The Siemens SIRIUS 3RT1926-3AF31 is a mechanical latching block designed to hold a contactor closed without continuous coil power — a common requirement for safety hold circuits or applications where a maintained state must survive a control-voltage dip. It clips onto S0 and S2 frame contactors in the 3RT1.2 and 3RT1.3 series, accepting a 110 V AC/DC control supply through its screw-type terminals.
What the ratings mean for fit
The latching block mounts via clip-on fastening to the contactor front, occupying no additional DIN-rail width — it adds depth only. Rated for any mounting position, it fits panels where the contactor is installed horizontally or inverted. The IP20 front protection means it is safe for finger contact inside an enclosed panel but not for washdown environments. Screw terminals accept 2x (0.5... 2.5 mm²) solid or 1x 4 mm² solid conductors, with equivalent AWG capacity of 2x 14 or 1x 12 for the auxiliary circuit. This matches the wire sizes typically run to contactor coils in control panels — no special crimping or ferruling required for solid wire, though the terminal also accepts stranded with core-end processing. The operating temperature range of -25 to +60 °C covers most indoor industrial panel environments; the storage range of -50 to +80 °C allows for cold warehouse or hot container shipping without damage.