What it is and what it does
The Siemens 3RV2021-1FA25 is a SIRIUS-branded motor protection circuit breaker with Class 10 trip and phase failure detection. Rated 5 A at both 480 V and 600 V, this breaker handles motor full-load currents up to that point. The breaking capacity tells the real story: 100 kA at 400 V and 500 V, dropping to 4 kA at 690 V. That 100 kA figure covers most industrial low-voltage fault levels without needing an upstream current-limiting fuse — it's a high-interrupting device for its frame size.
Mounting and wiring — panel fit
Mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 60715. The 45 mm width is a single modular unit, so it occupies one slot in a standard DIN-rail panel layout. Depth is 97 mm, height 119 mm — check gland-plate clearance if the panel is shallow. Mounting position is any, which helps when the panel layout is tight. Spring-loaded terminals on the main current circuit accept 2×(0.5 … 2.5 mm²) solid or stranded wire. That's a standard control-panel wire range; no special ferrules needed. Clearance distances: 50 mm above and below, 30 mm at the sides, zero forwards and backwards — the zero forward/backward clearance means you can butt it against the backplane or a cover without derating.
Temperature and environment
Operates from -20 to +60 °C ambient, stores and transports from -50 to +80 °C. No IP rating is listed in the evidence.