Integrator's first look — 3RT2015-1BF42
The Siemens 3RT2015-1BF42 is a SIRIUS power contactor in the Size S00 frame — the smallest of the SIRIUS contactor family, sized for motor loads up to about 5.5 kW at 400 V AC-3. The 110 V coil pulls in on a screw-type terminal block; the contactor carries an auxiliary switch as standard, so you can wire a feedback or status signal without an add-on block. Rated switching frequency hits 750 operations per hour in AC-3 duty, which is typical for a contactor this size driving a conveyor or pump motor in a standard production line.
What the ratings mean for fit
The 110 V coil (rated value) is the first fit gate — ensure your control transformer or PLC output matches that voltage; the contactor pulls in at 80 % of rated (0.8 initial value) and drops out reliably below that. The main contacts are rated for 10 A at 24 V DC and 3 A at 400 V AC, so this is a control-circuit or light-motor contactor, not a main-line breaker replacement. Switching frequency varies by duty: 1 000 cycles/hour for resistive loads (AC-1), 750 for AC-3 motor duty, and only 250 for AC-4 (plugging / inching) — if your application requires frequent reversing or jogging, you need to derate or step up to a larger frame.
Mounting and wiring constraints
Snap-on mounting onto 35 mm DIN rail per DIN EN 60715. The 45 mm width and 73 mm depth fit a standard 45 mm DIN slot; clearance to adjacent devices is 10 mm upward, 10 mm downward, and 6 mm to the side. Wire cross-section accepts 0.5 to 4 mm² solid or stranded, and up to 2 × 1.5 mm² or 2 × 2.5 mm² with ferrules. Mounting position is flexible: ±180° rotation on a vertical surface and ±22.5° tilt forward/backward.