What it is and what it protects
The Siemens 3RV1021-0HA15-ZW95 is a SIRIUS motor-protection circuit breaker rated for 0.8 A continuous current with a CLASS 10 trip characteristic. It carries a 100 kA breaking capacity across the full AC voltage range from 240 V to 690 V, so it can safely interrupt a bolted fault at the motor terminals without the upstream breaker needing to clear it first — useful for high-fault-current panels. Phase failure detection is built in, so a single-phased motor will trip before the winding temperature climbs past the insulation class — a common failure mode on older three-phase lines.
Mounting and wiring
Mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 50022, and the 45 mm width means it occupies a single modular unit — no extra space needed for side or backward clearance (0 mm at the side, 0 mm backwards). Screw-type terminals on both main and auxiliary circuits accept solid conductors from 0.5 to 1.5 mm² (two per clamp) and stranded from 1 to 2.5 mm², with AWG equivalents for the main contacts at 2× (14…10). The auxiliary switch is transverse-mounted and field-addable — the product extension auxiliary switch is supported, so you can add a signal contact without replacing the breaker.
Environmental and lifecycle
Shock-rated to 25 g / 11 ms, and the IP20 front protection means it's suited for enclosed panel use only — not for washdown or outdoor exposure. RoHS compliance date is listed as 01.05.2012, so it meets the EU substance restrictions for current builds.
Sourcing and fit
If you are replacing a 3RV1011-0HA10 or 3RV1011-0GA10, the 3RV1021-0HA15-ZW95 shares the same 45 mm width, DIN rail mounting, and screw-terminal pattern, but the 0.8 A rating and CLASS 10 trip are specific — verify the motor FLA before swapping.