The Siemens SIRIUS 3RH1981-1JA11 is a lateral auxiliary switch block designed to snap onto the side of a 3RT148 contactor, adding one normally-open and one normally-closed instantaneous contact. It uses screw-type terminals and is rated for 6 A at 24 V, 3 A at 230 V, and 1.5 A at 400 V, with a maximum AC-12 current of 16 A. The mirror contact function per IEC 60947-4-1 means the NC contact reliably reflects the main contact position — critical for safety circuits where you need positive feedback that the power contacts have opened.
Fit and mounting
This auxiliary switch is a lateral add-on, not a front-mount block. It clips onto the side of a 3RT148 contactor, occupying 12.8 mm of additional panel width. The screw terminals accept 2x (1 to 2.5 mm²) solid or stranded wire, or 2x (16 to 14) AWG. Depth is 65.5 mm, height 72 mm. Fastening is by screw fixing to the contactor. The IP00 front protection means it's intended for enclosed panels only — no washdown exposure.
Contact ratings and switching capacity
The switching capacity varies significantly with voltage. At 24 V the contacts handle 6 A; at 48 V and 60 V it drops to 2 A; at 110 V it's 1 A; at 230 V it's 3 A; at 400 V it's 1.5 A. The AC-12 rating of 16 A is the maximum thermal current for resistive loads. The surge voltage resistance is 6 kV, and the insulation voltage at pollution degree 3 is 600 V AC. Mechanical life is rated at 1 million operating cycles typical.