The Siemens 3RH1921-1FA22-ZX95 is a 4-pole auxiliary switch block from the SIRIUS family, designed for snap-on mounting alongside 3RT1 contactors and contactor relays. It provides 2 normally-open and 2 normally-closed instantaneous contacts, rated for a maximum of 10 A, with screw-type terminals for the auxiliary and control circuit wiring. Rated for 10 A at 24 V DC and 6 A at 230 V AC, this block handles the typical signal and interlock loads in motor control panels. The contact reliability specification — one faulty switching per 100 million operations at 17 V, 1 mA — means it is trustworthy for PLC-level signals where dry switching can cause oxide buildup on standard contacts. Mechanical service life is rated at 10 million switching cycles typical, and the insulation voltage stands at 690 V AC with degree of pollution 3, with a surge voltage resistance of 6 kV. The front face carries IP20 protection, suitable for enclosed panel installation.
Lifecycle and Sourcing
The 3RH1921-1FA22-ZX95 is a phased-out product. The manufacturer's official successor is the SIRIUS 3RH2 series. This part is sourced to order against an RFQ through independent distribution channels; availability and current pricing are confirmed at quote time.
Panel Integration
Snap-on mounting onto a DIN rail is the intended fastening method, matching the footprint of the 3RT1 contactor it attaches to. Dimensions are 44 mm wide, 38 mm high, and 51 mm deep. The screw-type terminals accept two conductors per clamp: 0.5 to 1.5 mm² or 0.75 to 2.5 mm² with core end processing, or 20 to 16 AWG and 18 to 14 AWG for solid/stranded wire.