SIRIUS 3RF33 solid-state contactor, 20 A AC-1
The Siemens 3RF3320-2DA22 is a 1-pole solid-state contactor from the SIRIUS 3RF33 family, rated for 20 A in AC-1 resistive load duty at 40 °C ambient. That AC-1 rating means it handles resistive heating loads, lighting banks, and transformer primaries without derating for motor inrush — the thermal curve is the limit, not the switching cycle. Control voltage spans 24-230 V UC (universal current) and 110-230 V AC, giving flexibility across 24 VDC PLC outputs and 120 V or 230 V AC control circuits without a separate interface relay. The contactor is specified as short-circuit-proof when paired with a B-curve miniature circuit breaker — a useful selectivity note for panel builders coordinating branch protection. Terminations are spring-loaded, which speeds wiring in high-vibration environments compared to screw clamps.