What this SIRIUS coupling contactor does in the panel
The Siemens 3RT2017-1MB42-0KT0 is a SIRIUS coupling contactor in Size S00 — the compact frame for light industrial loads. It switches resistive and motor loads via a 24 V DC coil with a pick-up threshold of 0.85 x rated value, so it pulls in reliably even if the control supply sags to about 20.4 V. The screw-type terminals on the magnet coil accept solid or stranded wire from 0.5 to 4 mm², and the main contacts are rated 20...12 A depending on duty class. At 24 V DC the contactor switches 10 A; at 400 V it handles 3 A. For motor starting on a 230 V single-phase supply it carries 2 hp.
DIN-rail fit and panel clearances
The body is 45 mm wide, 58 mm tall, and 73 mm deep — a tight footprint that leaves room for adjacent devices in a crowded enclosure.
Switching frequency and thermal limits
Rated for 1 000 operations per hour at AC-1 (resistive load), 750/h at AC-2 and AC-3 (motor starting/running), and 250/h at AC-4 (plugging/inching). The AC-3e rating also sits at 750/h. The mechanical life of the contactor typical is 30 million operations.