What the 40 A AC-1 rating means for your panel
The 3RF3340-1AA04 is a 1-pole solid-state contactor from the SIRIUS 3RF33 family, rated 40 A in AC-1 duty at 40 °C. AC-1 covers resistive loads — heaters, ovens, lighting banks — where the current waveform is nearly sinusoidal with no motor inrush. That 40 A figure is the continuous current the semiconductor can carry without exceeding its junction temperature at a 40 °C ambient. If your panel runs hotter, you derate; if you're switching motor loads (AC-3 or AC-4), this is not the right part — you'd need a 3RF34 or a hybrid contactor. Control is 24 V DC, screw-terminal connection. The supply voltage range spans 48-460 V AC, so it covers common line voltages from 48 V control circuits up to 277/480 V distribution without a separate tap. Mounts on standard DIN rail; the 105 x 27 x 122 mm envelope fits a single modular width, leaving room alongside overload relays or terminal blocks.
Sourcing posture for procurement
As an active, standard-product-class item (Class A per Siemens classification), the 3RF3340-1AA04 is a stockable SKU with standard return eligibility.