary and control circuits use the same screw terminal style. No backward or side clearance is required, so it can be packed tight on the rail.
Rated breaking capacity varies with voltage: 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. The 690 V rating drops to 4 kA, so at higher voltages coordination with a backup fuse or upstream breaker should be checked.
Shock resistance is rated at 25 g for 11 ms. The product complies with RoHS substance prohibitions as of May 1, 2012.