SIRIUS S00 power contactor — what it is and where it fits
The Siemens 3RT2016-2BM42 is a SIRIUS S00 power contactor — the smallest frame in the SIRIUS line, sized for motor loads and resistive heating in control panels up to around 7.5 kW at 400 V AC-3 duty. The S00 frame keeps the footprint tight at 45 mm wide by 70 mm tall by 73 mm deep, which matters when you're packing contactors into a crowded DIN-rail enclosure. It snaps onto 35 mm standard mounting rail per DIN EN 60715, with screw fixing as an option. The coil is 24 VDC with spring-type terminals — no screwdriver needed for the coil connection, which shaves a few seconds per termination on the line. Main contacts are rated for 20 to 12 A, and the contactor carries an auxiliary switch built in. Operating temperature spans -25 to +60 °C; storage range is -55 to +80 °C, so it handles the thermal swing in an unheated warehouse or a hot panel just fine.
What the ratings mean for your panel
The 45 mm width is the S00 standard — it occupies one 45 mm slot on the DIN rail, same as the rest of the S00 family. The 73 mm depth is shallow enough that most 200 mm deep enclosures leave clearance for wiring ducts and gland plates. Mounting position is flexible: the contactor can be rotated ±180° on a vertical surface and tilted forward or backward by ±22.5°, so you're not locked into a single orientation. Clearances are specified: 10 mm upward and forward, 10 mm downward, 6 mm at the sides. That's the air gap needed for arc extinction and heat dissipation — don't crowd it tighter. The arcing time is 10 to 15 ms, and the DC coil dropout time is 7 to 13 ms, which gives predictable timing for interlocking circuits. Wire sizes: solid or stranded conductors from 0.5 to 4 mm², and you can double up two conductors of the same range per terminal. The spring-type terminals on the coil side accept the same range.
Switching capacity and duty cycles
The main contacts are rated for 20 to 12 A — that's the continuous current range, not a single fixed value. For motor starting (AC-3 duty), the contactor can handle up to 750 operations per hour; for AC-4 (plugging/reversing) it's 250 per hour. AC-1 resistive loads allow 1,000 operations per hour. The mechanical life is typical 30 million operations, so it'll outlast most of the gear it's switching. Auxiliary contact ratings at DC voltages: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V. That covers most control-circuit voltages you'll see in industrial panels.