The Siemens 3RP1540-1BB31 is a SIRIUS-branded timing relay with an adjustable time range of 0.05 to 600 s, a 5 A thermal current rating, and a 24 V DC coil.
The 5 A thermal current (Ith) is the continuous carry rating through the relay contacts — sized for signal-level loads or pilot duty; it is not a motor-switching rating. The adjustable time range (0.05–600 s) covers most on-delay, off-delay, and pulse applications in conveyor sequencing, pump alternation, or HVAC staging. Recovery time of 150 ms between cycles sets the minimum interval before the relay can be re-triggered — relevant for rapid cycling applications. Contact ratings at 24 V DC are 1 A; at 125 V DC, 0.2 A; at 250 V DC, 0.1 A — these are the DC switching limits, which are lower than AC due to arc extinction. The relay output is electromechanical (not solid-state), so expect mechanical wear after 10⁵–10⁶ operations typical for this class.
Panel integration
Width of 22.5 mm (one DIN module) and depth of 91 mm. Screw terminals accept 20–14 AWG stranded or solid. Tightening torque 0.8–1.2 N·m. Mounting position any. Basic insulation, pollution degree 3 — suitable for standard industrial environments.