Motor Protection Circuit Breaker for 7.5 kW Loads at 400 V
The Siemens SIRIUS 3RV1021-4BA15-ZX95 is a motor protection circuit breaker rated for 20 A continuous current with a CLASS 10 trip characteristic, sized for a 7.5 kW motor at 400 V AC. It snaps onto a 35 mm DIN rail per DIN EN 50022 and occupies a 45 mm wide footprint, 97 mm tall, 96 mm deep — a standard panel-mount profile for motor starters in the SIRIUS family.
Breaking capacity varies with line voltage: 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. At 400 V — the most common industrial motor voltage — the 50 kA rating gives substantial headroom for high-fault-current panels, allowing selective coordination with upstream feeders without cascading failure. Maximum switching frequency under AC-3 duty is 15 operations per hour, and power dissipation in the hot operating state is 10.5 W — relevant for enclosure thermal calculations when grouping multiple breakers.
Main circuit and auxiliary/control circuit connections use screw-type terminals. Solid conductors accepted: 2× (0.5 to 1.5 mm²) and 2× (0.75 to 2.5 mm²). Stranded conductors: 2× (1 to 2.5 mm²) and 2× (2.5 to 6 mm²). AWG equivalents for main contacts: 2× (14 to 10). The auxiliary switch is transverse design, and the product extension for an auxiliary switch is supported.