The Siemens 3RT1935-5AL21 is a SIRIUS magnet coil designed for Size S2 contactors, rated at 230 V AC at both 50 Hz and 60 Hz with a screw terminal connection. This is a phased-out product; the official successor is the SIRIUS 3RT2 series.
For BOM freeze or long-term support planning, the 3RT2 series is the drop-in replacement path to quote against.
This coil mounts onto SIRIUS Size S2 contactors via screw terminals. The operating range at 50 Hz is 0.8 to 1.1 times the rated voltage, meaning the coil holds in reliably down to about 184 V and up to 253 V at the terminals.