What it is and what it's for
The Siemens SIRIUS 3RH1911-1HA01-ZW98 is a 4-pole auxiliary switch block designed for use with contactor relays and power contactors. It's a snap-on mounting block that adds four additional NO/NC contacts to the base contactor, giving you more signal or control-circuit switching capacity without a bigger footprint.
Key ratings and what they mean
Rated for a maximum of 10 A, this block handles typical auxiliary circuit loads. The AC-15 rating at 690 V is 1 A, which is the real-world figure for switching contactor coils and solenoid valves at higher voltages — that's where the inductive load curve bites. At 24 V DC the rated value is 10 A, dropping to 0.26 A at 600 V DC, so watch the voltage derating if you're switching DC control circuits. Contact reliability is spec'd at 1 faulty switching per 100 million operations at 17 V, 1 mA — that's gold for PLC input dry-contact circuits where a missed signal takes the line down. Mechanical service life is 10 million switching cycles typical. The block uses screw-type terminals, accepting 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with ferrule, or 2x (20 to 16) and 2x (18 to 14) AWG. Insulation voltage is 690 V AC at pollution degree 3, with a 6 kV surge voltage resistance — solid for industrial panel environments. Front-side IP20 protection means it's safe for finger contact but not washdown.