Motor Protection Circuit Breaker, 22 A, Class 10
The Siemens SIRIUS 3RV2021-4CA25 is a motor protection circuit breaker rated for 22 A at 480 V and 600 V, with a breaking capacity of 25 kA at 400 V. Spring-loaded terminals accept 2× (0.5 to 2.5 mm²) solid or stranded copper, which saves panel-wiring time compared to screw-clamp variants. Auxiliary contact ratings cover control voltages from 24 V (1 A) up to 690 V (gL/gG 50 A), so the same block can signal a PLC input at 24 VDC or switch a contactor coil at 230 VAC without derating.
Clearing Clearances and Panel Fit
Required clearances for heat dissipation: 50 mm above and below, 30 mm to the side, 0 mm forward and backward. The zero forward/backward clearance means the breaker can be mounted flush against a back panel or enclosure door without derating — a common gotcha on other breakers that demand 10–20 mm of breathing room.
Breaking capacity varies by voltage: 100 kA at 240 V, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. At 400 V — the most common industrial distribution voltage — 25 kA covers the vast majority of panel SCCR requirements (a typical MCC main bus is rated 25 kA or 35 kA). If your facility runs 480 V, the 22 A continuous rating matches a 7.5 hp motor at 460 V. The maximum switching rate is 15 operations per hour under AC-3 duty (starting and stopping a squirrel-cage motor). That's fine for a conveyor or pump that cycles a few times an hour; for a jogging or inching application that needs 100+ starts per hour, step up to a contactor with a higher mechanical life.