What it is and where it fits
The Siemens 3RH1981-1DA11 is a SIRIUS auxiliary switch block designed specifically for the 3RT148 contactor series. It adds one normally-open and one normally-closed instantaneous contact via screw-type terminals, mounted laterally on the contactor. The 65.5 mm depth and 12.8 mm width keep the assembly within the contactor's footprint — no extra DIN-rail space needed. Rated insulation voltage is 600 V at pollution degree 3, with a surge withstand of 6 kV. The AC-12 maximum operational current is 16 A, and the mirror-contact function per IEC 60947-4-1 is active when paired with the 3RT148 — meaning the NC contact reliably reflects the main contact position in safety circuits.
Switching capacity and terminal data
Contact ratings are given per voltage: 6 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.55 A at 125 V, 0.27 A at 220 V and 250 V, 3 A at 230 V, and 1.5 A at 400 V. These are the make/break limits for the auxiliary contacts — stay within these for reliable switching of pilot devices, relays, or PLC inputs. Screw terminals accept 2x (1 … 2.5 mm²) solid or finely stranded with ferrule, or 2x (16 … 14 AWG). Mechanical service life is 1 000 000 operating cycles typical. Storage temperature range is -40 … +80 °C; operating ambient is -25 … +55 °C.