Motor Protection Circuit Breaker — SIRIUS 3RV2021-4NA20-ZX95
The Siemens SIRIUS 3RV2021-4NA20-ZX95 is a motor protection circuit breaker designed to protect three-phase induction motors against overload, short-circuit, and phase failure. It is part of the SIRIUS modular system, integrating with contactors and overload relays on a common DIN rail for coordinated motor starting. Trip class CLASS 10 means it will trip within 10 seconds at 7.2× the current setting, which is the standard for standard-duty motor starting — adequate for most pump, fan, and conveyor applications where the starting transient is under 10 seconds. Rated for a rated insulation voltage of 20... 690 V, with a short-circuit breaking capacity of 100 kA at 240 V AC, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. This gives the panel designer selectivity headroom at the lower voltages common in industrial control panels. Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715, in any position. The 45 mm width and 97 mm depth fit a standard 45 mm modular device footprint — drop-in compatible with existing SIRIUS 3RV2 panel layouts.
Sourcing & Lifecycle
For compliance documentation, the SIRIUS series carries RoHS, REACH, and relevant IEC/EN 60947-2 and 60947-4-1 certifications. The manufacturer provides a Declaration of Conformity and UL/CSA file numbers upon request.
Integration & Clearance
Clearance requirements: 50 mm upwards, 50 mm downwards, 30 mm at the sides, and 0 mm forwards and backwards. This allows dense panel packing — adjacent devices can be mounted flush front-to-back, with only vertical and lateral breathing space for heat dissipation and wiring access. Spring-loaded terminals for the main current circuit accept 2x (1... 10 mm²) solid or stranded wire — no ring lugs needed, which speeds panel wiring and reduces the risk of loose connections under vibration. Operating temperature range -20... +60 °C, storage/transport -50... +80 °C. The wide storage range means it can sit in an unheated warehouse or truck without degradation.