The Siemens SIRIUS 3RH1921-2EA20-ZX95 is a first lateral auxiliary switch block that adds two normally-open (NO) contacts to a 3RT1 power contactor or contactor relay. It snaps onto the side of the contactor without tools, expanding the control circuit without increasing the panel's DIN-rail footprint. Rated for a maximum of 10 A, the switching capacity varies significantly with the applied DC voltage: 6 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, and 3 A at 400 V. These are not continuous ratings — they define the make/break capability for the auxiliary contacts in a control circuit. The spring-loaded terminals accept 2x (0.5... 2.5 mm²) stranded without ferrules, or 2x (0.5... 1.5 mm²) with core-end processing. AWG 20 to 14 for the auxiliary wiring. This is a tool-less connection — strip, insert, spring clamps it — which speeds panel wiring and eliminates screw-torque checks.
Switching performance and durability
Surge voltage resistance is 6 kV, and the insulation voltage at pollution degree 3 is 500 V AC.
The 3RH1921-2EA20-ZX95 is an active product in the Siemens SIRIUS line. No end-of-life notice or successor has been issued.