The Siemens 3RH1122-2KF80 is a SIRIUS coupling relay designed for switching auxiliary circuits in control panels — think interposing between a PLC output and a motor contactor coil, or isolating signal circuits. It carries a rated value of 100 V and switches 10 A at 24 V, 6 A at 230 V, and 1 A at 690 V, so it handles both low-voltage DC and higher-voltage AC auxiliary loads without derating surprises. The built-in varistor surge suppressor clips voltage spikes from the coil when it de-energizes — that means less noise coupled into nearby 24 VDC control wiring and longer contact life on the PLC output driving it.
Size S00 (45 mm wide, 60 mm tall, 73 mm deep) fits the standard Siemens S00 contactor footprint. Fastening is screw and snap-on mounting. The screw terminals accept 2x 0.25 to 2.5 mm² solid or stranded wire, standard for control wiring.
The 10 A at 24 V rating covers most 24 VDC auxiliary loads — PLC output modules, small contactor coils, indicator lamps. At 230 V it still carries 6 A, enough for a bank of contactor coils or a small motor starter pilot circuit. The 1 A at 690 V is useful for isolating higher-voltage control circuits in 400/690 V panels. Shock resistance is 10g/5 ms and 5g/10 ms, fine for industrial panels on machine frames.