Front-mounted auxiliary switch for SIRIUS contactors
The 3RH2911-1NL22-0MC0 is a front-mounted auxiliary switch block for Siemens SIRIUS contactors in frame sizes S00, S0, S2, and S3. It provides two NO and two NC instantaneous contacts, with one NO contact designated solid-state compatible — meaning it can switch low-level signals (5 V, 1 mA) reliably without the wiping action a standard contact needs, rated for one incorrect operation per 100 million cycles at that level.
Coil draw and termination details
The coil draws 0.3 A at 24 V, 48 V, and 60 V — the same current across all three voltages, so the control transformer sizing stays consistent regardless of which tap you land on. The IP20 front protection means it's touch-safe once installed in a closed panel.
Mechanical life and environmental limits
Mechanical service life is 5 million operating cycles typical — that's a lot of starts on a conveyor or pump before the switch block needs swapping.
Wiring note: solid-state compatible NO
The solid-state compatible NO contact (terminals 13/14) is the one to use for driving a PLC input or a solid-state relay directly — it's rated for low-energy switching without the contact resistance variability of a standard auxiliary. The other three contacts (21/22 NC, 31/32 NC, 43/44 NO) are standard instantaneous contacts. The switch block is not a mirror contact per IEC 60947-4-1, so it should not be used as the sole feedback for a safety function that requires a positively driven NC contact. For that, you'd need a separate mirror-contact auxiliary.