What it is and what it does
The Siemens 3RT1015-2BG42 is a SIRIUS power contactor in frame size S00, designed for switching motor loads and resistive loads in industrial control panels. It mounts via screw or snap-on onto 35 mm DIN rail per EN 50022, so it integrates into standard panel layouts without special brackets. The coil is rated 125 V DC, with a pick-up ratio of 0.85 and drop-out ratio of 1.1. Closing and holding power are both 3.3 W DC. Main contacts are spring-loaded terminals (cage-clamp style), accepting 2x 0.25 to 2.5 mm² solid or stranded, or 2x 24 to 14 AWG. That saves panel-wiring time compared to screw terminals — no torque check, no loosening over thermal cycles.
Key ratings and what they mean for fit
Rated operational current at AC-12 (resistive) is 10 A maximum. For motor switching, the AC-2 rating at 400 V is 3 kW, and AC-4 at 400 V is 6.5 A — that covers reversing or plugging duty on smaller motors where high inrush and frequent switching are expected. DC switching capability is given per voltage: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V. These are the make/break limits for DC loads, which arc harder than AC — so if you're switching DC solenoids or brakes, stay within these curves. AC switching at 230 V is 6 A, at 400 V is 3 A, at 500 V is 3.5 kW, and at 690 V is 4 kW. The 690 V rating is useful for 690 V line supplies common in mining or marine panels. Mechanical life is 30 million operations typical — that's the contactor body, not the contacts under load. For high-cycle applications like conveyor indexing or valve actuation, that's a solid baseline.
Mounting and environment
Width is 45 mm, depth 73 mm, height 60 mm. Side-by-side mounting is permitted without derating, with a 6 mm clearance at the side for airflow and wiring access. That means you can pack several S00 contactors on a rail segment without spacing gaps. Operating temperature range is -25 to +60 °C, with maximum operating altitude 2 000 m. Pollution degree 3 means it's rated for industrial environments with conductive dust or humidity — no need for a sealed enclosure in a typical panel. Front and terminal protection is IP20 — finger-safe but not sealed. Mount inside a cabinet with at least IP54 for washdown areas.
Coordination and protection
For Type 2 coordination (no damage to the contactor after a short circuit), the required upstream fuse is gL/gG 20 A. For Type 1 coordination (contactor may need replacement after fault), use gL/gG 35 A. This lets the panel designer choose between protection level and fuse economy. No instantaneous auxiliary contact is built in (0 auxiliary contacts). If you need feedback or status, add a separate auxiliary contact block that fits the S00 frame.