The Siemens 3RV2021-0KA20 is a SIRIUS motor protection circuit breaker in the Size S0 frame, designed for motor protection with phase failure detection and Trip Class 10. It carries a 100 kA interrupting capacity at 400 V AC, meaning it can safely clear faults up to that level without cascading upstream — critical for high-fault panels where selectivity and SCCR headroom are the deciding factors. The breaker is active in the current lifecycle stage, so it remains a standard BOM line item rather than a last-time-buy scavenge.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. Width is 45 mm, depth 97 mm, height 119 mm — fits a standard 45 mm slot on a DIN rail; the S0 frame leaves room for adjacent breakers in a motor control center. Any mounting position is allowed, so vertical or horizontal rail orientation works. Clearance: 50 mm above and below, 30 mm to the side, zero forward or backward — the breaker sits flush against the backplane.