What this SIRIUS S2 contactor is and what it does
The Siemens 3RT2035-1AL20-ZW96 is a SIRIUS size S2 power contactor — a 3-pole main contact device rated for switching motor loads up to 40 A at 480 V (AC-3 duty) or 7.5 hp at 230 V. The 24 V DC coil draws 10 A at rated value, and the screw-type terminals accept 2x (0.75 to 2.5 mm²) solid or stranded wire. It mounts via screw or snap-on onto standard 35 mm DIN rail per EN 60715, with a footprint of 55 mm wide, 114 mm tall, and 130 mm deep.
What the ratings mean for your panel
The 40 A AC-3 rating at 480 V is the motor-switching current — that's the figure that decides whether this contactor handles your pump, conveyor, or compressor load. The 7.5 hp at 230 V gives a quick horsepower cross-check for North American motor schedules. The 24 V DC coil at 10 A is the pick-up current; the coil holds at nominal voltage and the screw terminals are straightforward for panel wiring. Operating range is -25 to +60 °C, so it's fine inside a standard enclosure without derating for ambient heat.
Mounting and spacing
Snap it onto a 35 mm DIN rail or screw-mount it. Clearances: 10 mm upwards, forwards, and downwards; 6 mm at the side. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when the panel layout is tight. The S2 size (55 mm wide) leaves room for auxiliary contact blocks or a separate overload relay alongside.