Solid-State Contactor for Resistive Loads
The Siemens SIRIUS 3RF2330-1DA44 is a single-phase solid-state contactor rated 30 A in AC-51 duty, meaning it is sized for resistive or slightly inductive loads such as heater banks, ovens, or lighting panels — not for motor starting, where AC-53 or AC-58a ratings govern. The 48-460 V AC load voltage range (at 50/60 Hz) covers standard low-voltage heating circuits across most global line voltages. Control voltage spans 40-506 V AC at 50/60 Hz, drawing 18 mA DC from the control circuit, so a single 24 V DC PLC output or a 230 V AC pilot circuit can drive it directly. Side-by-side mounting is permitted, which is critical for panel density — you can gang multiple units without derating, provided ambient stays below 40 °C before the thermal derating curve applies.
Short-Circuit Coordination and Fusing
This contactor is designed as short-circuit resistant when paired with a B-curve miniature circuit breaker (MCB). The I²t withstand is 6,600 A²·s maximum, so upstream protection must clear before the thyristor junction exceeds that energy. Siemens specifies NH fuse 3NA6807, DIAZED fuse 5SB2711, or NEOZED fuse 5SE2320 as coordinated semiconductor fuses — these have a lower rated current than the relay itself, so they protect the thyristor without nuisance blowing on inrush. The contact gap of 7 mm provides visible isolation when the output is off.
Switching Performance and Derating
ON-delay and OFF-delay are both 1 ms plus a maximum of one half-wave, so this part switches within one mains cycle — fast enough for closed-loop temperature control but not for zero-cross critical applications where you need sub-cycle precision. Minimum operational current is 500 mA; below that the thyristor may not latch cleanly. For UL 508 installations the continuous rating is 26 A.
Main circuit terminals are screw-type, accepting solid wire 1x (0.5-2.5 mm²) or 2x (0.5-1.0 mm²), and stranded 1.5-6 mm². AWG for main contacts is 2x (14-10). Auxiliary and control circuit terminals are also screw-type. Pollution degree 3 (conductive pollution) means the unit is suitable for control panels without environmental sealing beyond the IP20 enclosure. Insulation voltage is rated 600 V.