What it is and where it fits
The Siemens SIRIUS 3RT2015-2AP02-1AA0 is a Size S00 power contactor — the smallest frame in the SIRIUS contactor family, built for switching motor loads and resistive loads in control panels up to 12 A continuous. It carries an integral auxiliary switch, so you get one NO/NC feedback contact without adding a separate block. The 45 mm width and 73 mm depth keep it tight on the DIN rail; the spring-type terminals (rated for solid or stranded 0.5 to 4 mm²) eliminate screw-torque checks during panel build.
What the ratings mean for your BOM line
The main contact rating of 20-12 A is the continuous thermal current (Ith) at 40 °C — it tells you the contactor can carry that current indefinitely in a resistive circuit. For motor duty (AC-3), the actual switching current will be lower; the S00 frame typically handles around 7 A for a 3-phase induction motor at 400 V. The switching frequency ratings give you the mechanical limits: 1 000 cycles/hour in AC-1, 750 in AC-2/AC-3, and 250 in AC-4 — so for frequent jogging or plugging (AC-4), you need to stay under 250 operations per hour to avoid overheating the coil or arc chamber. Operating temperature range of -25 to +60 °C covers most indoor panel environments, but derate the continuous current above 40 °C — the SIRIUS thermal curve drops about 1.5 % per °C past that. Storage range of -55 to +80 °C is wider; that's the handling limit, not the running limit. The spring-type terminals accept 0.5 to 4 mm² solid or stranded, and you can double up two conductors of the same cross-section (2x 0.5-4 mm²,). That's useful for daisy-chaining control voltage without extra terminal blocks.
Mounting and panel integration
Mounts via screw or snap-on onto standard 35 mm DIN rail per EN 60715. The standing position on a horizontal surface is specified — that means the arc chute vents upward, so don't mount it sideways or upside down without checking the derating. Clearance requirements: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm to the side. That's tight enough to pack multiple S00 contactors side-by-side in a 200 mm-wide enclosure.