Part identity and role
The Siemens SIRIUS 3RH7131-1AP00 is a contactor relay — a control-circuit switching device, not a power contactor. It provides 3 normally open and 1 normally closed auxiliary contacts (switching-element code 31 E) for signal interlocking, PLC inputs, or pilot-duty loads in a motor starter or control scheme. Rated operational current is 6 A at 24 V, 230 V, and 400 V AC, dropping to 1 A at 110 V and 690 V, and 0.3 A at 220 V. That 6 A curve covers the common control voltages for most industrial panels — 24 V, 230 V, and 400 V all carry the full 6 A rating, so the part does not derate across the typical panel supply range. The coil is AC-operated, drawing 27 VA pick-up and 5.4 VA holding at a power factor of 0.8 and 0.27 respectively.
The S00 footprint — 45 mm wide, 57.5 mm high, 72 mm deep — is the smallest SIRIUS contactor frame, so it fits tightly beside a motor contactor in a grouped starter column. Screw-type terminals accept 2 x (0.5...1.5 mm²), 2 x (0.75...2.5 mm²), or 2 x 4 mm² solid or stranded wire; finely stranded with ferrule uses the same ranges.
That means the contacts are designed to switch low-energy signals without oxide-film failure, a common issue when using power-rated contacts on PLC inputs. Surge voltage resistance is 19 kV, covering the impulse withstand for most industrial environments up to 2000 m altitude. Shock resistance is specified at 15g / 5 ms and 8g / 10 ms for sine pulse, and 10g / 5 ms, 5g / 10 ms for rectangular impulse. This qualifies the relay for applications on vibrating machinery or mobile equipment, though the IP20 front limits the enclosure requirement.