Motor protection circuit breaker — 12.5 A, CLASS 10, 100 kA
The Siemens SIRIUS 3RV1021-1KA15-ZX95 is a motor protection circuit breaker rated for 12.5 A continuous current and 5.5 kW motor load at 400 V. Trip class CLASS 10 means it clears overloads fast enough to protect standard induction motors during start-up — the breaker trips within 10 seconds at 7.2× rated current, so the motor windings don't cook on a stalled rotor. Breaking capacity hits 100 kA at 400 V AC, which is enough for most industrial distribution panels with high fault current; at 690 V it still holds 6 kA. Phase failure detection is built in — no separate phase-loss relay needed on the line.
Panel fit and wiring
Mounts on 35 mm DIN rail per EN 50022 — screw and snap-on, no tools for the snap. Width is 45 mm, height 97 mm, depth 96 mm. That 96 mm depth means it clears most 120 mm deep enclosures, but check your gland plate clearance if the rail is near the back wall. Screw terminals on the main circuit; solid wire accepts 2× (0.5…1.5 mm²) and 2× (0.75…2.5 mm²), stranded takes 2× (1…2.5 mm²) and 2× (2.5…6 mm²). IP20 on the front — fine inside a closed panel, not for washdown. Mounting position any, so vertical or horizontal rail works.