What it is and what it does
The Siemens SIRIUS 3RT2017-2BB42-1AA0 is a power contactor in the compact size S00 frame, designed for switching motor loads and resistive loads in control panels. It carries a 24 V DC coil and includes an integrated auxiliary switch, making it a self-contained switching element for a standard 24 V control circuit.
Key ratings and what they mean for fit
The main contacts are rated for 20 to 12 A — the lower figure likely corresponds to AC-3 motor duty, the higher to AC-1 resistive loads. That means it handles a 4 kW motor at 400 V three-phase in AC-3 service, or a resistive heater bank up to 20 A. The auxiliary contact is rated 10 A at 24 V, 3 A at 400 V, and 2 hp at 230 V — enough to signal a PLC input or drive a small contactor coil. Switching rates are specified per duty class: up to 1000 operations per hour for AC-1 (resistive), 750/h for AC-2 and AC-3 (motor start/run), and 250/h for AC-4 (plugging/inching). For a conveyor or pump cycling every few seconds, the AC-3 limit of 750/h is the governing constraint — stay under that to avoid overheating the contact tips. Mechanical life is rated at 30,000,000 operations typical — that is the mechanical endurance, not electrical. Electrical life depends on the switched current and duty; at full AC-3 load expect roughly 1–2 million operations before contact wear becomes a concern.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The size S00 footprint is 45 mm wide, 70 mm tall, 73 mm deep — a standard compact contactor that fits most 4-module-wide DIN rail slots. Clearance requirements: 10 mm upwards, forwards, and downwards; 6 mm at the sides. That is tight enough for dense panel layouts but leave the side gap for airflow if running near the switching rate limits. The coil connection uses spring-type terminals; main and auxiliary terminals accept solid or stranded wire from 0.5 to 4 mm², or two conductors of the same range. No screw torque to set — strip to 8 mm, push in, done. Rated operating temperature is -25 to +60 °C; storage range -55 to +80 °C.