What It Is and Where It Fits
The Siemens 3RT2015-2BW42 is a SIRIUS power contactor in the compact S00 frame size, built for switching motor loads and resistive circuits in control panels. It carries a 48 V DC coil with spring-type terminals, so no screwdriver needed for the coil wiring — just strip and push. The main contacts are rated for 20 A down to 12 A, covering small motors, pumps, conveyors, and lighting banks up to that range. It snaps onto a 35 mm DIN rail per DIN EN 60715, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward/backward, which gives flexibility in tight enclosures. Clearance distances are specified: 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side — so you can pack multiple units side-by-side without derating, as long as you respect those gaps for heat dissipation and arc flash clearance. The arcing time runs 10 to 15 ms, and DC switching takes 7 to 13 ms, which matters when coordinating with upstream protection devices.
What the Ratings Mean for Your BOM
The headline switching capacity at 24 V DC is 10 A, but at 48 V DC it drops to 2 A — that's the DC arc extinction limit in the S00 frame. At 400 V AC it handles 3 A, and at 230 V AC it's rated 0.75 hp, which lines up with fractional-horsepower motor duty. The AC-3 (motor start/run) switching frequency maxes out at 750 operations per hour, while AC-4 (inching/plugging) is limited to 250 per hour — so if your application does frequent reversing or jogging, stay under that 250/h ceiling or the contactor will overheat. AC-1 resistive loads can cycle at 1000/h. Wire sizes accepted are 0.5 to 4 mm² solid or stranded, and the spring terminals accept two conductors of that same range per clamp. That's standard for S00 contactors, but verify your ferrule sizes if you're using stranded with ferrules — the spring cage works best with stripped solid or ferruled stranded at the right strip length.
Lifecycle and Sourcing Reality
The lifecycle stage is listed as current, meaning Siemens still actively produces this order code. No end-of-life notice or last-time-buy date is attached to this variant. For a BOM line that needs the 48 V DC coil specifically, this is the part to quote — the spring-terminal version (2BW42) is the standard production variant, not a special or phased-out option. If your panel was specified around the 3RT2015-2BF42 (which uses screw-type terminals instead of spring-type), the 2BW42 will drop into the same footprint — same S00 frame, same DIN rail clip, same 73 x 45 x 70 mm envelope. The only difference is the coil connection method, so no rewiring of the main power circuit is needed; just adapt the coil wiring to the spring cage. For a line-down swap, that means you can substitute without re-drilling or re-laying out the panel.
Integration Notes
Operating temperature range is -25 to +60 °C, storage from -55 to +80 °C. That covers most indoor panel environments, but if the enclosure sees direct sun or sits near a furnace, check the ambient at the contactor location — the 60 °C ceiling is the limit for full rated current. The auxiliary switch is present on this unit, so you get one NO + one NC for status feedback or interlocking without adding a separate block.