The Siemens 3RH1921-1DA11-0KR0-ZX90 is a side-mounted auxiliary switch block for motor contactors in the S0 through S12 frame sizes. It provides one normally-open and one normally-closed contact, wired via screw terminals on a 10 mm pitch per EN 50012. This is a special-purpose device, and the manufacturer has designated it as a phased-out product.
Lifecycle and Replacement
The lifecycle stage for this order code is listed as current, but the description explicitly states it is a phased-out product. The official successor is the SIRIUS 3RH2 series.
Sourcing
For new designs or long-term BOM stability, the SIRIUS 3RH2 successor is the recommended specification.