SIRIUS solid-state contactor, 30 A AC-51, single-phase
The Siemens SIRIUS 3RF2330-1AA04 is a single-phase solid-state contactor rated for 30 A in AC-51 duty (resistive loads), switching 48-460 VAC at 50/60 Hz via zero-point switching — meaning the thyristor turns on at the voltage zero-crossing, minimizing inrush and EMI on heater or lamp banks. Control supply accepts 40-506 VAC at 50/60 Hz, drawing 13 mA DC from the control circuit. The 1 ms on/off delay (plus one half-wave max) is fast enough for cycling loads but not for high-speed PWM — this is a contactor replacement, not a chopper. The 45 mm width and side-by-side mounting capability mean it fits tightly in a multi-contactor panel without forced spacing — watch the 33 W dissipation at hot state; side-by-side mounting requires derating above 40 °C ambient.
Main and control circuits use screw-type terminals. Solid conductors: 1x (0.5-2.5 mm²) or 2x (0.5-1.0 mm²). Stranded: 1.5-6 mm². AWG for main contacts: 2x (14-10). The 7 mm contact gap on the main contacts is a physical air gap for isolation — not a switching gap; the thyristor does the switching.
Protection and ratings
Rated insulation voltage 600 V, pollution degree 3 (industrial environment). UL 508 rating: 27 A. I²t maximum 1,800 A²·s — use this for semiconductor fuse selection. Recommended fuses: NH type 3NA6807, DIAZED 5SB2711, NEOZED 5SE2320 (all with lower rated current than the relay). Minimum operational current 500 mA ensures reliable thyristor latching below that threshold. Derating begins at 40 °C. Reverse thyristor leakage 10 mA — negligible for most loads but factor it into off-state isolation checks.