The Siemens SIRIUS 3RT1924-5AD22 is a magnet coil for Size S0 contactors, rated 42 V AC at both 50 Hz and 60 Hz. It uses spring-type terminals for the control circuit connection. This is a phased-out product; the official successor is the SIRIUS 3RT2 series.
What the 42 V AC coil rating means for fit
The 42 V AC control supply voltage is common in industrial control panels where a lower control voltage is specified for safety or compatibility with existing transformer taps. The coil draws power across the 50/60 Hz range without a separate tap change, simplifying panel wiring. The operating range of 0.8...1.1 at 50 Hz indicates the coil's pickup and hold voltage tolerance relative to its rated voltage — it must see at least 80% of 42 V (about 33.6 V) to reliably pull in, and can tolerate up to 110% (about 46.2 V) without overheating.