What it is and where it lands
The Siemens 3RT2037-1NE34 is a SIRIUS power contactor in the Size S2 frame. The coil accepts 48 to 80 V AC or DC, with a pickup threshold of 0.8 x rated value. It mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 60715, and the mounting position allows +/-180° rotation on a vertical surface plus +/-22.5° tilt forward/backward — useful when you're squeezing it into a tight gland-plate layout.
Coil and switching ratings
Coil inrush peaks at 1 A, steady-state draw is 2 VA at both 50 and 60 Hz. The magnet coil uses screw-type terminals, and the main contacts are rated for 18 A at AC-3 duty (motor switching) — that's the number that governs real motor loads, not the AC-1 resistive rating. Operating rate at AC-3 is 700 cycles per hour max; AC-4 (plugging/inching) drops to 200 cycles per hour. Arcing time runs 10 to 20 ms, and the contactor is rated for 10 million mechanical operations typical — that's a long shelf life for a spare that sits in the bin.
Panel fit and clearances
Dimensions: 55 mm wide, 114 mm tall, 174 mm deep. That depth is the body plus coil terminals — measure your gland-plate clearance before you commit the panel layout. Minimum clearances: 10 mm upward, 10 mm downward, 10 mm forward, 6 mm at the side. Ambient operating range is -25 to +60 °C; storage range is -55 to +80 °C. Wire range: 2 x (0.5 to 1.5 mm²) or 2 x (0.75 to 2.5 mm²) solid or stranded.