What this contactor is and where it fits
The Siemens SIRIUS 3RT1015-2MB41-0KT0 is a size S00 power contactor with a 24 V DC coil, rated for switching motor loads up to 4 kW at 690 V AC (AC-3) or 3 kW at 400 V AC (AC-2). The spring-loaded main terminals accept 2x (0.25 to 2.5 mm²) solid or stranded wire, or 2x (24 to 14 AWG). It mounts via screw or snap-on onto a 35 mm DIN rail per DIN EN 50022. The 45 mm width and 73 mm depth mean it fits a standard 45 mm-wide DIN slot; side-by-side mounting is allowed with 6 mm spacing to adjacent devices for heat dissipation. The 24 V DC coil draws 1.4 W for both closing and holding — a single-supply, low-hold-power design that keeps the control transformer small. Rated operating temperature is -25 to +60 °C, with a maximum operating altitude of 2 000 m. Pollution degree 3 (conductive pollution) means it's suited for industrial control panels where some dust and condensation are present.
Switching ratings and what they mean for your load
The AC-3 rating (3.5 kW at 500 V, 4 kW at 690 V) covers standard squirrel-cage motor starting — the contactor makes and breaks the motor under full load. The AC-4 rating (6.5 A at 400 V) covers inching/plugging duty where the contactor breaks stalled-rotor current. The AC-12 rating (10 A maximum) covers resistive loads like heaters. For DC switching, the contactor is rated 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V — these are resistive DC ratings. DC arcs are harder to extinguish than AC, so the current drops sharply as voltage rises. If you're switching DC motor or solenoid loads, derate further per the manufacturer's DC-13 curve. Short-circuit protection: with type 2 coordination (no welding of contacts), use a gL/gG fuse rated 20 A. With type 1 coordination (welding allowed but no fire risk), a 35 A gL/gG fuse is permitted.
Lifecycle and sourcing posture
Mechanical endurance is rated at 30 million operating cycles typical — a solid figure for a size S00 contactor, reflecting the SIRIUS series' design for high-duty-cycle applications like conveyor systems or packaging lines.
Panel integration details
IP20 on the front and at the terminals — finger-safe but not washdown-rated. The contactor is intended for enclosed control panels, not open or wet environments. The spring-loaded terminals reduce wiring time: strip 8 mm, insert, release. No screwdriver needed for the main circuit.