SIRIUS Size S2 power contactor — 22 kW at 500 V, screw terminals, DIN rail mount
The Siemens 3RT1035-1AD20 is a SIRIUS Size S2 power contactor rated for 22 kW at 500 V in AC-3 duty (switching squirrel-cage motors), with a 400 V AC-3 rating of 18.5 kW. The contactor is 55 mm wide, 112 mm tall, and 115 mm deep — a standard S2 footprint that fits alongside other SIRIUS components on the rail.
Termination and wiring — screw terminals, solid and stranded ranges
Main circuit screw terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²). Stranded conductors: 2x (0.75 to 25 mm²). For mixed solid/stranded: 2x (0.75 to 16 mm²). These ranges cover most motor and distribution wiring up to 25 mm² stranded. The screw terminal design is field-serviceable with standard screwdrivers — no special tooling needed. Strip lengths and torque values follow standard Siemens SIRIUS practice for the S2 frame.
Duty ratings and switching frequency — match to your load profile
AC-1 (resistive) switching: 1200 operations per hour maximum. AC-2 (slip-ring motors): 600 ops/h. AC-3 (squirrel-cage motors, normal starting): 1000 ops/h. AC-4 (plugging/inching): 300 ops/h. The 10 million mechanical life cycles mean the contactor outlasts most panel designs under normal AC-3 duty. Coil operates on AC supply: 50 Hz at 0.8 to 1.1 times rated voltage, 60 Hz at 0.85 to 1.1. These are standard for the SIRIUS family — predictable for coordination with upstream breakers or fuses.