The Siemens 3RT1035-1AL20 is a SIRIUS S2 power contactor — screw-type terminals on the main circuit, sized for motor loads up to 18.5 kW at 400 V in AC-2 duty (slip-ring motors, wound-rotor applications). It snaps onto a 35 mm DIN rail per EN 50022 and measures 55 mm wide by 112 mm high by 115 mm deep, leaving room for side-by-side mounting without derating for heat buildup.
At 500 V AC-3 (squirrel-cage motors, normal starting) it delivers 22 kW; at 690 V AC-3 it delivers 11.4 kW. Mechanical life is rated at 10 million operations typical, with maximum switching rates of 1 200 cycles/hour in AC-1, 1 000 in AC-3, and 300 in AC-4 — the AC-4 figure is the one to watch if you're jogging or inching a load. The coil is rated for 230 V at 50 Hz (operating range 0.8 to 1.1 times nominal) and 230 V at 60 Hz (range 0.85 to 1.1). Pick-up time at AC is 7 to 20 ms; arcing time runs 10 to 15 ms.
Auxiliary contact ratings — what the side terminals can handle
The auxiliary contact block (integrated or add-on) is rated for 10 A at 24 V DC, 2 A at 60 V DC, 1 A at 110 V DC, and 0.3 A at 220 V DC. Wire range for the main circuit: solid accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded accepts 2x (0.75 to 25 mm²). Solid or stranded mixed: 2x (0.75 to 16 mm²). Strip length and ferrule sizing follow standard screw-terminal practice.