The Siemens 3RT2027-1AT60 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads in industrial control panels. Its headline rating is 27 A at 480 V AC-3 duty — that's the current it can make and break under full motor starting conditions, not just continuous carry. For a 480 V three-phase motor, that covers roughly a 15–20 hp range depending on service factor. The coil termination is screw-type, and the main power terminals accept solid or stranded conductors from 1 to 10 mm², with double-wire capability for daisy-chaining control wiring (2x 0.5–1.5 mm² or 2x 0.75–2.5 mm²). Mounts via screw or snap-on to a 35 mm DIN rail per EN 60715, with +/-180° rotation on vertical surfaces and +/-22.5° tilt allowance — useful when panel layout forces an unconventional orientation.
Mechanical and thermal limits
The contactor occupies a 45 mm wide slot on the DIN rail, 85 mm tall, 97 mm deep. That depth figure matters when you're laying out a 200 mm deep enclosure — you'll have just over 100 mm of wiring space behind the contactor. Clearance requirements: 10 mm upward, 10 mm downward, 10 mm forward, and 6 mm to the side. Operating ambient range is -25 to +60 °C; storage range extends from -55 to +80 °C. Mechanical life is rated at 10 million operations typical. Maximum switching frequency varies by duty: 1000 cycles/hour for AC-1 (resistive loads), 750 cycles/hour for AC-2 and AC-3 (motor starting and running), and 250 cycles/hour for AC-4 (plugging and inching). If your application cycles faster than that, you'll need to oversize or add a power resistor to limit thermal buildup.