The Siemens SIRIUS 3RT1945-5AP61 is a magnet coil for Size S3 contactors, designed for screw terminal connection and rated 220 V AC at 50 Hz or 240 V at 60 Hz. This is a phased-out product; the official successor is the SIRIUS 3RT2 series.
The manufacturer's designated replacement is the SIRIUS 3RT2 line.
Mounts directly onto SIRIUS Size S3 contactors via screw terminals. The 220 V AC / 240 V AC dual-frequency rating covers 50 Hz and 60 Hz mains without modification — a practical detail for panels that might ship to both 50 Hz and 60 Hz sites. No special tooling needed; the coil swaps in the field with the contactor de-energized.