The Siemens 3RP1540-2AW31 is a SIRIUS time relay with a universal control supply voltage covering 24-240 V AC at 50/60 Hz and 24-240 V DC, making it suitable for control panels fed by either mains or battery-backed DC buses without needing a separate supply variant. The adjustable time range spans 0.05 to 600 seconds, with a recovery time of 150 ms between cycles and a minimum ON period of 200 ms — important when sequencing fast-cycling loads like pneumatic valves or small contactors. Rated thermal current (Ith) is 5 A, with switching capacity at 24 V DC of 1 A, dropping to 0.2 A at 125 V DC and 0.1 A at 250 V DC — the DC derating curve matters if you're switching DC solenoids or indicator loads rather than AC contactor coils.
Housing is 22.5 mm wide, 84 mm tall, 91 mm deep — a standard single-module footprint that clips onto 35 mm DIN rail via the integrated snap-on mechanism, with screw terminals accepting 24-16 AWG solid or stranded wire. Mounting position is any orientation, with zero clearance required upwards, downwards, forwards, backwards, and to the side — useful when packing relays tightly in a crowded enclosure. Operating temperature range is -25 to +60 °C, storage and transport -40 to +85 °C; degree of pollution 3 and basic insulation type suit industrial control panels where conductive dust or condensation may be present.