Part overview and fit
The Siemens SIRIUS 3RH7122-1AB00 is a contactor relay — essentially a switching block for control circuits, not a main power contactor. It carries 2 normally-open and 2 normally-closed auxiliary contacts (designation 22 E) rated for PLC-level switching down to 17 V, 5 mA, which means it's reliable for digital input signals without contact wetting issues. The coil is 24 V AC, drawing 27 VA inrush and 5.4 VA holding. It snaps onto 35 mm DIN rail and accepts screw-type terminals for 2x 0.5–2.5 mm² or 2x 4 mm² solid/stranded wire.
The 6 A rated current at 24 V AC (and also at 230 V and 400 V) is the thermal continuous current through the auxiliary contacts — enough for pilot lights, contactor coils, or small solenoid valves. The 1 A rating at 690 V and 110 V reflects the switching capacity at those voltages. The surge voltage resistance of 22 kV means the contact gap can withstand lightning-induced transients common in industrial mains. The S00 size is the smallest SIRIUS frame, so it fits in tight DIN-rail layouts.
Operating temperature range is -10 to +55 °C; storage from -25 to +70 °C. Installation altitude up to 2000 m above sea level. The shock resistance is 15g / 5 ms sine pulse, adequate for most industrial panels.