The Siemens SIRIUS 3RV2021-1FA10-ZX95 is a motor protection circuit breaker built for the route — Class 10 trip, 100 kA breaking capacity at 400 V, and it'll handle the heat from -20 to +60 °C during operation. Screw terminals on the main circuit (M4, accepting 2x 1–2.5 mm² or 2x 2.5–10 mm² solid or stranded) and a 45 mm width mean it lands clean in a standard DIN-rail panel without reworking the gland plate. Phase failure detection is built in; ground fault detection is not — so if you're protecting a motor on a line that needs ground-fault tripping, you'll add an external module or pick another breaker.
Compared to the older 3RV1011-1HA10, this 3RV2021-1FA10-ZX95 shares the same 45 mm width and DIN-rail snap-on mounting, so it drops into a panel built for the 3RV1011 without rewiring. The key difference is the 100 kA breaking capacity at 400 V — a step up from the 3RV1011's typical 50 kA class — and the Class 10 trip curve that matches modern motor-starting profiles.
Mounts in any position via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. Clearance: 50 mm above and below, 30 mm at the sides, 0 mm forward or back — no extra breathing space needed behind the panel.