The Siemens 3RH1921-2FA22-ZX95 is an auxiliary switch block delivering 2 normally-open and 2 normally-closed contacts, spring-type per EN 50005, sized for S0 through S12 contactor relays and motor contactors. It clips onto the contactor front or side, expanding the control circuit without extra panel wiring.
The 2 NO + 2 NC contact arrangement follows EN 50005, which standardizes terminal numbering and spacing across the S0–S12 frame sizes. That means it swaps directly onto any Siemens contactor or contactor relay in that size range without re-terminating the control wiring. The spring-type actuation gives positive opening of the NC contacts — critical for safety circuits where a welded contact must be detected.
Deployment Context
Mounts directly onto the contactor's auxiliary slot — no DIN rail needed, no extra enclosure space. For a motor starter or reversing contactor assembly, this block adds the feedback and interlock contacts without increasing the panel footprint.