What it is and where it fits
The Siemens 3RT2038-1NB34-3MA0 is a SIRIUS power contactor in size S2, designed for switching motor loads and resistive loads in industrial control panels. It mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715, and the mounting position is flexible — +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward or backward. That helps when you're retrofitting into a cramped enclosure and the rail is at an odd angle. The coil is screw-type terminals, rated 20-33 V, with an inrush peak of 3 A and a holding draw of 2 VA at 50 or 60 Hz. Switching capacity at 24 V rated value is 6 A, at 48 V it's 2 A, and at 220 V it's 0.3 A. That's the inductive load curve — the contactor can handle a fair spread of control voltages, but the higher the voltage, the lower the current it can break.
Clearances and panel integration
Physical footprint: 55 mm wide, 114 mm tall, 174 mm deep. That depth includes the arc chamber and the coil terminals — you'll need at least that much clearance behind the panel door. Required clearances around the contactor: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm to the side. That's tight enough to pack several contactors side by side in a multi-row DIN rail assembly, but allow the forward gap for arc venting. Operating temperature range is -25 to +60 °C; storage range -55 to +80 °C. That covers most indoor panel environments, even unheated warehouses. The contactor is rated for AC-1 (resistive) at 700 operations per hour maximum, AC-3 (motor starting) at 500 ops/h, and AC-4 (plugging/inching) at 150 ops/h. If your application cycles faster than that, you'll need to derate or pick a larger frame.