What it is and what it does
The Siemens 3RT2036-3XF44-0LA2 is a SIRIUS power contactor, size S2, built for switching motor loads and resistive loads in industrial control panels. It carries a 110 V DC coil with spring-type terminals — no screwdriver needed for the coil connection, which saves a few minutes per panel when you're wiring a row of these. The main contacts are rated 52 A at both 480 V and 600 V, so it handles 3-phase motors in that current class without derating across common North American line voltages. Mechanical life is listed at 10 million operations, and the AC-4 switching rate maxes out at 250 cycles per hour — that's the heavy-duty jogging or reversing duty cycle, not just continuous run.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The mounting position is flexible — ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward, so you can orient it to fit the gland plate or busbar layout. Clearance distances: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the sides. Dimensions are 114 mm high, 55 mm wide, 178 mm deep — that depth is the main thing to check if your enclosure backplate is tight. Operating temperature range is -40 to +70 °C; storage range -55 to +80 °C.
Coil and switching characteristics
DC coil rated 110 V with an inrush current peak of 1.5 A. Switching time at DC is 30 to 55 ms; arcing time runs 10 to 20 ms. The auxiliary switch is present, so you can use it for status feedback or interlocking without adding a separate block. The coil hold-in is solid across the operating temperature range — the 0.7 initial value and 1.25 full-scale value suggest a wide pickup/hold margin, which matters if your DC supply sags under load.