The Siemens SIRIUS 3RV2021-1BA10-ZX95 is a motor protection circuit breaker designed for Class 10 trip response, meaning it will disconnect within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors from locked-rotor heat rise without nuisance tripping on normal starts. Breaking capacity hits 100 kA at 400 V AC and holds that figure at 240 V and 500 V AC, dropping to 10 kA at 690 V AC. No ground fault detection on this variant, so if that's needed, look at the GF versions in the same SIRIUS family.
Panel Fit & Mounting
That side clearance is tighter than some competitors; if you're packing breakers side-by-side, you can run them at 0 mm spacing only if the ambient stays within rating — otherwise leave the 30 mm for heat dissipation. Terminals accept 2x (1 to 2.5 mm²) or 2x (2.5 to 10 mm²) solid or stranded, with M4 screws for the main contacts. A 5–6 mm diameter screwdriver shaft is specified — standard Pozidriv #2 or flat-blade in that range works.
The rated operational voltage range is 20 to 690 V, covering low-voltage motor circuits from 24 V control transformers up to 690 V industrial mains. Horsepower ratings are given at specific voltages: 0.13 hp at 230 V, 1 hp at 460/480 V and at 575/600 V. The 2 A rating at 480 V and 600 V is the continuous current — match that to your motor's full-load amps. Switching frequency is rated at 15 operations per hour for AC-3 and AC-3e duty — that's typical for a motor starter protecting a pump or fan that cycles a few times an hour. Not designed for high-speed jogging or frequent reversing; for that, look at a dedicated contactor with a higher mechanical life.