The Siemens 3RT7037-1AC20 is a SIRIUS S2 contactor — three main poles, normally open, rated for AC-3 switching up to 690 V. The 24 VAC coil draws 0.36 A at 50 Hz and 0.38 A at 60 Hz, with a closing power of 0.76 W DC and holding power of 0.35 W DC.
The auxiliary contact reliability is specified as "acceptability for PLC control (17 V, 5 mA)" — meaning the contacts are designed to switch low-energy PLC inputs without needing a separate interface relay. The contactor is rated for 800 switching cycles per hour under AC-3 duty, and 250 per hour under the harsher AC-4 (plugging / inching).
The S2 frame is 55 mm wide, 112 mm tall, and 115 mm deep — a compact footprint for a 3-pole contactor at this rating. Screw terminals accept 2x 0.5–1.5 mm² solid or 2x 0.75–2.5 mm² stranded, with the same range for finely stranded wire with ferrules. A product extension for auxiliary switches is available if you need additional N/O or N/C contacts.