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.
The 3RH1921-1FA22-ZX95 is a phased-out product. The manufacturer's official successor is the SIRIUS 3RH2 series.
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.